Which boat are you in, and what year is it? FOTRS tried to have relatively accurate dates for both the SD and SJ radars, so it is like June 1942 before SD Air Search, and later for SJ Surface search.
There is an issue with at least one, possibly three ships in Stock that do not have the "sound" correct for sonar/hydrophones, and that is carried into FOTRS.
The Stock game mostly uses 44.1kHz, 16-bit audio, which would be "CD Quality", for the wave file sounds. Speech is mostly ogg vorbis. Music might be mp3 or wav. The 'modern' computer is usually running at 48kHz at 24-bit depth, since most of the online movies are at that or at 16-bits. That can sometimes lead to issues with older DirectX v9 games, such as SH4. Also, if I'm not mistaken, there are a few sounds in FOTRS that are not "Stock game compliant", and are either lower in frequency or bit-depth, which can throw the game's audio engine off. However, another factor could be if you hadn't deleted the Save folder after activating the mod, which could also contribute to radar, sonar and hydrophone issues. The only "problem" with FOTRS (besides the language barrier) is the number of what I call "run-away spawns" that occur, mostly from Japanese ports with IJN DD that were not docked properly, or were not terminated properly. I thought I had a "fix" posted for that on SubSim here, but cannot find that. I'll try to dig that out of the old computer and re-upload it.
