What does the FFT data in the Web Audio API correspond to?

Question

I\'ve used the FFT data from the Analyser node using the getByteFrequencyData method in the Web Audio API to create a spectrum visualizer as shown below:

<

Answer 1

With 256 bins, each one will be ~86 Hz apart (44100 kHz sample rate / fftSize, where fftSize is twice the number of bins). So you start at zero and go up in 86 Hz increments from there.

The actual values in the bins are just a representation of how much of each frequency is present in the signal (i.e. how "loud" the frequency is).