Patent ID: 6983242

Claim:
A method for classifying a speech signal having a background noise portion with a background noise level, the method comprising the steps of: extracting a parameter from the speech signal; estimating a noise component of the parameter; removing the noise component from the parameter to generate a noise-free parameter; selecting a pre-determined threshold, wherein the step of selecting said pre-determined threshold is unaffected by said background noise level; comparing the noise-free parameter with a said pre-determined threshold; and associating the speech signal with a class in response to the comparing step; wherein the extracting step extracts a plurality of parameters and the steps of estimating, removing selecting, comparing and associating are performed for each of the plurality of parameters, wherein the plurality of parameters include a spectral tilt parameter, a pitch correlation parameter and an absolute maximum parameter, and wherein said spectral tilt parameter is weighted to generate a noise-free spectral tilt parameter during the step of removing, said pitch correlation parameter is weighted to generate a noise-free pitch correlation parameter during the step of removing and said absolute maximum parameter is weighted to generate a noise-free absolute maximum parameter during the step of removing.