I record audio and create sound effects for game developers and sound designers. It's more in recent years that I've gotten into sound effects and it began shortly after I started to make assets to sell in the Unity Asset Store. I had my music in the Asset Store for a few years and those assets didn't see very many sales. I then created "SPACE for Unity" which was a best seller for a long time and it topped the Unity sales charts quite a few times. That's when I realized that music is probably something you add very late in the game development process, whereas graphic assets, and presumably sound effect assets, was something you add early on.
So in 2013 I bought a Zoom H4N handheld recorder and started to record sounds as well as designing sound effects using the raw material I had recorded. I started to read all I could about sound recording and listened to many podcasts to learn as much as I could. I quickly found out that the little handheld recorder would not be sufficient to capture high quality audio in many scenarios (e.g. gun recording, vehicle recording, ambience recordings, etc.) so I invested a lot in high quality field recorders, microphones, and I purpose built a sound recording room in my garage to capture as clean source material as I possibly could for my sound design process. I sell both the raw recordings (to sound designers) as well as designed sound effects (mainly to independent game developers).
Today the sound effects, and especially the multi game-genre low cost high quality game-ready sound pack Universal Sound FX, generates most of the revenue for Imphenzia.