Research in Underwater Sound

( hydrophones, loudspeakers, music instruments )


ITC-4066, approx. $550; ITC-8212, approx. $1,264 (see references for ITC).

"The hydrophone you need can be determined once you establish what the projector provides. For example, if you plan on transmitting the music in the audible range through 15 kHz, you may want to use the ITC-4066 or ITC-8212 hydrophone. Both should work, pending a review of the projectors output and location. The ITC-8212 has the same frequency range of the ITC-4066, but it has an integral preamplifier to boost the signal by approx. 20 dB" (Adelhelm).


(a.) Lubell Labs, basic portable system: $1172.79

--recommended to me by Cliff Adelhelm of ITC.

--used by Dan Harris (Redolfi's underwater engineer) for Ben Clarone Music in New York.

--"Our speakers have excellent output between 200Hz-20kHz. This type of design cannot put out good low frequencies. One of our customers has told us that they have had good luck using a Clark Synthesis transducer ( http://www.clarksyn.com) along with our unit, as theirs does good up to 200Hz" (Brian Lubell; e-mail correspondence, Fri, 06 Feb 1998).

(b.) Clark Synthesis, Tactile Sound Transducer; TST NEO 329F: $499, 200 Watt Amp: $499.

--"In response to your e-mail inquiry about how the Clark Synthesis TACTILE SOUND transducers perform so well underwater at low frequencies I can only reply that it's one of the reasons they were issued U.S. Patent #5,473,700. The real 'secret' behind the Clark design is in their unique shape and construction and they do perform, in the qualified opinion of this long-time audiophile, better than anything else that I've experienced both in and out of the water. Yes, you could expect some very respectable full-range and/or bass performance underwater (to dance music or anything else you chose to play) within the usual variables of pool size, number of transducers employed, amplifier power, mounting location(s) and method, etc. There are special versions of the Clark transducers made specially for underwater and/or high humidity locations (underneath boat docks is another popular installation) with special waterproof adhesives and wiring" (Rob Robinson, member of marketing team for Clark Synthesis; e-mail correspondence, Fri, 13 Feb 1998).

--"[The TST NEO 329F transducers] consist of two 1-in.-deep, 8-in.-dia. clear Lucite domes mounted back to back. One side of the dome contains the voice coil, and the other contains a huge 22 1/2-ounce neodymium magnet. When current is fed through the voice coil, the magnetic forces cause the domes to deflect, creating a transduction force of more than 1 pound per watt--which moves whatever the transducer is attached to. The domes are very rigid structures, so their response to the applied audio is very accurate" (Popular Mechanics, May 1997; read on Clark Synthesis webpage).

--in a phone conversation, Mr. Thomas Clark Fenner, inventor of the Tactile Sound Transducer, relayed to me that the TST NEO 329F produces power sufficient for underwater sound since Lucite, its transducing material, can create more displacement than aluminum--which is used in the construction of most normal loudspeakers. Lucite consists essentially of polymerized methyl methacrylate and is normally used as an acrylic resin or plastic. Recent innovations in the design of the TST, furthermore, have attained a flat frequency response for everything from 10 kHz to 100 kHz. Also, problems with underwater sealants had once negated underwater applications of the TST, but Fenner tells me that these problems have been solved and that Clark Synthesis is going to be the "next big thing" in underwater acoustics.

(c.) Underwater loudspeakers can also readily be found elsewhere, with reference to synchronized swimming: there are companies that make underwater speakers so that the swimmers know when to pop their heads out at the same time. Such loudspeakers are also commonly used to play music underwater at pools for recreation.




( Introduction, Main Body, Closing, References, Links and Addresses )

Underwater Sound Equipment and Costs