In what must be one of the worst design decisions to come out of Cupertino in its city's history since autocorrecting "omw" to "On my way!", Apple decided to make their AirPods blare a piercing sound when your battery is low.
I never really understood the logic. I take naps listening to calm music sometimes, and I don't want to be woken up by an abbreviated alarm just to be told I can't play sleep music anymore.
I listen to brain.fm sometimes to focus while I work, and the sound startles me and interrupts my focus.
There's a setting called "Tone volume" that controls the volume of the AirPods sound effects. Here's how you get there:
Go to Settings -> Accessibility -> AirPods, then choose your AirPods.
Choose Apple menu -> System Settings -> Accessibility in the sidebar, click Audio, then choose your AirPods.