MrNally asks: "Last night I was trying out my new harmonica when my cats started to freak. A quick check of google (isn't the internet wonderful - la la) reveals that, as a rule, cats hate the harmonica. Here's a small company that has used this to 'cat proof' your computer, playing harmonica sounds whenever the keyboard is used in cat-like ways. Does anyone know anything about feline physiology? Any ideas why my cats hate my Bob Dylan renditions when played on the harmonica, but don't seem to mind it on the guitar? And then there's the point that someone has turned this into a computer solution which suggests that there's a bandwidth limitation to their hatred (that is, their hatred is still true even after a low pass filter). Most importantly, is there any similar system that could be created for certain humans? ;-)" So remember, folks, if you don't want any household catastrophes, leave the harmonica renditions of your favorite songs to a feline-claw-free environment. Come to think of it, are there any particular instruments cats like?