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Re: speech degradation in a GSM network transmission


There are at least two different categories of degradation you can add to your signal, one is typical in the "continuous/analog" world, such as comb effects, echoes, undesired dynamic compressions, attenuation in bands around 4kHz (important for voice), harmonic distortion, etc, and the other is typically "digital generated", as artifacts generated by MP3 compression at lower bitrates, very harsh to listen to.

For the first one you can use for example audio effects/editing software, which offer several possibilities, and for the second one, you can pass your signal through a mp3 encoding-decoding chain. Matlab/Simulink has some sources of noise that could be useful also.

Hope these ideas are useful.
Regis Faria

Faten B.A. escreveu:

Hi list,

I want to introduce some artificial degradation to a speech signal in order to simulate speech degradation in a GSM network transmission.

The addition of a background noise seems to be simple but I don't know which type or noise distribution I have to use.

I want also introduce frequency degradation and I have no idea about the way this must be done.

Can anyone advice me or send me some documentations about this topic?

Best Regards.


Regis Rossi A. Faria

LSI - University of Sao Paulo
Audio Engineering and Coding Center