segunda-feira, 31 de maio de 2010

Hydrophones

How To: Hydrophones
Article by George Spanos

Hydrophones can provide some really interesting underwater recordings. Often bordering on the abstract, you can always get some new sounds from old techniques.

What is a hydrophone?

A hydrophone is essentially a microphone that can be used underwater. Much like
a contact microphone, hydrophones are often made from a piezoelectric-type
transducer. When submerged into water the hydrophone converts sound pressure
waves into electrical signals that can be recorded. There are many scientific uses
for hydrophones and they are often used by marine biologists to listen to
whalesongs and dolphins.










It is possible to use a normal dynamic microphone to record underwater sounds
but the results are often not as crisp and clear to listen to. A common technique
for submerging a dynamic microphone in water is to secure a non-lubricated
condom to the part of the microphone that is underwater. Because water and
electricity don't often mix, be careful when trying this or you'll end up with a
blown mic!

Ok, so now that the basics are covered where you may ask can one acquire one
of these underwater recording devices? I used the Aquarian Audio Products
H2A-XLR for the following recordings. The device itself is very light but heavy
enough to not move around in water, which is important or you will pick up noise
from the microphone cable.



The hydrophone terminates in a balanced XLR which can interface with any
recording device that can supply +48V of phantom power. I used my handy Zoom
H4 which I find is the most portable and quick to set-up piece of recording gear I
own. Sure, the screen is small but if you monitor your recordings carefully
through headphones that should not be a problem.


Recordings

Metal Springs

In addition to recording underwater sounds, a hydrophone can be used as a contact microphone. I found the H2A to be really sensitive and excellent at picking up minute details when used as a contact mic. This is a recording of thin metal strips being banged and scraped against a metal surface. Lots of nice detail that when pitched down can make for some interesting effects.


Hydrophone in bathutb

Larger Than Life Water Drips

For this next recording I attached to hydrophone to a long metal pole and dipped it into a bathtub filled with water. The result? Huge sounding water drops... add some reverb to these and you've got an interesting sound...


More Metal Springs

For this next sound I submerged the hydrophone into a tub filled with water and recorded a slinky being dipped into the water. The effect could definitely be used as some alien cricket sounds!

Running Water

What hydrophone recording session would be complete without some running water? What follows is the mic being suspended under running tap water which produces an interesting gurgly water sound.

link: http://www.gamesounddesign.com/Using-a-hydrophone-to-record-underwater-sounds.html
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Hydrophones são microfones utilizados para gravar sons debaixo da água! Ótimo para captar sons reais e editá-los (para produzir efeitos). Nos jogos, podem ajudar bastante na ambientação ou em algum momento crítico que tenha sons bem realistas.

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