> Peter, Robin, - I hope this topic will live on for a while, until
> "everyone" understands, as it is one of the most important ones.
> It's not only wind noise that gets worse, but handling noise as
> well.
> (I may add that also a pressure gradient microphone can have two
> membranes.)
Klas, Peter,
A nice explanation. What I should have said originally was that an
omni mic responds to instant air pressure and is relatively
insensitive to movement of the air or itself, because a forward
pressure is largely cancelled out by an opposite negative pressure on
the other side.
A pressure gradient (or velocity mic) like a fig-8 is sensitive to
the velocity of the sound waves passing it. It is therefore also
sensitive to its own movement and wind turbulence. A directional mic
combines both types so you get the noise effects from the velocity
component.
While I'm writing I'll try to explain the proximity effect of velocity
mics, including cardioids. The frequency balanced design gives a flat
response from a distant sound, but there is a strong bass tip-up with
close sources like a voice. I'll spare the theory, but the proximity
effect is used with noise-cancelling mics like close intercom face
mics and commentator's lip mics which are much less sensitive to
distant sources like a football crowd. An example is the Coles 4104
which is a rare example of a ribbon mic.
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
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