Maker Pro
Maker Pro

very directional speaker technology

A

amdx

Jan 1, 1970
0
Anybody heard these speakers?

Looking for a discussion of this technology.
It would be a neat homebrew project!

http://www.holosonics.com/technology.html

http://www.holosonics.com/brochure/Audio_Spotlight_Specifications.pdf

http://www.holosonics.com/products.html


What frequency is the ultrasound?
Do some systems mix two ultrasound sources?
There is correction for nonlinearity of air is that correction
performed at ultrasound frequency or audio frequency?

Here's a couple of youtube videos about the subject.
I'd like to hear your input. :)
Note the bnc connector to the speaker!
Mike
 
A

amdx

Jan 1, 1970
0
answerman said:
Because of air attenuation, as low as possible while still safely outside
the audible frequency range. Call the manufacturer and ask. Given that
it's easily measured, it can't be a secret.


That depends on your definition of a source. Two ultrasonic signals, yes.
Two ultrasonic transducers, only if they are stupid.



At the ultrasound frequency.




Here's a semi-technical review article published by another company on the
subject.

http://www.directionalsound-usa.com/hss/pdf/HSSWHTPAPERRevE.pdf
Thanks for the URL, nice history of development.
Mike
 
A

Angelo Campanella

Jan 1, 1970
0
amdx said:
Thanks for the URL, nice history of development.
Mike

Agreed. It a "must" read for speech communications folks. Keep an open
mind in reading it; nothing orthodox about these folks..

Angelo Campanella
 
M

mike

Jan 1, 1970
0
Angelo said:
Agreed. It a "must" read for speech communications folks. Keep an
open mind in reading it; nothing orthodox about these folks..

Angelo Campanella
Am I the only one who worries about sitting in a 140dB ultrasonic field?
This can't be good for biology???? My brain is already sufficiently
scrambled, thank you...
 
P

Peter Larsen

Jan 1, 1970
0
Am I the only one who worries about sitting in a 140dB ultrasonic
field?

No. Hearing damage does not in principle depend on anything but on the
amount of energy delivered to the sensory organ, ie. audio does not have to
be audible to do damage.
This can't be good for biology???? My brain is already
sufficiently scrambled, thank you...

Kind regards

Peter Larsen
 
A

Angelo Campanella

Jan 1, 1970
0
mike said:
Am I the only one who worries about sitting in a 140dB ultrasonic field?
This can't be good for biology???? My brain is already sufficiently
scrambled, thank you...

Good Point. Expseriens and measureemnts around 1950 at Penn State
showed that heat deposition occurs at an above this level. A ball of
cotton will smoulder and catch fire at and above 160 dB. Bare skin
reflects the energy, but who wants to take that chance.

Anglo campanella
 
J

JosephKK

Jan 1, 1970
0
Don't forget a couple dozen 1 million lumen strobe lights, flashed in
sequence to disorient them, till the cops arrive.

Not in any perceivable sequence, it becomes too easy to adjust.
 
R

rickman

Jan 1, 1970
0
No. Hearing damage does not in principle depend on anything but on the
amount of energy delivered to the sensory organ, ie. audio does not have to
be audible to do damage.

Kind regards

Peter Larsen

What do you base your statement on? I can see where the energy
*would* need to be in the audible range. The detectors in the human
ear are thousands of tiny cilia that are each tuned to a unique
frequency of sound. They literally resonate at a particular
frequency. The damage happens when the cilia are over stimulated and
mechanically damaged. So if the energy is not in the audible range,
they don't resonate and it is much harder to damage them. Of course
if you use a high enough level of sound, even outside the hearing
range, it can do damage. Like someone posted, at some point a ball of
cotton will burst into flame! I don't like the idea of spontaneous
human combustion.

Rick
 
P

Peter Larsen

Jan 1, 1970
0
rickman wrote:


[quoting me]
What do you base your statement on?

Reality. Notice that it is by design a very general statement.
I can see where the energy
*would* need to be in the audible range.

"Be audible" implies that it is heard by the actual person and "in the
audible range" implies that it could be heard by a ""normal"" person. It is
an important distinction to be aware of, because people with pre-existing
hearing damage often neglect obvious aural risks or plain fail to detect
them as being at "risk loudness level", whatever that may be.
The detectors in the human
ear are thousands of tiny cilia that are each tuned to a unique
frequency of sound. They literally resonate at a particular
frequency.

At what Q? - my level of information is that this is still kinda softish
tissue with a "frequency range preference" rather than metallic high Q
precision resonators a lá tuning forks. But the image you project is more
like the tuning fork model ....
The damage happens when the cilia are over stimulated and
mechanically damaged.

Seem to be the agreed facts on this.
So if the energy is not in the audible range,
they don't resonate and it is much harder to damage them.

Just how much harder?
Of course if you use a high enough level of sound, even outside the
hearing
range, it can do damage. Like someone posted, at some point a ball of
cotton will burst into flame! I don't like the idea of spontaneous
human combustion.

Just what part of my statement: "Hearing damage does not in principle depend
on anything but on the
amount of energy delivered to the sensory organ" is it that you disagree on,
you seem to me to have written exactly the same as a correction to what I
posted.


Kind regards

Peter Larsen
 
M

mike

Jan 1, 1970
0
Peter said:
rickman wrote:


[quoting me]
What do you base your statement on?

Reality. Notice that it is by design a very general statement.
I can see where the energy
*would* need to be in the audible range.

"Be audible" implies that it is heard by the actual person and "in the
audible range" implies that it could be heard by a ""normal"" person. It is
an important distinction to be aware of, because people with pre-existing
hearing damage often neglect obvious aural risks or plain fail to detect
them as being at "risk loudness level", whatever that may be.
The detectors in the human
ear are thousands of tiny cilia that are each tuned to a unique
frequency of sound. They literally resonate at a particular
frequency.

At what Q? - my level of information is that this is still kinda softish
tissue with a "frequency range preference" rather than metallic high Q
precision resonators a lá tuning forks. But the image you project is more
like the tuning fork model ....
The damage happens when the cilia are over stimulated and
mechanically damaged.

Seem to be the agreed facts on this.
So if the energy is not in the audible range,
they don't resonate and it is much harder to damage them.

Just how much harder?
Of course if you use a high enough level of sound, even outside the
hearing
range, it can do damage. Like someone posted, at some point a ball of
cotton will burst into flame! I don't like the idea of spontaneous
human combustion.

Just what part of my statement: "Hearing damage does not in principle depend
on anything but on the
amount of energy delivered to the sensory organ" is it that you disagree on,
you seem to me to have written exactly the same as a correction to what I
posted.


Kind regards

Peter Larsen
You guys are making the obvious (mis)assumption that hearing loss is the
ONLY danger here.
This technology has been proposed for use in an automobile to give each
passenger a different audio program.

"Hey mommy, what's inside this little hole I've got my eye plastered
against?"
"Makes my eye feel warm..."

Wonder the resonant frequency of the tails on your swimmers?
 
R

Riccardo Balistreri

Jan 1, 1970
0
mike said:
Peter said:
rickman said:
mike wrote:

rickman wrote:


[quoting me]
audio does not have to be audible to do damage.
What do you base your statement on?

Reality. Notice that it is by design a very general statement.
I can see where the energy
*would* need to be in the audible range.

"Be audible" implies that it is heard by the actual person and "in the
audible range" implies that it could be heard by a ""normal"" person. It
is an important distinction to be aware of, because people with
pre-existing hearing damage often neglect obvious aural risks or plain
fail to detect them as being at "risk loudness level", whatever that may
be.
The detectors in the human
ear are thousands of tiny cilia that are each tuned to a unique
frequency of sound. They literally resonate at a particular
frequency.

At what Q? - my level of information is that this is still kinda softish
tissue with a "frequency range preference" rather than metallic high Q
precision resonators a lá tuning forks. But the image you project is more
like the tuning fork model ....
The damage happens when the cilia are over stimulated and
mechanically damaged.

Seem to be the agreed facts on this.
So if the energy is not in the audible range,
they don't resonate and it is much harder to damage them.

Just how much harder?
Of course if you use a high enough level of sound, even outside the
hearing
range, it can do damage. Like someone posted, at some point a ball of
cotton will burst into flame! I don't like the idea of spontaneous
human combustion.

Just what part of my statement: "Hearing damage does not in principle
depend on anything but on the
amount of energy delivered to the sensory organ" is it that you disagree
on, you seem to me to have written exactly the same as a correction to
what I posted.


Kind regards

Peter Larsen
You guys are making the obvious (mis)assumption that hearing loss is the
ONLY danger here.
This technology has been proposed for use in an automobile to give each
passenger a different audio program.

"Hey mommy, what's inside this little hole I've got my eye plastered
against?"
"Makes my eye feel warm..."

Wonder the resonant frequency of the tails on your swimmers?

As I do agree with Rick on the damage of the specific sensory organ, nobody
says that damages could occur elsewhere i.e. in the ear due to temperature
raises when source is directly pointed at the membrane of the drum or other
kinds of effects. Ultrasounds can interfere with blood circulation...
fetuses do react when the beam is pointed at them in normal scanning, thus
while a listening commodity for the gravid it could be a torture for the
fetus. On the other hand many physiotherapy centers use ultrasounds to give
relief to subjects with particular pains or conditions, so such sound
systems could also make us feel better! hehehe (I know there hasn't been any
official research on that).

I believe that a company before placing in the market such technology must
do and must have done some homework to avoid any lawsuit against them. If
smart they might even seek some medical safety board approval...I see that
on the original question nobody has answered and personally I would take the
risk :) and have a listen... I'm very curious about that. If anybody in
south east Asia has any, please post.

Best regards,
Riccardo
 
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