Cable (AHK-XX MKII) for Ambient ASF-1 MKII hydrophone, length to choose from 25 to 100 meters
Price
$620.00
Availability:
Usually ships in 1-2 weeks, on request only, no refunds
Underwater Acoustics
The acoustic underwater differs in many ways from the airborne
sound we are used to. The sound velocity underwater is varying between
1450 and 1550 m/sec depending on temperature, salinity and depth. This
results in 4 to 4.5 times bigger wave lengths as well as in a special
sound phenomenon called the SOFAR, also known as Underwater Sound
Channel. Horizontally sound can travel over huge distances whereas
vertical propagation is strongly attenuated.
Here are some useful advices:
Sound Channels (USC, SSC,…) can be avoided by knowing their local depth
To avoid the noise from braking waves on the boat hull, take long
enough cables to go down deep enough or prepare to record in greater
distance to the vessel.
Take time for detailed micro-phasing when recording in pools or
artificial environments as bigger wave lengths underwater lead to
greater distances between sound maxima and minima.
Never forget how far low frequencies can spread underwater. Therefore, avoid touristic areas for documentary shots.
Water owns a reflection factor close to 1, thus, airborne sound
virtually can’t couple directly into water. This phenomenon can be used,
if barriers reach close to the water surface (reefs, wave-breakers,
e.g.) you can use them as acoustic barriers, independent of the current
depth. This way you may find acoustic cover in a pool with 1m depth
behind an 80 cm wooden block, even though the wavelength underwater
wouldn’t suggest this.
