Apologies if this is the wrong forum and/or sub-forum to post this
topic.
After learning about a Speech Jammer--or a device that stops people
talking--I've become interested in creating one. What off-the-shelf parts are available for such a project and would it be feasible to do?
[Edited on 6-12-2012 by sbovisjb1]IrC - 6-12-2012 at 02:45
Did you bother reading the information including the PDF in the links you posted? Shotgun Mike, amplifier, adjustable reverb (could be electronic or
mechanical), amplifier, speaker. sbovisjb1 - 6-12-2012 at 02:57
Did you bother reading the information including the PDF in the links you posted? Shotgun Mike, amplifier, adjustable reverb (could be electronic or
mechanical), amplifier, speaker.
Yes. I was more interested in have an on-board controller such as the Arduino. Then I realized they recommend you use a PIC18F-452 and I don't have to
fiddle around with software as I originally envisioned.
Long story short I posted before I read the whole thing. IrC - 6-12-2012 at 03:42
Actually while you could do it with processing and software methinks the old days of simpler mechanical-electrical methods would work. An old spring
reverb with adjustable tension (lengthwise), 2 transducers, amplifiers, a mike and speaker would do the same job. While I do have a pile of Arduinos
myself sometimes I think the simpler things in life are more fun to play with. Or how about an old bucket brigade IC. Just thinking out loud.
franklyn - 16-12-2012 at 15:27
Resonance is amplification by maintaining emitted sounds in phase with
reflected sounds to reinforce their amplitude. Reverberation is closely related
with very slight phase difference and as such the sound decays rather than
becoming amplified. An echo is a distinct phase delay in reflected sound.
This latter effect is what is being applied.
As described the device also has the means to adjust for distance to target
as this will effect the turnaround time of the echo. Proximity cannot exceed
beyond the range of an auditorium , being limited by the speed of sound.
~ 340 meters per second.
This device first required the invention of the directional speaker.
What is interesting is the device purports to have directionality as an acoustic
' laser ' exhibiting a coherent beam of sound , cryptically referred to as a
' directional speaker '. Specific frequencies can be made to behave this way
by having an array of emitters in phase set 1/4 wavelength apart. Ref [ # ] below
Doing this with the jumble of frequencies of audible speech is another matter entirely.
The lower the sound , the longer the wavelength and so the farther apart
the emitters or speakers need to be.
Mixing two slightly out of phase pure frequencies produces a heterodyne or
' beat frequency ' corresponding to the exact difference between the two.
In principal one can devise a scheme using a compact arrangement of
piezo-electric crystals as ultrasonic sound emitters to produce an audible
' beat frequency '. Modulation of one frequency enables that beat to
reproduce audible speech.
Nonlethal Weapon Concepts ( with references )
See PDF page 16 - Acoustics www.dtic.mil/dtic/tr/fulltext/u2/a365328.pdf
[ # ]
The concept as shown in this picture had originally been developed
by Vladimir Gavreau in the early 1960's
See _
V. Gavreau , R. Condat and H. Saul , " Infra-Sons: Générateurs , Détecteurs ,
Propriétésphysiques , Effets biologiques ," Acustica 17 (1) (1966) , pp. 1-10;
V. Gavreau, " Infrasound ," Science Journal 4 (1) (January 1968), pp. 33-37.
There was also a cover story in "Science and Mechanics" Magazine
either December 1969 or January 1970 , ( maybe even February )
