How to track no-sound area in a .wav file?

Question

How to track sections without sounds in a wav file?

A small software that I want to develop is dividing a wav file, and it consider a no volume area as a dividing point.

How can a program know that volume of a wav file is low? I'll use Java or MFC.

Answer 1

I've had success with silence detection by calculating RMS of the signal. This is done in the following manner (assuming you have an array of audio samples):

    long sumOfSquares = 0;
    for (int i = startindex; i <= endindex; i++) {
        sumOfSquares = sumOfSquares + samples[i] * samples[i];
    }
    int numberOfSamples = endindex - startindex + 1;
    long rms = Math.sqrt(sumOfSquares / (numberOfSamples));

if rms is below a certain threshold, you can consider it being silent.

Answer 2

Well, a wave file is basically a list of values, which represents a sound wave discretely divided with some rate (44100 Hz usually). Silence is basically when values are near 0. Just set some threshold value and look for continuous ( let's say 100ms length) regions where value is below that threshold.