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this thread immediately grew into two completely different fields:
Ultrasound and Infrasound.
very interesting!
>It's actually a very different idea than the Nazi's weapon.
>Hypersonic Sound utilizes ultrasonic sound waves to "encode" an
>incoming sound signal so that it can be reproduced directly in front
>of the listener. It relies on the "non-linearity principle" of air
>to cause collisions of ultrasonic sound waves to produce sum and
>difference frequencies of the colliding waves. Obviously the sum of
>ultrasonic waves will not even be close to audible frequencies, but
>the difference waves will be audible and will reproduce the input
>signal, and it will be extremely directed due to the precision of
>ultrasonic waves. While this could be used to produce ultra low
>frequencies such as 6.5Hz, the technology is designed simply to
>direct sound so that only certain people can hear it. I cannot
>provide a much more technical explanation, but if you search for
>Hypersonic Sound, you will find ATC's website with lots of technical
>docs on the process. Personally, I definitely understand how
>annoyingly it can be used as an advertising tool and more, but I
>think it has very novel uses for the field of sound art. Though,
>this might be just hopefulness coming from a Music Technology
>student.
never thought of that, thank you!
seems the guys have only practical ideas for aplications that dont
warm me, but we would end up doing different stuff...
they dont say how good the sound quality really gets.
Also, they only talk about using one source and hear only its distortions.
the difference of two ultrasonc waves should become audible where the
two meet in the right phase. Higher frequencies are more directed, so
you can create two beems and where they meet much more should be
audible than just with one beam. I wonder how exactly the sound can
be produced by calculating the two ultrasonic waves.
I suppose, if the two sound sources were mixtures of frequences (an
ultrasonic orchestra), then different sounds would become audible in
different spots.
those sounds could be added to "ordinary" music, so when you walk
arround in such a show you hear the basic music, enriched with sounds
that change according to your movements. Could be stimulating for
headbanging :-)
oh, just now, I realize that Rick came up with this thread.
no coincidence...
relax, Rick. All inventions end up being used from both sides.
seems to me like a great invention in hands like yours!
Rick had said:
>>>Finally, a cutting edge sonic technology that I DON"T want to
>purchase.
>>> Check out this very creepy article about the LRAD............a
>>>sonic device that can be used as a weapon or as
>>> a crowd controller.
>>
and Sweet and Ty came up with a very differnt story:
>>they had a parabolic sound cannon which fired a 6.5 hz sine wave at
>>some obscene dB level that could blow a soldier apart ... if he
>>stood still for 4 minutes.
hm... not quite that drastic
but there was also Jericho in the past...
as oposed to the ultrasound, infrasound is very well spread, so its
scary for us: We cannot run away, because we dont feel where it comes
from!
>>
>>btw: notice anything particular about that frequency? it's the
>>average resonant frequency of the human body, which also happens to
>>fall within the 6-7 hz range which we find most musically pleasing
>>for vibrato.
>>
>>coincidence?
>>
no... this is interesting... any instrument and loud speaker only
vibrates nicely above its resonance. Below it can only move, with no
tendency to repetition.
6 Hz means 360 waves per minutes, corresponding to 360 BPM, a rather
"nervous" speed :-)
its also where the eyes stop working, but still feels painful flickering.
its a transition in our perception.
whether an "average resonance" would matter, I dont, I dont know. But
it seems to me that each of our elements have their own resonances.
For example walking speed, breast swinging... :-)
so maybe 6 Hz is rather the resonance of some organ or nerve system?
--
---> http://Matthias.Grob.org