function preload() {
  soundFormats('mp3', 'ogg');
  soundFile = loadSound('../files/lucky_dragons_-_power_melody');
}
This example draws the frequency spectrum of a sound by using
the p5.FFT object's analyze() method.

FFT is a Fast Fourier Transform function that calculates
amplitude across the frequency spectrum. The analyze() method returns
an array of values. These values represent how much volume exists in a
sound at various frequencies (or pitches). The beginning of the
array represents the lowest frequencies (bass), and the end of the
array represents the highest frequencies (treble).

By default, the array length is 1024. We can determine the size of the array by including
an optional parameter, but the number must be a power of 2 between
16 and 1024.