Could be an issue related to “ground”. The high pitched sound may be caused by use of equipment that is not properly grounded. Try touching the back of the computer chasis to see if that has any affect on the sound. If it does, then may be you just need to find some way of grounding the computer.
If that doesn’t affect the sound, may be you could try a different kind of microphone. Try a USB mic instead of an analog mic.
Mail (will not be published) (required)