@Herra Tohtori: I can't see why that wouldn't work, but I have to show my inexperience with OpenAL in this, I don't know if it is able to (though I can't see why not, you can't be the first person to have thought of this). However, with in the nebula lighting in particular, being able to play 20 lighting sounds (of 48 available) channels seems like a waste to me, I can think of better sounds to be playing in those channels.
you should always try to make use of every sound channel there is. if sounds have a priority you could use up more sound channels for environmental effects when theres not much action going on, then have them use up fewer channels when there is combat. if priority worked like this:
1 self sounds (ship, hud, firing of player weapons etc)
2 combat sounds (beams, guns, missiles, other ships, explosions, etc)
3 environmental sounds (lightning)
priority 1 sounds always play and get first dibs on available sound channels
priority 2 and 3 sounds get 2nd and 3rd dibs on remaining sound channels.
sounds should also be further prioritized by distance from the player, play volume, and age in queue. drop distant and/or quiet sounds of priority 2 or greater. some sounds also need not be played on time, such as low priority sounds or sounds behind you that have no real effect on what your doing (things like shockwave explosions that hit you or that bogey on your six and its weapons would probably be excluded). so sounds are queued up as they are requested, and when this happens sounds are assigned a timestamp for its creation and also when it expires. expired sounds are removed from the queue. but an old sound that hasnt expired yet is a good candidate for de-prioritization.
of course before that happens you cull out a bunch of sounds if you have multiple instances of a single sound playing in close proximity to each other at close to the same time (probably determined using some 4d vector math), then the time and position should be averaged and a single sound played from that location and time (this would require some foreknowledge of what was gonna happen, as if the sounds were sitting in the queue for a couple of frames). this would improve the sounds of simultaneous lightning strikes and ship warpins, and assuming there wont be any clipping the sound could be played at a slightly higher volume (if your typical sound plays at 75% then you could amp the loud sound an additional 25% before clipping occurs). predictable events can even do this before hand making the sound queue smaller.