There are several standard and speaker configurations for 2-dimensional surround sound panning, such as quadraphonic (four speakers in a square or rectangular placement) and the 5.1 or 7.1 THX cinema surround specifications. There are also sound distribution encoding techniques that work for a variety of speaker configurations, such as the Ambisonics panning description, and there are processing techniques such as head-related transfer functions (HRTF) filtering.

This and the next few examples will show simple algorithms for intensity panning with a rectangular quadraphonic speaker configuration.

One way to implement two-dimensional panning is to specify the sound’s virtual location as a x,y coordinate point on a rectangular plane representing the floor of the room, with a speaker at each corner of the plane. The x value can be used to represent the left-right panning (0 to 1, going from left to right) and the y value represents the front-back panning (0 to 1, going from front to back). For some purposes, simple linear panning might suffice (or even be found to be preferable). I usually prefer to use a constant intensity panning algorithm. So I use the pan~ abstraction to calculate the amplitudes that will provide the left-to-right panning illusion, and then I use two other pan~ objects to pan each of those gains (the left and right amplitudes) from front to back.

This patch is an abstraction that enacts that plan. (It requires that the pan~ abstraction be somewhere in the Max file search path.) You can use this to pan any signal to four speakers in a rectangular quadraphonic layout. It takes a signal in its left inlet, an x coordinate in its second inlet, and a y coordinate in its right inlet. Similarly to the pan~ abstraction, it allows the panning coordinates to be specified as initial arguments, floats in the 2nd and 3rd inlets, or as signals.