U.S. patent application number 13/590749 was filed with the patent office on 2016-12-29 for system for objective qualification of listener envelopment of a loudspeaker-room environment.
This patent application is currently assigned to HARMAN BECKER AUTOMOTIVE SYSTEMS GMBH. The applicant listed for this patent is Wolfgang Hess. Invention is credited to Wolfgang Hess.
Application Number | 20160381478 13/590749 |
Document ID | / |
Family ID | 38134819 |
Filed Date | 2016-12-29 |
United States Patent
Application |
20160381478 |
Kind Code |
A9 |
Hess; Wolfgang |
December 29, 2016 |
SYSTEM FOR OBJECTIVE QUALIFICATION OF LISTENER ENVELOPMENT OF A
LOUDSPEAKER-ROOM ENVIRONMENT
Abstract
A system quantifies listener envelopment in a loudspeakers-room
environment. The system includes a binaural detector that receives
frequency modulated audible noise signals from multiple
loudspeakers. The binaural detector generates detected signals that
are analyzed to determine an objective listener envelopment. The
envelopment is based on binaural activity of one or more sub-bands
of the detected signal.
Inventors: |
Hess; Wolfgang; (Karlsbad,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hess; Wolfgang |
Karlsbad |
|
DE |
|
|
Assignee: |
HARMAN BECKER AUTOMOTIVE SYSTEMS
GMBH
Karlsbad
DE
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20120314873 A1 |
December 13, 2012 |
|
|
Family ID: |
38134819 |
Appl. No.: |
13/590749 |
Filed: |
August 21, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12032386 |
Feb 15, 2008 |
8270619 |
|
|
13590749 |
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Current U.S.
Class: |
381/17 |
Current CPC
Class: |
H04S 7/40 20130101; G01H
3/00 20130101; H04R 29/001 20130101; H04S 2420/01 20130101; H04S
7/30 20130101 |
International
Class: |
H04R 5/00 20060101
H04R005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 21, 2007 |
EP |
07003586.0 |
Claims
1. A method for estimating listener envelopment of a
loudspeakers-room environment comprising: binaurally detecting
first and second audible frequency modulated noise signals received
in a concurrent manner from first and second loudspeakers,
respectively, in a loudspeakers-room environment to generate
detected signals; and analyzing binaural activity of at least two
sub-bands of the detected signal to determine objective listener
envelopment of the loudspeakers-room environment.
2. The method of claim 1, where the binaurally detected first and
second audible frequency modulated noise signals comprise broadband
noise having sinusoidally varying interaural time differences.
3. The method of claim 1, where further comprising smoothing the
binaural activity of the at least two sub-bands in time using a
floating rectangular integration window.
4. A method for estimating listener envelopment of a
loudspeakers-room system comprising: generating first and second
electronic frequency modulated noise signals; concurrently
transducing the first and second electronic frequency modulated
noise signals using first and second loudspeakers, respectively, to
generate audible signals in a room environment containing the first
and second loudspeakers; binaurally detecting the audible signals
to obtain detected signals; filtering the detected signals to
obtain sub-band signals for at least two sub-bands of the detected
signals; determining binaural activity of the at least two
sub-bands of the detected signals; and determining objective
listener envelopment of the loudspeakers-room environment based on
the binaural activity of the at least two sub-bands of the detected
signal.
5. The method of claim 4, where filtering the detected signals
comprises: filtering the detected signals using a head-related
transfer function to obtain first filtered signals; and filtering
the first filtered signals using a filter function corresponding to
a human middle ear response.
6. The method of claim 4, where determining the binaural activity
comprises: determining interaural time differences and interaural
level differences for each of the at least two sub-bands of the
detected signal; and combining the interaural time differences and
the interaural level differences to obtain the binaural activity
over time and lateral deviation for each of the at least two
sub-bands of the detected signal.
7. The method of claim 4, further comprising smoothing of the
binaural activity in time using a floating rectangular integration
window.
8. The method of claim 4, further comprising weighting determined
listener envelopment values using a frequency-band weighting curve
to obtain a single value for the objective listener
envelopment.
9. The method of claim 4, further comprising determining a weighted
average of the listener envelopments of adjacent sub-band signals
for which binaural activities are determined to obtain a single
averaged listener envelopment value.
10. The method of claim 4, further comprising: transducing the
first electronic frequency modulated signal using a third
loudspeaker; and transducing the second electronic frequency
modulated signal using a fourth loudspeaker.
11. The method of claim 10, further comprising: obtaining a first
averaged listener envelopment value for the first and second
loudspeakers; obtaining a second averaged listener envelopment
value for the third and fourth loudspeakers; and weighting the
first and second averaged listener envelopment values depending on
positions of the loudspeakers in the room environment to obtain a
single weighted overall listener envelopment value.
12. The method of claim 4, further comprising applying a cutting
function with an adaptive threshold to edges of the binaural
activity, where the objective listener envelopment is determined
based on the cut binaural activity.
Description
PRIORITY CLAIM
[0001] This application is a Divisional application claiming
priority to U.S. patent application Ser. No. 12/032,386, filed on
Feb. 15, 2008, now U.S. Pat. No. ______, which claims priority to
EP07003586.0, filed Feb. 21, 2007, each of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to loudspeakers-room
environments and, more particularly, a system for objective
quantification of listener envelopment of a loudspeakers-room
environment.
[0004] 2. Related Art
[0005] The acoustic quality of audio entertainment and audio
information systems may depend on the acoustic characteristics of
the listening rooms. Such rooms differ in their dimensions and
shapes, (e.g., in the range from concert halls to vehicle
compartments).
[0006] As a sound travels away from its source, a certain
proportion of it reaches the listener as direct sound following a
straight path. A certain proportion of the sound radiates in all
directions from the source and encounters the boundaries of an
enclosure. The direct sound and reflections may cause auditory
spatial perception. The reflected sound may be delayed and
frequency colored. The delay, frequency coloration and
reverberation may be captured and interpreted cognitively to give
an auditory perception of the sound system and the space in which
the sound travels.
[0007] Sound reflections may include lateral reflections that are
perceived within 1 to 80 ms after the direct sound is received.
Late reflections may be perceived more than 80 ms after arrival of
a direct sound. The relationship of early lateral reflections with
direct sound may provide a person with a sense of the direction and
location of the sound source. An auditory source in a room may be
perceived as a finite lateral extent. The temporal and spatial
separation of sound energy of the late reflection may cause a
listener to feel completely enclosed by the sound. This phenomenon
is known as the listener envelopment (LEV). The LEV represents the
degree of envelopment or fullness of auditory events surrounding
the listener.
[0008] Derivation and measurement of objective quantifications of
the spatial auditory characteristics of a closed listening room are
difficult to achieve. Monaural parameters do not often correlate
well with perceptible characteristics. Measurement results of
binaural parameters may depend on the actual measurement position
and are difficult to implement. A ranking of the listener rooms,
e.g., concert halls, based on established parameters may not
sufficiently match the auditory perception and preferences of human
listeners. Therefore, it is difficult to adjust sound-systems
including loudspeakers in closed rooms to provide optimum audio
quality.
SUMMARY
[0009] A system quantifies listener envelopment in a
loudspeakers-room environment. The system includes a binaural
detector that receives frequency modulated audible noise signals
from multiple loudspeakers. The binaural detector generates
detected signals that are analyzed to determine an objective
listener envelopment. The objective listener envelopment is based
on binaural activity of one or more sub-bands of the detected
signal.
[0010] Other systems, methods, features, and advantages of the
invention will be, or will become, apparent to one with skill in
the art upon examination of the following figures and detailed
description. It is intended that all such additional systems,
methods, features and advantages be included within this
description, be within the scope of the invention, and be protected
by the following claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention can be better understood with reference to the
following drawings and description. The components in the figures
are not necessarily to scale, emphasis instead being placed upon
illustrating the principles of the invention. Moreover, in the
figures, like referenced numerals designate corresponding parts
throughout the different views.
[0012] FIG. 1 is system that may be used to determine listener
envelopment of a loudspeakers-room environment.
[0013] FIG. 2 is a second system that may be used to determine
listener envelopment of a loudspeakers-room environment.
[0014] FIG. 3 is a third system that may be used to determine
listener envelopment of a loudspeakers-room environment.
[0015] FIG. 4 is a three-dimensional graph of exemplary binaural
activity in sub-bands of a detected binaural signal over time that
may occur using the systems shown in FIG. 1 through FIG. 3.
[0016] FIG. 5 is a system employing multiple pairs of loudspeakers
that may be used to determine listener envelopment of a
loudspeakers-room environment.
[0017] FIG. 6 is a process that may determine listener envelopment
of a loudspeakers-room environment.
[0018] FIG. 7 is a second process that may determine listener
envelopment of a loudspeakers-room environment.
[0019] FIG. 8 is a process that may implement the filtering
operations shown in FIG. 7.
[0020] FIG. 9 is a process that may determine the binaural activity
of the sub-bands as shown in FIG. 7.
[0021] FIG. 10 is a process that may obtain a single averaged
listener envelopment value.
[0022] FIG. 11 it is a process may obtain a single averaged
listener envelopment value in a system having multiple loudspeaker
pairs.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] FIG. 1 is a system 100 that may determine listener
envelopment of a loudspeakers-room environment. The system 100
includes a first loudspeaker 110 that provides an audible first
frequency modulated noise signal and a second loudspeaker 115 that
provides an audible second frequency modulated noise signal. The
noise signals may be stereo signals respectively generated by
combining two narrow band signals that are limited to one auditory
band and exhibit some degree of phase coincidence from band to band
to one signal. The degree of listener envelopment may depend on
phase-coincidence and distance of auditory bands. The larger the
phase-coincidence, the less listener envelopment is perceived. The
higher the band distance, the less listener envelopment is
perceived. Signals in two directly adjacent bands with opposite
phases in binaural activity have the highest amount of perceived
listener envelopment.
[0024] The audible first and second frequency modulated noise
signals may be in the form of broadband noise having sinusoidally
varying interaural time differences and may correspond to left and
right stereo channels of the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi. f i
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00001## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. f i .DELTA. t sin ( 2
.pi. F M t F s ) ) , ##EQU00001.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index. Alternatively, the left and
right stereo channels may have the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi.
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00002## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. .DELTA. t sin ( 2 .pi.
F M t F s ) ) . ##EQU00002.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index.
[0025] In each instance, the interaural time difference caused by
the time interval .DELTA.t is included in the generated noise
signals independent of the actual loudspeakers-room transfer
function and the actual position of signal measurement. As a
result, an objective measurement of the listener envelopment may be
obtained.
[0026] Thus, two frequency-modulated broadband noise signals are
generated with a predetermined maximum interaural time difference
that changes periodically as a function of time. The distance of
the carrier frequencies of the two signals may be chosen as a tenth
part of 1 Hz, e.g., 0.1 Hz. Modulation frequencies may range from
greater than zero Hz to several thousand Hz. The maximum interaural
time difference may be chosen from .DELTA.t=10 to 1000 .mu.s, such
as about, 60, 90, 120, 150, 180 .mu.s. The phases are randomly
chosen for every signal from 0 to about 2.pi. and may be initially
coincident with one another. The sampling rate may be 48 kHz.
Noises may be generated with center frequencies of 490 Hz, 630 Hz,
800 Hz, 100 Hz and/or 1250 Hz. Phase shifted narrowband signals may
be combined to obtain single signals output by each
loudspeaker.
[0027] System 100 also includes a binaural detector 120 that is
adapted to transduce the audible first and second frequency
modulated noise signals received from the loudspeakers 110 and 115
to generate detected signals. The loudspeakers 110 and 115 and
binaural detector 120 may be disposed in a common loudspeakers-room
environment. The binaural detector 120 detects both noise signals.
If a sound source is closer to one ear of a listener than to the
other ear, the sounds generated by the sound source will arrive at
slightly different times at the respective ears. This difference in
arrival times is termed interaural time difference. Experiments
have shown that the interaural time difference as well as the
interaural level difference (caused by some shading due to the head
position), and the sound spectrum are the main clues for auditory
localization in three dimensions. The human auditory system
processes the respective qualities for auditory spatial perception.
Interaural time differences and interaural level differences are
present in the detected signals provided by the binaural detector
120 similar to the perception of a human listener.
[0028] The amount of listener envelopment may depend on the phase
shift between the interaural time difference noise signals and the
frequency distance of the narrowband noise signals. If two
narrow-band signals not within the same frequency band are
combined, a continuous increase of the perceived listener
envelopment with increasing phase shift occurs.
[0029] When incoming interaural time difference noise signals are
output by loudspeakers in a loudspeakers-room environment, the
surrounding surfaces will reflect, scatter and bundle sound signals
and mix phase relations. By this affect, the listener envelopment
is altered by the room. The phase information of the detected
signals may be determined and used to provide an indication of the
listener envelopment of the loudspeakers-room environment.
[0030] The detected signals are provided to an analyzer 125. The
analyzer 125 is adapted to determine objective listener envelopment
of the loudspeakers-room environment based on binaural activity of
at least two sub-bands of the detected signals. The binaural
activity represents a three-dimensional output obtained by
processing of the detected signals. The binaural activity obtained
by processing audio signals close to the processing of the human
auditory system may be seen as a measure for binaural neural
activity.
[0031] Determination of the objective listener envelopment by the
analyzer 125 may include execution of a correlation analysis of the
phase relationship of binaural activities in the two sub-bands.
Alternatively, or in addition, the analyzer 125 may determine the
binaural activity over time and the lateral deviation of the
sub-bands by combining the interaural time differences and the
interaural level differences of the sub-bands. Superposing periodic
parts of the binaural activities of different auditory frequency
bands and executing a pattern recognition using correlation
analysis allows reconstruction of sinusoidal fluctuations in those
sub-bands. A measure for the amount of listener envelopment may be
obtained by combining the temporal shift of the signal functions
and the auditory band distance.
[0032] The analyzer 125 may have additional functionality. The
binaural activity may be smoothed by the analyzer in time using a
floating rectangle or integration window. The floating rectangular
integration window may have a duration of about 10-200
milliseconds. The temporal smoothing may be used to model the
auditory processing of the human auditory system. The analyzer may
also operate to weight objective listener envelopment values using
a frequency-band weighting curve to obtain a single objective
listener envelopment value 130. The frequency-band weighting curve
may correspond to an equal loudness curve such as an ISO 226 or
468-weighting curve.
[0033] FIG. 2 is a second system 200 that may be used to determine
the listener envelopment of a loudspeakers-room environment. System
200 includes a processor 205 that may access memory storage 210.
Memory storage 210 may include software code that is executable by
the processor 205. The executable code may include sound generating
code 215, signal processing code 220, and analysis code 225. Memory
storage 210 may also include a data area 230 that is accessible to
the processor 205 to store and retrieve data used in executing the
software code.
[0034] The processor 205 executes the sound generating code 215 to
generate first and second frequency modulated electronic noise
signals. Digital values corresponding to the first and second
frequency modulated noise signals are provided to a
digital-to-analog converter 233. The output of the
digital-to-analog converter 233 may be provided to a sound
generator 235 that supplies the electronic first and second
frequency modulated noise signals to a first loudspeaker 240 and a
second loudspeaker, respectively. The electronic first and second
frequency modulated noise signals may be in the form of broadband
noise having sinusoidally varying interaural time differences and
may correspond to left and right stereo channels of the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi. f i
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00003## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. f i .DELTA. t sin ( 2
.pi. F M t F s ) ) , ##EQU00003.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index. Alternatively, the left and
right stereo channels may have the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi.
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00004## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. .DELTA. t sin ( 2 .pi.
F M t F s ) ) . ##EQU00004.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index.
[0035] The loudspeakers 240 and 245 transduce the first and second
electrical frequency modulated noise signals to audible signals.
Loudspeaker 240 may be used to transduce the first electrical
frequency modulated noise signal to a first audible frequency
modulated noise signal. Loudspeaker 245 may be used to transduce
the second electrical frequency modulated noise signal to a second
audible frequency modulated noise signal.
[0036] The audible signals from the loudspeakers 240 and 245 are
detected by a binaural detector 250 disposed in a loudspeakers-room
environment with the loudspeakers. The binaural detector 250
transduces the audible signals to electrical signals that may be
converted to digital signals by an analog-to-digital converter
255.
[0037] The converted digital signals may be stored in data area 230
for processing using the signal processing code 220. The detected
signals may be filtered to obtain sub-band signals for at least two
sub-bands of the detected signals. This filtering may be part of
the signal processing code 220, separate filtering code, and/or the
binaural detector 250. The filtering may simulate physiological
properties of a human ear.
[0038] The signal processing code 220, executable by the processor
205, may determine binaural activity in at least two sub-bands of
the detected signals and may determine binaural activity in some or
all sub-bands of the filtered detected signals. It may be used to
determine the interaural time differences and the interaural level
differences of the sub-bands of the detected signals. The
interaural time differences and the interaural level differences
may be combined through execution of the signal processing code 220
to obtain the binaural activity over time and lateral deviation for
each of the sub-bands.
[0039] Digital values corresponding to the binaural activity in
each of the sub-bands of the detected signals may be stored in data
area 230 for use by the processor 205 in execution of the analysis
code 225. The analysis code 225 is executed by the processor 205 to
determine objective listener envelopment of the loudspeakers-room
environment based on the binaural activity of at least two
sub-bands of the detected signal. Alternatively, all detected
sub-bands may be used to determine the objective listener
envelopment. The objective listener envelopment may be determined
by executing a correlation analysis of the phase relationship of
binaural activities in adjacent to sub-bands.
[0040] The analysis code 225 may also provide further
functionality. Execution of the analysis code 225 may be used to
smooth the binaural activity in time using a floating rectangular
integration window. The integration window may have a duration of
about 10-200 milliseconds. The analysis code 225 also may be
executed to weight objective listener envelopment values using a
frequency-band weighting curve to obtain a single objective
listener envelopment value.
[0041] FIG. 3 is a third system 300 that may be used to determine
listener envelopment of a loudspeakers-room environment. The system
300 includes first and second loudspeakers 305 and 310 that provide
first and second audible frequency modulated noise signals,
respectively. The audible noise signals are supplied to a
loudspeakers-room environment and may be in the form of broadband
noise having sinusoidally varying interaural time differences that
correspond to left and right stereo channels where:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi. f i
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00005## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. f i .DELTA. t sin ( 2
.pi. F M t F s ) ) , ##EQU00005.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index. Alternatively, the left and
right stereo channels may have the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi.
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00006## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. .DELTA. t sin ( 2 .pi.
F M t F s ) ) . ##EQU00006.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index.
[0042] The audible signals are detected and transduced to
electrical signals by a binaural detector 315. In system 300, the
binaural detector 315 includes a dummy head 320 having a first
microphone 325 disposed on the left side of the dummy head 320 and
to a second microphone 330 disposed on the right side of the dummy
head 320. Microphones 325 and 330 may be disposed in ear molds that
filter the audible signals to simulate the outer ear response of a
human being. Additionally, or in the alternative, the outer ear
response may be simulated using a head related transfer function
335.
[0043] The signal corresponding to the left outer ear response is
provided to a first bandpass filter bank 340 and the signal
corresponding to the right outer ear response is provided to a
second bandpass filter bank 345. The bandpass filter banks 340 and
345 may simulate the physiological response of the middle ear of a
human being. The output of each bandpass filter of the bandpass
filter banks 340 and 345 is provided to a respective half-wave
rectifier 350 and 355. The half-wave rectified signals are provided
to respective low pass filters 360 and 365. The half-wave
rectification and subsequent low pass filtering of each sub-band
signal provided from bandpass filter banks 340 and 345 may simulate
the physiological response of the inner ear of a human being.
[0044] The low pass filtered sub-band signals are provided to a
signal processor/analyzer 370. The signal processor/analyzer 370
may determine binaural activity of two or more sub-bands of the
detected binaural signal as filtered by the bandpass filter banks
340 and 345. The binaural activity may be determined for some or
all sub-bands of the bandpass filter banks 340 and 345. The signal
processor/analyzer 370 may determine the interaural time
differences and the interaural level differences of the sub-bands
and combine them to obtain the binaural activity over time and
lateral deviation for each of the sub-bands. The binaural activity
of the sub-bands may be smoothed in time using a floating
rectangular integration window. The window may have a duration of
about 10-200 milliseconds.
[0045] The binaural activity in at least two of the sub-bands may
be used by the signal processor/analyzer 370 to determine the
objective listener envelopment of the loudspeakers-room
environment. The objective listener envelopment may be determined
by executing a correlation analysis of the phase relationship of
binaural activities in the sub-bands. A monaural signal may be
provided at line 375 to supplement the binaural activity detection
and provide an estimate of the objective listener envelopment by
the signal processor/analyzer 370. A single objective listener
envelopment value may be determined by weighting objective listener
envelopment values using a frequency-band weighting curve.
[0046] FIG. 4 is a three-dimensional graph 400 of binaural activity
in sub-bands of a detected binaural signal over time that may occur
using the systems shown in FIG. 1 through FIG. 3. The binaural
activity in each of the sub-bands varies with time and corresponds
to the interaural time difference and/or interaural level
difference of the noise signals.
[0047] FIG. 5 is a system 500 employing multiple pairs of
loudspeakers that may be used to determine listener envelopment of
a loudspeakers-room environment. System 500 includes a first pair
of loudspeakers 505 and 510, and a second pair of loudspeakers 510
and 520. Loudspeaker 505 provides a first audible frequency
modulated noise signal and loudspeaker 510 provides a second
audible frequency modulated noise signal during a first time
interval to determine a first averaged listener envelopment value
for the loudspeakers-room environment. Loudspeaker 515 provides the
first audible frequency modulated noise signal and loudspeaker 520
provides the second audible frequency modulated noise signal during
a second time interval to determine a second averaged listener
envelopment value for the loudspeakers-room environment.
[0048] The averaged envelopment values are determined through
cooperation of the binaural detector 525 and analyzer 530. The
first averaged listener envelopment value and the second averaged
listener envelopment value are weighted by the analyzer 530
depending on the positions of the loudspeakers in the
loudspeakers-room environment to obtain a single weighted overall
objective listener envelopment value 535.
[0049] The first and second audible frequency modulated noise
signals may be broadband noise signals having sinusoidally varying
interaural time differences and may correspond to left and right
stereo channels of the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi. f i
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00007## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. f i .DELTA. t sin ( 2
.pi. F M t F s ) ) , ##EQU00007.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index. Alternatively, the left and
right stereo channels may have the form:
l ( t ) = i = 1 N A sin ( 2 .pi. f i t F s + .theta. i + .pi.
.DELTA. t sin ( 2 .pi. F M t F s ) ) ##EQU00008## r ( t ) = i = 1 N
A sin ( 2 .pi. f i t F s + .theta. i - .pi. .DELTA. t sin ( 2 .pi.
F M t F s ) ) . ##EQU00008.2##
respectively, where A corresponds to an amplitude, f.sub.i
corresponds to carrier frequencies, F.sub.M corresponds to a
modulation frequency, F.sub.s corresponds to a sampling rate,
respectively, .DELTA.t corresponds to a maximum interaural time
difference, and .theta..sub.i corresponds to arbitrary phases, and
t corresponds to a discrete time index.
[0050] FIG. 6 shows a process that may determine listener
envelopment of a loudspeakers-room environment. At 605, the process
binaurally detects first and second audible frequency modulated
noise signals. The binaural activities in the sub-bands of the
detected signals are determined at 610. The binaural activities are
used to determine objective listener envelopment of the
loudspeakers-room environment.
[0051] FIG. 7 shows a second process that may determine listener
envelopment of a loudspeakers-room environment. At 705, the process
generates first and second electronic frequency modulated noise
signals. The first and second electronic frequency modulated noise
signals are concurrently transduced into audible signals at 710. At
715 the binaural signals are audibly detected to obtain detected
signals. The detected signals are filtered at 720 to obtain
sub-band signals. The filtering at 720 may correspond to the
physiological response of a human ear to the noise signals. At 725,
the process determines the binaural activity of the sub-bands. The
objective listener envelopment of the loudspeakers-room environment
is determined based on the binaural activity in the sub-bands at
730.
[0052] FIG. 8 is a process that may implement the filtering
operations at 720 of FIG. 7. The process filters the detected
signals using a head-related transfer function at 805. The first
filtered signals are filtered using a filter function corresponding
to a human middle ear response to generate second filtered signals
at 810. The second filtered signals are filtered at 815 using a
filter function corresponding to a human inner ear response.
[0053] FIG. 9 is a process that may determine the binaural activity
of the sub-bands at 725 in FIG. 7. At 905, the process may
determine the interaural time difference and interaural level
difference for each detected subject-band of the detected signal.
The interaural time differences and the interaural level
differences are combined at 910 to obtain the binaural activity
over time and lateral deviation for each sub-band of the detected
signal.
[0054] FIG. 10 shows a process that may be used to obtain a single
averaged listener envelopment value. At 1005, the binaurally
detected signals are being passed filtered to generate signals in a
plurality of adjacent sub-bands. The listener envelopments for each
of the adjacent sub-bands signals are determined at 1010. At 1015,
the process determines a weighted average of listener envelopments
for the adjacent sub-band signals to obtain a single averaged
listener envelopment value. The weighting values may be based on
the frequency of the sub-band signals used to determine listener
envelopment values.
[0055] FIG. 11 shows a process that may obtain a single averaged
listener envelopment value in a system having multiple loudspeaker
pairs. At 1105, the process obtains a first averaged listener
envelopment value for first and second loudspeakers. The process
obtains a second averaged listener envelopment value for the third
and fourth loudspeakers at 1110. At 1115, the first and second
averaged listener envelopment values are weighted to obtain a
single weighted overall listener envelopment value. The weighting
of the first and second averaged listener envelopment values may be
based on the positions of the loudspeakers within the
loudspeakers-room environment.
[0056] The systems and processes may further comprise cutting of
the binaural activity at the edges using a cutting function with an
adaptive threshold. The listener envelopment of the generated noise
signals in this case may be determined based on the cut binaural
activity. Cutting the edges may be used to avoid side-lobes. The
higher the binaural activity density, the more side-lobes may
occur. And adaptive threshold depending on the activity density may
be used to suppress side-lobes. Single auditory events below the
adaptive threshold may be cut to weight lateral deviation of
binaural activity. a
[0057] The systems and processes may be implemented in hardware,
software, or a combination of hardware and software. The noise
signals may be generated using hardware, software executing noise
generation algorithms, hardware and/or software using noise
generation tables, and/or other noise signal generation mechanisms.
Filtering operations may be implemented using hardware filters,
software filters, or a combination of hardware and software
filters. Detection of the binaural activity may be implemented
using hardware and/or software, or a combination of both. Analysis
of the binaural activity may be implemented using hardware,
software, or a combination of both.
[0058] While various embodiments of the invention have been
described, it will be apparent to those of ordinary skill in the
art that many more embodiments and implementations are possible
within the scope of the invention. Accordingly, the invention is
not to be restricted except in light of the attached claims and
their equivalents.
* * * * *