Quote Originally Posted by HideoKojima View Post
Thanks guess there's no way to disable battle music only
This has actually been a feature that's been requested. The devs have responded by, in many of the later dungeons, keeping the music consistent when in and out of battle. Unfortunately, for both older dungeons and the overworld, we're left with the annoying constant fade-in-fade-out.

On the upside, there actually is some variation on the music depending the zone you're fighting in. But in short, correct: There is no "disable battle music only" option.