I have noticed a difference in behaviour when exposed to different types of music too! I find when there is classical music they are much more active. They seem to go about looking for the source of the sound, while the more repetitive dancy music sends them into hiding.
Both Deejay and Stitch really seemed to take a liking to traditional choir-sung Christmas carols during the holidays.
I didn't realise other people had even looked into this type of thing, Greg........glad you posted this info!
