Ahhhh fascinating.
For years, I've been adamant that when I stir a cup of hot tea or coffee, the pitch of the scraping spoon almost imperceptibly shifts, and assumed it was because of the gradual slight cooling of the water. Nobody else could seem to hear what I heard.
Wasn't sure if it was my music producer ears or imagination.
Pouring a cup of hot water for tea def sounds different
Always wondered about this. Article is pay-walled though.
TL;DR the difference in density at different temperatures changes the sound
Another commenter posted a Tom Scott/Steve Mould video with the same subject. In case you haven't seen it already.
The viscosity of hot water is much lower.