Oh, and a couple of other tips for anyone wanting to use condoms for
protecting microphones - wipe as much of the lubricant off as you can
before use (it's a b***er to remove from microphone) and use the
featherlite variety for maximum acoustic transparence.
Dave
On 19 February 2013 21:46, Dave Malham <dave.mal...@york.ac.uk> wrote:
> The trouble with the sort of materials used in condoms is that they
> are inherently stretchy. Under any sort of pressure (more than a quite
> small depth of water) the material presses through any holes and
> either (a) rips or be (b) comes into contact with the diaphragm which
> is potentially almost as big a disaster. That's why the first DIY
> hydrophone I linked to uses an electret capsule immersed in oil in a
> canister. I have uses both condoms and cling film to waterproof
> microphones but only really for splash proofing. For those situations
> you can measure the mic before wrapping and after so that compensation
> can be made for the inevitable resonances. Probably not possible for
> underwater systems without the the same problems of needing a
> calibrated source and a lot of underwater space which, given the fact
> that it probably won't be possible to use the assembly at any sort of
> depth, is not going to be easy.
>
> Dave
>
> PS The wackiest thing I ever sealed a microphone for (with cling film)
> was to listen to worms under the ground for a biologist who was trying
> to find a way to assess the number of worms in a given volume of soil
> without crushing them up with the soil and extracting the (now dead)
> biological material.
>
> On 19 February 2013 17:48, Martin Leese <martin.le...@stanfordalumni.org>
> wrote:
>> Fons Adriaensen wrote:
>>
>>> Don't know what Len will think of it, but putting a Tetramic
>>> (or any such mic) in a plastic bag isn't likely to produce
>>> anything usable. Basic problem is that the acoustic impedance
>>> of water is around 3400 times higher than that of air, so the
>>> water/air interface will reflect almost all energy. You need
>>> a transducer that is more or less matched to the acoustic
>>> impedance.
>>
>> I have read that the standard trick is to use a
>> condom. However, I puzzle whether this would
>> work with a Tetramic.
>>
>> Regards,
>> Martin
>> --
>> Martin J Leese
>> E-mail: martin.leese stanfordalumni.org
>> Web: http://members.tripod.com/martin_leese/
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>
>
>
> --
> As of 1st October 2012, I have retired from the University, so this
> disclaimer is redundant....
>
>
> These are my own views and may or may not be shared by my employer
>
> Dave Malham
> Ex-Music Research Centre
> Department of Music
> The University of York
> Heslington
> York YO10 5DD
> UK
>
> 'Ambisonics - Component Imaging for Audio'
--
As of 1st October 2012, I have retired from the University, so this
disclaimer is redundant....
These are my own views and may or may not be shared by my employer
Dave Malham
Ex-Music Research Centre
Department of Music
The University of York
Heslington
York YO10 5DD
UK
'Ambisonics - Component Imaging for Audio'
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