Also, if it's an iOS audio theme for the Audio Themes add-on you're looking for, I can't find one on the GitHub page or elsewhere via web search.
It is entirely possible that someone has created one, but as you've requested, they'd have to share it here.  And it's fine to do so if we're talking about a audio theme of any sort that can be used with the Audio Themes Add-On.
--
Brian *-*Windows 10 Pro, 64-Bit, Version 1909, Build 18363
*/Science has become just another voice in the room; it has lost its platform.  Now, you simply declare your own truth./*
~ Dr. Paul A. Offit, in /New York Times/ article, /How Anti-Vaccine Sentiment Took Hold in the United States/ <https://www.nytimes.com/2019/09/23/health/anti-vaccination-movement-us.html>;/,/September 23, 2019