Callers can't hear me properly. Heeelp!

[strewth101]

Hello all. I'm new to the forum.

I have a Gen. 1 iPhone SE running iOS15.1. It's not new, but it's new to me. Callers keep telling me I sound muffled. But I sound loud and clear when I leave Whatsapp messages. So it's probably a software issue. I've tried cleaning the mic holes with an old toothbrush, but it didn't help. Does anyone have any ideas? Is there a noise-cancelling option somewhere in the settings app?

 

[strewth101]

Further to last message, I found the noise-cancellation option. It was off.

 

[strewth101]

I turned the noise cancellation on. Restarted. No joy. I turned it back off again. Restarted. Still... no joy. Oh dear. Anyone got any ideas?