Audio feedback occurs when the signal produced by a microphone (or other sound transducer) is amplified and distributed in a manner that allows the same amplified sound to be detected by that same microphone, only to be amplified again. This cycle repeats and keeps adding gain to the most dominant frequency, producing the well known occurrence known as feedback.
Although microphone use for “house” sound and microphone use for broadcasting have their differences, sometimes their paths do collide. Typically, in a broadcast studio environment, feedback is rarely a problem. In a studio, the only times feedback might be a problem is when a monitor speaker gets turned up too loud or is placed in the wrong position. Studio feedback can usually be managed by having limits on monitor outputs and having the monitors anchored to fixed points.
However, television broadcasts do not always originate from a studio. Producing television programming from stages with live audiences can be a challenge, as it is quite common for “house” audio and monitor audio to be very loud. In this case, there are a few measures that can decrease the opportunity for feedback.
First, limit the amount of sound projected directly into the microphone by “house” and monitor speakers. This can be done by making sure that the microphones are behind the loudspeakers, and eliminating reflective surfaces from immediately behind the talent. If monitor speakers must be used (ear sets can eliminate the need for actual monitor speakers), place them where they direct their sound directly into the back of the microphone. Microphone selection is also very important. A cardioid pattern or directional is preferred, and microphones that don’t have any peaks in their response help alleviate the problem as well. Finally, the closer the microphone is to the sound source, the better.
