Can FFT be used to find peaks and pits on audio files
FFT is a tool to look at your signal content in frequency domain. So if you want to find peaks of your time domain signal, FFT cannot help you. However if you want to see what frequency component in the signal is the largest then you can use FFT.
To find peaks of your time domain signal you can load it into MATLAB and use command "max" for example if your signal is called "mySignal" in MATLAB type: max(mySignal) and it will give you the location of value of the peak.