A report written by Richard Adams and Nick Anaya of Rice University in Houston, Texas states that "the two most prominent causes of feedback are position of the mic with respect to the acoustics of the room and the gain of the output signal." If you've ever been at a music concert or a public meeting where a microphone is being used and the speakers suddenly send out a high-pitched, ear-deafening squeal, then you have experienced this microphone echo firsthand. There are a few things that can be done to reduce or try to eliminate feedback into a microphone.

Instructions
1 Turn down the gain or volume on the microphone channel with your fingers by grasping the knob on the mixer or amplifier and turning it to the left.

2 Position the microphone stand so that it faces away from the direct sound path of the speakers. Turn the microphone off to eliminate the immediate squealing echo.

3 Reposition the speakers so that they are not directly behind the microphone. Place them on speaker stands (if available) to elevate their sound path above the level of the microphone. Attach 100-foot speaker cords to the speakers from the amplifier so you can move the speakers farther away from the microphone.

4 Hang long curtains or sound reduction foam on the walls of the venue to reduce the amount of sound waves bouncing off the walls and feeding back into the microphone. Turn the microphone back on once you have adjusted the microphone stand, speakers and amplifier volumes and do a sound check by speaking or singing into the microphone. If the microphone echo continues, add more curtains or foam to any bare walls.