Patent ID: 6968352

Claim:
A method for zeroing a portion of a time domain impulse response of a speech filter for zeroing a portion of a time domain impulse response of a filter in a speech transmission apparatus which filter has a frequency domain transfer function Z(k), said method comprising: implementing convolution with a function U on the frequency domain transfer function Z(k) where k lies in the range 0 to N−1, wherein the function U has the form: U ⁡ ( k ) = sin ⁢ ⁢ c ⁡ ( k - k 0 2 ) · ⅇ - jπ ⁡ ( a ⁡ ( k - k 0 ) 2 ) · P ⁡ ( k ) where α is a parameter, k 0 is a constant integer and P(k) is a weighting window that is symmetrical about k=k 0 .