My left APP recently started hissing.

Noise is most prominent in transparency mode, better in "off" and best with noise suppression turned on. When I play with it in my ear it may go off for a second but comes right back. Tried putting it in the case and that worked once, but that doesn't help any more. Related to microphone? I tried covering different parts of the air pod but couldn't get it to stop reliably. Any suggestions?