How do you deal with feedback and ambient noise when using an omnidirectional microphone on stage?

1 What is feedback?

Feedback is the annoying squealing or howling sound that occurs when the sound from a speaker is picked up by a microphone and amplified again, creating a loop. This can happen with any microphone, but omnidirectional mics are more prone to it because they have no rejection of sound from the rear or sides. Feedback can damage your equipment and your ears, so you want to avoid it at all costs.

5 What are polar patterns?

Polar patterns are the diagrams that show how a microphone responds to sound from different angles. They indicate the directionality and sensitivity of a microphone. There are different types of polar patterns, such as omnidirectional, cardioid, supercardioid, hypercardioid, bidirectional, and shotgun. Each one has its advantages and disadvantages, depending on the application and the environment.

6 How to choose a polar pattern

When choosing a polar pattern for your microphone, several factors should be taken into account. The sound source should be recorded clearly and accurately, without distortion or coloration, as well as avoiding feedback and phase issues. For instance, a cardioid microphone might be used for recording a solo singer, while an omnidirectional microphone is better suited for recording a choir. Additionally, the ambient noise should be minimized to ensure sound quality and clarity. For example, a supercardioid or hypercardioid microphone could be used in a noisy environment to reject sound from the sides. On the other hand, an omnidirectional or bidirectional microphone may be more suitable in a quiet environment. Lastly, the desired effect should be considered when selecting a polar pattern; an omnidirectional microphone with low proximity effect and smooth frequency response may create an intimate atmosphere, while a shotgun microphone with high directional effect and narrow frequency response can create distance and separation.

7 How to use multiple polar patterns

Sometimes, you might want to use multiple microphones with different polar patterns to capture different aspects of your sound source or environment. For example, an omnidirectional microphone can be used to capture room ambience and a cardioid microphone for direct sound of an instrument. Or, a bidirectional microphone may be used to capture two singers facing each other and a shotgun microphone for the sound of the audience. When using multiple polar patterns, there are several factors to consider such as placement, level, and processing. Placement should optimize pickup patterns and avoid feedback and phase issues, while avoiding comb filtering and interference from other microphones. Level should balance the signals and create the desired mix, while avoiding clipping and distortion from overloading inputs. Processing should enhance sound quality and clarity while avoiding adding unwanted noise or artifacts from over-processing.

8 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?