Choice of relationship between n_fft and window_length in STFT

1. How do you choose a sampling frequency in FFT?
2. What is N_fft in Librosa?
3. What is FFT windowing?

How do you choose a sampling frequency in FFT?

The frequency resolution is equal to the sampling frequency divided by FFT size. For example, an FFT of size 256 of a signal sampled at 8000Hz will have a frequency resolution of 31.25Hz. If the signal is a sine wave of 110 Hz, the ideal FFT would show a sharp peak at 110Hz.

What is N_fft in Librosa?

The default value, n_fft=2048 samples, corresponds to a physical duration of 93 milliseconds at a sample rate of 22050 Hz, i.e. the default sample rate in librosa. This value is well adapted for music signals.

What is FFT windowing?

A window function provides a weighted selection of a portion of a time waveform for fast Fourier transform (FFT) analysis. It is generated by multiplying the original time waveform by a user-defined window function of some width. In this case, width equals two times the number of analysis lines.