Making a cup of coffee for myself, and tea for SWMBO, I was intrigued that when stirring it sounded like the pitch of the teaspoon tinkling the cup was rising in my coffee as the milk dispersed but seemed to be falling when I did the same to the tea.
I found myself wondering what principles are at work ...
Amazingly (given TV sound quality) I was on the money about sound of hot/ cold water being poured when demonstrated on "QI" a while back. As was most of the audience.