Noise threshold matrix for controlling audio processing
A telephone is operated in accordance with a matrix having as one column several zones of noise level, a second column a plurality of thresholds, and having a third column of noise cancellation coefficients. The level of noise in either the receive channel or the transmit channel of the telephone is detected and the telephone is operated in accordance with the data in the row corresponding to the noise level.
1 . A method for operating an audio processor having noise reduction circuitry, said method comprising the steps of:
defining a matrix having as one column several zones of noise level, a second column a plurality of thresholds, and having a third column of noise cancellation coefficients;
detecting the level of noise in a signal in the audio processor; and
operating the audio processor in accordance with the matrix.
2 . The method as set forth in claim 1 , wherein said audio process or includes a comfort noise generator, and further including the step of:
adjusting a threshold for inserting comfort noise in accordance with the matrix.
3 . The method as set forth in claim 1 and further including the step of:
controlling the amount of noise cancellation in accordance with the matrix.
4 . The method as set forth in claim 1 and further including the step of:
controlling the sensitivity of a receive/transmit state decision to the transmit signal in accordance with the matrix.
5 . The method as set forth in claim 1 wherein the matrix is 4×4.
6 . The method as set forth in claim 5 wherein the same entry appears more than once in a column of the matrix.
7 . A method for operating a telephone having an echo cancelling circuit and a comfort noise generator, said method comprising the steps of:
subtracting the amplitude of a signal at the output of the echo cancelling circuitry from a signal at the input of the echo cancelling circuit;
comparing the difference with a threshold;
coupling either the echo cancelling circuit or the comfort noise generator to an output depending upon the result of the comparison.
8 . The method as set forth in claim 7 wherein said telephone further includes a noise cancelling circuit coupled to the output of the echo cancelling circuit and further including the steps of:
defining a matrix having as one column several zones of noise level, a second column a plurality of thresholds, and having a third column of noise cancellation coefficients;
calculating average signal amplitude at the input of the echo cancelling circuit;
controlling the noise cancelling circuit in accordance with the matrix.