Hey Zippy, glad you know it ain't just you. I listen to Off the Ball mostly, or podcasts via Bluetooth, not keen on the rest of what's broadcast.

I haven't done anything about it, but I don't think it's the particular frequency now. I forced myself to sit through some other radio stations which I'll leave unnamed, and the volume spike occurred on them too.

The correlation with damp suggests the potentiometer as first suspect.