Patent ID: 6032114
Filing Date: 2000-02-29
Classification: G10L

Abstract:
A method for reducing noise in an input speech signal, the method comprising the steps of:converting the input speech signal into a frequency spectrum;determining filter characteristics byobtaining a first value representing a ratio of a signal level of the frequency spectrum to an estimated noise level of a noise spectrum contained in the frequency spectrum from a table containing a plurality of pre-set signal levels of the frequency spectrum of the input speech signal and a plurality of pre-set estimated noise levels of the noise spectrum in order to determine an initial value of the filter characteristics, andobtaining a second value representing a maximum value of a ratio of a frame-based signal level of the frequency spectrum to a frame-based estimated noise level and the frame-based estimated noise level for variably controlling the filter characteristics; andreducing noise in the input speech signal by noise filtering using the determined filter characteristics, includingdecreasing the noise filtering when the frame-based signal level is greater than the frame-based estimated noise level, andincreasing the noise filtering when the frame-based signal level is less than the frame-based estimated noise level.