Matrixed audio means multiple audio channels are combined together into a single track, rather than being split out into separate individual tracks. For example: Track 1 would contain 2 channels: Stereo Left and Right. Track 2 would contain 6 channels: L, R, C, LFE, LS, RS (this is your surround sound mix). Matrixed audio is our preferred format for delivery. The alternative is delivering 8 separate mono tracks (one channel per track). We can accept this format, but it's less preferred.