I second Cameron´s advice... we hear your complaint with the noise level - I hate to say it, but I feel it is spot on, especially in being really bothersome . And engines are NOT the most prevalent sounds in a jetliner cockpit, I know that most users (sitting in the passenger cabin) have a different experience...Maybe some other 737 pilots can join in on the discussion and share their view?
Currently the sound-level sliders aren´t working very well - the "cockpit" slider is also reducing the engines sound - we will fix this.
So soon you can turn down cockpit sounds, while retaining loud engines. We are discussing making "realistic AC-noise" an option, so you can turn that lower if you need to keep the noise down in your house...
Cheers, Jan