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Wireless telephone having multiple microphonesRelated Patent Categories: Electrical Audio Signal Processing Systems And Devices, Directive Circuits For MicrophonesWireless telephone having multiple microphones description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060133621, Wireless telephone having multiple microphones. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates generally to mobile telecommunication devices, and in particular to wireless telephones. [0003] 2. Background Art [0004] Background noise is an inherent problem in wireless telephone communication. Conventional wireless telephones include a single microphone that receives a near-end user's voice and outputs a corresponding audio signal for subsequent encoding and transmission to the telephone of a far-end user. However, the audio signal output by this microphone typically includes both a voice component and a background noise component. As a result, the far-end user often has difficulty deciphering the desired voice component against the din of the embedded background noise component. [0005] Conventional wireless telephones often include a noise suppressor to reduce the detrimental effects of background noise. A noise suppressor attempts to reduce the level of the background noise by processing the audio signal output by the microphone through various algorithms. These algorithms attempt to differentiate between a voice component of the audio signal and a background noise component of the audio signal, and then attenuate the level of the background noise component. [0006] Conventional wireless telephones often also include a voice activity detector (VAD) that attempts to identify and transmit only those portions of the audio signal that include a voice component. One benefit of VAD is that bandwidth is conserved on the telecommunication network because only selected portions of the audio signal are transmitted. [0007] In order to operate effectively, both the noise suppressor and the VAD must be able to differentiate between the voice component and the background noise component of the input audio signal. However, in practice, differentiating the voice component from the background noise component is difficult. [0008] What is needed then, is a wireless telephone that better mitigates the effect of background noise present in an input audio signal as compared to conventional wireless telephones, thereby resulting in the transmission of a cleaner voice signal during telephone communication. In particular, the desired wireless telephone should better differentiate between a voice component and a background noise component of an input audio signal as compared to conventional wireless telephones. Based on this differentiation, the improved wireless telephone should operate to cancel the background noise component of the audio signal. Additionally or alternatively, based on this differentiation, the improved wireless telephone should provide improved noise suppression and/or VAD functionality. BRIEF SUMMARY OF THE INVENTION [0009] The present invention is directed to a wireless telephone having a first microphone and a second microphone, wherein an audio signal output from the second microphone is used to differentiate between a voice component and a background noise component of an audio signal output from the first microphone. Based on this differentiation, a wireless telephone in accordance with an embodiment of the present invention operates to cancel the background noise component of the audio signal output from the first microphone. Additionally or alternatively, based on this differentiation, a wireless telephone in accordance with an embodiment of the present invention provides better noise suppression and/or VAD functionality. [0010] In particular, a wireless telephone in accordance with an embodiment of the present invention includes a first microphone, a second microphone, and a signal processor. The first microphone outputs a first audio signal that includes a voice component and a background noise component. The second microphone outputs a second audio signal. The signal processor increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal. [0011] In one embodiment of the present invention the signal processor includes a background noise cancellation module. The background noise cancellation module receives the first and second audio signals and cancels at least a portion of the background noise component of the first audio signal based on the content of the second audio signal to produce the third audio signal. [0012] In an alternative embodiment of the present invention the signal processor includes a noise suppressor. The noise suppressor receives the first and second audio signals and suppresses at least a portion of the background noise component of the first audio signal based on the content of the first audio signal and the second audio signal to produce the third audio signal. [0013] A wireless telephone in accordance with another embodiment-of the present invention includes a first microphone, a second microphone, and a voice activity detector (VAD). The first microphone outputs a first audio signal that includes a voice component and a background noise component. The second microphone outputs a second audio signal. The VAD receives the first and second audio signals and detects time intervals in which the voice component is present in the first audio signal based on the content of the first audio signal and the second audio signal. In an example embodiment, the VAD provides input to a transmitter relating to the time intervals in which a voice component is present in the first audio signal. The transmitter selectively transmits the first audio signal to another telephone responsive to the input. [0014] The present invention also provides a method for processing audio Signals in a wireless telephone having a first microphone and a second microphone. In an embodiment, the method includes outputting a first audio signal from the first microphone, wherein the first audio signal includes a voice component and a background noise component. A second audio signal is output from the second microphone. A ratio of the voice component to the noise component of the first audio signal is increased based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal. [0015] Increasing the ratio of the voice component to background noise component may include canceling at least a portion of the background noise component of the first audio signal based on the content of the second audio signal to produce the third audio signal. Alternatively, increasing the ratio of the voice component to background noise component may include suppressing at least a portion of the background noise component of the first audio signal based on the content of the first audio signal and the second audio signal to produce the third audio signal. [0016] A further method for processing audio signals in a wireless telephone having a first microphone and a second microphone in accordance with an embodiment of the present invention includes outputting a first audio signal from the first microphone, wherein the first audio signal comprises a voice component and a background noise component. A second audio signal is output from the second microphone. Time intervals in which the voice component is present in the first audio signal are detected based on the content of the first audio signal and the second audio signal. [0017] Further embodiments and features of the present invention, as well as the structure and operation of the various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES [0018] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. [0019] FIG. 1A is a functional block diagram of the transmit path of a Conventional wireless telephone. [0020] FIG. 1B is a functional block diagram of the receive path of a conventional wireless telephone. [0021] FIG. 2 is a schematic representation of the front portion of a wireless telephone in accordance with an embodiment of the present invention. 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