Buzz
Prevent uncomfortable high-pitched feedback with this user-friendly guide
Microphone feedback, a common nuisance when connecting microphones to speakers, can result in unpleasant high-pitched noises. This occurs when the output noise is captured by the microphone, causing a piercing sound that can harm your equipment. While you can't entirely eliminate microphone feedback, there are methods to minimize its occurrence. This article by Mytour offers easy-to-follow tips for reducing microphone feedback.
Essential Knowledge
- Direct the microphone away from speakers or monitors, consider using in-ear monitors, and position the speakers in front of the microphone.
- Adjust the equalizer settings to reduce prominent frequencies.
- Lower the microphone gain and mute or turn off unused microphones.
Procedures
Minimizing Audio Disturbance
Direct the microphone away from nearby speakers. Avoid positioning the microphone directly in front of speakers or monitors to prevent immediate feedback. When arranging a sound system, ensure that the speakers are placed in front of the microphone to avoid capturing unwanted audio. If handheld, exercise caution to prevent the microphone from passing by the speakers, potentially causing feedback.
- Consider using directional or cardioid microphones as they focus on specific sound sources.
- Avoid omnidirectional microphones if possible, as they capture sound from all directions and are prone to feedback.
- If positioning speakers in front of the microphone is not feasible, increase the distance between them to minimize interference.
Maintain close proximity to the microphone. Keeping the audio source nearby reduces the likelihood of interference. Whether singing or speaking, position the microphone directly in front of your mouth to prioritize your voice over ambient noise. When connecting a microphone to an amplifier or instrument, place it as near as possible to minimize interference from other sources.
- Prefer direct input for instruments when available to bypass the need for a microphone.
Caution: Avoid cupping your hand around the microphone, as it can exacerbate feedback.
Use headphones or in-ear monitors to mitigate feedback from speakers. When vocalizing through a stage monitor or speaker, there's a risk of the microphone picking up the output. For performances or speeches, inquire about in-ear monitors from the sound technician, providing direct audio feedback. During vocal recordings, utilize headphones to prevent audio bleed into the microphone.
- Many recording microphones feature headphone ports for direct monitoring of audio.
Switch off or silence the microphone when not in use. After utilizing the microphone, locate the power control or button and turn it off to prevent unintended audio pickup. For managing audio or handling multiple microphones simultaneously, mute inactive ones on your mixer or computer. When required again, reactivate the microphones.
- If the microphone lacks a switch or button, consider unplugging the attached cable instead.
Minimize the presence of hard surfaces in the space to reduce sound reflections. Flat surfaces reflect and echo sound, leading to potential feedback issues. Begin by removing hard surfaces like tables from the room. Next, cover surfaces with softer materials such as carpeting or blankets. Utilize acoustic foam to create irregular surfaces that mitigate echo.
- Avoid aiming speakers at walls, ceilings, or windows, as they exacerbate sound reflection. Instead, direct speakers towards individuals or audiences.
Adjusting Mixer Settings
Lower the microphone's gain setting to minimize sensitivity to noise. Gain determines a microphone's responsiveness to sound. Increase the gain until feedback is faintly audible, then reduce it by 5–10 decibels (dB) to prevent feedback occurrence.
- Adjust gain using controls on the audio mixer or digital audio workstation.
- Some microphones feature gain control knobs for pre-sound system adjustment.
Decrease speaker volume to reduce potential interference. Excessive speaker volume causes increased room sound reflections. To mitigate feedback, gradually lower speaker volumes by approximately 5 dB increments. Test for feedback, adjusting volumes as needed.
- Exercise caution to maintain audibility while adjusting speaker volumes.
- Simply reducing speaker volumes may not completely eliminate feedback, necessitating additional measures.
Gradually reduce EQ frequencies by 5 dB increments to identify feedback sources. Adjust frequency controls to 0 dB. Increase each frequency by 5 dB, testing for feedback with your microphone. Reset frequencies to 0 dB before testing the next. Note frequencies causing feedback and lower their volume to minimize prominence.
- With experience, you may identify problematic frequencies by ear.
Typical Feedback Frequencies: Hooting and howling occur in the 250–500 Hz range, while whistling or screeching noises occur above 2 kHz.
Utilize an automatic feedback eliminator for mobile microphones. These devices detect interference and adjust frequencies accordingly. Connect the microphone line to the eliminator's input, then run an XLR cord to the equalizer. The eliminator reduces frequencies upon detecting feedback.
- Automatic feedback eliminators are available at audio supply stores and online.
- They're ideal for live performances or presentations.
Employ a noise gate on the microphone. Set a threshold to silence sounds below a certain decibel level. Connect a noise gate directly or via plug-in to a DAW. Set the threshold 10–15 dB below input volume, adjusting gradually if necessary.
- Avoid setting the threshold too high to prevent cutting off recorded audio.
Recommendations
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Always be mindful of microphone placement and handling.
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Conduct a soundcheck prior to performances or presentations to preempt feedback issues.
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Lowering the master volume on a mixer before activation can help prevent speaker feedback.
Cautions
- Avoid aiming microphones directly at speakers.
- Avoid cupping the microphone as it may impede audio clarity and lead to feedback.
