If you are using
wavwrite(Y,FS,WAVEFILE)
then the acceptable range for the data, Y, is -1.0 <= Y < +1.0
so I'm assuming that you have values in your output equal to 1, which is resulting in the clipping. One thing you can do is to use 32 bits to write the file. That has output format implications -- see the help for wavwrite
wavwrite(Y,FS,32,WAVEFILE)
or you can add a small deltaA to your scaling factor that would avoid you getting a 1.
deltaA = 0.1;
signal = signal./(max(abs(signal))+deltaA);
