Getting a sound sample from RAM

The buffer~ object holds audio data in RAM as an array of 32-bit floating point numbers (floats). The fact that the sound is loaded into RAM, rather than read continuously off the hard drive as the sfplay~ object does, means that it can be accessed quickly and in various ways, for diverse audio effects (including normal playback).

Indexing and accessing the bins of an FFT

The Fast Fourier Transform (FFT) is a mathematical procedure for converting a time-domain signal (such as a sound wave) into an equivalent frequency-domain representation (the sound’s spectrum). The inverse transform (IFFT) reverses that process. The Max object pfft~ allows you to encapsulate an FFT and IFFT (with the objects fftin~ and fftout~ respectively) and program some sort of frequency-domain processing (alteration of the spectrum) between the two.