Calculate Amplitude for Frequencies (

Outputs a list of amplitudes, with each representing a range of frequencies in the audio.

This node is useful for finding the loudness of different ranges of pitches. The output can be used to create an audio spectrum visualizer.

This node performs a calculation called a Fourier transform. It divides up the full range of frequencies from the audio into subranges called bins, calculates the amplitude for each bin, and optionally aggregates the list of amplitudes to more closely match how humans perceive audio.

If you want a specific number of outputs, use the table below to pick the right Frequency Bins and Frequency Bin Averaging.

Frequency Bins Quadratic
3 3 3
7 4 4
15 6 5
31 8 6
63 11 7
127 16 8
255 23 9
511 32 10
1023 45 11
2047 64 12
4095 91 13
8191 128 14

Technical details about the calculation: It’s a fast Fourier transform (FFT). The total number of bins used in the FFT is 2 * (Frequency Bins + 1) (a power of 2). Frequency Bins is the number of real-valued (frequency domain) coefficients minus the DC coefficient. The windowing function is Blackman-Harris.

Keywords: equaliser, equalizer, filter, fourier, music, pass, signal, sound, spectrum, waveform

Example compositions:

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