U.S. patent application number 15/431029 was filed with the patent office on 2018-08-16 for audio systems and method for perturbing signal compensation.
The applicant listed for this patent is BOSE CORPORATION. Invention is credited to Paraskevas Argyropoulos, Elie Bou Daher, Cristian M. Hera, Vigneish Kathavarayan, Jeffery R. Vautin.
Application Number | 20180233159 15/431029 |
Document ID | / |
Family ID | 61283337 |
Filed Date | 2018-08-16 |
United States Patent
Application |
20180233159 |
Kind Code |
A1 |
Hera; Cristian M. ; et
al. |
August 16, 2018 |
AUDIO SYSTEMS AND METHOD FOR PERTURBING SIGNAL COMPENSATION
Abstract
Audio systems and methods for providing intelligible audio
content within a vehicle cabin. In one example, the audio system
includes a first speaker to provide first audio content to a first
seating position based on an audio signal received from an audio
signal source, a second speaker to provide second audio content to
a second seating position, a first microphone assembly positioned
to detect speech content originating at the second seating
position, leaked second audio content from the second speaker, and
road noise, and audio signal processing circuitry configured to
determine a perturbing signal based at least in part on a
combination of the first speech content, the leaked second audio
content, and the road noise, and adjust the audio signal to the
first speaker to compensate for an effect of the perturbing signal
on the first audio content at the first seating position.
Inventors: |
Hera; Cristian M.;
(Lancaster, MA) ; Vautin; Jeffery R.; (Worcester,
MA) ; Bou Daher; Elie; (Marlborough, MA) ;
Argyropoulos; Paraskevas; (Everett, MA) ;
Kathavarayan; Vigneish; (Marlborough, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BOSE CORPORATION |
Framingham |
MA |
US |
|
|
Family ID: |
61283337 |
Appl. No.: |
15/431029 |
Filed: |
February 13, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G10L 2021/02087
20130101; H04R 3/005 20130101; G10L 25/78 20130101; G10L 2021/02166
20130101; H04S 7/301 20130101; G10L 2021/02082 20130101; H04R
2499/13 20130101; G10L 21/0208 20130101; H03G 5/165 20130101; G10L
21/0364 20130101; G10L 21/0232 20130101 |
International
Class: |
G10L 21/0232 20060101
G10L021/0232; H03G 5/16 20060101 H03G005/16; H04R 1/40 20060101
H04R001/40; G10L 21/0364 20060101 G10L021/0364; G10L 25/78 20060101
G10L025/78; H04R 1/02 20060101 H04R001/02; H04R 3/04 20060101
H04R003/04 |
Claims
1. A vehicle cabin audio system comprising: a first speaker
positioned to provide first audio content to a first seating
position within a vehicle cabin based on an audio signal received
from an audio signal source; a second speaker positioned to provide
second audio content to a second seating position within the
vehicle cabin; a first microphone assembly positioned to detect
first speech content originating at the second seating position,
leaked second audio content from the second speaker, and road
noise; a second microphone assembly positioned to detect at least
second speech content originating at a third seating position, the
second speech content being different from the first speech
content, wherein each of the first microphone assembly and the
second microphone assembly includes an array of microphones; and
audio signal processing circuitry coupled to at least the first
microphone assembly and the second microphone assembly, the audio
signal processing circuitry being configured to filter the leaked
second audio content from the second speaker and the road noise to
isolate the first speech content, and determine a perturbing signal
based at least in part on a combination of the first speech
content, the second speech content, the leaked second audio content
from the second speaker, and the road noise, and wherein the audio
signal processing circuitry is configured to adjust the audio
signal to the first speaker based on a frequency of the audio
signal to compensate for an effect of the perturbing signal on the
first audio content at the first seating position.
2. (canceled)
3. The vehicle cabin audio system of claim 1, wherein the second
audio content is different from the first audio content, and
wherein the second seating position is in one of a forward facing
direction, a rearward facing direction, a first sideways facing
direction, or a second sideways facing direction of the first
seating position.
4. (canceled)
5. (canceled)
6. The vehicle cabin audio system of claim 1, wherein the first
microphone assembly is further configured to detect the second
speech content, and wherein the audio signal processing circuitry
is configured to distinguish the first speech content detected by
the first microphone assembly from the second speech content
detected by the first microphone assembly based on a direction of
each of the first speech content and the second speech content
relative to the first microphone assembly.
7. The vehicle cabin audio system of claim 1, wherein the first
microphone assembly is further configured to detect the second
speech content, and wherein the audio signal processing circuitry
is further configured to select and apply a first beamforming
configuration to attenuate the second speech content detected by at
least the first microphone assembly.
8. The vehicle cabin audio system of claim 7, wherein the
beamforming configuration includes at least a set of weight
vectors, and wherein in applying the first beamforming
configuration the audio signal processing circuitry is configured
to apply the set of weight vectors to a combination of the first
speech content and the second speech content.
9. The vehicle cabin audio system of claim 8, further comprising a
data store including a look-up table having a plurality of
beamforming configurations, wherein the audio signal processing
circuitry is configured to reference the look-up table to select
the first beamforming configuration from among the plurality of
beamforming configurations.
10. The vehicle cabin audio system of claim 1, wherein the audio
signal processing circuitry includes volume-based equalization
circuitry configured to control an attenuation or amplification
applied to the audio signal to the first speaker to adjust the
audio signal to compensate for the effect of the perturbing
signal.
11. The vehicle cabin audio system of claim 10, wherein the audio
signal includes at least a first frequency band and a second
frequency band, and the volume-based equalization circuitry is
configured to control a first attenuation or amplification applied
to the first frequency band and a second attenuation or
amplification applied to the second frequency band, the first
attenuation or amplification being different from the second
attenuation or amplification.
12. The vehicle cabin audio system of claim 10, wherein the
volume-based equalization is configured to control an attenuation
or amplification applied to the audio signal independently for each
frequency of the audio signal.
13. The vehicle cabin audio system of claim 1, wherein the first
seating position is a driver's seat within the vehicle cabin, and
wherein the first audio content is a telephone conversation.
14. A vehicle cabin audio system comprising: a first speaker
positioned to provide first audio content to an occupant within a
vehicle cabin based on an audio signal received from an audio
signal source; a first microphone assembly positioned to detect
first speech content originating at a first seating position within
the vehicle cabin, second speech content originating at a second
seating position within the vehicle cabin, road noise, and leaked
audio content; a second microphone assembly positioned to detect at
least the second speech content, the second speech content being
different from the first speech content, wherein each of the first
microphone assembly and the second microphone assembly includes an
array of microphones; and audio signal processing circuitry coupled
to each of the first and second microphone assemblies and
configured to filter the leaked audio content and the road noise to
isolate the first speech content, the audio signal processing
circuitry being further configured to estimate at least a first
speech signal for the first speech content originating at the first
seating position and at least a second speech signal for the speech
content originating at the second seating position, and wherein the
audio signal processing circuitry is configured to adjust the audio
signal to compensate for an effect of the estimated first speech
signal for the first speech content, and the estimated second
speech signal for the second speech content, on the first audio
content.
15. (canceled)
16. The vehicle cabin audio system of claim 14, wherein the audio
signal processing circuitry is configured to select and apply a
first beamforming configuration to a combination of the first
speech content and the second speech content detected by at least
the first microphone assembly.
17. The vehicle cabin audio system of claim 16, wherein the first
beamforming configuration includes at least a first set of weight
vectors, and wherein in applying the first beamforming
configuration the audio signal processing circuitry is configured
to apply the first set of weight vectors to the combination of the
first speech content and the second speech content to reject or
attenuate the second speech content.
18. The vehicle cabin audio system of claim 17, wherein the audio
signal processing circuitry is configured to select and apply a
second beamforming configuration to a combination of the first
speech content and the second speech content detected by at least
the second microphone assembly.
19. The vehicle cabin audio system of claim 18, wherein the second
beamforming configuration includes a second set of weight vectors,
and wherein in applying the second beamforming configuration the
audio signal processing circuitry is configured to apply the second
set of weight vectors to the combination of the first speech
content and the second speech content to reject or attenuate the
first speech content.
20. (canceled)
21. The vehicle cabin audio system of claim 14, wherein the audio
signal processing circuitry includes volume-based equalization
circuitry configured to control an attenuation or amplification
applied to the audio signal to the first speaker to compensate for
the effect of the estimated first speech signal and the estimated
second speech signal.
22. A method of operating a vehicle cabin audio system, the method
comprising: providing first audio content to a first seating
position within a vehicle cabin, with a first speaker, based on an
audio signal received from an audio signal source; providing second
audio content to a second seating position within the vehicle cabin
with a second speaker; detecting, at a first microphone assembly,
first speech content originating at the second seating position,
leaked second audio content from the second speaker, and road
noise; detecting, at a second microphone assembly, second speech
content originating at a third seating position, the second speech
content being different from the first speech content; filtering
the leaked second audio content from the second speaker and the
road noise to isolate the first speech content; determining a
perturbing signal based at least in part on a combination of the
first speech content, the second speech content, the leaked second
audio content from the second speaker, and the road noise; and
adjusting the audio signal based on a frequency of the audio signal
to compensate for an effect of the perturbing signal on the first
audio content at the first seating position.
23. (canceled)
24. (canceled)
25. The method of claim 22, further comprising: detecting, at the
first microphone assembly, the second speech content; and
distinguishing between the first speech content detected by the
first microphone assembly and the second speech content detected by
the first microphone assembly based on a direction of each of the
first speech content and the second speech content relative to the
first microphone assembly.
26. The method of claim 22, further comprising: detecting, at the
first microphone assembly, the second speech content; and selecting
and applying a first beamforming configuration to attenuate the
second speech content detected by at least the first microphone
assembly.
27. The method of claim 26, wherein applying the first beamforming
configuration includes applying a set of weight vectors to a
combination of the first speech content and the second speech
content to reject or attenuate the second speech content.
28. The method of claim 22, wherein the audio signal includes at
least a first frequency band and a second frequency band, and
wherein adjusting the audio signal includes controlling a first
attenuation or amplification applied to the first frequency band
and a second attenuation or amplification applied to the second
frequency band, the first attenuation or amplification being
different from the second attenuation or amplification.
29. The method of claim 22, wherein adjusting the audio signal
includes controlling an attenuation or amplification applied to the
audio signal independently for each frequency of the audio signal.
Description
TECHNICAL FIELD
[0001] Aspects and implementations of the present disclosure are
directed generally to audio systems, and in some examples, more
specifically to audio systems for providing an improved listening
experience in a vehicle.
BACKGROUND
[0002] Traditional vehicle audio systems deliver common audio
content to all passengers of a vehicle irrespective of passenger
occupancy within the vehicle. In such systems, an audio signal
supplied by a vehicle radio (or other signal source) is amplified,
processed, and corresponding acoustic energy is delivered through
the speakers to convey audio content to the occupants of the
vehicle. More recently, modern vehicle audio systems have been
designed to customize audio content for each seating position
within the vehicle. In such systems, each seating position may
receive the same audio content, or receive personalized audio
content. Regardless of the configuration, in many cases, the
presence of perturbing signals within the vehicle degrades the
fidelity of the audio content and can be an annoyance for the
occupants of the vehicle.
SUMMARY
[0003] In accordance with an aspect of the present disclosure,
there is provided an audio system which compensates for one or more
perturbing signals within a vehicle cabin to provide intelligible
audio content for at least one intended location within the
vehicle. Specifically, the perturbing signal may include road
noise, leaked audio content from interfering speakers, and/or
speech content from locations within the vehicle. Based on at least
the perturbing signal, the audio system may adjust the audio
content for the intended location such that the road noise, leaked
audio content, and/or speech content has substantially no effect on
the intelligibility of the audio content. Such aspects and
implementations are particularly advantageous when included in
vehicles having at least two rows of seats, where noise, leaked
audio content, and speech content from the rear of the vehicle may
undesirably interfere with audio content delivered to a seat in the
front of the vehicle (or vice versa).
[0004] According to an aspect, provided is a vehicle cabin audio
system. In one example, the vehicle cabin audio system comprises a
first speaker positioned to provide first audio content to a first
seating position within a vehicle cabin based on an audio signal
received from an audio signal source, a second speaker positioned
to provide second audio content to a second seating position within
the vehicle cabin, a first microphone assembly positioned to detect
first speech content originating at the second seating position,
leaked second audio content from the second speaker, and road
noise, and audio signal processing circuitry coupled to at least
the first microphone assembly and configured to determine a
perturbing signal based at least in part on a combination of the
first speech content, the leaked second audio content from the
second speaker, and the road noise, and adjust the audio signal to
the first speaker based on a frequency of the audio signal to
compensate for an effect of the perturbing signal on the first
audio content at the first seating position.
[0005] According to an example, the vehicle cabin audio system may
further comprise a second microphone assembly positioned to detect
at least second speech content originating at a third seating
position, the second speech content being different from the first
speech content, wherein the audio signal processing circuity is
coupled to the second microphone assembly and further configured to
determine the perturbing signal based on the second speech content.
In one example, the second audio content is different from the
first audio content, and the second seating position is in one of a
forward facing direction, a rearward facing direction, a first
sideways facing direction, or a second sideways facing direction of
the first seating position. According to an example, each of the
first microphone assembly and the second microphone assembly
includes an array of microphones.
[0006] In at least one example, the audio signal processing
circuitry is configured to filter the leaked second audio content
from the second speaker and the road noise to isolate the first
speech content. According to various examples, the first microphone
assembly is further configured to detect the second speech content,
and the audio signal processing circuitry is configured to
distinguish the first speech content detected by the first
microphone assembly from the second speech content detected by the
first microphone assembly based on a direction of each of the first
speech content and the second speech content relative to the first
microphone assembly.
[0007] According to various examples, the first microphone assembly
is further configured to detect the second speech content, and the
audio signal processing circuitry is further configured to select
and apply a first beamforming configuration to attenuate the second
speech content detected by at least the first microphone assembly.
In one example, the beamforming configuration includes at least a
set of weight vectors, and in applying the first beamforming
configuration the audio signal processing circuitry is configured
to apply the set of weight vectors to a combination of the first
speech content and the second speech content. In a further example,
the vehicle cabin audio system further comprises a data store
including a look-up table having a plurality of beamforming
configurations, and the audio signal processing circuitry is
configured to reference the look-up table to select the first
beamforming configuration from among the plurality of beamforming
configurations.
[0008] In various examples, the audio signal processing circuitry
includes volume-based equalization circuitry configured to control
an attenuation or amplification applied to the audio signal to the
first speaker to adjust the audio signal to compensate for the
effect of the perturbing signal. In one example, the audio signal
includes at least a first frequency band and a second frequency
band, and the volume-based equalization circuitry is configured to
control a first attenuation or amplification applied to the first
frequency band and a second attenuation or amplification applied to
the second frequency band, the first attenuation or amplification
being different from the second attenuation or amplification. In an
example, the volume-based equalization is configured to control an
attenuation or amplification applied to the audio signal
independently for each frequency of the audio signal. In one
example, the first seating position is a driver's seat within the
vehicle cabin, and the first audio content is a telephone
conversation.
[0009] According to an aspect, provided is a vehicle cabin audio
system. In one example, the vehicle cabin audio system comprises a
first speaker positioned to provide first audio content to an
occupant within a vehicle cabin based on an audio signal received
from an audio signal source, a plurality of microphone assemblies
positioned to detect speech content originating at a corresponding
seating position within the vehicle cabin, other speech content
from the other seating positions within the vehicle cabin, road
noise, and leaked audio content, and audio signal processing
circuitry coupled to each of the plurality of microphone assemblies
and configured to attenuate or reject the other speech content,
road noise, and leaked audio content and estimate at least one
speech signal for the speech content from each of the corresponding
seating positions.
[0010] In one example, the plurality of microphone assemblies
includes at least a first microphone assembly and a second
microphone assembly, and the speech content from the seating
position corresponding to the first microphone assembly includes
first speech content and the speech content from the seating
position corresponding to the second microphone assembly includes
second speech content. According to an example, the audio signal
processing circuitry is configured to select and apply a first
beamforming configuration to a combination of the first speech
content and the second speech content detected by at least the
first microphone assembly.
[0011] In various examples, the first beamforming configuration
includes at a least first set of weight vectors, and in applying
the first beamforming configuration the audio signal processing
circuitry is configured to apply the first set of weight vectors to
the combination of the first speech content and the second speech
content to reject or attenuate the second speech content. In an
example, the audio signal processing circuitry is configured to
select and apply a second beamforming configuration to a
combination of the first speech content and the second speech
content detected by at least the second microphone assembly.
According to an example, the second beamforming configuration
includes a second set of weight vectors, and in applying the second
beamforming configuration the audio signal processing circuitry is
configured to apply the second set of weight vectors to the
combination of the first speech content and the second speech
content to reject or attenuate the first speech content.
[0012] In some examples, the audio signal processing circuitry is
further configured to adjust the audio signal to compensate for an
effect of the estimated speech signal for the speech content from
each of the corresponding seating positions on the first audio
content. In an example, the audio signal processing circuitry
includes volume-based equalization circuitry configured to control
an attenuation or amplification applied to the audio signal to the
first speaker to compensate for the effect of the estimated speech
signal.
[0013] According to another aspect, provided is a method of
operating a vehicle cabin audio system. In one example, the method
comprises the acts of providing first audio content to a first
seating position within a vehicle cabin, with a first speaker,
based on an audio signal received from an audio signal source,
providing second audio content to a second seating position within
the vehicle cabin with a second speaker, detecting, at a first
microphone assembly, first speech content originating at the second
seating position, leaked second audio content from the second
speaker, and road noise, determining a perturbing signal based at
least in part on a combination of the first speech content, the
leaked second audio content from the second speaker, and the road
noise, and adjusting the audio signal based on a frequency of the
audio signal to compensate for an effect of the perturbing signal
on the first audio content at the first seating position.
[0014] In one example, the method further comprises the acts of
detecting, at a second microphone assembly, second speech content
originating at a third seating position, the second speech content
being different from the first speech content, and determining the
perturbing signal based on the second speech content. According to
an example, the method further comprises the act of filtering the
leaked second audio content from the second speaker and the road
noise to isolate the first speech content. In one example, the
method further comprises the acts of detecting, at the first
microphone assembly, the second speech content, and distinguishing
between the first speech content detected by the first microphone
assembly and the second speech content detected by the first
microphone assembly based on a direction of each of the first
speech content and the second speech content relative to the first
microphone assembly.
[0015] According to various examples, the method further comprises
the acts of detecting, at the first microphone assembly, the second
speech content, and selecting and applying a first beamforming
configuration to attenuate the second speech content detected by at
least the first microphone assembly. In one example, applying the
first beamforming configuration includes applying a set of weight
vectors to a combination of the first speech content and the second
speech content to reject or attenuate the second speech
content.
[0016] In one example, the audio signal includes at least a first
frequency band and a second frequency band, and adjusting the audio
signal includes controlling a first attenuation or amplification
applied to the first frequency band and a second attenuation or
amplification applied to the second frequency band, the first
attenuation or amplification being different from the second
attenuation or amplification. In an example, adjusting the audio
signal includes controlling an attenuation or amplification applied
to the audio signal independently for each frequency of the audio
signal.
[0017] Still other aspects, examples, and advantages of these
exemplary aspects and examples are discussed in detail below.
Examples disclosed herein may be combined with other examples in
any manner consistent with at least one of the principles disclosed
herein, and references to "an example," "some examples," "an
alternate example," "various examples," "one example" or the like
are not necessarily mutually exclusive and are intended to indicate
that a particular feature, structure, or characteristic described
may be included in at least one example. The appearances of such
terms herein are not necessarily all referring to the same example.
Various aspects and examples described herein may include means for
performing any of the described methods or functions.
[0018] Furthermore, in the event of inconsistent usages of terms
between this document and documents incorporated herein by
reference, the term usage in the incorporated references is
supplementary to that of this document; the term usage in this
document controls. In addition, the accompanying drawings are
included to provide illustration and a further understanding of the
various aspects and examples, and are incorporated in and
constitute a part of this specification. The drawings, together
with the remainder of the specification, serve to explain
principles and operations of the described and claimed aspects and
examples.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Various aspects of at least one example are discussed below
with reference to the accompanying figures, which are not intended
to be drawn to scale. The figures are included to provide
illustration and a further understanding of the various aspects and
examples, and are incorporated in and constitute a part of this
specification, but are not intended as a definition of the limits
of the disclosure. In the figures, each identical or nearly
identical component that is illustrated in various figures is
represented by a like numeral. For purposes of clarity, not every
component may be labeled in every figure. In the figures:
[0020] FIG. 1 is a schematic view of a vehicle cabin audio system
according to various examples;
[0021] FIG. 2 is an input/output diagram of the signal processor
illustrated in FIG. 1, according to various examples;
[0022] FIG. 3 is another schematic view of a vehicle cabin audio
system according to various examples; and
[0023] FIG. 4 is a process flow for operating a vehicle cabin audio
system, according to various examples.
DETAILED DESCRIPTION
[0024] Aspects and examples discussed herein are generally directed
to an audio system for a vehicle cabin that provides intelligible
audio content to a desired location within the vehicle cabin
despite the presence of speech content (e.g., a conversation)
within the vehicle cabin. According to certain examples, the audio
system may include one or more microphone assemblies which detect
speech content within the vehicle cabin, and audio signal
processing circuitry which determines a perturbing signal based on
the speech content and other acoustic interference (e.g., road
noise and/or leaked audio content) within the vehicle cabin. Based
on the perturbing signal, the audio signal processing circuitry
adjusts audio content delivered to the desired location (e.g., a
seating position) to mitigate the effects of the speech content and
other acoustic interference on the audio content.
[0025] Accordingly, various aspects and examples discussed herein
concurrently compensate for numerous types of interference (e.g.,
speech content, road noise, and leaked auto content) to provide a
dynamic range of noise compensation functionality. Among the
various other benefits discussed herein, certain aspects and
examples of the vehicle cabin audio systems provided herein improve
the listening experience and sound quality of audio content
delivered to a vehicle occupant when compared to traditional audio
systems.
[0026] It is to be appreciated that examples of the systems and
methods discussed herein are not limited in application to the
details of construction and the arrangement of components set forth
in the following description or illustrated in the accompanying
drawings. The methods and apparatuses are capable of implementation
in other examples and of being practiced or of being carried out in
various ways. Examples of specific implementations are provided
herein for illustrative purposes only and are not intended to be
limiting. Also, the phraseology and terminology used herein is for
the purpose of description and should not be regarded as limiting.
The use herein of "including," "comprising," "having,"
"containing," "involving," and variations thereof is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. References to "or" may be construed as
inclusive so that any terms described using "or" may indicate any
of a single, more than one, and all of the described terms. Any
references to front and back, left and right, top and bottom, upper
and lower, and vertical and horizontal are intended for convenience
of description, not to limit the present systems and methods or
their components to any one positional or spatial orientation.
[0027] Though the elements of several views of the drawings herein
may be shown and described as discrete elements in a block diagram
and may be referred to as "circuit" or "circuitry," unless
otherwise indicated, the elements may be implemented as one of, or
a combination of, analog circuitry, digital circuitry, or one or
more microprocessors executing software instructions. For example,
software instructions may include digital signal processing (DSP)
instructions to be executed by a digital signal processor. Unless
otherwise indicated, signal lines may be implemented as discrete
analog or digital signal lines, as a single discrete digital signal
line with appropriate signal processing to process separate streams
of audio signals, or as elements of a wireless communication
system.
[0028] Some of the processing operations discussed herein may be
expressed in terms of determining, adjusting, filtering,
distinguishing, and/or controlling, to name a few. The equivalent
of determining, adjusting, filtering, distinguishing, and/or
controlling can be performed by either analog or digital signal
processing techniques and are included within the scope of this
disclosure. Unless otherwise indicated, audio signals may be
encoded in either digital or analog form; conventional
digital-to-analog or analog-to-digital converters may not be shown
in the figures but are intended to be within the scope of this
disclosure.
[0029] Various examples of the vehicle cabin audio systems
discussed herein can be utilized in combination with speakers which
provide discrete audio content zones at different seating positions
within a listening area, such as a vehicle cabin. While the audio
systems are shown and described herein as being incorporated within
a vehicle cabin having four seating positions, it is appreciated
that in various other implementations the audio systems may be
adapted for vehicle cabins having other seating arrangements and/or
other listening spaces which accommodate multiple occupants, such
as theaters, auditoriums, and amusement park rides, to name a
few.
[0030] Referring to FIG. 1, illustrated is one example of a vehicle
cabin audio system ("audio system") 100 according to certain
aspects. As illustrated, the audio system 100 may include an audio
signal source 102, audio signal processing circuitry 104, control
circuitry 106, one or more speakers 108a-h, and one or more
microphone assemblies 110a-d, among other components. FIG. 1
illustrates the vehicle cabin 112 as including a first seating
position 114a, a second seating position 114b, a third seating
position 114c, and a fourth seating position 114d. In particular
instances, the first seating position 114a may include a driver's
seat within a first row of seats of the vehicle cabin 112, the
second seating position 114b may include a front passenger's seat
within the first row of seats, the third seating position 114c may
include a first rear passenger's seat within a second row of seats
of the vehicle cabin 112, and the fourth seating position 114d may
include a second rear passenger's seat within the second row of
seats. Unless otherwise specified, the one or more speakers 108a-h
are generally referred to as speakers 108, the one or more
microphone assemblies 110a-d are generally referred to as
microphone assemblies 110, and the seating positions 114a-d are
generally referred to as seating positions 114.
[0031] Each of the speakers 108 may be positioned proximate a
corresponding seating position 114. In particular, the speakers
108a, 108b are positioned to provide audio content to the first
seating position 114a, the speakers 108c, 108d are positioned to
provide audio content to the second seating position 114b, the
speakers 108e, 108f, are positioned to provide audio content to the
third seating position 114c, and the speakers 108g, 108h are
positioned to provide audio content to the fourth seating position
114d. While in certain examples, each speaker 108 may include a
"near-field speaker" (or near-field speaker array) located near a
head position of an occupant of a corresponding seating position
114, any suitable speaker and arrangement may be used. That is,
while FIG. 1 illustrates an example where each seating position
114a, 114b, 114c, 114d has a pair of corresponding speakers, in
certain other examples, each seating position 114a, 114b, 114c,
114d, may include more or less than the illustrated pair of
corresponding speakers 108. Moreover, the speakers 108 may be
arranged in locations other than those illustrated in FIG. 1. For
example, speakers 108 may be positioned in one or more of a
headrest, a seat back, an armrest, a door of the vehicle cabin 112,
a headliner, and/or an instrument panel, to name a few
examples.
[0032] In the shown example of FIG. 1, each of the speakers 108 are
incorporated within the headrest of the corresponding seating
position 114. That is, the speakers 108a, 108b may be positioned
within a headrest 116a of the first seating position 114a, the
speakers 108c, 108d may be positioned within a headrest 116b of the
second seating position 114b, the speakers 104e, 104f may be
positioned within a headrest 116c of the third seating position
114c, and the speakers 104g, 104h may be positioned within a
headrest 116d of the fourth seating position 114d. Each speaker 108
of the audio system 100 may include a directional loudspeaker
including a cone-type acoustic driver. However, in various other
implementations the speakers 108 may include directional
loudspeakers of a type other than cone-types, such as dome-types,
flat-panel type, or any other suitable forward firing
electro-acoustic transducer.
[0033] In various examples, the audio signal source 102 is coupled
to the audio signal processing circuitry 104 and configured to
provide one or more audio signals. The audio signal source 102 may
include one or more audio components of a vehicle sound system
(e.g., car radio), an MP3 player, a CD player, a cell phone, or a
mobile device, to name a few. The audio signal source 102 may be
integral to the audio system 100, or may be external and
communicate via a communication interface with the audio system
100. In certain examples, the audio signal source 102 may include a
separate audio source designated for each seating position 114 or
audio content zone within the vehicle (e.g., a first audio content
zone for the seating positions 114a, 114b and a second audio
content zone for the seating positions 114c, 114d).
[0034] According to various examples, the audio signal processing
circuitry 104 receives the audio signal(s) from the audio signal
source 102, performs one or more signal processing operations on
the received audio signal(s), and delivers the processed audio
signal(s) to the respective speaker 108. Once received, the audio
signal drives the respective speaker 108 to provide audio content
to the corresponding seating position 114 based on the received
audio signal. As further described below, in particular examples,
the audio signal processing circuitry 104 may include a signal
processor (e.g., a Digital Signal Processor (DSP)) 118 and
volume-based equalization circuitry 120, among other
components.
[0035] In certain other examples, the audio signal processing
circuitry 104 may include additional circuitry not illustrated for
the convenience of explanation. For instance, the audio signal
processing circuitry 104 can include a wireless component having
hardware or software configured to receive the audio signal via a
wireless protocol such as BLUETOOTH.RTM., Bluetooth Low Energy
(BLE), WiFi, Zigbee, or Propriety Radio. As used herein,
BLUETOOTH.RTM. refers to a short range ad hoc network, otherwise
known as piconets. In further examples, the wireless component may
include hardware or software to support both BLUETOOTH.RTM. and
Bluetooth Low Energy.
[0036] As further illustrated in the example of FIG. 1, the control
circuitry 106 is coupled to at least the audio signal processing
circuitry 104 and the audio signal source 102. In response to an
input (e.g., user input), the control circuitry 106 provides one or
more audio source selection signals to the audio signal source 102
selecting the particular audio content for each seating position
114 (or audio content zone). As discussed above, the control
circuitry 106 may select the same audio signal source 102 for each
seating position 114, or may select a combination of different
audio signal sources 102 for different seating positions 114. Based
on selection signal received from the control circuitry 106, the
audio signal source 102 provides the audio signal(s) to the audio
signal processing circuitry 104, which may then provide the audio
content to the appropriate speaker(s) 108.
[0037] The control circuitry 106 may include any processor,
multiprocessor, or controller. The processor may be connected to a
memory and a data storage element (e.g., data store 122). The
memory stores a sequence of instructions coded to be executable by
the processor to perform or instruct the various components
discussed herein to perform the various processes and acts
described in this disclosure. For instance, the control circuitry
106 may communicate with, and provide one or more control signals
to, the audio signal source 102, the volume-based equalization
circuitry 120, and the signal processor 118. Thus the memory may be
a relatively high performance, volatile random access memory such
as a dynamic random access memory (DRAM) or static memory (SRAM).
However the memory may include any device for storing data, such as
a disk drive or other nonvolatile storage device.
[0038] In additional examples, the processor may be configured to
execute an operating system. The operating system may provide
platform services to application software. These platform services
may include inter-process and network communication, file system
management, and standard database manipulation. One or more of many
operating systems may be used, and examples are not limited to any
particular operating system or operating system characteristic. In
some examples, the processor may be configured to execute a
real-time operating system (RTOS), such as RTLinux, or a non-real
time operating system, such as BSD or GNU/Linux.
[0039] The instructions stored on the data storage (e.g., data
store 122) may include executable programs or other code that can
be executed by the processor. The instructions may be persistently
stored as encoded signals, and the instructions may cause the
processor to perform the functions and processes described herein.
The data storage may include information that is recorded, on or
in, the medium, and this information may be processed by the
processor during execution of instructions. The data storage
includes a computer readable and writeable nonvolatile data storage
medium configured to store non-transitory instructions and data. In
addition, the data storage includes processor memory that stores
data during operation of the processor.
[0040] As discussed, in certain examples the audio system 100 may
provide different audio content for different seating positions 114
within the vehicle cabin 112. That is, the audio source 102 may
provide first audio content (e.g., a telephone conversation) for
the first seating position 114a and second audio content (e.g., a
movie sound track) for the second, third, and/or fourth seating
position 114b, 114c, 114d. Each of the seating positions 114 may
receive individual audio content, or receive shared audio content
with another seating position 114. Once received, the respective
speaker(s) 108 radiate the audio content to the corresponding
seating position 114.
[0041] In certain examples, the seating positions 114 may be
arranged in one or more audio content zones. Each seating position
114 within the same audio content zone receives the same audio
content. For example, the first seating position 114a and the
second seating position 114b may be designated as a first audio
content zone, and the third seating position 114c and the fourth
seating position 114d may be designated as a second audio content
zone. Accordingly, the first and second seating positions 114a,
114b may receive audio content designated for the first audio
content zone, and the third and fourth seating positions 114c, 114d
may receive audio content designated for the second audio content
zone. Each audio content zone may share the same audio source 102,
or may have a separate audio content source. Moreover, each audio
content zone may have more than one audio content source 102.
[0042] While each speaker 108 is intended to provide audio content
to the seating position 114 proximate that speaker 108, it is
appreciated that within enclosed spaces, such as the vehicle cabin
112, the provided audio content may reflect from surfaces proximate
the speaker 108, and may be undesirably leaked to other seating
positions. This is often the case when one seating position 114 is
in a forward or rearward facing direction, or a sideways direction,
of the seating position 114 that is intended to receive the audio
content. For example, audio content provided by the speakers 108g,
108h may be undesirably leaked to one, or all, of the first,
second, and third seating positions 114a, 114b, 114c. As discussed
herein, this unintended acoustic reflection is referred to as
leaked audio content.
[0043] While in some instances, recipients of the leaked audio
content may enjoy receiving audio content intended for other
listeners, generally, the leaked audio content is an inconvenience
for those unintended recipients. In particular, the leaked audio
content may interfere with other audio content actually intended
for that listener, and may degrade the fidelity of that audio
content. Moreover, other interference within the vehicle cabin 112
can further degrade the fidelity of audio content delivered to a
seating position 114. In particular, speech content from other
locations within the vehicle cabin 112 can destructively interfere
with the audio content and make the audio content challenging to
hear. This is especially the case when the speech content
interferes with a telephone conversation provided to a seating
position. Road noise and other noises within the vehicle cabin 112
(e.g., vehicle noise, ventilation noise, etc.) can have a similar
effect on the audio content.
[0044] Accordingly, in various examples the audio signal processing
circuitry 104 is configured to determine a perturbing signal which
accounts for the interfering acoustic energy in the vehicle cabin
112, and adjust the audio content (e.g., a telephone conversation,
one or more vehicle alerts or alarms, music, etc.) to compensate
for the perturbing signal such that the audio content is clearly
intelligible at the intended seating position 114. That is, the
audio signal processing circuitry 104 is configured to adjust the
audio content to mitigate the effects of the speech content, leaked
audio content, and road noise, if present within the vehicle cabin
112, on the audio content at the desired seating position 114.
Accordingly, in some instances the audio system 100 may isolate an
occupant of a single seating position 114 (e.g., a driver's seat)
from the destructive effects of acoustic interference.
[0045] In certain examples, the audio signal processing circuitry
104 is adapted to dynamically adjust the audio content based on the
frequency components thereof to provide an improved listening
experience at the desired seating position 114. While various acts
and processes are described herein as being performed by the audio
signal processing circuitry 104, it is appreciated that these acts
and processes may be performed by the individual components of the
audio signal processing circuitry 104 (e.g., the illustrated signal
processor 118 and dynamic-volume control circuitry 120) and are
described in this manner purely for the convenience of
explanation.
[0046] In certain examples, the audio system 100 includes the
microphone assemblies 110, each of which are positioned to detect
speech or other audio content from a corresponding seating position
114 (i.e., a target location). However, as a result of the confined
dimensions of many vehicle cabins, each of the microphone
assemblies 110 may also detect other acoustic energy within the
vehicle cabin. For instance, each microphone assembly 110 may
detect speech content of a corresponding seating position (i.e.,
target speech content), leaked audio content, road noise, and
speech content originating at other seating positions 114. As
illustrated in FIG. 1, in one example the audio system 100 includes
a first microphone assembly 110a positioned to detect speech
content originating from the first seating position 114a, among
other acoustic interference. Similarly, a second microphone
assembly 110b may be positioned to detect speech content
originating from the second seating position 114b, a third
microphone assembly 110c may be positioned to detect speech content
originating from the third seating position 114c, and a fourth
microphone assembly 110d may be positioned to detect speech content
originating from the fourth seating position 114d, among other
acoustic interference.
[0047] While each illustrated as a single microphone assembly, in
various examples each microphone assembly 110 may include one or
more microphones. For instance, each microphone assembly 110 may
include an array of microphones arranged in predetermined pattern.
Each microphone may be an omnidirectional microphone, such as an
omnidirectional electret microphone or an omnidirectional
Microelectromechanical systems (MEMS) microphone. In another
example, each microphone assembly 110 may include a directional
microphone positioned to increase reception in a desired direction,
and reject the acoustic energy arriving from other directions. Each
microphone assembly 110 is in communication with the audio signal
processing circuitry 104 (e.g., the signal processor 118) and
configured to provide a corresponding microphone signal responsive
to detection of the speech content, leaked audio content, road
noise, and other acoustic energy.
[0048] Responsive to receiving the one or more microphone signals,
the audio signal processing circuitry 104 is configured to
determine the perturbing signal. As discussed herein, the
perturbing signal refers to a summation of the acoustic energy
which interferes with the audio content delivered to a desired
seating position 114 within the vehicle cabin 112. That is, the
perturbing signal refers to the summation of signals which may mask
(e.g., render unintelligible) the delivered audio content. It is
appreciated that the perturbing signal will be time-dependent and
will vary during the operation of the audio system 100 (and
vehicle).
[0049] According to various embodiments the perturbing signal can
be represented as:
P total ( t ) = ( k = 1 , k D K P k ( t ) ) + ( k = 1 K M k ( t ) )
+ N ( t ) ##EQU00001##
where, P.sub.total is the perturbing signal, t is the timeframe, k
is a particular seating position 114 within the vehicle cabin 112,
P.sub.k is the speech content for the particular seating position
114, D is the set of desired seating locations, P.sub.k, kD,
denotes the set of perturbing speech content signals to be
measured, M.sub.k is the leaked audio content for the particular
seating position 114, K is the number of seating positions 114
within the vehicle cabin 112, and N is the road noise. Once the
perturbing signal is calculated, the audio signal processing
circuitry 104 may adjust the audio content delivered to a desired
seating position 114 such that the audio content is audible and the
speech content, leaked audio content, and/or road noise do not
affect the intelligibility of the audio content.
[0050] To determine the perturbing signal, in various examples the
signal processor 118 determines a speech signal for the speech
content originating from each seating position 114. However, often
the microphone assemblies 110 will detect speech content
originating from more than one seating position 114 within the
vehicle cabin 112. Accordingly, the signal processor 118 may
isolate the target speech content for each seating position.
Moreover, the signal processor 118 is configured to further filter
the microphone signals to isolate the speech content from the
leaked audio content and road noise also detected by the microphone
assemblies 110. Once filtered, the speech signal(s) remain, and the
signal processor 118 may calculate the level (e.g., power) of each
speech signal within the vehicle cabin 112, and sum the levels, to
determine the total interference from speech content within the
vehicle cabin 112.
[0051] As discussed herein, speech content may refer to the
sustained delivery of vocal words or sounds from an occupant of the
vehicle cabin 112 other than the occupant of the seating position
114 at which noise reduction is desired. For example, speech
content may include words spoken by an occupant of the third
seating position 114c when noise reduction is desired at the first
seating position 114a. However, in certain other examples, speech
content may include acoustic interference that is generated by an
artificial source at a seating position 114 and that mimics organic
speech content. For instance, speech content may include acoustic
interference that originates from a cell phone, a mobile device, a
tablet computer operating in a hands-free mode (i.e., not coupled
to the control circuit 106) at a seating position 114. Accordingly,
in some instances speech content may include other types of
acoustic interference aside from a conversation between two
occupants of the vehicle cabin 112.
[0052] To estimate each speech signal, the signal processor 118 may
first filter each microphone signal to remove the road noise and
leaked audio content. Since the audio content is received directly
from the audio signal source 102, the leaked audio content may be
identified and removed based on the known characteristics of the
received audio content. The road noise may be identified and
removed based on estimated characteristics of the noise in a
similar manner. In one example, the signal processor 118 implements
an acoustic echo canceller and noise reduction filter which use
spectral subtraction to remove the road noise and leaked audio
content.
[0053] Once the road noise and leaked audio content have been
removed from each microphone signal, in many instances, the
remaining components of the microphone signal are the speech
content from a corresponding seating position 114 (i.e., the target
speech content) and speech content originating at non-corresponding
seating positions 114. To attenuate the speech content from the
non-corresponding seating positions 114 and isolate the target
speech content, in various examples the signal processor 118 treats
all microphone assemblies 110 within the system 100 as a single
array, and applies a beamforming configuration in either the
time-domain or the frequency-domain. In particular, the signal
processor 118 may select different predesigned beamforming
configurations based on the particular combination of microphone
signals that are received by the signal processor 118. Each
beamforming configuration may consist of a set of weight vectors
which are applied to reject and/or attenuate the speech content
that is not the target speech content. According to an example,
attenuation factors (or gain factors) that are associated with each
beamforming configuration can be measured a priori and retrieved
during the operation of the audio system 100.
[0054] In one example, a first beamforming configuration can be
designed to detect target speech content originating at the first
seating position 114a and reject or attenuate the speech content
originating from the second seating position 114b, third seating
position 114c, and/or fourth seating position 114d of the vehicle
cabin 112. Similarly, a second beamforming configuration can be
designed to detect speech content originating at the second seating
position 114b and reject or attenuate speech content originating
from the first seating position 114a, third seating position 114c,
or fourth seating position 114d. Accordingly, when a microphone
array is in use, the weight vector of the corresponding beamforming
configuration allows that microphone array to steer its beam to
receive the target speech content, and filter out or reduce the
unwanted speech content. The attenuation (or gain) factors
associated with each beamforming configuration specify the
particular amount of attenuation (or gain) applied to the
non-corresponding speech signals.
[0055] In one example, if beamforming is applied in the
frequency-domain, each beamforming configuration may include a set
of weight vectors, w.sub.f, f=1, . . . , F. In the example, w.sub.f
is the weight vector at a frequency, f, and F is the total number
of frequencies. Accordingly, w.sub.f includes gains that are
applied to the frequency components (at each frequency, f) of each
microphone signal. A frequency component of the output may be
obtained as the linear combination:
Y(f)=.SIGMA.w.sub.f,iS.sub.i(f)
where S.sub.i(f) is the frequency component of the signal at the
ith microphone assembly 110 and with w.sub.f,i is the associated
gain.
[0056] In certain examples the weight vectors of each beamforming
configuration may be obtained by applying a Minimum Variance
Distortionless Response (MVDR) on different combinations of the
received microphone signals. Once obtained, each set of weight
vectors, along with the attenuation factors, may be stored in
program storage accessible to the control circuitry 106 during
operation. For instance, the plurality of weight vectors may be
stored in a lookup table, a register, or similar reference table.
The control circuitry 106 may use the look-up table to determine
the appropriate beamforming configuration (e.g., set of weight
vectors and attenuation factors) for a given condition during the
operation of the vehicle cabin audio system 100, and provide the
weight vectors and the attenuation factors to the audio signal
processing circuitry 104. The look-up table may include any array
that replaces a runtime computation with an indexing operation.
[0057] Owing to the fact that the speech content originating from
each seating position 114 is largely uncorrelated, a system of
linear equations, including the level of the speech signals, and
the appropriate attenuation factors, may be formed. This system is
then solved by the signal processor 118 on a timeframe basis to
estimate the levels of the speech signals when a mixture (i.e.,
combination) of speech content is present. For example, the speech
signals of the speech content may be denoted by s.sub.k, i=1, . . .
, K, where K is the total number of seating positions 114 within
the vehicle cabin. The corresponding levels of the speech signals
may be denoted by P.sub.k, and the number of beamforming
configurations may be denoted by M. In such an example, a set of
attenuation factors {.alpha..sub.m,k, k=1, . . . , K} is associated
with the mth beamforming configuration. The attenuation factors may
be calculated, a priori, by measuring the input and output powers
when different test signals are independently passed through the
different beamforming configurations. The attenuation factor of the
kth signal (target speech signal from kth seating position in this
scenario), when passed through the mth beamforming configuration is
denoted by .alpha..sub.m,k, and computed using:
.alpha. m , k = P m , k P k , ##EQU00002##
where P.sub.m,k is the speech signal level at the output of the
microphone assembly 110 when the mth configuration is used, and
P.sub.k is the speech signal level of the kth speech signal.
[0058] Due to the fact that the speech content is largely
uncorrelated, as discussed, the level of a linear combination of
the speech signals is a linear combination of their levels, as
shown in the following equation:
P i n ( t ) = k = 1 K P k ( t ) ##EQU00003##
[0059] where P.sub.in is the level of the combined mixture of the
speech signals at a microphone assembly 110.
[0060] The timeframe over which the levels are computed is denoted
by t. It should be noted that the correlation between the speech
signals might not be zero if a small timeframe is used. That is, in
certain examples as the timeframe increases the correlation
approaches zero. For this reason, in certain examples the window
length may be a tuning parameter for signal processor 118. After
passing the combined signal through the mth beamforming
configuration, the level of the output signal can be expressed
as:
P out , m ( t ) = k = 1 K .alpha. m , k P k ( t ) ##EQU00004##
Accordingly, a system of linear equations can then be formed by the
signal processor 118 as follows:
[ P out , 1 ( t ) P out , M ( t ) ] = .alpha. [ P 1 ( t ) P 2 ( t )
P K ( t ) ] = [ .alpha. 1 , 1 .alpha. 1 , 2 .alpha. 1 , K .alpha. M
, 1 .alpha. M , 2 .alpha. M , K ] [ P 1 ( t ) P 2 ( t ) P K ( t ) ]
##EQU00005##
and speech signal levels, at timeframe t, can then be estimated by
the signal processor 118 as follows:
[ P 1 ( t ) P 2 ( t ) P K ( t ) ] = .alpha. .dagger. [ P out , 1 (
t ) P out , M ( t ) ] ##EQU00006##
where, a.sup..dagger. is the Moore-Penrose pseudoinverse of
.alpha..
[0061] The discussed system of equations may be further extended,
in other examples, to incorporate other types of acoustic
interference within the vehicle cabin 112, such as the road noise
and the leaked audio content. Different sets of weight vectors and
attenuation factors can be constructed offline and may correspond
to certain combinations of interfering acoustic energy. Then,
depending on which of these combinations is detected, the
corresponding beamforming configuration may be selected by the
control circuitry 106, and applied by the signal processor 118.
[0062] As discussed above, the presence of certain audio content,
such as leaked audio content, road noise, and other noise, can
easily be determined by examining the audio signal source 102
outputs, a multimedia bus of the associated vehicle, and/or a
vehicle Control Area Network (CAN). As for the speech signals, in
certain examples the audio system 100 may further include one or
more Voice Activity Detectors (VAD), each of which can be designed
for a seating position 114 within the vehicle cabin 112. The one or
more VADs may be coupled to the control circuitry 106 and may
inform the control circuitry 106 when speech content is being
generated at a given seating position 114. While the signal level
calculations of the speech content are based on the location of the
microphone assemblies, 110 and not the location at which isolation
is desired, discrepancies can be compensated by measuring a priori
the difference in the levels of the acoustic interference at these
locations, and adjusting the audio content accordingly.
[0063] Once determined, the speech signal(s) may be combined with
the leaked audio content and the road noise to determine the total
perturbing signal, as discussed above. In certain examples, the
leaked audio content from each seating position 114 may be
determined based the audio signal(s) provided to the audio signal
processing circuitry 104 and one or more leakage functions. Each
leakage function may correspond to a spatial relationship between
the speakers 108 which leak the audio content and the seating
position 114 at which the leaked audio content is received. Since
this relationship is fixed and may be determined during the
production of the vehicle, for example, each of the leakage
functions may be predetermined and stored in the data store 122.
Similar processes may be performed by the signal processor 118 for
the road noise during operation of the vehicle.
[0064] As discussed herein, the audio signal processing circuitry
104 may adjust an audio signal to compensate for the perturbing
signal. This may include compensating for one or all of the various
sources of acoustic interference within the vehicle cabin 112. In
one example, the audio signal processing circuitry 104 includes
volume-based equalization circuitry 120 which dynamically adjusts a
level of an audio signal, based on a frequency of the audio signal,
to compensate for the perturbing signal. Specifically, the
volume-based equalization circuitry 120 may dynamically adjust a
balance between frequency components of the audio signal,
independently or in frequency bands, to mitigate the effects of the
perturbing signal at the desired seating position 114. For
instance, the volume-based equalization circuitry 120 may include
one or more linear filters or dynamic gain circuitry which
amplifies or attenuates the frequency components of the audio
signal.
[0065] In one example, the level of adjustment (e.g., gain or
attenuation adjustment) made to the audio signal may be based on an
adjustment curve selected from among a group of adjustment curves.
Each adjustment curve specifies the gain or attenuation to be
applied to the audio signal based on the frequency components
thereof. In particular, adjustment values within each adjustment
curve may correspond to a Signal-to-Noise Ratio for each frequency
component, or frequency band. Based on the received desired audio
content, and a calculated SNR, the audio signal processing
circuitry 104 may select the appropriate adjustment curve, and
apply the appropriate adjustment value(s) to dynamically adjust the
desired audio content to mitigate the effects of the perturbing
signal. In particular instances, frequency-based adjustments to the
audio signal may be performed by executing the techniques described
in U.S. Pat. Pub. No. 2015/0281864, titled "DYNAMIC SOUND
ADJUSTMENT", which is hereby incorporated by reference herein in
its entirety. Once adjusted, the volume-based equalization
circuitry 120 provides the audio signal to the corresponding
speakers 108.
[0066] In one example, the volume-based equalization circuitry 120
is configured to apply a different amplification or attenuation for
different frequency bands of the audio content. For instance, the
volume-based equalization circuitry 120 may apply a first
attenuation or amplification to a first frequency band (e.g., a low
frequency band) and apply a second attenuation or amplification to
a second frequency band (e.g., a high frequency band). In such an
example, the low frequency band may include frequencies between 50
Hz and 500 Hz and the high frequency band may include frequencies
between 500 Hz and 5 kHz. Amplification and/or attenuation
adjustment values for each frequency band may be specified by a
selected adjustment value, as discussed above.
[0067] As discussed herein, certain examples of the vehicle cabin
audio system 100 may provide significant benefits when a telephone
conversation is played to a single seating position within a noisy
vehicle cabin. For instance, referring to FIG. 1, the audio signal
processing circuitry 104 may provide an adjusted telephone
conversation to the occupant of the first seating position 114a,
which mitigates the effects of speech content originating at any or
all of the second seating position 114b, the third seating position
114c, and the fourth seating position 114d. In addition to
adjusting the telephone conversation to compensate for the speech
content, the audio signal processing circuitry 104 may further
adjust the telephone conversation to mitigate the effects of other
audio content within the cabin 112 (e.g., music) and vehicle
noise.
[0068] Referring to FIG. 2, illustrated is one example of an
input/output diagram of the signal processor illustrated in FIG. 1.
As shown, the signal processor 118 may receive a microphone signal
which includes a road noise component 204, a speech content
component 206, a leaked audio content component 210, and an other
noise component 214 (e.g., vehicle noise, ventilation noise, etc.).
As discussed with reference to the audio system 100 of FIG. 1, in
certain examples the microphone signal may include detected speech
content originating at more than one seating position and leaked
audio content originating at more than one speaker. Accordingly, in
FIG. 2 the microphone signal is shown as also including an
additional speech content component (n) 208 and an additional
leaked audio content component (n) 212.
[0069] As further illustrated, the signal processor 118 may also
receive an audio signal 216 from the audio signal source 102 and
one or more control signal 218 from the control circuitry 106.
Based on at least these signals, and the microphone signal 202, the
signal processor 118 may determine the perturbing signal 220. The
determined perturbing signal 220 may then be provided to the other
components of the audio signal processing circuitry 104 illustrated
in FIG. 1, such as the volume-based equalization circuitry 118.
[0070] Referring now to FIG. 3, illustrated is another example of a
vehicle cabin audio system 300. As illustrated, the vehicle cabin
audio system 300 of FIG. 3 may include many of the same components
as the audio system 100 described with reference to FIG. 1. For
instance, the audio system 300 may include an audio signal source
302, audio signal processing circuitry 304, control circuitry 306,
one or more speakers 308a-h, one or more microphone assemblies
310a-b, and a data store 312, among other components. Each of the
speakers 308 may be positioned proximate a corresponding seating
position 314a-d, as also discussed with reference to the vehicle
cabin audio system 100 of FIG. 1. Unless otherwise specified, the
one or more speakers 308a-h are generally referred to as speakers
308, the one or more microphone assemblies 310a-b are generally
referred to as microphone assemblies 310, and the seating positions
314a-d are generally referred to as seating positions 314.
[0071] According to certain examples, each microphone assembly 310
may include an array of individual microphones. While in the
example illustrated in FIG. 1, each microphone assembly 310 is
positioned to detect speech content originating at a corresponding
seating position 314, in certain other examples, each seating
position 314 may not have a corresponding microphone assembly 310,
and instead, share one or more common microphone assemblies 310.
For instance, FIG. 3 shows a first microphone assembly 310a
positioned to detect speech content originating at the first and
second seating positions 314a, 314b and a second microphone
assembly 310b positioned to detect speech content originating at
the third and fourth seating positions 314c, 314d. In certain
examples, each microphone assembly 310 may be positioned at a
central location between the respective seating positions 314, as
shown in FIG. 3.
[0072] Each microphone assembly 310 may distinguish between the
speech content originating at the different seating positions 314
based on a direction at which the speech content is received at the
microphone assembly 310. That is, as a result of the central
location of each microphone assembly 310, speech content from each
seating position 314 will be received at the microphone assemblies
310 in a different direction. Specifically, the speech content
waveforms will propagate along the individual microphones of the
microphone assembly 310 in a different order. Based on the delay
between when each microphone in the assembly detects the speech
content, the audio signal processing circuitry 304 may determine
the originating seating position 314 of the detected speech
content.
[0073] As also shown in FIG. 3, the audio signal processing
circuitry 304 may further receive one or more noise signals from
one or more road noise sensors 316. Each road noise sensor 316 may
be positioned within the vehicle cabin to detect road noise during
the operation of the vehicle. For instance, each road noise sensor
316 may also include a microphone. Noise signals from each road
noise sensor 316 may be used to filter each microphone signal as
further discussed with reference to the vehicle cabin audio system
100 illustrated in FIG. 1.
[0074] In certain examples, the audio signal processing circuitry
304 includes dynamic volume-equalization circuitry 318 coupled to
one or more filters 320 and a signal processor 322. Each filter 320
may receive one or more control signals from the control circuitry
306 which adjusts the parameters of the filters 320 (e.g., a filter
coefficient). While in one example, each filter 320 may be
controlled to filter leaked audio content from the microphone
signals and provide cross-talk cancellation, in various other
examples, each filter 320 may reduce or remove other acoustic
interference within the vehicle cabin, such as road noise or
vehicle noise. In particular examples, each filter 320 may include
a cross-talk cancellation filter which provides an amplitude
adjusted audio signal to the dynamic volume-based equalization
circuitry 318.
[0075] As described above with reference to at least FIG. 1,
several examples perform processes that compensate for the effects
of acoustic interference at a desired seating position within a
vehicle cabin. In some examples, these processes are executed by
vehicle cabin audio system, such as the audio system 100 described
above with reference to FIG. 1. One example of such a process is
illustrated in FIG. 4. According to this example, the process 400
includes the acts of providing audio content to a first seating
position based on an audio signal, providing audio content to a
second seating position, detecting speech content, leaked audio
content, and road noise, determining a perturbing signal based on
the detected speech content, leaked audio content, and road noise,
and adjusting the audio signal to compensate for an effect of the
perturbing signal on the audio content provided to the first
seating position. The process 400 of FIG. 4 is described with
continuing reference to the audio system 100 illustrated in FIG. 1,
and the components thereof.
[0076] In act 402, the process 400 first includes providing first
audio content to a first seating position (e.g., seating position
114a in FIG. 1) within a vehicle cabin based on an audio signal
received from an audio signal source. For instance, in act 402 the
process may include providing a telephone conversation from the
speakers 108a, 108b to the first seating position 114a (shown in
FIG. 1). In certain examples, providing audio content to a seating
position may include driving one or more speaker(s) proximate the
seating position (e.g., within a headrest, a seat back, an armrest,
a cabin door, a headliner, and/or an instrument panel) with a
processed audio signal and radiating acoustic energy to an occupant
of the seating position.
[0077] In certain examples, the audio system may provide different
audio content for different seating positions, or different audio
content zones, within the vehicle cabin. That is, the audio source
may provide first audio content (e.g., the telephone conversation)
for the first seating position 114a and second audio content (e.g.,
a movie sound track) for a second, third, and/or fourth seating
position (e.g., seating positions 114b, 114c, 114d in FIG. 1). Once
received, the respective speaker(s) radiate the audio content to
the corresponding seating position. Accordingly, at the same time,
or at about the same time, the first audio content is being
delivered, the process 400 may include providing second audio
content to the second seating position within the vehicle cabin
with a second speaker. Similarly, the process 400 may include
providing the second audio content to a third seating position, or
providing third audio content to the third seating position. In at
least one example, the second audio content and the third audio
content is different from the first audio content.
[0078] In act 406 the process 400 includes detecting, at a
microphone assembly, speech content originating at the second
seating position, leaked second audio content from one or more
speakers near the second seating position, and road noise. Once
detected, the process 400 may then include determining a perturbing
signal based at least in part on a combination of the speech
content, the leaked second audio content from the second speaker,
and the road noise (act 410). Once the perturbing signal is
calculated, the process 400 may include adjusting the audio signal
provided to the first speaker based on a frequency of the audio
signal to compensate for an effect of the perturbing signal on the
audio content at the first seating position (act 412).
[0079] As discussed herein, in many instances each microphone
assembly may detect speech content originating from multiple
seating positions. That is, in addition to detecting the speech
content originating from a corresponding seating position (e.g.,
target speech content), each microphone assembly may detect the
speech content originating at non-corresponding seating positions.
For instance, the third microphone assembly 110c illustrated in
FIG. 1 may detect speech content originating at the third seating
position 114c, as well as, speech content originating at the fourth
seating position 114d. Accordingly, the process 400 may further
include the act of distinguishing the detected speech content
originating at the corresponding seating position (e.g., target
speech content) from the speech content received from
non-corresponding seating positions, and rejecting or attenuating
the undesired speech content (act 408). However, it is appreciated
that such acts may not be necessary if speech content is detected
from only one seating position.
[0080] To attenuate speech content from non-corresponding seating
positions, one or more acts may be performed to treat all
microphone assemblies of the system as a single array. For
instance, if speech content originating from multiple seating
positions is detected by a microphone assembly, the process 400 may
include selecting and applying a beamforming configuration in
either the time-domain or the frequency-domain to the detected
mixture of speech. In a situation where multiple microphone
assemblies each detect speech content from a corresponding seating
position, as well as, speech content corresponding to other seating
positions, a separate beamforming configuration may be applied to
the microphone signal of each individual microphone assembly.
[0081] In particular examples, the process 400 may include
selecting a different predesigned beamforming configuration for
each microphone assembly based on the particular combination of
microphone signals that are present. As discussed with reference to
at least FIG. 1, each beamforming configuration may consist of a
set of weight vectors which are applied to reject and/or attenuate
the speech content that is not the target speech content of a given
microphone assembly. Accordingly, when a microphone assembly is in
use, the weight vector of the corresponding beamforming
configuration allows that microphone array to steer its beam to
receive the target speech content, and filter out or reduce the
unwanted speech content. Attenuation (or gain) factors associated
with each beamforming configuration specify the particular amount
of attenuation applied to the non-corresponding speech signals.
Once the appropriate beamforming configuration has been applied,
all undesired speech content is rejected or attenuated and a speech
signal for the target speech content remains.
[0082] Each speech signal may be combined with the leaked audio
content and the road noise to determine the total perturbing
signal, as discussed above. Referring to act 412, the process 400
may include adjusting the audio signal provided to the first
speaker to compensate for the effects (e.g., masking effects) of
the perturbing signal on the audio content. This may include
compensating for one or all of the various sources of acoustic
interference within the vehicle cabin. In one example, the process
400 includes dynamically adjusting a level of the audio signal
based on a frequency of the audio signal to mitigate the effects of
the perturbing signal. Specifically, process 400 may include
dynamically adjusting the balance between frequency components of
the audio signal, independently or in one or more frequency bands,
such that the perturbing signal has substantially no effect on the
intelligibility of the audio content at the desired seating
position.
[0083] While FIG. 4 illustrates one example of a process for
reducing acoustic interference at a desired seating position within
a vehicle cabin, the process may further include additional acts
not explicitly illustrated in FIG. 4 for the convenient of
explanation. Such acts are discussed and described herein with
reference to one or more of FIGS. 1, 2, and 3.
[0084] Having described above several aspects of at least one
implementation, it is to be appreciated various alterations,
modifications, and improvements will readily occur to those skilled
in the art. Such alterations, modifications, and improvements are
intended to be part of this disclosure and are intended to be
within the scope of the description. Accordingly, the foregoing
description and drawings are by way of example only, and the scope
of the disclosure should be determined from proper construction of
the appended claims, and their equivalents.
* * * * *