6. The audio signal segmentation algorithm according to claim 5 , further comprising: mixing the noise segment and the other noiseless speech/music segments, respectively, and repeating the audio activity detection step and the judging step to obtain a plurality of thresholds; and comparing the thresholds with the first threshold to choose a smallest value as the noise threshold.
5. The audio signal segmentation algorithm according to claim 1 , wherein the estimation of the noise threshold further comprises: extracting a noise segment from the initial part of the audio signal; mixing the noise segment with one of a plurality of noiseless speech/music segments to a predetermined signal-to-noise ratio (SNR) to form a mixing audio segment; applying the audio activity detection step to the mixing audio segment to divide the mixing audio segment into at least one speech segment and at least one music segment by using a first threshold; and judging if the speech segment and the music segment match the noiseless speech/music segment and obtaining a result, if the result is yes, the first threshold being equal to the noise threshold, and if the result is no, adjusting the first threshold and repeating the audio activity detection step and the judging step on the mixing audio segment.