U.S. patent application number 14/863368 was filed with the patent office on 2016-06-16 for system and method for compressed audio enhancement.
The applicant listed for this patent is Psyx Research, Inc.. Invention is credited to Robert W. Reams.
Application Number | 20160171987 14/863368 |
Document ID | / |
Family ID | 56111772 |
Filed Date | 2016-06-16 |
United States Patent
Application |
20160171987 |
Kind Code |
A1 |
Reams; Robert W. |
June 16, 2016 |
SYSTEM AND METHOD FOR COMPRESSED AUDIO ENHANCEMENT
Abstract
A system for processing digitally-encoded audio data comprising
a compressed audio source device providing a sequence of frames of
compressed digital audio data. A compressed audio enhancement
system configured to receive the sequence of frames of compressed
digital audio data and to generate enhanced audio data by adding
masked digital audio data to the sequence of frames of compressed
digital audio data, where the masked digital audio data has an
energy level sufficient to keep a kinocilia of a listener active.
One or more speakers configured to receive the enhanced audio data
and to generate sound waves using the enhanced audio data.
Inventors: |
Reams; Robert W.; (Bellevue,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Psyx Research, Inc. |
Irvine |
CA |
US |
|
|
Family ID: |
56111772 |
Appl. No.: |
14/863368 |
Filed: |
September 23, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62092603 |
Dec 16, 2014 |
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62133167 |
Mar 13, 2015 |
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62156061 |
May 1, 2015 |
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62156065 |
May 1, 2015 |
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Current U.S.
Class: |
704/500 |
Current CPC
Class: |
H04N 21/439 20130101;
H04R 2225/43 20130101; H04R 2420/01 20130101; G10L 21/02 20130101;
G10L 21/034 20130101; H04R 3/00 20130101; H04R 25/356 20130101;
H04R 3/14 20130101; G10L 19/02 20130101; G10L 19/028 20130101; H04R
25/505 20130101; H04S 3/02 20130101; G10L 21/0364 20130101; G10L
25/06 20130101; H04N 5/60 20130101; H04N 5/52 20130101; H03G 5/165
20130101 |
International
Class: |
G10L 21/02 20060101
G10L021/02; G10L 21/034 20060101 G10L021/034; G10L 19/02 20060101
G10L019/02 |
Claims
1. A system for processing digitally-encoded audio data comprising:
a compressed audio source device providing a sequence of frames of
compressed digital audio data; a compressed audio enhancement
system configured to receive the sequence of frames of compressed
digital audio data and to generate enhanced audio data by adding
masked digital audio data to the sequence of frames of compressed
digital audio data, where the masked digital audio data has an
energy level sufficient to keep a kinocilia of a listener active;
and one or more speakers configured to receive the enhanced audio
data and to generate sound waves using the enhanced audio data.
2. The system of claim 1 wherein the compressed audio enhancement
system comprises a high pass filter configured to remove low
frequency components of the sequence of frames of compressed
digital audio data prior to generation of the enhanced audio
data.
3. The system of claim 1 wherein the compressed audio enhancement
system comprises a low pass filter configured to remove high
frequency components of the sequence of frames of compressed
digital audio data prior to generation of the enhanced audio
data.
4. The system of claim 1 wherein the compressed audio enhancement
system comprises a Hilbert transform configured to apply a phase
shift to the sequence of frames of compressed digital audio data
prior to generation of the enhanced audio data.
5. The system of claim 1 wherein the compressed audio enhancement
system comprises an absolute value processor configured to generate
an absolute value of the sequence of frames of compressed digital
audio data prior to generation of the enhanced audio data.
6. The system of claim 1 wherein generation of the enhanced audio
data comprises generating modulation distortion of the enhanced
audio data.
7. The system of claim 1 wherein generation of the enhanced audio
data comprises generating modulation distortion for one or more
frequency components of the enhanced audio data, wherein the
modulation distortion has a magnitude at least 13 dB lower than the
associated frequency component.
8. The system of claim 1 wherein generation of the enhanced audio
data comprises generating modulation distortion for one or more
frequency components of the enhanced audio data, the modulation
distortion having a frequency range centered at each of the
associated frequency components, wherein the modulation distortion
has a magnitude at least 13 dB lower than the associated frequency
component.
9. The system of claim 1 wherein the compressed audio enhancement
system comprises a downward expander.
10. The system of claim 1 wherein the compressed audio enhancement
system comprises a downward expander having an attack time of less
than one millisecond.
11. A method for processing digitally-encoded audio data
comprising: receiving digitally encoded audio data at an audio
processing system; modifying the digitally encoded audio data to
add additional perceptually-masked audio data having an energy
sufficient to prevent kinocilia of a listener from becoming
dormant; and generating sound waves with a sound wave generating
device using the modified digitally encoded audio data.
12. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises filtering low frequency
components of the digitally encoded audio data from the digitally
encoded audio data.
13. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises filtering high frequency
components of the digitally encoded audio data from the digitally
encoded audio data.
14. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises applying a Hilbert
transform to the digitally encoded audio data.
15. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises determining an absolute
value of the digitally encoded audio data.
16. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises adding modulation
distortion to the digitally encoded audio data.
17. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises processing the digitally
encoded audio data with a downward expander.
18. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises processing the digitally
encoded audio data with a downward expander having an attack time
of less than 1 millisecond.
19. The method of claim 11 wherein modifying the digitally encoded
audio data to add the additional perceptually-masked audio data
having the energy sufficient to prevent the kinocilia of the
listener from becoming dormant comprises adding modulation
distortion to the digitally encoded audio data having a magnitude
of at least 13 dB less than a magnitude of an associated audio
frequency component.
20. In a system for processing digitally-encoded audio data that
has a compressed audio source device providing a sequence of frames
of compressed digital audio data, a compressed audio enhancement
system configured to receive the sequence of frames of compressed
digital audio data and to generate enhanced audio data by adding
masked digital audio data to the sequence of frames of compressed
digital audio data, where the masked digital audio data has an
energy level sufficient to keep a kinocilia of a listener active,
one or more speakers configured to receive the enhanced audio data
and to generate sound waves using the enhanced audio data, a high
pass filter configured to remove low frequency components of the
sequence of frames of compressed digital audio data prior to
generation of the enhanced audio data, a low pass filter configured
to remove high frequency components of the sequence of frames of
compressed digital audio data prior to generation of the enhanced
audio data, a Hilbert transform configured to apply a phase shift
to the sequence of frames of compressed digital audio data prior to
generation of the enhanced audio data, an absolute value processor
configured to generate an absolute value of the sequence of frames
of compressed digital audio data prior to generation of the
enhanced audio data, wherein generation of the enhanced audio data
comprises generating modulation distortion of the enhanced audio
data, wherein generation of the enhanced audio data comprises
generating modulation distortion for one or more frequency
components of the enhanced audio data, wherein generation of the
enhanced audio data comprises generating modulation distortion for
one or more frequency components of the enhanced audio data, the
modulation distortion having a frequency range centered at each of
the associated frequency components, wherein the modulation
distortion has a magnitude at least 13 dB lower than the associated
frequency component, wherein the compressed audio enhancement
system comprises a downward expander having an attack time of less
than one millisecond, a method, comprising: receiving digitally
encoded audio data at an audio processing system; modifying the
digitally encoded audio data to add additional perceptually-masked
audio data having an energy sufficient to prevent kinocilia of a
listener from becoming dormant; generating sound waves with a sound
wave generating device using the modified digitally encoded audio
data; filtering low frequency components of the digitally encoded
audio data from the digitally encoded audio data; filtering high
frequency components of the digitally encoded audio data from the
digitally encoded audio data; applying a Hilbert transform to the
digitally encoded audio data; determining an absolute value of the
digitally encoded audio data; adding modulation distortion to the
digitally encoded audio data; processing the digitally encoded
audio data with a downward expander having an attack time of less
than 1millisecond; and adding modulation distortion to the
digitally encoded audio data having a magnitude of at least 13 dB
less than a magnitude of an associated audio frequency component.
Description
RELATED APPLICATIONS
[0001] The present application claims priority to and benefit of
U.S. Provisional Patent Application No. 62/092,603, filed on Dec.
16, 2014, U.S. Provisional Patent Application No. 62/133,167, filed
on Mar. 13, 2015, U.S. Provisional Patent Application No.
62/156,061, filed on May 1, 2015, and U.S. Provisional Patent
Application No. 62/156,065, filed on May 1, 2015, each of which are
hereby incorporated by reference for all purposes as if set forth
herein in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates generally to audio
processing, and more specifically to a system and method for
compressed audio enhacement that improves the perceived quality of
the compressed audio signal to the listener.
BACKGROUND OF THE INVENTION
[0003] Compressed audio data is notoriously poor in quality.
Despite this problem, no known solutions exist to improve the
listener experience.
SUMMARY OF THE INVENTION
[0004] A system for processing digitally-encoded audio data is
provided that includes a compressed audio source device providing a
sequence of frames of compressed digital audio data. A compressed
audio enhancement system receives the sequence of frames of
compressed digital audio data and generates enhanced audio data by
adding masked digital audio data to the sequence of frames of
compressed digital audio data, where the masked digital audio data
has an energy level sufficient to keep a kinocilia of a listener
active. One or more speakers configured to receive the enhanced
audio data and to generate sound waves using the enhanced audio
data.
[0005] Other systems, methods, features, and advantages of the
present disclosure will be or become apparent to one with skill in
the art upon examination of the following drawings 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 present disclosure, and be
protected by the accompanying claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0006] Aspects of the disclosure can be better understood with
reference to the following drawings. The components in the drawings
are not necessarily to scale, emphasis instead being placed upon
clearly illustrating the principles of the present disclosure.
Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the several views, and in which:
[0007] FIG. 1 is a diagram of a frequency diagram showing the
effect of compressed audio processing in accordance with the
present disclosure;
[0008] FIG. 2 is a diagram of a system for enhancing compressed
audio data with controlled modulation distortion in accordance with
an exemplary embodiment of the present disclosure;
[0009] FIG. 3 is a diagram of a system for providing modulation
distortion in accordance with an exemplary embodiment of the
present disclosure; and
[0010] FIG. 4 is a diagram of an algorithm for processing
compressed audio data to provide kinocilia stimulation, in
accordance with an exemplary embodiment of the present
disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0011] In the description that follows, like parts are marked
throughout the specification and drawings with the same reference
numerals. The drawing figures might not be to scale and certain
components can be shown in generalized or schematic form and
identified by commercial designations in the interest of clarity
and conciseness.
[0012] FIG. 1 is a diagram of a frequency diagram 100 showing the
effect of compressed audio processing in accordance with the
present disclosure. Frequency diagram 100 shows a frequency
distribution for compressed audio data with frequency components at
+/-Fl, F2 and F3. These frequency components are relatively sparse.
Frequency diagram 100 also shows a frequency distribution for
enhanced compressed audio data with frequency components centered
at +/-Fl, F2 and F3 and associated modulation distortion components
in a range around the centered frequency components. Although the
modulation distortion components are represented as having an
essentially flat profile, a Gaussian distribution, an exponential
decay or any suitable profile can also or alternatively be used.
The magnitude of the modulation distortion components is also at
least 13 dB below the signal magnitude, in order to mask the
modulation distortion components from perception by the user.
[0013] Typically, modulation distortion is avoided. However, the
present disclosure recognizes that kinocilia require a certain
level of stimulation to remain in an active state, and otherwise
will go into a dormant state, until a threshold level of audio
energy causes them to switch from the dormant state to the active
state. By generating modulation distortion, the kinocilia can be
stimulated to remain in the active state, even if the audio signals
are masked by being more than 13 dB in magnitude relative to a
major frequency component. The use of modulation distortion in this
manner enhances the audio listening experience, because the
kinocilia remain active and can detect frequency components of the
compressed audio data that would otherwise not have sufficient
energy to switch them out of the dormant state.
[0014] FIG. 2 is a diagram of a system 200 for enhancing compressed
audio data with controlled modulation distortion in accordance with
an exemplary embodiment of the present disclosure. System 200
includes compressed audio source device 202, compressed audio
enhancement 204 and speakers 206, each of which are specialized
devices or apparatuses that can be implemented in hardware or a
suitable combination of hardware and software.
[0015] As used herein, "hardware" can include a combination of
discrete components, an integrated circuit, an application-specific
integrated circuit, a field programmable gate array, or other
suitable hardware. As used herein, "software" can include one or
more objects, agents, threads, lines of code, subroutines, separate
software applications, two or more lines of code or other suitable
software structures operating in two or more software applications,
on one or more processors (where a processor includes a
microcomputer or other suitable controller, memory devices,
input-output devices, displays, data input devices such as a
keyboard or a mouse, peripherals such as printers and speakers,
associated drivers, control cards, power sources, network devices,
docking station devices, or other suitable devices operating under
control of software systems in conjunction with the processor or
other devices), or other suitable software structures. In one
exemplary embodiment, software can include one or more lines of
code or other suitable software structures operating in a general
purpose software application, such as an operating system, and one
or more lines of code or other suitable software structures
operating in a specific purpose software application. As used
herein, the term "couple" and its cognate terms, such as "couples"
and "coupled," can include a physical connection (such as a copper
conductor), a virtual connection (such as through randomly assigned
memory locations of a data memory device), a logical connection
(such as through logical gates of a semiconducting device), other
suitable connections, or a suitable combination of such
connections.
[0016] Compressed audio source device 202 provides a stream of
digitally-encoded audio data, such as frames of encoded digital
data, from a memory storage device such as a random access memory
that has been configured to store digitally-encoded audio data,
from an optical data storage medium that has been configured to
store digitally-encoded audio data, from a network connection that
has been configured to provide digitally-encoded audio data, or in
other suitable manners. Compressed audio source device 302 can be
implemented as a special purpose device such an audio music player,
a cellular telephone, an automobile audio system or other suitable
audio systems that are configured to provide streaming compressed
audio data.
[0017] Compressed audio enhancement 204 is coupled to compressed
audio source device 202, such as by using a wireless or wireline
data communications medium. Compressed audio enhancement 204
enhances the compressed audio data for a listener by introducing
modulation distortion or by otherwise introducing audio signal
components that are masked by the compressed audio signal data but
which are of sufficient magnitude to stimulate the kinocilia of the
listener, so as to prevent the kinocilia from switching to a
dormant state that requires a substantially higher amount of energy
to switch back to an active state than might be provided by the
compressed audio data at any given instant. By keeping the
kinocilia in an active state, compressed audio enhancement 204
improves the ability of the listener to hear the audio signals
encoded in the compressed audio data.
[0018] Speakers 206 receive the enhanced compressed audio data and
generate sound waves that can be perceived by a listener. Speakers
206 can be implemented as mono speakers, stereo speakers, N.1
surround speakers, automobile speakers, headphone speakers,
cellular telephone speakers, sound bar speakers, computer speakers
or other suitable speakers.
[0019] In operation, system 200 enhances compressed and
digitally-encoded audio data by introducing additional frequency
components that are masked by the compressed and digitally-encoded
audio data, but which are of a sufficient magnitude to keep the
listener's kinocilia active. In this manner, the listener is able
to hear additional compressed and digitally-encoded audio data
signals that would otherwise not be perceived, which results in an
improved listening experience.
[0020] FIG. 3 is a diagram of a system 300 for providing modulation
distortion in accordance with an exemplary embodiment of the
present disclosure. System 300 includes high pass filter 302, low
pass filter 304, Hilbert transform 306, summation unit 308, high
pass filter 310 and modulation distortion 312, each of which can be
implemented in hardware or a suitable combination of hardware and
software.
[0021] High pass filter 302 is configured to receive compressed and
digitally-encoded audio data signals and to filter out low
frequency components from the signal. In one exemplary embodiment,
high pass filter 302 can be implemented as a high-pass order 1
Butterworth filter having a 118 Hz corner frequency, using the
Audio Weaver design environment from DSP Concepts or other suitable
design environments, hardware or hardware and software.
[0022] Low pass filter 304 is coupled to high pass filter 302 and
is configured to receive the filtered, compressed and
digitally-encoded audio data signals and to filter out high
frequency components from the signal. In one exemplary embodiment,
low pass filter 304 can be implemented as a low-pass order 4
Butterworth filter having a 10400 Hz corner frequency, using the
Audio Weaver design environment from DSP Concepts or other suitable
design environments, hardware or hardware and software.
[0023] Hilbert transform 306 is coupled to low pass filter 304 and
is configured to receive the filtered, compressed and
digitally-encoded audio data signals and to apply a Hilbert
transform to the signal. In one exemplary embodiment, Hilbert
transform 306 can be implemented using the Audio Weaver design
environment from DSP Concepts or other suitable design
environments, hardware or hardware and software, and can receive a
split output from low pass filter 304 and can apply a Hilbert +/-90
degree phase shift to each output.
[0024] Summation unit 308 is coupled to Hilbert transform 306 and
is configured to square each split output signal and to then take
the square root of the sum, in order to obtain an absolute value of
the signal.
[0025] High pass filter 310 is coupled to summation unit 308 and is
configured to filter out low frequency components from the signal.
In one exemplary embodiment, high pass filter 310 can be
implemented as a high-pass order 2 Butterworth filter having a 1006
Hz corner frequency, using the Audio Weaver design environment from
DSP Concepts or other suitable design environments, hardware or
hardware and software.
[0026] Modulation distortion 312 is coupled to high pass filter 310
and is configured to receive the filtered and compressed audio
signal data and to add modulation distortion to the data. In one
exemplary embodiment, modulation distortion 312 can be implemented
using a downward expander of the Audio Weaver design environment
from DSP Concepts or other suitable design environments, hardware
or hardware and software. In this exemplary embodiment, the
downward expander can be implemented as a software system operating
on a specialized processor that has a plurality of settings, such
as a threshold setting, a ratio setting, a knee depth setting, an
attack time setting, a decay time setting and other suitable
settings. These settings can be selected to optimize the generation
of modulation distortion in the vicinity of the frequency
components of the compressed audio data, such as by setting the
threshold setting to a range of -23 dB +/-20%, the ratio setting to
range of 1.0 to 1.016 dB/dB +/-20%, the knee depth setting to 0 dB
+/-20%, the attack time setting to 0.01 milliseconds +/-20%, the
decay time setting to 3 milliseconds +/-20% or in other suitable
manners. In general, the attack time may have the greatest
influence on generation of phase distortion, and a setting of 1
millisecond or less can be preferable. These exemplary settings can
result in the generation of modulation distortion, which is
typically avoided, but which is used in this exemplary embodiment
specifically to cause the compressed and digitally-encoded audio
data to have modulation distortion signals that are below a
perceptual threshold by virtue of being masked by the encoded
signal components. As the encoded signal components change over
time, the kinocilia in the frequency range surrounding the encoded
signal components are stimulated enough to prevent them from
switching from an active state to a dormant state, thus ensuring
that they are able to detect encoded audio signals that are at a
magnitude that would otherwise be insufficient to cause dormant
kinocilia to switch to an active state. The output of modulation
distortion 312 can be provided to an amplifier, a speaker or other
suitable devices.
[0027] In operation, system 300 provides optimal audio signal
processing for compressed audio data to provide a level of
modulation distortion that is below a perceptual level but which is
sufficient to improve the quality of the listening experience, by
providing sufficient stimulation to the kinocilia to prevent them
from switching from an active to a dormant state. In this manner,
the listening experience is improved, because the listener can
perceive audio signals that would otherwise not be perceived.
[0028] FIG. 4 is a diagram of an algorithm 400 for processing
compressed audio data to provide kinocilia stimulation, in
accordance with an exemplary embodiment of the present disclosure.
Algorithm 400 can be implemented in hardware or a suitable
combination of hardware and software, and can be one or more
software systems operating on a special purpose processor.
[0029] Algorithm 400 begins at 402, where compressed audio data is
received from a source device. In one exemplary embodiment, a frame
of the compressed audio data can be received at an input port to an
audio data processing system and stored to a buffer device, such as
random access memory that has been configured to store audio data.
In addition, a processor can be configured to sense the presence of
the audio data, such as by checking a flag or other suitable
mechanism that is used to indicate that audio data is available for
processing. The algorithm then proceeds to 404.
[0030] At 404, low frequency components are removed from the audio
data. In one exemplary embodiment, a high pass filter can be used
to filter out low frequency components from the audio data, such as
a high-pass order 1 Butterworth filter having a 118 Hz corner
frequency or other suitable filters. The filtered audio data can
then be stored in a new buffer, in the same buffer or in other
suitable manners. The algorithm then proceeds to 406.
[0031] At 406, high frequency components are removed from the audio
data. In one exemplary embodiment, a low pass filter can be used to
filter out high frequency components from the signal, such as a
low-pass order 4 Butterworth filter having a 10400 Hz corner
frequency or other suitable filters. The filtered audio data can
then be stored in a new buffer, in the same buffer or in other
suitable manners. The algorithm then proceeds to 408.
[0032] At 408, Hilbert filtering is performed on the low pass
filtered data, to generate two sets of data having a +/-90 degree
phase shift. The Hilbert filtered audio data can then be stored in
a new buffer, in the same buffer or in other suitable manners. The
algorithm then proceeds to 410.
[0033] At 410, the absolute value of the signal is obtained, such
as by using a summation unit that is configured to square each set
of data and to then take the square root of the sum, in order to
obtain an absolute value of the signal, or in other suitable
manners. The absolute value audio data can then be stored in a new
buffer, in the same buffer or in other suitable manners. The
algorithm then proceeds to 412.
[0034] At 412, the absolute value data is filtered to remove low
frequency components from the signal, such as by using a high-pass
order 2 Butterworth filter having a 1006 Hz corner frequency or in
other suitable manners. The filtered audio data can then be stored
in a new buffer, in the same buffer or in other suitable manners.
The algorithm then proceeds to 414.
[0035] At 414, modulation distortion is generated in the audio
data, such as by processing the audio data using a downward
expander having a threshold setting of -23 dB, a ratio setting of
1.016 dB/dB, a knee depth setting of 0 dB, an attack time setting
of 0.01 milliseconds, a decay time setting of 3 milliseconds or
other suitable settings. These exemplary settings can result in the
generation of modulation distortion, which is typically avoided,
but which is used in this exemplary embodiment specifically to
cause the compressed and digitally-encoded audio data to have
modulation distortion signals that are below a perceptual threshold
by virtue of being masked by the encoded signal components. As the
encoded signal components change over time, the kinocilia in the
frequency range surrounding the encoded signal components are
stimulated enough to prevent them from switching from an active
state to a dormant state, thus ensuring that they are able to
detect encoded audio signals that are at a magnitude that would
otherwise be insufficient to cause dormant kinocilia to switch to
an active state. The algorithm then proceeds to 416.
[0036] At 416, the processed audio data is output to an amplifier,
a speaker or other suitable devices. In one exemplary embodiment,
the processed audio data can be stored in a buffer and can be
retrieved periodically for provision to a digital signal processor,
a digital to analog converter, an amplifier or other suitable
devices for generation of an analog signal that is provided to
speakers.
[0037] It should be emphasized that the above-described embodiments
are merely examples of possible implementations. Many variations
and modifications may be made to the above-described embodiments
without departing from the principles of the present disclosure.
All such modifications and variations are intended to be included
herein within the scope of this disclosure and protected by the
following claims.
* * * * *