Modern mode (infinite polyphony): Leave this parameter undefined and the index will simply increment forever.
Or, force monophony by choosing a channel index. This is the more retro-style playback option. Whatever was playing before is stopped. This can, for example, be used to reduce audible clutter on often-repeated sfx by stopping the last one before the next one plays. Shoving many sfx into one channel is either a mistake, or an artful technique -- depending on your sound design skills.
Loop a sound forever. Be sure to keep track of its channel index, otherwise you'll later rely on calling Audio.stopAll or Audio.stopWave later.
seek position, aka how many seconds into the sound we are.
In update, this changes live position. Or, in status
this is calculated on the fly.
Affects speed and pitch both, like a tape or vinyl. 0.5 = slow and low, 2.0 = high and fast.
Keep in mind that volume is multiplied by global volume.
The current state of a playing channel.