Signal noise reduction by time-domain spectral subtraction using fixed filters

A method for suppressing a noise component of a communications signal, comprising the steps of:

• convolving the communications signal with a time-domain spectral subtraction gain function to provide a noise suppressed output signal;
• selecting a frequency-domain spectral subtraction gain function from a number of available spectral subtraction gain functions in dependence upon a value of the communications signal;
• and
• transforming the selected frequency-domain spectral subtraction gain function to provide the time-domain spectral subtraction gain function.

A telephone, comprising:

• a microphone receiving near-end sound and providing a corresponding near-end signal;
• and
• a spectral subtraction processor configured to suppress a noise component of the near-end signal, said spectral subtraction processor including
• a time-domain filter configured to convolve the near-end signal with a time-domain spectral subtraction gain function to provide a noise-reduced near-end signal,
• a spectral subtraction gain function processor configured to select a frequency-domain spectral subtraction gain function from a number of available spectral subtraction gain functions, and
• a transform processor configured to provide the time-domain spectral subtraction gain function by transforming the frequency-domain spectral subtraction gain function.