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Marine Research


         The Cetacean Effect

Dolphins      The marine environment beyond imagined limits

  An onboard full spectrum listening system for marine mammal (cetacean) sounds

Blue Whale







We go boating to be out in nature because of the feeling it gives us, that feeling of oneness with our environment. Using this system we can enjoy a dimension that was previously unavailable to us. Marine cetaceans (whales and dolphins) produce sounds that are rich in hypersonic frequencies (Above the human hearing limit of 20,000 Hz) which studies have shown to produce deep activation of the brain.1 Boaters have the unique opportunity to hear these sounds in their natural environment and in their entirety with this product, as opposed to only the limited frequencies standard audio equipment is capable of reproducing. Standard audio equipment only encompasses sounds within- or very near the range of human hearing, truncating these rich and varied components that, although they do not create an auditory experience, have been shown to have clear effects on human physiology. Our studies over the last 25 years into the effect of sound on the human organism have brought us to the point where we can now offer a very specific enhancement to the marine experience. 

How does it work?

The sounds are captured by a high sensitivity transducer (hydrophone) and played back live. The frequencies captured and played back go all the way up to 120,000 Hz. To achieve this the audio is divided into two components, high and low, each with it's own Amplifier and Speakers particularly suited to that range of frequencies. The transducer is either lowered into the water by a mounting system on the transom, or via a thruhull mount. 

Please Contact Seattle Boatworks For More Information

Research Papers into Hypersonic Sounds Effect on Humans

[1] Oohashi T. et al.: Multidisciplinary study on the hypersonic effect, In: Inter-areal Coupling of Human Brain Function (Ed. by Shibasaki H. et al.), Elsevier, Amsterdam, 27-42, 2002.
[2] Oohashi T. et al.: High frequency sound above the audible range affects brain electric activity and sound perception, AES 91st Convention Preprint 3207, 1-25, 1991.
[3] Yagi R. et al.: Multidisciplinary evaluation on the hypersonic effect with the Authentic hypersonic sound systems (in Japanese), Proc. 2001 autumn meeting of Acoustical Society of Japan, 527 528, 2001.
[4] Oohashi T. et al.: Inaudible high-frequency sounds affect brain activity: hypersonic effect, Journal of Neurophysiology 83: 3548-3558, 2000.

Although best suited to sailboats, this system can also be used in power boats, but they must be stationary because of engine and propeller noise. It is not recommended for sailboats under 35 feet because of small overall listening space.    

System ComponentsLayout Diagram  -  Installations and Mounting Systems  -  


 System components:

1.  Full spectrum hydrophone (1 Hz to 120,000 Hz range)

2.  Compatible preamp

3.  Crossover  

4.  Low Frequency Component Amplifier and Speakers

5.  High Frequency Component Amplifier and Speakers (thin film technology)

6.  Oxygen free copper cabling

7.  Mounting Kit (Thruhull or Transom mount)  

Cost of a typical system:  $4500


Layout Diagram

 Layout Specifications Diagram


 Installation and Mounting Systems

Transom or thru hull mountings are available. In both cases the hydrophone extends down through a tube into the water so that the acoustic center is completely available to capture the ambient sounds. See below for mounting diagrams.

 Transom Installation Diagram

 Thruhull Installation Diagram
In the thru hull mount the tube extends just above the waterline so that the hydrophone can be inserted or retracted while the boat is in the water without water coming in. The end of the tube is fitted with 2 caps- 1 with a hole in it for the hydrophone (transducer) while in use, and the other without hole for when not in use.


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These methods are a part of the field of complementary/alternative medicine. They are not a replacement for licensed medical care.