Man! I want me one of these!!
Riley would be up near the top of the scale, he has a relatively high-pitched voice. Usually, he says “Mee! Mee!” and occasionally says “Meu. Meu.” I’ll have to get out the pitch pipe and figure out his most usual “note.”
Stuey, on the other hand, would have been a non-musical sound effect near the lower end of the scale, making his trademark nasal “Ow. Ow. Error. Error.” sounds. Guess he would have been a contiuno kitty.