I have a book entitled "Outwitting Mice" and I just read it cover to
cover.  There is really no mention of anything practical and proven
that would repel mice from a particular location.

The best strategy is to exclude them but this can be impossible in
carelessly constructed building where there are numerous points of
entry that are impossible to block.  Therefore, trapping is really all
you can do.  A cat or a snake in the piano would probably work but
would not be entirely practical.

No one agrees on whether the ultrasonic repellers work but it is
certainly worth a try and a report back on their usefulness.  I have
no mice in my house or I would give it a try.  I do have mice a plenty
on the outside of the house and in the insulation under it and have
thought about the ultrasonic method but have not tested it yet.

I have a few serious ultrasonic generators that I bought surplus for
almost nothing.  They each drive 12 piezo transducers and were intended
to be used for heavy hot solvent cleaning of optical components.  The
transducers could be mounted to various places in a large organ
installation and might do the job or might just rattle everything apart
over time.  I would imagine that there are adjustments for frequency
etc inside the units and that it would be possible to adjust them to
produce an non objectionable frequency.

This project has actually been on my list of things to do before winter
when the mice and rats move in and do their damage.  If anyone is
seriously interested in trying this, we could discuss it further and
I could lend one of the units for testing.

Spencer Chase
http://www.SpencersErolls.com/