RF ( radio frequencies ) knows knows no bounds as far as brand or type of device. As a licensed radio amateur I've been on both ends of the problem. Any electronic device with speakers can be affected, ( examples of devices without speakers that can be affected are car alarms and garage door openers ) and the more electronics and circuits, the more susceptible the device seems to be. Problems often occur with both the equipment that transmits ( cell phones, CB radios, etc ) and the receivers or "passive " equipment ( your keyboard and / or sound system ,CD players, TV,s etc ). This happens because of faulty design or lack of RF protection circuitry in the receivers end and lack of proper filtering in the transmitting device.

There are ways to help fix this that work with varying degrees of success. There are simple rf chokes that are available that may help. If your own transmitting device is to blame, you can often apply ferrite toroids or beads to the ac lines of both the offending equipment and your keyboard ( or to the wires of your external speakers ) . In one case I did this with a neighbor's stereo system and it solved the problem ( they no longer heard me "broadcasting" into their stereo which of course immediately upgraded my popularity with them ).

AJ