Automatic microphone calibration for video teleconferencing

Details Automatic microphone calibration for video teleconferencing Automatic microphone calibration for video teleconferencing

1995-08-28

1998-12-01

Isen, Forester W.

Electrical audio signal processing systems and devices

Monitoring of sound

381107, 381110, 381 943, H04R 2900

Patent

active

058449949

ABSTRACT:
A method of automatically calibrating a microphone having a microphone input gain comprises the steps of receiving an input signal generated by the microphone in response to an audio input, sampling the input signal to produce a plurality of samples, detecting a plurality of instances of voice energy in the samples, creating a power density function (PDF) from the detected instances of voice energy, wherein the acquired signal level differs from a predefined voice reference level by an offset amount, and adjusting the value of the input gain so that the acquired signal level equals the predefined voice reference level. The step of detecting a plurality of instances of voice energy comprises the step of generating a noise floor by creating a noise power density function (NPDF) from the samples. The NPDF is based on a relationship between an approximate peak power level of the signal and a current power level of the signal and based on a plurality of standard deviation values of the signal, each of the standard deviation values corresponding to one of a plurality of time intervals. The NPDF is repeatedly updated to produce a current state of the NPDF to update the noise floor. If a predetermined relationship exists between the current power level of the audio signal and the updated noise floor, an instance of voice energy is detected.

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