Hi Sofiane,
As per my understanding, you have an audio signal, and you want to increase its speed without changing affecting its pitch.
You can do this using the stretchAudio function-
SignalOut = stretchAudio(SignalIn,Speed);
% Where Speed is the desired signal speed, for example for your case
% Speed=1.5
You can also try the below MATLAB example for this function -
openExample('audio/ApplyTimeScaleModificationExample')
For more details, you can refer to the following documentation on https://in.mathworks.com/help/audio/ref/stretchaudio.html
