There are two slightly different areas here:
In terms of the programming side of things in the Oolite core, that's not particularly complicated and I'm happy to work on that as needed. The sound generation is the hard bit and would need a volunteer (or few) to work on this, probably at least over the course of the 1.83/1.84 development cycle.
For the existing sound effects
The current ideal format is ogg, mono (very important to get positional sounds to work), at 44kHz. All of the existing sound effects probably need at least some work to get a coherent sound set together; additionally if you look at customsounds.plist
of potentially distinct sounds use the same "beep" and "boop" noises and could perhaps be differentiated a lot more.
My preference would be to avoid speech in the soundset, to keep the core game at least somewhat multi-lingual and easily translatable.
Obviously to be accepted into core all sounds would need to be dual-licensed GPL2+/CC-BY-NC-SA 3+ ... which in practice is a sufficiently unusual licensing combination that the sounds would almost certainly need to be made (or relicensed) specifically for this purpose.
For new sound effects
We upgraded to the OpenAL sound library in the lead up to 1.80 and don't really use any of the features that gives us at all (other than the ability to stream sounds directly out of an OXZ file)
Features that are relatively easily available with some core programming - especially if the use is tied to a specific effect: ability to fade sounds in and out, ability to adjust the pitch of a sound up or down, ability to position the sound in stereo space and to move it around while it's playing. We use positioning a bit - put some headphones on, and compare firing starboard, forward and port lasers, for example - but not particularly much.
Pitch and volume variation of laser, shield, engine, etc. noises with status would be easy to implement though obviously need a lot of fine-tuning. There's also the possibility to allow a bit of randomisation (e.g. have multiple "ship taking damage" sounds that are selected at random on each hit)
Obviously any new sounds would - like the existing ones - be customisable by OXPs to point to different sound files, including "silence".
What new sounds (or sound modification effects) are added is obviously somewhat up for discussion and somewhat dependent on what anyone has time to produce. Currently the convention is that only sounds you'd actually be able to hear from your ship are played (with an arguable exception for the "laser hit" / "laser miss" distinction), but whether that's an intentional decision or simply a consequence of external sounds not really working without stereo-positioning support I don't know.
(For the realism fans - not that Oolite particularly goes for that angle in anything else! - we could require the purchase of a "situational sound simulator" equipment item before external sounds became available)