I'm curious, never heard about people creating small audio tracks and selling them. Is there a market for such things?
For example, I bet a lot of people creating apps and games for the mobile markets need a loot of sounds to make those apps and games not only look good but also have the sounds to make it professional enough.
Where are those people getting their sounds from? Is there a place where you can buy already recorded soundtracks?
Given the fact that we have similar niches in photography I think it's only normal people out there are looking to create and sell but also buy audio stock tracks.
LD already has a wide variety of audio-based services to offer: https://listingdock.com/categories/Audio