U.S. patent application number 14/181037 was filed with the patent office on 2014-09-18 for eyewear spectacle with audio speaker in the temple.
This patent application is currently assigned to KOPIN CORPORATION. The applicant listed for this patent is KOPIN CORPORATION. Invention is credited to Kenny W.Y. Chow, Dashen Fan, Kenneth A. Kokinakis, Sam So.
Application Number | 20140268016 14/181037 |
Document ID | / |
Family ID | 50179966 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140268016 |
Kind Code |
A1 |
Chow; Kenny W.Y. ; et
al. |
September 18, 2014 |
EYEWEAR SPECTACLE WITH AUDIO SPEAKER IN THE TEMPLE
Abstract
Audio eyewear includes a front frame and at least one side frame
member secured to the front frame for engaging a user's ear. The
side frame members have speakers therein that are oriented to
direct an audio port of the speaker face downwardly at an angle
away from at least one side frame member, thereby directing sound
downwardly and rearwardly into the users ear generally along the
vertical plane. Embodiments of the invention include microphones
for use in, for example, noise cancellation.
Inventors: |
Chow; Kenny W.Y.; (Hong
Kong, CN) ; Kokinakis; Kenneth A.; (Naples, FL)
; So; Sam; (Hong Kong, CN) ; Fan; Dashen;
(Bellevue, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOPIN CORPORATION |
WESTBOROUGH |
MA |
US |
|
|
Assignee: |
KOPIN CORPORATION
WESTBOROUGH
MA
|
Family ID: |
50179966 |
Appl. No.: |
14/181037 |
Filed: |
February 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61912844 |
Dec 6, 2013 |
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61780108 |
Mar 13, 2013 |
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61839211 |
Jun 25, 2013 |
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61839227 |
Jun 25, 2013 |
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Current U.S.
Class: |
351/158 ;
29/428 |
Current CPC
Class: |
H04R 3/005 20130101;
G10L 21/0208 20130101; H04R 1/028 20130101; G10K 11/002 20130101;
G02C 11/06 20130101; G10L 2021/02166 20130101; Y10T 29/49826
20150115; G02C 11/10 20130101 |
Class at
Publication: |
351/158 ;
29/428 |
International
Class: |
G02C 11/00 20060101
G02C011/00 |
Claims
1. Audio eyewear, comprising: a) a front frame; and b) at least one
side frame member secured to the front frame for engaging a user's
ear, the at least one side frame member having a speaker therein,
the speaker being oriented such that an audio port of the speaker
faces downwardly at an angle away from said at least one side frame
member, thereby directing sound downwardly rearwardly into said
user's ear generally along a vertical plane.
2. The eyewear of claim 1 in which said at least one side frame
member includes a relatively thick forward portion containing the
speaker, and a relatively thin rearward portion extending
rearwardly from the thick forward portion for engaging said user's
ear, the speaker being positioned at a downward facing lower
transition surface that narrows from the thick forward portion into
the thin rearward portion along a rearwardly extending upward
angle, and angles the audio port of speaker downwardly
rearwardly.
3. The eyewear of claim 2 in which the speaker is positioned within
a cavity defined by said at least one side frame member.
4. The eyewear of claim 2 in which the speaker defines a speaker
plane that is angled downwardly at least about 20 degrees relative
to a longitudinal plane of said at least one side frame member.
5. The eyewear of claim 3 in which the speaker is mounted against
an inner side of the lower transition surface with a sealing
arrangement, the lower transition surface defining audio openings
to thereby cause sound from the speaker to pass there through.
6. The eyewear of claim 1 in which said at least one side frame
member includes right and left side frame members secured to
opposite sides of the front frame, each side frame member having a
respective speaker therein.
7. The eyewear of claim 6 in which at least one of the right and
left side frame members and front frame contains at least one of
electronics, at least one microphone, and at least one battery.
8. The eyewear of claim 7 in which electrical signals from the
speakers and the at least one microphone are functionally linked to
a cell phone, and at least one of the electronics and software in
at least one of the eyewear and cell phone are capable of
automatically adjusting volume of the speakers according to ambient
noise measured by the microphones.
9. The eyewear of claim 8, wherein at least one of the left and
right side frame members and front frame includes an array of the
microphones, including at least a first microphone and a second
microphone, the first microphone coupled to at least one of the
left and right side frame members and the front frame about a
temple region of the user, the temple region being located
approximately between a top corner of a lens opening defined by the
front frame, and providing a first audio channel output, and the
second microphone coupled to at least one of the left and right
side frame members and front frame about an inner edge of the lens
opening and providing a second audio channel output.
10. The eyewear of claim 9, further including a digital signal
processor located at least one of the left and right side frame
members and the front frame member, the digital signal processor
including: a) a beam-former electronically linked to at least the
first and second audio channel outputs and output a main channel
and one or more reference channels; b) a voice activity detector
electronically linked to the main and reference channels and output
a desired voice activity channel; c) an adaptive noise canceller
electronically linked to the main, reference, and desired voice
activity channels and output an adaptive noise cancellation
channel; and d) a noise reducer electronically linked to the voice
activity detector of adaptive noise canceller to thereby receive
the desired voice activity and adaptive noise cancellation channels
and output a desired speech channel.
11. The eyewear device of claim 10, wherein the array of
microphones are digital microphones and the beam-former is a
digital beam-former.
12. The eyewear device of claim 9, wherein the array of microphones
further includes: a) a third microphone coupled to the eyeglasses
frame about an outer lower corner of the lens opening below the
first microphone and providing a third audio channel output; and b)
a fourth microphone coupled to the glasses frame about a bridge
support region above the second microphone and providing a fourth
audio channel output.
13. The eyewear device of claim 12, wherein the array of
microphones are omni-directional microphones.
14. The eyewear device of claim 13, wherein the omni-directional
microphones are any combination of the following: electret
condenser microphones, analog microelectromechanical systems (MEMS)
microphones, or digital MEMS microphones.
15. The eyewear device of claim 12, wherein the array of
microphones is coupled to the eyeglasses frame using at least one
flexible printed circuit board (PCB) strip.
16. The eyewear device of claim 15, wherein the array of
microphones is coupled to the eyeglasses frame using an upper
flexible PCB strip including the first and fourth microphones and a
lower flexible PCB strip including the second and third
microphones.
17. The eyewear device of claim 16, wherein: a) the eyeglasses
frame further includes an array of vents corresponding to the array
of microphones; b) the array of microphones are bottom port
microelectromechanical systems (MEMS) microphones; c) the first and
fourth MEMS microphones are coupled to the upper flexible PCB
strip; d) the second and third MEMS microphones are coupled to the
lower flexible PCB strip; and e) the array of MEMS microphones
being arranged such that the bottom ports receive acoustic signals
through the corresponding vents.
18. The eyewear device of claim 17, further including a membrane
sandwiched between the eyeglasses frame and the microphone.
19. The eyewear device of claim 18, wherein the membrane is a
wind-screen membrane and a water-proofing membrane.
20. The eyewear device of claim 1, further including an array of
microphones coupled to at least one of the front frame and the at
least one side frame member, the array of microphones including at
least a first and second microphone, the first microphone coupled
to the eyewear at a temple region, the temple region being located
approximately between a top corner of a lens opening defined by the
front frame and having an inner edge, and the at least one side
frame member, and the second microphone at an inner edge of the
lens opening, and providing a first and second audio channel output
from the first and second microphones, respectively.
21. The eyewear device of claim 20, further including a digital
signal processor having: a) a beam-former electronically linked to
the first and second microphones, for receiving at least the first
and second audio channels and outputting a main channel and one or
more reference channels; b) a voice activity detector
electronically linked to the beam-former, for receiving the main
and reference channels and outputting a desired voice activity
channel; c) an adaptive noise canceller electronically linked to
the beam-former and the voice activity detector for receiving the
main, reference, and desired voice activity channels and outputting
an adaptive noise cancellation channel; and d) a noise reducer
electronically linked to the voice activity detector and the
adaptive noise canceller for receiving the desired voice activity
and adaptive noise cancellation channels and outputting a desired
speech channel.
22. The eyewear device of claim 21, wherein at least one of the
beam-former, the voice activity detector, the adaptive noise
canceller and the noise reducer are integrated into at least one of
the front frame and the at least one side frame member.
23. The eyewear device of claim 1, further including a sound
channel member attached to said at least one side frame member for
directing sound from the speaker into said user's ear.
24. The eyewear of claim 23 in which the sound channel member
includes a sound deflecting surface that extends from an outer
surface of said at least one side frame member and over a portion
of said user's ear for channeling sound from the speaker into said
user's ear while also allowing ambient sound to be heard.
25. The eyewear of claim 23 in which the sound channel member
includes a sound tube mounted to the at least one side frame
member, and having an inlet opening for receiving sound from the
speaker and an outlet opening facing said user's ear for directing
the sound from the speaker to said user's ear.
26. A method of hearing audio, comprising the steps of: a)
providing audio eyewear frame having a front frame and at least one
side frame member secured to the front frame for engaging a user's
ear, the at least one side frame member having a speaker therein;
and b) orienting the speaker such that an audio port of the speaker
faces downwardly rearwardly at an angle away from said at least one
side frame member for directing sound downwardly rearwardly into
said user's ear generally along a vertical plane.
27. The method of claim 26, further including the steps of: a)
providing said at least one side frame member with a thick forward
portion containing the speaker, and a thin rearward portion
extending rearwardly from the thick forward portion for engaging
said user's ear; and b) positioning the speaker at a downward
facing lower transition surface that narrows from the thick forward
portion to the thin rearward portion along a rearwardly extending
upward angle, and angling the audio port of the speaker downwardly
rearwardly.
28. The method of claim 27, further including positioning the
speaker within a cavity formed within said at least one side frame
member.
29. The method of claim 28, further including mounting the speaker
against an inner side of the lower transition surface with a
sealing arrangement, the lower transition surface having audio
openings for allowing sound from the speaker to pass through.
30. The method of claim 27, further including angling a speaker
plane of the speaker downwardly at least about 20 degrees relative
to a longitudinal plane of said at least one side frame member.
31. The method of claim 26, further including providing right and
left side frame members secured to opposite sides of the front
frame, each side frame member having a respective speaker
therein.
32. The method of claim 31, further including containing within at
least one of the right and left side frame members and front frame,
and at least one of electronics, at least one microphone and at
least one battery.
33. The method of claim 32, further including linking electrical
signals from at least one of the speakers and the at least one
microphone to a cell phone, and with at least one of the
electronics and software in at least one of the eyewear and cell
phone, automatically adjusting volume of the speakers according to
ambient noise measured by the microphones.
34. The method of claim 26, further comprising the steps of: a)
coupling an array of microphones to the eyewear, the array of
microphones including at least a first and second microphone; b)
arranging the first microphone to couple to the eyewear about a
temple region, the temple region being located approximately
between a top corner of a lens opening and a support arm; c)
arranging the second microphone to couple to the eyewear frame
about an inner edge of the lens opening; and d) providing a first
and second audio channel output from the first and second
microphones, respectively.
35. The method of claim 34, further including the steps of: a)
forming beams at a beam-former, the beam-former receiving at least
the first and second audio channels and outputting a main channel
and one or more reference channels; b) detecting voice activity at
a voice activity detector, the voice activity detector receiving
the main and reference channels and outputting a desired voice
activity channel; c) adaptively cancelling noise at an adaptive
noise canceller, the adaptive noise canceller receiving the main,
reference, and desired voice activity channels and outputting an
adaptive noise cancellation channel; and d) reducing noise at a
noise reducer receiving the desired voice activity and adaptive
noise cancellation channels and outputting a desired speech
channel.
36. The method of claim 35, wherein the first and second audio
channels are produced digitally and the beams are formed
digitally.
37. The method of claim 34, further including the steps of: a)
arranging a third microphone to couple to the eyewear about an
outer lower corner of the lens opening below the first microphone;
b) arranging a fourth microphone to couple to the eyewear about a
bridge support region above the second microphone; and c) providing
a third and fourth audio channel output from the third and fourth
microphones, respectively.
38. The method of claim 37, wherein an array of omni-directional
microphones are coupled to the eyeglasses frame.
39. The method of claim 38, wherein the coupled array of
omni-directional microphones are any combination of the following:
electret condenser microphones, analog microelectromechanical
systems (MEMS) microphones, or digital MEMS microphones.
40. The method of claim 37, wherein coupling the array of
microphones to the eyewear uses at least one flexible printed
circuit board (PCB) strip.
41. The method of claim 40, wherein coupling the array of
microphones to the eyeglasses frame uses an upper flexible PCB
strip including the first and fourth microphones and a lower
flexible PCB strip including the second and third microphones.
42. The method of claim 41, wherein coupling the array of
microphones to the eyeglasses frame further includes the steps of:
a) coupling each microphone of the array of microphones to a
corresponding vent of an array of vents, the array of microphones
being bottom port or top port microelectromechanical system (MEMS)
microphones and the vents being located in the eyeglasses frame,
wherein the first and fourth MEMS microphones are coupled to the
upper flexible PCB strip and the second and third MEMS microphones
are coupled to the lower flexible PCB strip; and b) arranging the
array of MEMS microphones such that the ports received acoustic
signals through the corresponding vents.
43. The method of claim 42, further including coupling a membrane
between the eyeglasses frame and the microphones.
44. The method of claim 43, further including wind-screening and
water-proofing the array of microphones using the membrane, the
membrane being made of a wind-screen and water-proofing
material.
45. The method of claim 26, further including directing sound from
the speaker into said user's ear with a sound channel member
attached to said at least one side frame member.
46. The method of claim 45, further including channeling sound from
the speaker into said user's ear while also allowing ambient sound
to be heard with the sound channel member, the sound channel member
including a sound deflecting surface that extends from an outer
surface of said at least one side frame member and over a portion
of said user's ear.
47. The method of claim 45, further including directing the sound
from the speaker to said user's ear with the sound channel member,
the sound channel member including a sound tube mounted to the at
least one side frame member, and having an inlet opening for
receiving sound from the speaker and an outlet opening facing said
user's ear through which the sound exits.
Description
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/912,844, filed on Dec. 6, 2013. This application
also claims the benefit of U.S. Provisional Application No.
61/780,108, filed on Mar. 13, 2013. This application also claims
the benefit of U.S. Provisional Application No. 61/839,211, filed
on Jun. 25, 2013. This application also claims the benefit of U.S.
Provisional Application No. 61/839,227, filed on Jun. 25, 2013.
[0002] This application is being co-filed on the same day, Feb. 14,
2014, with "Eye Glasses With Microphone Array" by Dashen Fan,
Attorney Docket No. 0717.2220-001. This application is being
co-filed on the same day, Feb. 14, 2014, with "Sound Induction Ear
Speaker For Eye Glasses" by Dashen Fan, Attorney Docket No.
0717.2221-001. This application is being co-filed on the same day,
Feb. 14, 2014, with "Noise Cancelling Microphone Apparatus" by
Dashen Fan, Attorney Docket No. 0717.2216-001.
[0003] The entire teachings of the above applications are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0004] Traditionally, earphones have been used to present acoustic
sounds to an individual when privacy is desired or it is desired
not to disturb others. Examples of traditional earphone devices
include over-the-head headphones having an ear cup speaker (e.g.
Beats.RTM. by Dr. Dre headphones), ear bud style earphones (e.g.,
Apple iPod.RTM. earphones and Bluetooth.RTM. headsets),
bone-conducting speakers (e.g., Google Glass). Another known way to
achieve the desired privacy or peace and quiet for others is by
using directional multi-speaker beam-forming. Also well-known but
not conventionally used to present acoustic sounds to an individual
that is not hearing-impaired are hearing aids. An example of which
is the open ear mini-Behind-the-Ear (BTE) with Receiver-In-The-Aid
(RITA) device. Such a hearing aid typically includes a clear "hook"
that acts as an acoustic duct tube to channel audio speaker (also
referred to as a receiver in telephony applications) sound to the
inner ear of a user and act as the mechanical support so that the
user can wear the hearing aid, the speaker being housed in the
behind-the-ear portion of the hearing aid body. However, the
aforementioned techniques all have drawbacks, namely, they are
either bulky, cumbersome or unreliable.
[0005] Therefore, a need exists for earphones that overcome or
minimize the above-referenced problem.
SUMMARY OF THE INVENTION
[0006] The present invention generally is directed to audio eyewear
and methods of their use.
[0007] In one embodiment, the audio eyewear of the invention
includes a front frame and at least one temple or side frame member
secured to the front frame for engaging a user's ear. The at least
one side frame member has a speaker therein which can be oriented
such that an audio port of the speaker faces downwardly at an angle
away from the front frame and the at least one side frame member,
thereby directing sound downwardly rearwardly into the user's ear
generally along a vertical plane.
[0008] In a particular embodiment, the eyewear device further
includes an array of microphones coupled to at least one of the
front frame and at least one side frame member. The array of
microphones includes at least a first and second microphone. The
first microphone is located at a temple region between a top corner
of a lens opening defined by the front frame and having an inner
edge, and the at least one side frame member. The second microphone
is located at an inner edge of the lens opening. This embodiment of
the eyewear device also includes first and second audio channel
outputs from the first and second microphones, respectively.
[0009] In a still more particular embodiment of the invention, the
eyewear device additionally includes a beam-former electronically
linked to the first and second microphones, for receiving at least
the first and second audio channels and outputting the main channel
and one or more reference channels. A voice activity detector is
electronically linked to the beam-former for receiving the main and
reference channels and outputting the desired voice activity
channel. An adaptive noise canceler is electronically linked to the
beam-former and the voice activity detector for receiving the main,
reference and desired voice activity channels and outputting an
adaptive noise cancellation channel. The noise reducer is
electronically linked to the voice activity detector and the
adaptive noise canceller for receiving the desired voice activity
and adaptive noise cancellation channels and for outputting a
desired speech channel.
[0010] Still another embodiment of the invention is a method of
hearing audio, including the steps of providing audio eyewear
having a front frame and at least one side frame member secured to
the front frame for engaging a user's ear, the at least one side
frame member having a speaker therein, and orienting the speaker
such that an audio port of the speaker faces downwardly relatedly
at an angle away from said at least one side frame member for
directing sound downwardly rearwardly in to said users' ear
generally along the vertical frame.
[0011] In one embodiment of the method, an array of microphones is
coupled to the eyewear, wherein the array of microphones includes
at least a first and second microphone. The first microphone is
arranged to couple to the eyewear above the temple region, the
temple region being located approximately between the top corner of
a lens opening defined by the front frame and a support frame. The
second microphone is coupled to the eyewear frame about an inner
edge of the lens opening. First and second channel outputs are
provided from the first and second microphones, respectively.
[0012] In yet another embodiment of the method, the method further
includes the steps of forming beams at a beam-former, the
beam-former receiving at least the first and second audio channels
and outputting a main channel and one or more reference channels.
Voice activities are detected by a voice activity detector, wherein
the voice activity detector receives main and reference channels
and outputs a desired voice activity channel. Noise is adaptively
canceled at an adaptive noise canceller, the adaptive noise
canceller receiving the main, reference and desired voice activity
channels and outputting an adaptive noise cancellation channel.
Noise is then reduced at a noise reducer receiving the desired
voice activity and adaptive noise cancellation channels, and
outputting a desired speech channel.
[0013] The present invention has many advantages. For example, the
eyewear spectacle of the invention is relatively compact,
unobtrusive, and durable. Further, the device and method can be
integrated with noise cancellation apparatus and methods that are
also, optionally, components of the eyewear itself. In one
embodiment, noise cancellation apparatus, including microphones,
electrical circuitry, and software can be integrated with and,
optionally, on board the eyewear worn by the user. In another
embodiment, microphones mounted on board the eyewear can be
integrated with the speakers and with circuitry, such as a
computer, receiver or transmitter to thereby process signals
received from an external source or the microphones, or to process
and transmit signals from the microphone, and to selectively
transmit those signals, whether processed or unprocessed, to the
user of the eyewear through the speakers mounted in the eyewear.
For example, human-machine interaction through the use of a speech
recognition user interface is becoming increasingly popular. To
facilitate such human-machine interaction, accurate recognition of
speech is useful. It is also useful as a machine that can present
information to the user through spoken words, for example by
reading a text to the user. Such a machine output presentation
facilitates hands-free activities of a user, which is increasingly
popular. Users also do not have to hold a speaker or device in
place, nor do they need to have electronics behind their ear, or
earbuds blocking their ear. There are also no flimsy wires, and
users do not have to tolerate the skin contact or pressure
associated with the bone conduction speakers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1A is a perspective view of one embodiment of the
invention.
[0015] FIG. 1B is a perspective view from below of the embodiment
shown in FIG. 1A.
[0016] FIG. 1C is an elevated side-top view in perspective of the
embodiment of the invention shown in FIG. 1A.
[0017] FIG. 2 is a side view of the embodiment of FIGS. 1A-1C shown
being worn by a user.
[0018] FIG. 3 is a perspective view of a left side frame member of
the embodiment shown in FIGS. 1A-1C, wherein an interior panel has
been removed to show the speaker assembly within an audio chamber
defined by the left side frame member.
[0019] FIG. 4 is an exploded view of the left side frame member of
the embodiment shown in FIGS. 1A-1C, showing a speaker assembly,
also exploded, and a compartment cover for the side frame member
(missing from FIG. 3).
[0020] FIG. 5 is an elevated side view in perspective of another
embodiment of the eyewear of the invention, including sound tubes
to direct sound more approximately to the users audio canal.
[0021] FIG. 6 is a close-up view of the left side frame member of
the embodiment shown in FIG. 5, showing more particularly an exit
hole defined by the sound tube to direct sound toward the audio
canal of the user.
[0022] FIG. 7 is still another embodiment of the audio eyewear of
the invention, including a sound deflector for deflecting sound
from speakers within the side frame members toward the audio canal
of the wearer.
[0023] FIG. 8 is an illustration of an embodiment of an eyewear and
sound induction ear speaker device of the invention that includes
two remote microphones that are electronically linked with the
eyewear frame of the eyewear sound induction ear speaker
device.
[0024] FIG. 9 is an illustration of another embodiment of eyewear
of the invention that includes three remote microphones.
[0025] FIG. 10A is an exploded view of a rubber boot and
microphone, the rubber boot being suitable for use with the
microphone according to one embodiment of the invention.
[0026] FIG. 10B is a perspective view of the assembled rubber boot
shown in FIG. 10A.
[0027] FIG. 11 is a representation of another embodiment of the
invention showing alternate and optional placement positions of the
microphones.
[0028] FIG. 12 is a block diagram illustrating an example
embodiment of the noise cancellation circuit employed in one
embodiment of the eyewear sound induction user speaker device of
the invention.
[0029] FIG. 13 is a block diagram of a beam-forming module suitable
for use in the embodiment of the invention illustrated in FIG.
12.
[0030] FIG. 14 is a block diagram illustrating an example
embodiment of a desired voice activity detection module employed in
another embodiment of the eyewear sound induction ear speaker
device of the invention.
[0031] FIG. 15 is a block diagram illustrating an example
embodiment of a noise cancellation circuit employed in an
embodiment of the eyewear sound induction ear speaker device of the
invention.
[0032] FIG. 16 is an example embodiment of a boom tube housing
three microphones in an arrangement of one embodiment of the
eyewear sound induction ear speaker device of the invention.
[0033] FIG. 17 is an example embodiment of a boom tube housing four
microphones in an arrangement of another embodiment of the eyewear
sound induction ear speaker device of the invention.
[0034] FIG. 18 is a block diagram illustrating an example
embodiment of a beam-forming module accepting three signals and
another embodiment of the eyewear sound induction ear speaker
device of the invention.
[0035] FIG. 19 is a block diagram illustrating an example
embodiment of a desired voice activation detection module of yet
another embodiment of the eyewear sound induction ear speaker
device of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] The foregoing will be apparent from the following more
particular description of example embodiments of the invention, as
illustrated in the accompanied drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis being placed
upon illustrating embodiments of the present invention.
[0037] The invention generally is directed to audio eyewear and
methods of its use.
[0038] In one embodiment of the invention, shown in FIGS. 1A-1C,
audio eyewear 10 includes front frame 12. Side frame members 14, 16
are secured to front frame member 12. Side frame members 14, 16
include speakers (not shown) therein. The speakers are configured
so that audio ports of the speakers face downward at an angle away
from side frame members 14, 16, thereby directing sound downwardly
rearwardly into the users' ear generally along a vertical plane.
FIGS. 1B and 1C show alternate views of audio eyewear 10 of FIG.
1A.
[0039] In particular embodiments, such as is shown in FIG. 2, side
frame member 14, includes thick forward portion 24 containing
speaker 18, and thin rearward portion 26 extending rearwardly from
thick forward portion 24 for engaging the user's ear. Speaker 18
can be positioned within cavity 20 formed within the at least one
side frame member 14. As can be seen in FIG. 3 speaker 18 can be
positioned at a downward facing lower transition surface 28 that
narrows the thick forward portion 24 into the thin rearward portion
26 along a rearwardly extending upward angle 30, and angles audio
port 22 of speaker 18 downwardly rearwardly. Referring back to FIG.
2, speaker 18 is in speaker plane 34 that is normal to a sound
direction axis 36 of audio port 22 that is angled downwardly at
least about 20 degrees or greater (preferably about 20 to 70
degrees) relative to the horizontal or longitudinal plane of the at
least one side frame member 14, and represented by angle 30.
Referring back to FIG. 2, speaker 18 is mounted against inner 42
side of lower transition surface 28 with sealing arrangement 48.
Lower transition surface 28 defines audio openings 46 for allowing
sound from speaker 18 to pass through, as shown in FIG. 4, which is
an exploded view of left side frame 14. As shown therein, sealing
arrangement 48 seals speaker 18 and printed circuit board 50
between mask 52 and audio openings 46 with gasket 54 and sticky
gasket 56. Mask 52 is fabricated from a suitable material, such as
is known in the art, including, for example, rubber or silicone.
Gasket 54 and sticky gasket 56 are also fabricated from a suitable
material, such as is known in the art. Compartment cover 58
overlays sealing arrangement 48 and is secured to the remainder of
left side frame 14 by screws.
[0040] In some embodiments left 14 and right 16 frame members can
be secured to opposite sides of front frame 12. Each side frame
member 14, 16 has a respective speaker therein for providing sound
to both ears of the user. At least one of the right 16 and left 14
side frame members and front frame 12 can contain electronics,
microphones (not shown) and a battery (not shown). Electrical
signals from the speakers and the microphones can be connected to a
cell phone (not shown). At least one of the electronics and
software in at least one of eyewear 10 and the cell phone can
automatically adjust volume of the speakers according to ambient
noise measured by the microphones.
[0041] In another embodiment, shown in FIGS. 5 and 6, a sound tube
60 is attached to the at least one of side frame members 14, 16 for
directing sound from a speaker (not shown) in side frame member 14,
16 into the users' ear. Sound tube 60 is mounted to the at least
one side frame member 62 and defines inlet 64 opening for receiving
sound from the speaker, and an outlet opening facing the user's ear
for directing the sound from the speaker to the user's ear or into
the ear canal.
[0042] In another embodiment, shown in FIG. 7, sound deflecting
surface 66 extends from an outer surface of the at least one side
frame member 64 and over a portion of the user's ear for channeling
sound from a speaker (not shown) into the user's ear while also
allowing ambient sound to be heard. The sound channel members,
whether a sound tube or a sound deflecting surface are, in one
embodiment, removably attached by magnetic or mechanical attachment
fittings, and can be attached to both right and left side frame
members for directing sound to both ears.
[0043] The present invention can also provide a method of hearing
audio signals including, with reference to FIGS. 1-4, providing
audio eyewear 10 having a front frame 12 and at least one side
frame member 14, 16 secured to front frame 12 for engaging a user's
ear. Speaker 18, for example, is oriented such that audio port 22
of speaker 18, faces downwardly rearwardly at an angle 30 away from
the at least one side frame member 14, for directing sound
downwardly rearwardly into the user's ear generally along a
vertical plane.
[0044] FIG. 8 is a diagram 800 illustrating another example
embodiment of eye-glasses 802 of the invention having two embedded
microphones, in addition to the speakers and side frame members
discussed above. Eye-glasses 802 have two microphones 804 and 806,
a first microphone 804 being arranged in the middle of eye-glasses
802 frame and second microphone 806 being arranged on the side of
eye-glasses 802 frame. Microphones 804 and 806 can be
pressure-gradient microphone elements, either bi- or
uni-directional. Each microphone 804 and 806 is an assembly that
includes a microphone (not shown) within a rubber boot as further
described infra with reference to FIGS. 10A and 10B. The rubber
boot provides an acoustic port on the front and the back side of
the microphone with acoustic ducts. The two microphones 804 and 806
and their respective boots can be identical. Microphone elements
804 and 806 can be sealed air-tight (e.g., hermetically sealed)
inside the rubber boots. The acoustic ducts are filled with
wind-screen material. The ports are sealed with woven fabric
layers. The lower and upper acoustic ports are sealed with a
water-proof membrane. The microphones can be built into the
structure of the eye glasses frame. Each microphone has top and
bottom holes, being acoustic ports. In an embodiment, the two
microphones 804 and 806, which can be pressure-gradient microphone
elements, can each be replaced by two omni-directional
microphones.
[0045] FIG. 9 is a diagram 950 illustrating an example embodiment
of eye-glasses 952 having three embedded microphones. Each
pressure-gradient microphone element can be replaced with two
omni-directional microphones at the location of each acoustic port,
resulting in four total microphones. The signal from these two
omni-directional microphone can be processed by electronic or
digital beam-forming circuitry described above to produce a
pressure gradient beam pattern. This pressure gradient beam pattern
replaces the equivalent pressure-gradient microphone.
[0046] In an embodiment of the present invention, if a
pressure-gradient microphone is employed, each microphone is within
a rubber boot that extends an acoustic port on the front and the
back side of the microphone with acoustic ducts. At the end of
rubber boot, the new acoustic port is aligned with the opening in
the tube, where empty space is filled with wind-screen material. If
two omni-directional microphones are employed in place of one
pressure-gradient microphone, then the acoustic port of each
microphone is aligned with the opening.
[0047] In an embodiment, a long boom dual-microphone headset can
look like a conventional close-talk boom microphone, but is a big
boom with two-microphones in parallel. An end microphone of the
boom is placed in front of user's mouth. The close-talk long boom
dual-microphone design targets heavy noise usage in military,
aviation, industrial and has unparalleled noise cancellation
performance. For example, one main microphone can be positioned
directly in front of mouth. A second microphone can be positioned
at the side of the mouth. The two microphones can be identical with
identical casing. The two microphones can be placed in parallel,
perpendicular to the boom. Each microphone has front and back
openings. DSP circuitry can be in the housing between the two
microphones.
[0048] Microphone is housed in a rubber or silicon holder (e.g.,
the rubber boot) with an air duct extending to the acoustic ports
as needed. The housing keeps the microphone in an air-tight
container and provides shock absorption. The microphone front and
back ports are covered with a wind-screen layer made of woven
fabric layers to reduce wind noise or wind-screen foam material.
The outlet holes on the microphone plastic housing can be covered
with water-resistant thin film material or special water-resistant
coating.
[0049] In another embodiment, a conference gooseneck microphone can
provide noise cancellation. In large conference hall, echoes can be
a problem for sound recording. Echoes recorded by a microphone can
cause howling. Severe echo prevents the user from tuning up speaker
volume and causes limited audibility. Conference hall and
conference room can be decorated with expensive sound absorbing
materials on their walls to reduce echo to achieve higher speaker
volume and provide an even distribution of sound field across the
entire audience. Electronic echo cancellation equipment is used to
reduce echo and increase speaker volume, but such equipment is
expensive, can be difficult to setup and often requires an acoustic
expert.
[0050] In an embodiment, a dual-microphone noise cancellation
conference microphone can provide an inexpensive, easy to implement
solution to the problem of echo in a conference hall or conference
room. The dual-microphone system described above can be placed in a
desktop gooseneck microphone. Each microphone in the tube is a
pressure-gradient bi-directional, uni-directional, or
super-directional microphone.
[0051] In a head mounted computer, a user can desire a
noise-canceling close-talk microphone without a boom microphone in
front of his or her mouth. The microphone in front of the user's
mouth can be viewed as annoying. In addition, moisture from the
user's mouth can condense on the surface of the Electret Condenser
Microphone (ECM) membrane, which after long usage can deteriorate
microphone sensitivity.
[0052] In an embodiment, a short tube boom headset can solve these
problems by shortening the boom, moving the ECM away from the
user's mouth and using a rubber boot to extend the acoustic port of
the noise-canceling microphone. This can extend the effective
close-talk range of the ECM. This maintains the noise-canceling ECM
property for far away noises. In addition, the boom tube can be
lined with wind-screen form material. This solution further allows
the headset computer to be suitable for enterprise call center,
industrial, and general mobile usage. In an embodiment with
identical dual-microphones within the tube boom, the respective
rubber boots of each microphone can also be identical.
[0053] In an embodiment, the short tube boom headset can be a wired
or wireless headset. The headset includes the short microphone
(e.g., and ECM) tube boom. The tube boom can extend from the
housing of the headset along the user's cheek, where the tube boom
is either straight or curved. The tube boom can extend the length
of the cheek to the side of the user's mouth, for instance. The
tube boom can include a single noise-cancelling microphone on its
inside.
[0054] The boom tube can further include a dual microphone inside
of the tube. A dual microphone can be more effective in cancelling
out non-stationary noise, human noise, music, and high frequency
noises. A dual microphone can be more suitable for mobile
communication, speech recognition, or a Bluetooth headset. The two
microphones can be identical, however a person of ordinary skill in
the art can also design a tube boom having microphones of different
models.
[0055] In an embodiment having dual-microphones, the two
microphones enclosed in their respective rubber boats are placed in
series along the inside of the tube.
[0056] The tube can have a cylindrical shape, although other shapes
are possible (e.g., a rectangular prism, etc.). The short tube boom
can have two openings, one at the tip, and a second at the back.
The tube surface can be covered with a pattern of one or more holes
or slits to allow sound to reach the microphone inside the tube
boom. In another embodiment, the short tube boom can have three
openings, one at the tip, another in the middle, and another in the
back. The openings can be equally spaced, however, other a person
of ordinary skill in the art can design other spacings.
[0057] The microphone in the tube boom is a bi-directional
noise-cancelling microphone having pressure-gradient microphone
elements. The microphone can be enclosed in a rubber boot extending
acoustic port on the front and the back side of the microphone with
acoustic ducts. Inside of the boot, the microphone element is
sealed in the air-tight rubber boot.
[0058] Within the tube, the microphone with the rubber boot is
placed along the inside of the tube. An acoustic port at the tube
tip aligns with the boom opening, and an acoustic port at the tube
back aligns with boom opening. The rubber boot can be offset from
the tube ends to allow for spacing between the tube ends and the
rubber boot. The spacing further allows breathing room and for room
to place a wind-screen of appropriate thickness. The rubber boot
and inner wall of the tube remain air-tight, however. A wind-screen
foam material (e.g., wind guard sleeves over the rubber boot) fills
the air-duct and the open space between acoustic port and tube
interior/opening.
[0059] Referring to FIG. 9, the eye-glasses 952 of FIG. 9 are
similar to the eye-glasses 802 of FIG. 8, but instead employs three
microphones instead of two. The eye-glasses 952 of FIG. 9 have a
first microphone 954 arranged in the middle of the eye-glasses 952,
a second microphone 956 arranged on the left side of the
eye-glasses 952, and a third microphone 958 arranged on the right
side of the eye-glasses 952. The three microphones can be employed
in the three-microphone embodiment described above.
[0060] FIG. 10A is a diagram 1000 illustrating an example
embodiment of a rubber boot 1002a-b shown in an expanded view. The
rubber boot 1002a-b is separated into a first half of the rubber
boot 1002a and a second half of the rubber boot 1002b. Each rubber
boot 1002a-b is lined by a wind-screen 1008 material, however FIG.
10A shows the wind-screen in the second half of the rubber boot
1002b. In a pressure-gradient microphone, the air-duct and the open
space between acoustic port and boom interior is filled with
wind-screen foam material, such as wind guard sleeves over the
rubber boots.
[0061] A microphone 1004 is arranged to be played between the two
halves of the rubber boot 1002a-b. The microphone 1004 and rubber
boot 1002a-b are sized such that the microphone 1004 fits in a
cavity within the halves of the rubber boot 1002a-b. The microphone
is coupled with a wire 1006, that extends out of the rubber boot
1002a-b and can be connected to, for instance, the noise
cancellation circuit described above.
[0062] FIG. 10B is a diagram 1050 illustrating an example of a
rubber boot 1052. The rubber boot 1052 of FIG. 10B is shown to have
both halves joined together, where a microphone (not shown) is
inside. A wire 1056 coupled to the microphone exist the rubber boot
1052 such that it can be connected to, for instance, the noise
cancellation circuit described below, with reference to FIGS. 12
through 15.
[0063] FIG. 11 is an illustration of an embodiment of the invention
1100 showing various optional positions of placements of the
microphones 1104a-e. As described above, the microphones are
pressure-gradient. In an embodiment, microphones can be placed in
any of the locations shown in FIG. 11, or any combination of the
locations shown in FIG. 10. In a two-microphone system, the
microphone closest to the user's mouth is referred to as MIC1, the
microphone further from the user's mouth is referred to as MIC2. In
an embodiment, both MIC1 & MIC2 can be inline at position 1
1004a. In other embodiments, the microphones can be positioned as
follows: [0064] MIC1 at position 1 1104a and MIC2 at position 2
1104b; [0065] MIC1 at position 1 1104a and MIC2 at position 3
1104c; [0066] MIC1 at position 1 1104a and MIC2 at position 4
1104d; [0067] MIC1 at position 4 1104d and MIC2 at position 5
1104e; [0068] Both MIC1 and MIC2 at position 4 1104d.
[0069] If position 4 1104d has a microphone, it is employed within
a pendant.
[0070] The microphones can also be employed at other combinations
of positions 1104a-e, or at positions not shown in FIG. 11.
[0071] FIG. 12 is a block diagram 1200 illustrating an example
embodiment of a noise cancellation circuit employed in the present
invention. Signals 1210 and 1212 from two microphones are digitized
and fed into the noise cancelling circuit 1201. The noise
cancelling circuit 1201 can be a digital signal processing (DSP)
unit (e.g., software executing on a processor, hardware block, or
multiple hardware blocks). In an embodiment, the noise cancellation
circuit 1201 can be a digital signal processing (DSP) chip, a
system-on-a-chip (SOC), a Bluetooth chip, a voice CODEC with DSP
chip, etc. Noise cancellation circuit 1201 can be located in a
Bluetooth headset near the user's ear, in an inline control case
with battery, or inside the connector, etc. Noise cancellation
circuit 1201 can be powered by a battery or by a power source of
the device that the headset is connected to, such as the device's
batter, or power from a USB, micro-USB, or Lightening
connector.
[0072] Noise cancellation circuit 1201 includes four functional
blocks, all of which are electronically linked, either wirelessly
or by hard-wire: beam-forming (BF) module 1202, Desired Voice
Activity Detection (VAD) Module 1208, adaptive noise cancellation
(ANC) module 1204 and single signal noise reduction (NR) module
1206. Two signals 1210 and 1212 are fed into the BF module 1202,
which generates main signal 1230 and reference signal 1232 to the
ANC module 1204. A closer microphone signal 1210 is collected from
a microphone closer to the user's mouth and a further microphone
signal is collected from a microphone further from the user's
mouth, relatively. BF module 1202 also generates a main signal 1220
and reference signal 1222 for desired VAD module 1208. The main
signal 1220 and reference signal 1222 can, in certain embodiments,
be different from the main signal 1230 and reference signal 1232
generated for the for ANC module 1204.
[0073] The ANC module 1204 processes the main signal 1230 and the
reference signal 1232 to cancel out noises from the two signals and
output noise cancelled signal 1242 to single channel NR module
1206. Single signal NR module 1206 post-processes the noise
cancelled signal 1242 from the ANC module 1204 to remove any
further residue noise. Meanwhile, the VAD module 108 derives, from
the main signal 1220 and reference signal 1222, a desired voice
activity detection (DVAD) signal 1140 that indicates the presence
or absence of speech in the main signal 1220 and reference signal
1222. The DVADs signal 1240 can then be used to control the ANC
modules 1204 and the NR module 1206 from the result of BF modules
1202. The DVAD signal 1240 indicates to the ANC module 1204 and
Single Channel NR module 106 which sections of the signal have
voice data to analyze, which can increase the efficiency of
processing of the ANC module 1204 and single channel NR modules
1206 by ignoring sections of the signal without voice data. Desired
speech signal 1244 is generated by single channel NR module
1206.
[0074] In an embodiment, the BF modules 1202, ANC module 1204,
single NR reduction module 1206, and desired VAD module 1208
employs linear processing (e.g., linear filters). A linear system
(which employs linear processing) satisfies the properties of
superposition and scaling or homogeneity. The property of
superposition means that the output of the system is directly
proportional to the input. For example, a function F(x) is a linear
system if:
F(x.sub.1+x.sub.2+ . . . )=F(x.sub.1)+F(x.sub.2)+ . . .
[0075] A satisfies the property of scaling or homogeneity of degree
one if the output scales proportional to the input. For example, a
function F(x) satisfies the properties of scaling or homogeneity
if, for a scalar .alpha.:
F(.alpha.x)=.alpha.F(x)
[0076] In contract, a non-linear function does not satisfy both of
these conditions.
[0077] Prior noise cancellation systems employ non-linear
processing. By using linear processing, increasing the input
changes the output proportionally. However, in non-linear
processing, increasing the input changes the output
non-proportionally. Using linear processing provides an advantage
for speech recognition by improving feature extraction. Speaker
recognition algorithm is developed based on noiseless voice
recorded in quiet environment with no distortion. A linear noise
cancellation algorithm does not introduce nonlinear distortion to
noise cancelled speech. Speech recognition can deal with linear
distortion on speech, but not non-linear distortion of speech.
Linear noise cancellation algorithm is "transparent" to the speech
recognition engine. Training speech recognition on the variations
of nonlinear distorted noise is impossible. Non-linear distortion
can disrupt the feature extraction necessary for speech
recognition.
[0078] An example of a linear system is a Weiner Filter, which is a
linear single channel noise removal filter. The Wiener filter is a
filter used to produce an estimate of a desired or target random
process by linear time-invariant filtering an observed noisy
process, assuming known stationary signal, noise spectra, and
additive noise. The Wiener filter minimizes the mean square error
between the estimated random process and the desired process.
[0079] FIG. 13 is a block diagram 1300 illustrating an example
embodiment of a beam-forming module 1302 that can be employed in
noise cancelling circuit 1201 of FIG. 12. The BF module 1302
receives closer microphone signal 1310 and further microphone
signal 1312.
[0080] A further microphone signal 1312 is inputted to a frequency
response matching filter 1304. The frequency response matching
filter 1304 adjusts gain, phase, and shapes the frequency response
of the further microphone signal 1312. For example, the frequency
response matching filter 1304 can adjust the signal for the
distance between the two microphones, such that an outputted
reference signal 1332 representative of the further microphone
signal 1312 can be processed with the main signal 1330,
representative of the closer microphone signal 1310. The main
signal 1330 and reference signal 1332 are sent to the ANC
module.
[0081] Closer microphone signal 1310 is outputted to the ANC module
as a main signal 1330. Closer microphone signal 1310 is also
inputted to a low-pass filter 1306. Reference signal 1332 is input
to low-pass filter 1308 to create reference signal 1322 sent to the
Desired VAD module. Low-pass filters 1306 and 1308 adjust the
signal for a "close talk case" by, for example, having a gradual
low off from 2 kHz to 4 kHz, in one embodiment. Other frequencies
can be used for different designs and distances of the microphones
to the user's mouth, however.
[0082] FIG. 14 is a block diagram illustrating an example
embodiment of a Desired Voice Activity Detection Module 1402. The
DVAD module 1402 receives a main signal 1420 and a reference signal
1422 from the beam-forming module. The main signal 1420 and
reference signal 1422 are processed by respective short-time power
modules 1404 and 1406. The short-time power modules 1404 and 1406
can include a root mean square (RMS) detector, a power (PWR)
detector, or an energy detector. The short-time power modules 1404
and 1406 output signals to respective amplifiers 1408 and 1410. The
amplifiers can be logarithmic converters (or log/logarithmic
amplifiers). The logarithmic converters 1408 and 1410 output to a
combiner 1412. The combiner 1412 is configured to combine signals,
such as the main signal and one of the at least one reference
signals, to produce a voice activity difference signal by
subtracting the detection(s) of the reference signal from the main
signal (or vice-versa). The voice activity difference signal is
inputted into a single channel VAD module 1414. The single channel
VAD module can be a conventional VAD module. The single channel VAD
1414 outputs the desired voice activity signal.
[0083] FIG. 15 is a block diagram 1500 illustrating an example
embodiment of a noise cancellation circuit 1501 employed to receive
a closer microphone signal 1510 and a first and second further
microphone signal 1512 and 1514, respectively. The noise
cancellation circuit 1501 is similar to the noise cancellation
circuit 1201, described in relation to FIG. 12, however, the noise
cancellation circuit 1501 is employed to receives three signals
instead of two. A beam-forming (BF) module 1502 is arranged to
receive the signals 1510, 1512 and 1514 and output a main signal
1530, a first reference signal 1532 and second reference signal
1534 to an adaptive noise cancellation module 1504. The
beam-forming module is further configured to output a main signal
1522, first reference signal 1520 and second reference signal 1524
to a voice activity detection (VAD) module 1508.
[0084] The ANC module 1504 produces a noise cancelled signal 1542
to a Single Channel Noise Reduction (NR) module 406, similar to the
ANC module 1204 of FIG. 12. The single NR module 1506 then outputs
desired speech 1544. The VAD module 1508 outputs the DVAD signal to
the ANC module 1504 and the single channel NR module 1506.
[0085] FIG. 16 is an example embodiment of beam-forming from a boom
tube 1602 housing three microphones 1606, 1608, and 1610. A first
microphone 1606 is arranged closest to a tip 1604 of the boom tube
1602, a second microphone 1608 is arranged in the boom tube 1602
further away from the tip 1604, and a third microphone 1610 is
arranged in the boom tube 1602 even further away from the tip 1604.
The first microphone 1606 and second microphone 1608 are arranged
to provide data to output a left signal 1626. The first microphone
is arranged to output its signal to a gain module 1612 and a delay
module 1614, which is outputted to a combiner 1622. The second
microphone is connected directly to the combiner 1622. The combiner
1622 subtracts the two provided signals to cancel noise, which
creates the left signal 1626.
[0086] Likewise, the second microphone 1608 is connected to a gain
module 1616 and a delay module 1618, which is outputted to a
combiner 1620. The third microphone 1610 is connected directly to
the combiner 1620. The combiner 1620 subtracts the two provided
signals to cancel noise, which creates the right signal 1620.
[0087] FIG. 17 is an example embodiment of beam-forming from a boom
tube 1752 housing four microphones 1756, 1758, 1760 and 1762. A
first microphone 1756 is arranged closest to a tip 1754 of the boom
tube 1752, a second microphone 1758 is arranged in the boom tube
1752 further away from the tip 1754, a third microphone 1760 is
arranged in the boom tube 1752 even further away from the tip 1754,
and a fourth microphone 1762 is arranged in the boom tube 1752 away
from the tip 1754. The first microphone 1756 and second microphone
1758 are arranged to provide data to output a left signal 1786. The
first microphone is arranged to output its signal to a gain module
1772 and a delay module 1774, which is outputted to a combiner
1782. The second microphone is connected directly to the combiner
1758. The combiner 1782 subtracts the two provided signals to
cancel noise, which creates the left signal 1786.
[0088] Likewise, the third microphone 1760 is connected to a gain
module 1776 and a delay module 1778, which is outputted to a
combiner 1780. The fourth microphone 1762 is connected directly to
the combiner 1780. The combiner 1780 subtracts the two provided
signals to cancel noise, which creates the right signal 1784.
[0089] FIG. 18 is a block diagram 1800 illustrating an example
embodiment of a beam-forming module 1802 accepting three signals
1810, 1812 and 1814. A closer microphone signal 1810 is output as a
main signal 1830 to the ANC module and also inputted to a low-pass
filter 1817, to be outputted as a main signal 1820 to the VAD
module. A first further microphone signal 1812 and second closer
microphone signal 1814 are inputted to respective frequency
response matching filters 1806 and 1804, the outputs of which are
outputted to be a first reference signal 1832 and second reference
signal 1834 to the ANC module. The outputs of the frequency
response matching filters 1806 and 1804 are also outputted to
low-pass filters 1816 and 1818, respectively, which output a first
reference signal 1822 and second reference signal 1824,
respectively.
[0090] FIG. 19 is a block diagram 1900 illustrating an example
embodiment of a desired voice activity detection (VAD) module 1902
accepting three signals 1920, 1922 and 1924. The VAD module 1902
receives a main signal 1920, a first reference signal 1922 and a
second reference signal 1924 at short-time power modules 1904, 1905
and 1906, respectively. The short-time power modules 1904, 1905,
and 1906 are similar to the short-time power modules described in
relation to FIG. 14. The short-time power modules 1904, 1905, and
1906 output to respective amplifiers 1908, 1909 and 1910, which can
each be a logarithmic converter. Amplifiers 1908 and 1909 output to
a combiner module 1911, which subtracts the two signals and outputs
the difference to a single channel VAD module 1914. Amplifiers 1910
and 1908 output to a combiner module 1912, which subtracts the two
signals and outputs the difference to a single channel VAD module
1916. The single channel VAD modules 1914 and 1916 output to a
logical OR-gate 1918, which outputs a DVAD signal 1940.
[0091] The relevant teaching of all patents, published applications
and references cited herein are incorporated by reference in their
entirety.
[0092] While this invention has been particularly shown and
described with references to example embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *