My wife and I are singing in a project choir for a colleague's DMus conducting recital. One of the pieces he is doing is a short piece called "I Am the Great Sun" by Jussi Chydenius of Rajaton.
The start of the piece calls for the tenors and altos to sing with overtones at the start, otherwise knows as harmonic singing. I've done a bit of this with some success, but thought I should practice a bit at home. Which made me discover something interesting.
Cats HATE overtone singing! Both our cats ran out of the room in a panic. It was close to feeding time too - and both of them refused to come back into the room to eat - which with these two felines, is a first.
I'm going to try this on them next time they start to scratch the furniture.