Occasional static-like sound on muted speakers: can Cat7 cables be a possible culprit?

The topic belies my limited expertise on networks and such. I am starting to troubleshoot this just-occasional-enough-to-irritate phenomenon: a 15- to 30-minute bout of static coming over the speakers, even when muted. I haven’t been able to identify any environmental factors that occur in sync with the static.

I was looking at the rear of my AVR (MRX 720 Anthem) and noticed the CAT 7 cables I installed 3-4 years ago. I recall reading since, though, that CAT 7 cable may not be all that good for audio.

Anyway, kind of grabbing at straws here. If replacing CAT 7 cables is a misguided step, what would be the top two things to try first? Many thanks.