Background Noise Cancellation on a Budget
There may be locations where background noise can overpower your microphone to a point where it’s almost impossible to understand what the announcer is saying.
Sporting events and concerts are two examples. Whether recording or live, if you cannot understand the announcer, the signal is pretty useless. In this age of wonderful digital audio processing, some effort can be made to recover the voice. However, everyone may not have access to the latest and greatest equipment.
One way to get around this problem is to wire two microphones in parallel yet out of phase, creating a noise cancellation or differential microphone.
The microphones should be mounted directly beside each other, as close as possible. Ambient sound will be picked up by both mics, however it will be nulled out by the microphones being out of phase.
If the announcer speaks in very close proximity to only one of the mics, with their lips almost touching the mic, there will be a reasonable output thanks to the inverse-square law.
The inverse-square law states that a decrease in distance by one-half between the sound source and the microphone increases sound intensity at the microphone by a factor of four, and the SPL by a factor of two. This will allow the announcer to have an advantage over the ambient noise.
Certainly the audio will not be optimum; however it will very likely be useable.
Obviously, a proper environment would be preferred!
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