Taking a audio signal and driving a DC Motor

Hello all,

I am trying to build something for my deaf brother. I want to hookup an
amplified audio signal to a small 1.5v - 6v DC motor. It needs to be
able to speed up when the sound is louder, slow down when there is less
sound and stop if no sound. It needs some type of regulator or
something to cut the voltage to a max of 6V DC.

Can someone help me figure this out? Please help! As I said, this is
for my deaf brother and I would like to make this for him for x-mas. It
would make him VERY happy! It would also make my parents happy since
they get mad at him for turning the volume up real loud so he can feel
the sound.

It can be either a stand alone unit with an input from a headphone jack,
or something integrated into a headphone amplifier. The integrated way
would be the best but either way will work.

Thank you very much!

Eric