Color Tracking a Red Laser Height
I can only say something about the computer vision part.

If your doing color tracking you have to take different lighting conditions into consideration, although it will be easier with a laser (compared to other things) since it at least have the same color.

If you are to use this device professionally you should have a delay about 20ms else it will be noticeable. This forces you to use a high speed camera of at least 100fps (10ms per frame) to have time for processing and sending the sound through the amplifiers.

Since you are only tracking straight lines I would recommend to first filter out everything but the laser-color and then hough transform it to find all straight laser lines. And as a final step implement an ad-hoc method to find where the laser ends shouldn't be that hard.