Sound Noise Measurement

Question

I am trying to get a high-quality descriptor of the amount of static sound or noise present in an audio stream. The usual contents of a stream are voice or music.

I experimented with accepting stddev samples and this gives me some handle of voice presence or empty channel noise (i.e. high stddev usually indicates voice or music)

I wonder if anyone has any pointers to this.

Answer 1

Is the peak value of the response not responding? If you are looking at a signal from a good ADC, the surrounding level should be in 1 or 10 counts, while voice or music will stand in thousands of counts. Is there some kind of automatic gain control that makes this strategy inoperative?

- , RMS , RMS- (RMS = stddev). 3-5, , , RMS 1,4. , spectrum . , . , , . , x , , 0,5 , Matlab:

Sx = fft(x .* hann(length(x), 'periodic'))

HANN Hann , FFT . . , x /, RMS :

pk2rms = max(abs(Sx))/sqrt(sum(abs(Sx).^2)/length(Sx))

, RMS 3-5 ( ), / . , "" .

, Sx , :

Gxx = ((k-1)*Gxx + Sx.*conj(Sx))/k

Gxx , , . , ( ).

:
1. 0,5 x, , . , x . . , RMS-, , Sx, DC.
2. , k, . , k, . x.

Answer 2

. , , . . 60 ?

fft , , .