Why to multiply all audio input with 1000/sqrt(sumsofInputSquare/datalength)

Question

My thesis is about voice segeration. I am reading a code which has been used in this field. It most probably not needed but here is the fullCode

I can't understand something which owner code did ,

if ((fp = fopen(filename, "r")) == NULL){
    printf("Cannot open input file!\n");
    exit(0);
}

while (!feof(fp))
{
    float f;
    fscanf(fp, "%f\n", &f);
    Input[SigLength]=f;
    SigLength++;
}
fclose(fp);

float sumE=0;
for(int n=0; n<SigLength; n++)
    sumE += Input[n]*Input[n];

sumE /= float(SigLength);

for(int n=0; n<SigLength; n++)
    Input[n] *= 1000/sqrt(sumE);

return(1000/sqrt(sumE));

He opens a file which has DB of sound like 48, 200 etc..

My question why he is doing the process below ? To apply just logic is common in sound analysis ?

for(int n=0; n<SigLength; n++)
    Input[n] *= 1000/sqrt(sumE);

This question appears to be off-topic because it is not about electronic design. — Leon Heller, Sep 07 '13 at 14:17
@Leon please tell me which stackexchange site would be more appropriate? I thought because it is part of DSP project, this place would be best. — Kadir Erdem Demir, Sep 07 '13 at 14:22
Looks like they are calculating and multibying by [RMS](https://en.wikipedia.org/wiki/Root_mean_square) (root mean square) — jippie, Sep 07 '13 at 14:25
@jippie yes , I am tring to understand why. Ignacio's answer seems logical . — Kadir Erdem Demir, Sep 07 '13 at 14:27
Just as an aside, the [Signal Processing StackExchange](http://dsp.stackexchange.com/) might be of interest. — Anindo Ghosh, Sep 07 '13 at 14:53

score 1 · Accepted Answer · answered Sep 07 '13 at 16:28

1

This normalizes the RMS power of the data set, per unit time, but based on a measurement over the entire data set rather than the periodic or sliding type of power measurement used by a continuous AGC.

answered Sep 07 '13 at 16:28

Chris Stratton

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Why to multiply all audio input with 1000/sqrt(sumsofInputSquare/datalength)

1 Answers1