US Army subwoofer - WOMD? ;-)

[Circlotron]

An infrasonic Helmholtz resonator capable of producing clean sinusoidal frequencies in the range of 6-14 Hz is described.
http://patft.uspto.gov/netacgi/nph-P...RS=CCL/381/351

[paulspencer]

It appears to be just a very large vented box with a pair of 18" pa drivers. 130 db is claimed as max output at 6 - 20 Hz. The two vents are each tuned to the extents of the passband, like in a bandpass box, except the diagram of the box makes it appear that it's just a variation of a vented box.

I'm not sure how this warrants a patent!

It would be interesting to see what results people got if they modelled this box.

[Zero Cool]

I beleive the Servodrive Subwoofers will do this. thats why they were invented! to reproduce the 5Hz sounds elephants can make.


The bigger question i have is WHY does the MILITARY need such a device????

It cannot be because they like realistic home movies!

Low frequency energy has been know to make people sick or ill at ease. i would bet they use this as sort of a weapon why they want to drive someone out of a compound etc.



Zero

[DSP_Geek]

Originally posted by Zero Cool
I beleive the Servodrive Subwoofers will do this. thats why they were invented! to reproduce the 5Hz sounds elephants can make.


The bigger question i have is WHY does the MILITARY need such a device????

It cannot be because they like realistic home movies!

Low frequency energy has been know to make people sick or ill at ease. i would bet they use this as sort of a weapon why they want to drive someone out of a compound etc.

Zero

<Blazing Saddles>
Not only elephants make 5Hz sounds.
</Blazing Saddles>

But seriously, that's exactly why the military wants WOMDs - as an area interdiction device, it's distinctly more civilian-friendly than sustained fire.


Francois.

[paulspencer]

My thoughts precisely! What does the army want with something like this! It was discussed in terms of its in room output level and power to drive it. Sounds like a big subwoofer to me, not a military device. A weapon would be much more robust, and would be constructed along similar lines as the servodrive, except they would probably make it more robust, not use exposed paper drivers! If you wanted to make a weapon subwoofer you would probably make a horn loaded servodrive!

Coming back down to earth, perhaps they would use it in their training in some way, in simulators. Perhaps the fact that subsonic sound makes people feel sick is part of it - getting pilots, soldiers, etc accustomed to what makes most people feel sick. Who knows ...

[paulspencer]

What's a WOMD?

[phase_accurate]

WOMD = Weapon Of Mass Destruction

I don't think they use this as a weapon as such. Maybe for training simulators or maybe for the development of acoustical homing devices. The infrasonic waves generated by tank engines or helicopter rotors travel quite far in the open space.
For this purpose they once developed a thingie they called MOAS (mobile acoustic source) that could generate 145 dB down to 15 Hz. It was a huge horn on a trailer fed by a steerable valve, controlling air-flow from a car-engine driven compressor.
I wasn't able to find any pictures on the web anymore unfortunately (it looked impressive to say the least).

BTW: I also agree that the discussed construction wouldn't be worth being patented IMHO.

Regards

Charles

P.S.: Some said that the meaning of MOAS was Mother Of All Speakers.

[mike.e]

[phase_accurate]

Yes, that's the one !!

Regards

Charles

[MEXXX]

It sounds like its just a big box with something along the lines of a driver coupled in a sealed box to a passive radiator that in turn plays into another enclosure tuned to the same frequency as the PR but using ports instead.

Heh, I guess BOSE isn't the only one who wastes time and money patenting things that don't warrant a patent.