HyperSonic Sound - The future of tranducers

[jasonc]

Has anyone ever worked with or listened to a HyperSonic audio transducer?



http://www.atcsd.com/tl_hss.html

This type of high frequency piezoelectric technology has existed for quite some time now (since the 60's), and I hope that it will take of into the marketplace soon.

The main principle is wave interference, much like the ones used in a superhet, mix two different frequencies together and you get a sum and a difference:



They use a patented process using square rooting of the mixing frequencies to eliminate all of the unwanted harmonics.

Check out the whitepaper:

http://www.atcsd.com/pdf/HSSWHTPAPERRevE.pdf

Popular Science has an article on this technology too, apparently the military uses could turn sound into a weapon, ouch!

http://www.popsci.com/popsci/science...1353%2C00.html

[Nappylady]

There's a fundamental problem with this technology, which is the reason it hasn't taken off yet.

Remember that, as frequency increases, the volume displacement required for a given SPL decreases at a rate of 12dB/octave. (40dB/decade) By astonishing coincidence, cone transducers' excursion matches this rolloff exactly, until you reach the cone breakup region.

If I want to use interference patterns to make a 200hz sinewave, I could use a 2000hz and a 2200hz sinewave. If the SPL I wanted for 200hz was only 70dB, the 2000 and 2200hz waves would have to be 110dB in order to create it! Making sounds that loud at that high frequencies is not only difficult, but dangerous. When the military says it could be a weapon, they're not joking.

This technology is not new, and while it's a cool idea, the practical problems of it have prevented it from going anywhere, and will probably continue to prevent it for some time.

[jasonc]

Indeed low frequency reproduction is a BIG issue, but they are being rolled off of a production line as we speak.

The initial application targets a < 500Hz frequency range, due to the limitations opposed. Psychoacoustic techniques may be used, such as TrueBass from SRS Labs:

http://www.srslabs.com/ConsumerTechMonoStereo.asp#WOW

I would suspect that animals like bats, dogs and such will behave strangely due to the harmonics produced from this technology.

I will try to find some resources on the effects on animals.

[Svante]

Sennheiser has a commercial product that seems similar to this. I have also seen this described in JAES or if it was JASA, I don't remember.
It is a rather interesting way to acheive directivity from a small source at low frequencies.

[phase_accurate]

Psychoacoustic techniques may be used, such as TrueBass from SRS Labs

Despite it's name it wouldn't generate "true bass" and couldn't be compared to the "real thing".
I assume that if checked properly it shouldn't even be patentable because it is prior art (just two examples: 1. Organs use this principle for centuries 2. there was an article in Wireless World during the fifties, describing such a system).

Regards

Charles

[kevindd992002]

Anybody who has much technical experience in ATC's HyperSonic Sound Technology? I need assistance in accomplihsing my thesis project.