How does unidirectional microphones work?

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#1
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How can an unidirectional microphone receive sound only from one direction, unlike directional mics..?

thanks

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"Uni" = One, which in this case means "directional". (Pick up the sound from one direction only).

"Omni" is non-directional, meaning it picks up sounds from all directions.

Have a look at this Wiki Microphone for a rather lengthy description of microphones, and their directionality. It says it all much better than I can!

Scroll down a bit and read the section on Microphone Polar Patterns, which deals directly with your question.

Spark Fun sells some Mems microphones, if you wish to play with one. It is yet another cool application to micro mechanical and electronic systems.

JC

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Good article. I read the whole thing. I was surprised to see the Optical microphone... something really new. Howsoever... what kruz asked was how does the directional stuff work, and its easier to understand than electronics, because you can see it... omnis have sealed backs, and directional mics have slits on the sides and back that lets sound get to the BACK of the diaphragm. Where the sound path length to the back of the diaphragm is a half wavelength at the frequency of cancellation. So a bunch of different location slits and different path lengths give an attenuation of sounds coming from the sides and rear over some freq range. I guess electrical waves out of phase cancel like the sound waves do, but you cant see the electrons. You can at least see the holes where the sound waves go in and out.

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