Some players are way too loud or way too quiet. A way to adjust the volume per player would help balance the loud players over the more quiet players.

I would love to boost the volume of my friends/teammates and reduce the volume of loud kids. I'd still like to hear the louder players, but their loudness drowns out my dad friends that whisper to not disturb their sleeping kids.

This could either be a button or a slider, it doesn't really matter. Having an "increase"/"decrease"-button next to the "mute"-button would be a fast way to adjust the volume.