Attorney Docket No. ALPH.P020
`
`Attorney Docket No. ALPH.P020
`
`Transmittal of Patent Application for Filing
`
`Certification Under 37 C.F.R. §I.JO (if applicable)
`
`EV 235 875 739 US
`
`"Express Mail" Label Number
`
`March 27, 2003
`Date of Deposit
`
`I hereby certify that this application, and any other documents referred to as enclosed herein are being deposited in an
`·ce under 37 CFR §1.10
`envelope with the United States Postal Service "Express Mail Post Office to Addressee" s
`on the date indicated above and addressed to the Assistant Comm· o
`for Patents, Was n on, D.C. 20231
`Richard L. Gregory, Jr.
`
`(Print Name of Person Mailing Application)
`
`Microphone and Voice Activity Detection (VAD) Configurations For Use With
`
`5
`
`10
`
`Communication Systems
`
`INVENTORS:
`
`GREGORY C. BURNETT
`NICOLAS J. PETIT
`ANDREW E. EINAUDI
`ALEXANDER M. ASSEIL Y
`
`RELATED APPLICATIONS
`
`This application claims priority from United States Patent Application Number
`
`60/368,209, entitled MICROPHONE AND VOICE ACTIVITY DETECTION (V AD)
`
`15
`
`CONFIGURATIONS FOR USE WITH PORTABLE COMMUNICATION SYSTEMS,
`
`filed March 27~ 2002, which is currently pending.
`
`Further, this application relates to the following United States Patent
`
`Applications: Application Number 09/905,361, entitled METHOD AND APPARATUS
`
`FOR REMOVING NOISE FRQM ELECTRONIC SIGNALS, filed July 12, 2001;
`
`20 Application Number 10/159,770, entitled DETECTING VOICED AND UNVOICED
`
`SPEECH USING BOTH ACOUSTIC AND NONACOUSTIC SENSORS, filed May 30, .
`
`2002; Application Number 10/301,237, entitled METHOD AND APPARATUS FOR
`
`REMOVING NOISE FROM ELECTRONIC SIGNALS, filed November 21, 2002; and
`
`Application number 10/383,162, entitled VOICE ACTIVITY DETECTION (VAD)
`
`1 .
`
`Amazon v. Jawbone
`U.S. Patent 8,280,072
`Amazon Ex. 1012
`
`

`

`Attorney Docket No. ALPH.P020
`
`DEVICES AND METHODS FOR USE WITH NOISE SUPPRESSION SYSTEMS,
`
`filed March 5, 2003.
`
`TECHNICAL FIELD
`
`5
`
`The disclosed embodiments relate to systems and methods for detecting and
`
`processing a desired acoustic signal in the presence of acoustic noise.
`
`BACKGROUND
`
`Many noise suppression algorithms and techniques have been developed over the
`
`10
`
`years. Most of the noise suppression systems in use today for speech communication
`
`systems are based on a single-microphone spectral subtraction technique first develop in
`
`the 1970's and described, for example, by S. F. Boll in "Suppression of Acoustic Nois~ in
`
`Speech using Spectral Subtraction," IEEE Trans. on ASSP, pp. 113-120, 1979. These
`
`techniques have been refined over the years, but the basic principles of operation have
`
`15
`
`remained the same. See, for example, United States Patent Number 5,687,243 of
`
`McLaughlin, et al., and United States Patent Number 4,811,404 ofVilmur, et al.
`
`Generally, these techniques make use of a single-microphone Voice Activity Detector
`
`(VAD) to determine the background noise characteristics, where "voice" is generally
`
`understood to include human voiced speech, unvoiced speech, or a combination of voiced
`
`20
`
`and unvoiced speech.
`
`The V AD has also been used in digital cellular systems. As an example of such a
`
`use, see United States Patent Number 6,453,291 of Ashley, where a VAD configuration
`
`appropriate to the front-end of a digital cellular system is described. Further, some Code
`
`Division Multiple Access (CDMA) systems utilize a VAD to minimize the effective radio
`
`25
`
`spectrum used, thereby allowing for more system capacity. Also, Global System for
`
`Mobile Communication (GSM) systems can include a V AD to reduce co-channel
`
`interference and to reduce battery consumption on the client or subscriber device.
`
`These typical singk-microphone V AD systems are significantly limited in
`
`capability as a result of the analysis of acoustic information received by the single
`
`30 microphone, wherein the analysis is performed using typical signal processing
`
`techniques. In particular, limitations in performance of these single-microphone VAD
`
`2
`
`

`

`Attorney Docket No. ALPH.P020
`
`systems are noted when processing signals having a low signal-to-noise ratio (SNR), and
`
`in settings where the background noise varies quickly. Thus, similar limitations are
`
`found in noise suppression systems using these single-microphone V ADs.
`
`Many limitations of these typical single-microphone V AD systems were
`
`5
`
`overcome with the introduction of the Pathfinder noise suppression system by Aliph of
`
`San Francisco, California (http://www.aliph.com), described in detail in the Related
`
`Applications. The Pathfinder noise suppression system differs from typical noise
`
`cancellation systems in several important ways. For example, it uses an accurate voiced
`
`activity detection (V AD) signal along with two or more microphones, where the
`
`10 microphones detect a mix of both noise and speech signals. While the Pathfinder noise
`
`suppression system can be used with apd integrated in a number of communication
`
`systems and signal processing systems, so can a variety of devices and/or methods be
`
`used to supply the V AD signal. Further, a number of microphone types and
`
`configurations can be used to provide acoustic signal information to the Pathfinder
`
`15
`
`system.
`
`3
`
`

`

`Attorney Docket No. ALPH.P020
`
`BRIEF DESCRIPTION OF THE FIGURES
`
`Figure 1 is a block diagram of a signal processing system including the Pathfinder
`
`noise removal or suppression system and a V AD system, under an embodiment.
`
`Figure lA is a block diagram of a noise suppression/communication system
`
`5
`
`including hardware for use in receiving and processing signals relating to V AD, and
`
`utilizing specific microphone configurations, under the embodiment of Figure 1.
`
`Figure lB is a block diagram of a conventional adaptive noise cancellation system
`
`of the prior art.
`
`Figure 2 is a table describing different types of microphones and the associated
`
`I O
`
`spatial responses in the prior art.
`
`Figure 3A shows a microphone configuration using a unidirectional speech
`
`microphone and an omnidirectional noise microphone, under an embodiment.
`
`Figure 3B shows a microphone configuration in a handset using a unidirectional
`
`speech microphone and an omnidirectional noise microphone, under the embodiment of
`
`15
`
`Figure 3A.
`
`Figure 3C shows a microphone configuration in a headset using a unidirectional
`
`speech microphone and an omnidirectional noise microphone, under the embodiment of
`
`Figure 3A.
`
`Figure 4A shows a microphone configuration using an omnidirectional speech
`
`20 microphone and a unidirectional noise microphone, under an embodiment.
`
`· Figure 4B shows a microphone configuration in a handset using an omnidirectional
`
`speech microphone and a unidirectional noise microphone, tinder the embodiment of
`
`Figure 4A.
`
`Figure 4C shows a microphone configuration in a headset using an omnidirectional
`
`25
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure4A.
`
`Figure SA shows a microphone configuration using an omnidirectional speech
`
`microphone and a unidirectional noise microphone, under an alternative embodiment.
`
`Figure SB shows a microphone configuration in a handset using an omnidirectional
`
`30
`
`speech microphone and a unidirectional noise microphone, under the embodiment of ·
`
`Figure 5A.
`
`4
`
`

`

`Attorney Docket No. ALPH.P020
`
`Figure SC shows a microphone configuration in a headset using an omnidirectional
`
`speech microphone and a unidirectional noise microphone,. under the embodiment of
`
`Figure 5A.
`
`Figure 6A shows a microphone configuration using a unidirectional speech
`
`5 microphone and a unidirectional noise microphone, under an embodiment.
`
`Figure 6B shows a microphone configuration in a handset using a unidirectional
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 6A.
`
`Figure 6C shows a microphone configuration in a headset using a unidirectional
`
`10
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 6A.
`
`Figure 7 A shows a microphone configuration using a unidirectional speech
`
`microphone and a unidirectional noise microphone, under an alternative embodiment.
`
`Figure 7B shows a microphone configuration in a handset using a unidirectional
`
`15
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 7A.
`
`Figure 7C shows a microphone configuration in a headset using a unidirectional
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 7A.
`
`20
`
`Figure 8A shows a microphone configuration usirig a unidirectional speech
`
`microphone and a unidirectional noise microphone, under an embodiment.
`
`Figure SB shows a microphone configuration in a handset using a unidirectional
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 8A.
`
`25
`
`Figure 8C shows a microphone configuration in a headset using a unidirectional
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 8A.
`
`Figure 9A shows a microphone configuration using an omnidirectional speech
`
`microphone and an omnidirectional noise microphone, under an embodiment.
`
`5
`
`

`

`Attorney Docket No. ALPH.P020
`
`Figure 9B shows a microphone configuration in a handset using an omnidirectional
`
`speech microphone and an omnidirectional noise microphone, under the embodiment of
`
`Figure 9A.
`
`Figure 9C shows a microphone configuration in a headset using an omnidirectional
`
`5
`
`speech microphone and an omnidirectional noise microphone, under the embodiment of
`
`Figure 9A.
`
`Figure lOA shows an area of sensitivity on the human head appropriate for
`
`receiving a GEMS sensor, under an embodiment.
`
`Figure 1 OB shows GEMS antenna placement on a generic handset or headset
`
`10
`
`device, under an embodiment.
`
`Figure llA shows areas of sensitivity on the human head appropriate for placement
`
`of an accelerometer/SSM, under an embodiment.
`
`Figure 11B shows accelerometer/SSM placement on a generic handset or headset
`
`device, under an embodiment.
`
`15
`
`In the drawings, the same reference numbers identify identical or substantially
`
`similar elements or acts. To easily identify the discussion of any particular element or
`
`act, the most significant digit or digits in a reference number refer to the~Figure number
`
`in which that element is first introduced (e.g., element 105 is first introduced and
`
`discussed with respect to Figure 1 ).
`
`20
`
`The headings provided herein are for convenience only and do not necessarily
`
`affect the scope or meaning of the claimed invention. The following description provides
`
`specific details for a thorough understanding of, and enabling description for,
`
`embodiments of the invention. However, one skilled in the art will understand that the
`
`invention may be practiced without these details. In other instances, well-known
`
`25
`
`structures and functions have not been shown or described in detail to avoid
`
`unnecessarily obscuring the description of the embodiments of the invention.
`
`6
`
`

`

`Attorney Docket No. ALPH.P020
`
`DETAILED DESCRIPTION
`
`Numerous communication systems are described below, including both handset
`
`and headset devices, which use a variety of microphone configurations to receive
`
`acoustic signals of an environment. The microphone configurations include, for example,
`
`5
`
`a two-microphone array including two unidirectional microphones, and a two(cid:173)
`
`microphone array including one unidirectional microphone and one omnidirectional
`
`microphone, but are not so limited. The communication systems can also include Voice
`
`J
`
`Activity Detection (VAD) devices to provide voice activity signals that include
`
`information of human voicing activity. Components of the communications systems
`
`10
`
`receive the acoustic signals and voice activity signals and, in response, automatically
`
`generate control signals from data of the voice activity signals. Components of the
`
`communication systems use the control signals to automatically select a denoising
`
`method appropriate to data of frequency subbands of the acoustic signals. The selected
`
`denoising method is applied to the acoustic signals to generate denoised acoustic signals
`
`15 when the acoustic signals include speech and noise.
`
`Numerous microphone configurations are described below for use with the
`
`Pathfinder noise suppression system. As such, each configuration is described in detail
`
`along wit.µ a method of use to reduce noise transmission in communication devices, in the
`
`context of the Pathfinder system. When the Pathfinder noise suppression system is
`
`20
`
`referred to, it should be kept in mind that noise suppression systems that estimate the
`
`noise waveform and subtract it from a signal and that use or are capable of using the
`
`disclosed microphone configurations and V AD information for reliable operation are
`
`included in that reference. Pathfinder is simply a convenient referenced implementation
`
`for a system that operates on signals comprising desired speech signals along with noise.
`
`25
`
`Thus, the use of these physical microphone configurations includes but is not limited to
`
`applications such as communications, speech recognition, and voice-feature control of
`
`applications and/or devices.
`
`The terms "speech" or "voice" as used herein generally refer to voiced, unvoiced,
`
`or mixed voiced and unvoiced human speech. Unvoiced speech or voiced speech is
`
`30
`
`distinguished where necessary. However, the term "speech signal" or "speech", when
`
`used as a converse to noise, simply refers to any desired portion of a signal and does not
`
`7
`
`

`

`Attorney Docket No. ALPH.P020
`
`necessarily have to be human speech. It could, as an example, be music or some other
`
`type of desired acoustic information. As used in the Figures, "speech" is meant to mean
`
`any signal of interest, whether human speech, music, or anything other signal that it is
`
`desired to hear.
`
`5
`
`In the same manner, "'noise" refers to unwanted acoustic information that distorts
`
`a desired speech signal or makes it more difficult to comprehend. "Noise suppression"
`
`generally describes any method by which noise is reduced or eliminated in an electronic
`
`signal.
`
`Moreover, the term "V AD" is generally defined as a vector or array signal, data,
`
`10
`
`or information that in some manner represents the occurrence of speech in the digital or
`
`analog domain. A common representation ofVAD information is a one-bit digital signal
`
`sampled at the same rate as the corresponding acoustic signals, with a zero value
`
`representing that no speech has occurred during the corresponding time ~ample, and a
`
`unity value indicating that speech has occurred during the corresponding time sample.
`
`15 While the embodiments described herein are generally described in the digital domain,
`
`the descriptions are also valid for the analog domain.
`
`The term "Pathfinder", unless otherwise specified, denotes any denoising system
`
`using two or more microphones, a V AD device and algorithm, and which estimates the
`
`noise in a signal and subtracts it from that signal. The Aliph Pathfinder system is simply
`
`20
`
`a convenient reference for this type of denoising system, although it is more capable than
`
`the above definition. In some cases (such as the microphone arrays described in Figures
`
`8 and 9), the "full capabilities" or "full version" of the Aliph Pathfinder system are used
`
`( as there is a significant amount of speech energy in the noise microphone), and these
`
`cases will be enumerated in the text. "Full capabilities" indicates the use of both H 1(z)
`
`25
`
`and H2(z) by the Pathfinder system in denoising the signal. Unless otherwise specified, it
`
`is assumed that only H 1(z) is used to denoise the signal.
`
`The Pathfinder system is a digital signal processing- (DSP) based acoustic noise
`
`suppression and echo-cancellation system. The Pathfinder system, which can couple to
`
`the front-end of speech processing systems, uses V AD information and received acoustic
`
`30
`
`information to reduce or eliminate noise in desired acoustic signals by estimating the
`
`8
`
`

`

`Attorney Docket No. ALPH.P020
`
`noise waveform and subtracting it from a signal including both speech and noise. The
`
`Pathfinder system is described further below and in the Related Applications.
`
`Figure 1 is a block diagram of a signal processing system 100 including the
`
`Pathfinder noise removal or suppression system 105 and a V AD system 106, under an
`
`5
`
`embodiment. The signal processing system 100 includes two microphones MIC 1 103
`
`and MIC 2 104 that receive signals or information from at least one speech signal source
`
`101 and at least one noise source 102. The path s(n) from the speech signal source 101 to
`
`MIC 1 and the path n(n) from the noise source 102 to MIC 2 are considered to be unity.
`
`Further, H 1(z) represents the path from the noise source 102 to MIC 1, and H2(z)
`represents the path from the speech signal source 101 to MIC 2.
`
`10
`
`Components of the signal processing system 100, for example the noise removal
`
`system 105, couple to the microphones MIC 1 and MIC 2 via wireless couplings, wired
`
`couplings, and/or a combination of wireless and wired couplings. Likewise, the VAD
`
`system 106 couples to components of the signal processing system 100, like the noise
`
`15
`
`removal system 105, via wireless couplings, wired couplings, and/or a combination of
`
`wireless and wired couplings. As an example, the V AD devices and microphones
`
`described below as components of the V AD system 106 can comply with the Bluetooth
`
`wireless specification for wireless communication with other components of the signal
`
`processing system, but are not so limited.
`
`20
`
`Figure lA is a block diagram of a noise suppression/communication system
`
`including hardware for use in receiving and processing signals relating to V AD, and
`
`utilizing specific microphone configurations, under an embodiment. Referring to Figure
`
`lA, each of the embodiments described below includes at least two microphones in a
`
`25
`
`specific configuration 110 and one voiced activity detection (V AD) system 130, which
`includes both a V AD device 140 and a V AD algorithm 150, as described in the Related
`Applications. Note that in some embodiments the microphone configuration 110 and the
`
`V AD device 140 incorporate the same physical hardware, but they are not so limited.
`
`Both the microphones 110 and the V AD 130 input information into the Pathfinder noise
`
`suppression system 120 which uses the received information to denoi.se the information
`
`30
`
`in the microphones and output denoised speech 160 into a communications device 170.
`
`9
`
`

`

`Attorney Docket No. ALPH.P020
`
`The communications device 1 70 includes both handset and headset communication
`
`devices, but is not so limited. Handsets or handset communication devices include, but
`
`are not limited to, portable communication devices that include microphones, speakers,
`
`communications electronics and electronic transceivers, such as cellular telephones,
`
`5
`
`portable or mobile telephones, satellite telephones, wireline telephones, Internet
`
`telephones, wireless transceivers, wireless communication radios, personal digital
`
`assistants (PDAs), and personal computers (PCs).
`
`Headset or headset communication devices include, but are not limited to, self(cid:173)
`
`contained devices including microphones and speakers generally attached to and/or worn
`
`10
`
`on the body. Headsets often function with handsets via couplings with the handsets,
`
`where the couplings can be wired, wireless, or a combination of wired and wireless
`
`connections. However, the headsets can communicate independently with components of
`
`a communications network.
`
`The V AD device 140 includes, but is not limited to, accelerometers, skin surface
`
`15 microphones (SSMs ), and electromagnetic devices, along with the associated software or
`
`algorithms. Further, the V AD device 140 includes acoustic microphones along with the
`
`associated software. The V AD devices and associated software are described in United
`
`States Patent Application number 10/383,162, entitled VOICE ACTIVITY DETECTION
`
`(V AD) DEVICES AND METHODS FOR USE WITH NOISE SUPPRESSION
`
`20
`
`SYSTEMS, filed March 5, 2003.
`
`The configurations described below of each handset/headset design include the
`
`location and orientation of the microphones and the method used to obtain a reliable
`
`V AD signal. All other components (including the speaker and mounting hardware for
`
`headsets and the speaker, buttons, plugs, physical hardware, etc. for the handsets) are
`
`25
`
`inconsequential for the operation of the Pathfinder noise suppression algorithm and will
`
`not be discussed in great detail, with the exception of the mounting of unidirectional
`
`microphones in the handset or headset. The mounting is described to provide information
`
`for the proper ventilation of the directional microphones. Those familiar with the state of
`
`· the art will not have difficulty mounting the unidirectional microphones correctly given
`
`30
`
`the placement and orientation information in this application.
`
`10
`
`

`

`Attorney Docket No. ALPH.P020
`
`Furthermore, the method of coupling ( either physical or electromagnetic or
`
`otherwise) of the headsets described below is inconsequential. The headsets described
`
`work with any type of coupling, so they are not specified in this disclosure. Finally, the
`
`microphone configuration 110 and the V AD 130 are independent, so that any microphone
`
`5
`
`configuration can work with any V AD device/method, unless it is desired to use the same
`
`microphones for both the V AD and the microphone configuration. In this cas·e the V AD
`
`can place certain requirements on the microphone configuration. These exceptions are
`
`noted in the text.
`
`10
`
`MICROPHONE CONFIGURATIONS
`
`The Pathfinder system, although using particular microphone types
`
`( omnidirectional or unidirectional, including the amount of unidirectionality) and
`
`microphone orientations, is not sensitive to the typical distribution of responses of
`
`individual microphones of a given type. Thus the microphones do not need to be
`
`15 matched in terms of frequency response nor do they need to be especially sensitive or
`
`expensive. In fact, configurations described herein have been constructed using
`
`inexpensive off-the-shelf microphones, which have proven to be very effective. As an
`
`aid to review, the Pathfinder setup is shown in Figure 1 and is explained in detail below
`
`and in the Related Applications. The relative placement and orientation of the
`
`20 microphones in the Pathfinder system is described herein. Unlike classical adaptive noise
`
`cancellation (ANC), which specifies that there can be no speech signal in the noise
`
`microphone, Pathfinder allows speech signal to be present in both microphones which
`
`means the microphones can be placed very close together, as long as the configurations in
`
`the following section are used. Following is a description of the microphone
`
`25
`
`configurations used to implement the Pathfinder noise suppression system.
`
`There are many different types of microphones in use today, but generally speaking,
`
`there are two main categories: omnidirectional (referred to herein as "OMNI
`
`microphones" or "OMNI") and unidirectional (referred to herein as "UNI microphones"
`
`or "UNI"). The OMNI microphones are characterized by relatively consistent spatial
`
`30
`
`response with respect to relative acoustic signal location, and UNI microphones are
`
`characterized by responses that vary with respect to the relative orientation of the
`
`11
`
`

`

`Attorney Docket No. ALPH.P020
`
`acoustic source and the microphone. Specifically, the UNI microphones are normally
`
`designed to be less responsive behind and to the sides of the microphone so that signals
`
`from the front of the microphone are emphasized relative to those from the sides and rear.
`
`There are several types of UNI microphones (although really only one type of
`
`5 OMNI) and the types are differentiated by the microphone's spatial response. Figure 2 is
`
`a table describing different types of microphones and the associated spatial responses
`
`(from the Shure microphone company website at http://www.shure.com). It has been
`
`found that both cardioid and super-cardioid unidirectional microphones work well in the
`
`embodiments described herein, but hyper-cardioid and bi-directional microphones may
`
`10
`
`also be used. Also, "close-talk" ( or gradient) microphones (which de-emphasize acoustic
`
`sources more than a few centimeters away from the microphone) can be used as the
`
`speech microphone, and for this reason the close-talk microphone is considered in this
`
`disclosure as a UNI microphone.
`
`15
`
`Microphone Arrays Including Mixed OMNI And UNI Microphones
`
`In an embodiment, an OMNI and UNI microphone are mixed to form a two(cid:173)
`
`microphone array for use with the Pathfinder system. The two-microphone array
`
`includes combinations where the UNI microphone is the speech microphone and
`
`combinations in which the OMNI microphone is the speech microphone, but is not so
`
`20
`
`limited.
`
`UNI Microphone As Speech Microphone
`
`With reference to Figure 1, in this configuration the UNI microphone is used as the
`
`speech microphone 103 and an OMNI is used as the noise microphone 104. They are
`
`25
`
`normally used within a few centimeters of each other, but can be located 15 or more ,
`
`centimeters apart and still function adequately. Figure 3A shows a general configuration
`
`300 using a unidirectional speech m1crophone and an omnidirectional noise microphone,
`
`under an embodiment. The relative angle/between a vector normal to the face of the
`
`microphones is approximately in the range of 60 to 135 degrees. The distances d 1 and d2
`are each approximately in the range of zero (0) to 15 centimeters. Figure 3B shows a
`
`30
`
`general configuration 310 in a handset using a unidirectional speech microphone and an
`
`12
`
`

`

`Attorney Docket No. ALPH.P020
`
`omnidirectional noise microphone, under the embodiment of Figure 3A. Figure 3C
`
`r
`shows a general configuration 320 in a headset using a unidirectional speech microphone
`
`and an omnidirectional noise microphone, under the embodiment of Figure 3A.
`
`The general configurations 310 and 320 show how the microphones can be oriented
`
`5
`
`in a general fashion as well as a possible implementation of this setup for a handset and a
`
`headset, respectively. The UNI microphone, as the speech microphone, points toward the
`
`· user's mouth. The OMNI has no specific orientation, but its location in this embodiment
`
`physically shields it from speech signals as much as possible. This setup works well for
`
`the Pathfinder system since the speech microphone contains mostly speech and the noise
`
`10 microphone mainly noise. Thus, the speech microphone has a high signal-to-noise ratio
`
`(SNR) and the noise microphone has a lower SNR. This enables the Pathfinder algorithm
`
`to be effective.
`
`OMNI Microphone As Speech Microphone
`
`15
`
`In this embodiment, and referring to Figure 1, the OMNI microphone is the speech
`
`microphone 103 and a UNI microphone is positioned as the noise microphone I 04. The
`
`reason for this is to keep the amount of speech in the noise microphone small so that the
`
`Pathfinder algorithm can be simplified and de-signaling (the undesired removal of
`
`speech) can be kept to a minimum. This configuration has the most promise for simple
`
`20
`
`add-ons to existing handsets, which already use an OMNI microphone to capture speech.
`
`Again, the two microphones can be located quite close together (within a few
`
`centimeters) or 15 centimeters or more away. The best performance is seen when the two
`
`microphones are quite close (less than approximately 5 cm), and the UNI is far enough
`
`away from the user's mouth (approximately in the range of 10 to 15 centimeters
`
`25
`
`depending on the microphone) so that the UNI directionality functions effectively.
`
`In this configuration where the speech microphone is an OMNI, the UNI is oriented
`
`in such a way as to keep the amount of speech in the UNI microphone small compared to
`
`the amount of speech in the OMNI. This means that the UNI will be oriented away from
`
`the speaker's mouth, and the amount it is oriented away from the speaker is denoted by f,
`
`· 30 which can vary between O and 180 degrees, where f 1escribes the angle between the
`
`direction of one microphone and the direction of another microphone in any plane.
`
`13
`
`

`

`Attorney Docket No. ALPH.P020
`
`Figure 4A shows a configuration 400 using an omnidirectional speech microphone
`
`and a unidirectional noise microphone, under an embodiment. The relative angle f
`
`between vectors normal to the faces of the microphones is approximately 180 degrees.
`
`The distance dis approximately in the range of zero (0) to 15 centimeters. Figure 4B
`
`5
`
`shows a general configuration 410 in a handset using an omnidirectional speech
`
`microphone and a unidirectional noise microphone, under the embodiment of Figure 4A.
`
`Figure 4C shows a general configuration 420 in a headset using an omnidirectional
`
`speech microphone and a unidirectional noise microphone, under the embodiment of
`
`Figure 4A.
`
`10
`
`Figure SA shows a configuration 500 using an omnidirectional speech microphone
`
`and a unidirectional noise microphone, under an alternative embodiment. The relative
`
`anglefbetween vectors normal to the faces of the microphones is approximately in a
`
`range between 60 and 135 degrees. The distances d1 and d2 are each approximately in the
`range of zero (0) to 15 centimeters. Figure 5B shows a general configuration 510 in a
`
`15
`
`handset using an omnidirectional speech microphone and a unidirectional noise
`
`microphone, under the embodiment of Figure 5A. Figure SC shows a general
`
`configuration 520 in a headset using an omnidirectional speech microphone and a
`
`unidirectional noise microphone, under the embodiment of Figure 5A.
`
`The embodiments of Figures 4 and 5 are such that the SNR of MIC 1 is generally
`
`20
`
`greater than the SNR of MIC 2. For large values off(around 180 degrees), the noise
`
`originating in front of the speaker may not be significantly captured, leading to slightly
`
`reduced denoising performance. In addition, if f gets too small, a significant amount of
`
`speech can be captured by the noise microphone, increasing the denoised signal distortion
`
`and/or computational expense. Therefore it is recommended for maximum performance
`
`25
`
`that the angle of orientation for the UNI microphone in this configuration to be
`
`approximately 60-135 degrees, as shown in Figure 5. This allows the noise originating
`
`from the front of the user to be captured more easily, improving the denoising
`
`performance. It also keeps the amount of speech signal captured by the noise
`
`microphone small so that the full capabilities of Pathfinder are not required. One skilled
`
`30
`
`in the art will be able to quickly determine efficient angles for numerous other
`
`UNI/OMNI combinations through simple experimentation.
`
`14
`
`

`

`Attorney Docket No. ALPH.P020
`
`Microphone Arrays Including Two UNI Microphones
`
`The microphone array of an embodiment includes two UNI microphones, where a
`
`first UNI microphone is the speech microphone and a second UNI microphone is the
`
`5
`
`noise microphone. In the following description the maximum of the spatial response of
`
`the speech UNI is assumed oriented toward the user's mouth.
`
`Noise UNI Microphone Oriented Away From Speaker
`
`Similar to the configurations described above with reference to Figures 4A, 4B,
`
`IO
`
`and 4C and Figures SA, 5B, and SC, orienting the noise UNI away from the speaker can
`
`reduce the amount of speech captured by the noise microphone, allowing for_ the use of
`
`the simpler version of Pathfinder that only uses the calculation of H 1(z) (as described
`
`below). Once again the angle of orientation with respect to the speaker's mouth can vary
`
`between approximately zero (0) and 180 degrees. At or near 180 degrees noise generated
`
`15
`
`from in front of the user may not be captured well enough by the noise microphone to
`
`allow optimal suppression of the noise. Therefore if this configuration is used, it will
`
`work best if a cardioid is used as the speech microphone and a super-cardioid as the noise
`
`microphone. This will allow limited capture of noise to the front of the user, increasing
`
`the noise suppression. However, more speech may be captured as well and can result in
`
`20
`
`de-si