Acoustic feedback is a problem which plagues many performers, particularly during live shows. While professional musicians may be able to handle feedback and eliminate the chances of it occurring completely, people who are learning guitar music or any other type of music for the first time must learn to control acoustic feedback before performing in front of an audience.
Feedback occurs when amplified sound from a speaker re-enters the sound system through an open microphone and is amplified continuously creating an annoying piercing screech. It can be used as part of the performance, but that takes a lot of practice and it is not something novice guitar players should attempt.
Sound engineers also frown on anyone who tries to use feedback as part of their music because it makes their lives hell. Here are seven ways to control and eliminate feedback during live performances.
- If you are performing alone in front of a live audience, turn off any open microphones which are not in use. This will greatly reduce the chances of feedback.
- Keep the microphone and speakers as far away from each other as possible. Do not put the microphone in front or behind the speakers. This is a common mistake made by first time performers.
- Use a directional microphone which amplifies sound from the direction of your choosing. This is one of the best ways to completely eliminate feedback during a performance.
- Move the microphone closer to the source of sound. If you are singing, then keep the microphone close to your mouth. If you are playing a guitar, then put the microphone close the strings. This rule applies to groups of performers as well.
- Reduce the system output of your speakers, or move them further away from the microphone you plan on using. Each time you double the distance between the mic and the speakers, you can increase the sound system output by 6 decibels.
- Use heavier gauge strings on your guitar. Heavier strings vibrate for longer and require less feedback from the speakers to hold a note.
- Acoustically treat the room you are going to perform in and remove any hard reflective surfaces like glass, marble, and wood. Sound tends to bounce of such surfaces and re-enter the microphone. This might be impossible in many cases, but do what you can to lower the chances.