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Can You Hear Me Now?

Article #153 • Written by Greg Bjerg

Jean Ausgher
Jean Ausgher

When the Big Bad Wolf donned grandmothery garb so as to surprise Little Red Riding Hood, he assured her that the big ears were "all the better to hear you with." Essentially, the Big Bad Wolf was explaining the basic operating principle behind most of the world's acoustic location devices.

Originally, acoustic location was used for ship detection in fog conditions but from mid-World-War-One to the early years of World War Two the devices were often used for aircraft detection. They were all rendered obsolete by the introduction of radar, but for a time they served a useful purpose in national defense.

If not effective they were at least distinctive. At the Brussels Inventor's Fair of 1960, Frenchman Jean Ausgher exhibited his wearable acoustic navigation device. It was to be used by small ships in case of radar failure. The distance between the horns increased the observer's ability to localize the direction of a sound. Unfortunately, in this case the horns weren't far enough apart. With Ausgher's device you would hear an oncoming vessel about the time it was to collide with you.

German Ringtrichterrichtungshoerer
German Ringtrichterrichtungshoerer

Operation of most large acoustic detectors usually required the use of three crewmen and four horns. One man's task was to operate and adjust the elevation of the device for maximum reading, another adjusted for the greatest direction bearing, and a third reported the settings to a central location. Using several results from multiple detectors, the target's location could be triangulated, and the information was then passed on to anti-aircraft defenses. The whole process was done in a surprisingly short period of time.

No detector was better than the German Ringtrichterrichtungshoerer (RRH). The detector was used mainly in anti-aircraft searchlight batteries for the detection of British night bomber formations. The RRH could detect targets at a distance of twelve kilometers, and depending upon weather conditions and operator skill, it could help detect the size of the aircraft formation. It had a directional accuracy of 2 degrees. The device had a crew of three with the dial reader in the middle. The rolled up material over the operator's heads could be unfurled to provide cover in bad weather.

The Japanese war tuba
The Japanese war tuba

The Japanese "war tuba" is a name sometimes applied to Imperial Japanese military acoustic locators due to their visual resemblance to a musical tuba. The name derived from a misidentification, probably in jest, of a historical photo from the 1930s featuring the Japanese emperor Hirohito inspecting the acoustic locators with anti-aircraft guns in the background. It was used around major military targets and Tokyo.

The British and Americans also had small acoustic detectors of limited effectiveness. However, the British did build a series of huge stationary concrete "acoustic mirrors", some of which are still standing to this day.

Another remarkable machine was a French acoustic locator based on a hexagonal layout. Each of the four assemblies carried thirty-six smaller, hexagonally-shaped horns. This layout was presumably used to increase the directional gain of the equipment. Because the detector was so large and out in the open, the type was abandoned after being repeatedly bombed by the enemy.

Acoustic detectors are still used today by television crews to pick up the sounds of players and coaches on the field during televised sporting events, where use of conventional microphones would be too intrusive. They are also used as novelty items — "whisper dishes" — in science museums to allow patrons to whisper across long distances.

Article written by Greg Bjerg, published on 01 April 2006. Greg was born and raised in Iowa and graduated with a degree in Journalism from Drake University. Sadly, he passed away on 20 March 2011.

Article design by Alan Bellows. Edited by Alan Bellows.
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15 Comments
StargateX1
Posted 01 April 2006 at 08:44 pm

April fools?


Brett Holman
Posted 01 April 2006 at 09:14 pm

"April fools?"

Not at all, sound locators were indeed widely used for aircraft location before the Second World War. I've been reading about the First World War ones in Britain -- supposedly they sometimes had blind men operate them, because it was assumed they would have more sensitive hearing. Also, I found it interesting that when the Germans started attacking with Giant bombers, it confused the sound locator units, because they had louder engines than the previous bombers (Gothas) and so were interpreted as being much closer than they actually were.


Arcangel
Posted 01 April 2006 at 11:14 pm

Acoustic sounders have been used since the mid to late 70's for weather predicting. The sounders are used for determining the inversion layer (a point in the atmosphere where the temperature begins to rise instead of continuing to fall), wind speeds, etc. Surprised that you did not mention that fact but damn interesting as usual.


Armani
Posted 02 April 2006 at 12:55 am

Theres this one thing at the Omniplex, its like 2 radar dishes facing each other. U could whisper into one and like 30 feeet away u could hear it. neato


another viewpoint
Posted 02 April 2006 at 06:03 am

I believe the Museum of Science and Industry in Chicago also has a "whisper chamber"...

While it appears that accoustic listening devices were born out of military application (like so many things in this day and age), the article reminded us applications in sports where sideline reporters can get all the grunts, groans, body impacts and yes...and all the out-of-place language that you don't really want to hear. Technology...you gotta luve it!


Gaffer
Posted 02 April 2006 at 08:18 am

This should probably be merged with the British acoustic mirror device article since they deal with the exact same subject.


Dr.Grimgravy
Posted 02 April 2006 at 04:32 pm

The dome of the Missouri State Capital Building in Jefferson City was designed like a "Whisper Dish", if you are the on the exact opposite of another person, you can hear one another whisper, all 360* around.

It was assumed the designer did this so politicians could discuss matters without actually having to look at one another... Hip Hip Hooray for 8th grade history class...


PresMatt
Posted 02 April 2006 at 10:13 pm

The dome of St Pauls cathedral is also a "whisper dish."


clayton
Posted 02 April 2006 at 10:42 pm

Hey Armani. Omniplex. Are you an Oklahoman? Elk City here.


steveisgay
Posted 03 April 2006 at 03:38 am

Wow. Out of that entire article I only noticed one thing: my favourite new German word

Ringtrichterrichtungshoerer. What a phrase. What a mouthful . And I would know.


jchristman
Posted 03 April 2006 at 10:53 am

Steveisgay, your sexual inuendo was uncalled for.


steveisgay
Posted 06 April 2006 at 06:58 am

Deal with it.


ichkenne
Posted 11 August 2006 at 01:27 am

How 'bout diesse worte:
Trichterroergedeckt 8'
Ophicleide 16'
Gemsroerfluit 4'
Septsesquialtera 2 2/3'
Holzprincipal 16'
Untersatz 32'
and an easy one:
Vlakfluit 2'


Waglok2110
Posted 11 May 2007 at 07:16 am

ahahhhahahah lol the japanese war tuba... hahahahhaha that cracks me up.


dacoobob
Posted 26 November 2007 at 08:55 pm

Waglok2110 said: "ahahhhahahah lol the japanese war tuba… hahahahhaha that cracks me up."

Yah, seeing that phrase in conjunction wit the photo almost put me on the floor laughing. Unfortunate, since I was looking at this while at work. Damn DI, now my coworkers know I was screwing around on the job... :)


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