# Why is Short-Time Fourier Transform used for preprocessing audio samples?

I've been told this is how I should be preprocessing audio samples, but what information does this method actually give me? What are the alternatives and why shouldn't I use them.

• Do you perhaps mean "Fast Fourier Transform" (FFT)? – Neil Slater Oct 2 '18 at 15:35
• I don't believe so. – Faissaloo Oct 2 '18 at 15:55
• OK, I just looked it up. ccrma.stanford.edu/~jos/sasp/Mathematical_Definition_STFT.html . . . it seems STFT includes a sliding window function. Probably you would implement STFT using FFT at a lower-level. I was just suspicious that something had been "lost in translation" with "Short-Time" having very similar meaning to "Fast" :-) – Neil Slater Oct 2 '18 at 16:11

For example, raw audio data usually represented by a one-dimensional array, x[n], which has a length n (number of samples). x[i] is an amplitude value of the i-th sample point.
Using the Fourier transform, your audio data will be represented as a two-dimensional array. Now, x[i] is a not a single value of amplitude, but a list of frequencies which compose original value at the i-th frame (a frame consists of a few samples).