Is anyone familiar with both Phenderix's Magic Sounds Improved and lt_better_horses?

When I run Better Horses without Magic Sounds, it gets bugged and I hear the horse whistle as soon as I start the game. The whistle then continues every other time I perform an action. With Magic Sounds Improved running, there's no whistle. I didn't see any common references changed by these mods.

What the heck?