Multi Channel Files (i.e. 7.1)

I am trying to create sinewaves at a given frequency and I want to have multiple channels (more than 2, at least 4) with each channel phase shifted by some amount. I have a external sound card with 7.1 capability. How do i desiginate channes to the surrond sound channels? Is the software only capable of stereo files?

Audacity is only capable of mono/stereo playback. However, Audacity can export multi-channel audio files which could then be played in another application. (see