Near-field vector signal enhancement

Abstract

Near-field sensing of wave signals, for example for application in headsets and earsets, is accomplished by placing two or more spaced-apart microphones along a line generally between the headset and the user's mouth. The signals produced at the output of the microphones will disagree in amplitude and time delay for the desired signal-the wearer's voice-but will disagree in a different manner forthe ambient noises. Utilization of this difference enables recognizing, and subsequently ignoring, the noise portion of the signals and passing a clean voice signal. A first approach involves a complex vector difference equation applied in the frequency domain that creates a noise-reduced result. A second approach creates an attenuation value that is proportional to the complex vector difference,and applies this attenuation value to the original signal in order to effect a reduction of the noise. The two approaches can be applied separately or combined.

Description

technical field [0001] The present invention relates to near field sensing systems. Background technique [0002] When communicating in noisy environmental conditions, the speech signal may be contaminated by simultaneously picking up ambient noise. Single-channel noise reduction methods are able to provide a measure of noise cancellation to separate and reduce noise by using prior knowledge about the difference between speech-like signals and noise signals. However, single-channel methods cannot be used when the "noise" includes other speech or speech-like signals. Furthermore, as the amount of noise removal increases, some speech signals are also removed, thereby changing the purity of the remaining speech signals—that is, the speech becomes distorted. Additionally, the residual noise in the output signal becomes more speech-like. These deficiencies reduce recognition accuracy when used with speech recognition software. [0003] Array techniques attempt to use spatial ...

AI Technical Summary

Problems solved by technology

These approaches introduce additional problems: near-field effects, severe wind noise sensitivity and electronic noise, frequency response coloration of far-field (noise) signals, the need for equalization filters, and if dual microphones are used electronically implemented, also requires the microphone to match the

Furthermore, among the many drawbacks, the ratio of noise attenuation to distance is limited and the residual noise in the output signal is strongly colored by

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