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3. Re: speaking of fetch

Subject: 3. Re: speaking of fetch
From: "Raimund" animalsounds
Date: Fri Mar 15, 2013 12:56 am ((PDT))
> Yes,
> typically we only get one number for that at a 94 dBSPL test figure, but =
it
> doesn't follow that the mV/Pa is a linear function over varying pressures=
,

Keith, common microphones have a linear characteristic. So, the mV/Pa speci=
fication is valid for any sound level (except of clipping and very low leve=
ls that are masked by the self-noise of course). If that was not true, the =
microphone would introduce severe distortion.

> Let's say we have our scene with a distant source of particular interest
> producing say, 10dBSPL less than some other nearer source.
>
> Now, let's assume for  this purpose, we have 2 gun mics with the same pol=
ar
> pattern and the transfer functions are both linear but have different
> slopes. #1 has a sensitivity of 20mV/Pa,  #2 is 10mV/Pa, -  I'm guessing =
#1
> likely has a steeper TF slope than #2. Both have a sufficiently low
> self-noise to be used  for nature work and our mic pre's are near
> noiseless, at the gains applied. We adjust gains so that both mics are
> reading the same max dB value.
> I'm thinking the less sensitive mic will do a better job of 'fetching' th=
e
> more distant sound since the difference between the source-of-interest's
> output voltage and that of the near sound will be less.

Both microhones should provide exactly the same results under these conditi=
ons.

Regards,
Raimund









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