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Re: Cheap electret microphones for environmental noise measurements

Subject: Re: Cheap electret microphones for environmental noise measurements
From: "Eric Benjamin" ericbenjamin2
Date: Thu Jun 26, 2014 1:05 am ((PDT))
You may want to ask this question in the Yahoo micbuilders group. =C2=A0But=
 meanwhile I have a couple of comments and questions.

The question is: How many microphone/transmitter systems do you need to mak=
e? =C2=A0and how much are you prepared to pay for them?

About 35 years ago I fabricated some microphones in support of a friend's f=
ield research in the Amazon jungle. =C2=A0For that I sealed the front of th=
e microphone with 1/10 mil polycarbonate film, and the back of the micropho=
ne with electronic type silicone rubber. =C2=A0I wouldn't say that those ca=
psules were waterproof, but they did survive six months in the jungle. =C2=
=A0If I had to do it today, I'd check out the waterproof capsules made by K=
nowles; their WP series:

Those capsules are typically guaranteed down to an immersion depth of 3 met=
ers. =C2=A0These capsules are typically in the range of $25 at Digikey and =

I'm a bit more concerned with the concept of using a radio link. =C2=A0Why =
can't you use cable?

On Thursday, June 26, 2014 12:33 AM, " [naturerecordists=
]" <> wrote:

I'm a Ph.D. student and I need to make some long term environmental noise m=
easurements. I need to deploy a noise measurement network using small nodes=
 equipped with a microphone and a radio interface (for transmiting measurem=

I don't need very accurate results, but as I will have to deploy a lot of m=
easurement nodes, I need each of them to be very cheap. Electret microphone=
s such as Panasonic WM-61 are enough for my purposes. My only concern with =
them is that as I need to do measurements for a year or more, I need the mi=
crophones to last as much as possible.

Does anybody know (and if backed with data, better) if these microphones ca=
n last when placed outdoors without breaking or suffering severe sensitivit=
y/frequency response deviations? How can I properly (and cheaply) protect t=
hem? I can correct measurements with temperature data, and maybe also with =
humidity. Any other advices are welcome!

Please avoid expensive commercial solutions (such as Class1/Class2 outdoor =



PS: This topic is not 100% related to this group, as it deals with environm=
ental noise, and not with nature sounds, but I think people in this group h=
as for sure the experience and knowledge necessary to solve my problem, and=
 the community might be interested in how to record sounds for long term wi=
th cheap microphones.

Sorry if I bother someone.

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