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Science Forum Index » Electronics - Design Forum » very directional speaker technology
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| amdx |
 Posted: Thu Apr 24, 2008 10:04 am |
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| answerman |
| Posted: Thu Apr 24, 2008 3:46 pm |
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"amdx" <amdx@knology.net> wrote in news:d8c1a$48109d20$450139ad$8021
@KNOLOGY.NET:
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.
Quote: Do some systems mix two ultrasound sources?
That depends on your definition of a source. Two ultrasonic signals, yes.
Two ultrasonic transducers, only if they are stupid.
Quote: There is correction for nonlinearity of air is that correction
performed at ultrasound frequency or audio frequency?
At the ultrasound frequency.
Quote: 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
Here's a semi-technical review article published by another company on the
subject.
http://www.directionalsound-usa.com/hss/pdf/HSSWHTPAPERRevE.pdf |
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| amdx |
| Posted: Fri Apr 25, 2008 7:15 am |
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"answerman" <answerman@lunch.> wrote in message
news:9oednVMukY8zbI3VnZ2dnUVZ_ryqnZ2d@giganews.com...
Quote: "amdx" <amdx@knology.net> wrote in news:d8c1a$48109d20$450139ad$8021
@KNOLOGY.NET:
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?
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.
Do some systems mix two ultrasound sources?
That depends on your definition of a source. Two ultrasonic signals, yes.
Two ultrasonic transducers, only if they are stupid.
There is correction for nonlinearity of air is that correction
performed at ultrasound frequency or audio frequency?
At the ultrasound 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
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 |
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| Angelo Campanella |
| Posted: Sat Apr 26, 2008 2:54 am |
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amdx wrote:
Agreed. It a "must" read for speech communications folks. Keep an open
mind in reading it; nothing orthodox about these folks..
Angelo Campanella |
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| Terry Given |
| Posted: Sat Apr 26, 2008 7:41 pm |
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Angelo Campanella wrote:
Quote: amdx wrote:
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
Agreed. It a "must" read for speech communications folks. Keep an
open mind in reading it; nothing orthodox about these folks..
Angelo Campanella
and (as usual) the moral of the story is: be aware when using
approximations - like, for example, linear analysis of pretty much
anything :)
but yes, fascinating stuff to read. For some further reading, try
"acoustic waveguides" by Boyle.
Cheers
Terry |
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| mike |
| Posted: Wed Apr 30, 2008 9:21 pm |
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Angelo Campanella wrote:
Quote: amdx wrote:
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
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...
--
Return address is VALID!
Bunch-O-Stuff Forsale Here:
http://mike.liveline.de/sale.html |
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| Peter Larsen |
| Posted: Thu May 01, 2008 4:01 am |
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mike wrote:
Quote: Angelo Campanella wrote:
amdx wrote:
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
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?
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.
Quote: This can't be good for biology???? My brain is already
sufficiently scrambled, thank you...
Kind regards
Peter Larsen |
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| Terry Given |
| Posted: Thu May 01, 2008 5:40 am |
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Peter Larsen wrote:
Quote: mike wrote:
Angelo Campanella wrote:
amdx wrote:
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
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?
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
Wouldnt a honking great phased array of ultrasound transducers, in
conjunction with IR cameras and some clever software make a great
burglar "alarm" - 140dB that tracks their head. Betcha that'd make you
leave a room, fast.
Cheers
Terry |
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| Don Pearce |
| Posted: Thu May 01, 2008 11:24 am |
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On Thu, 01 May 2008 22:40:04 +1200, Terry Given <my_name@ieee.org>
wrote:
Quote: Peter Larsen wrote:
mike wrote:
Angelo Campanella wrote:
amdx wrote:
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
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?
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
Wouldnt a honking great phased array of ultrasound transducers, in
conjunction with IR cameras and some clever software make a great
burglar "alarm" - 140dB that tracks their head. Betcha that'd make you
leave a room, fast.
Cheers
Terry
It exists. It is used on ships to deter pirates. Just point the array
at the little attacking speedboat, and they get out of there fast (as
you say).
d
--
Pearce Consulting
http://www.pearce.uk.com |
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| Michael A. Terrell |
| Posted: Thu May 01, 2008 11:49 am |
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Terry Given wrote:
Quote:
Wouldnt a honking great phased array of ultrasound transducers, in
conjunction with IR cameras and some clever software make a great
burglar "alarm" - 140dB that tracks their head. Betcha that'd make you
leave a room, fast.
Don't forget a couple dozen 1 million lumen strobe lights, flashed in
sequence to disorient them, till the cops arrive.
--
http://improve-usenet.org/index.html
Use any search engine other than Google till they stop polluting USENET
with porn and junk commercial SPAM
If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm |
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| AZ Nomad |
| Posted: Thu May 01, 2008 4:59 pm |
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On Thu, 01 May 2008 22:40:04 +1200, Terry Given <my_name@ieee.org> wrote:
Quote: Wouldnt a honking great phased array of ultrasound transducers, in
conjunction with IR cameras and some clever software make a great
burglar "alarm" - 140dB that tracks their head. Betcha that'd make you
leave a room, fast.
Just take a high speed drill to your eardrums. Such a boobytrap invariably
nails the owner more than anybody else.
It sure would be a lot less work and yield the same results. |
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| Terry Given |
| Posted: Thu May 01, 2008 5:59 pm |
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AZ Nomad wrote:
Quote: On Thu, 01 May 2008 22:40:04 +1200, Terry Given <my_name@ieee.org> wrote:
Wouldnt a honking great phased array of ultrasound transducers, in
conjunction with IR cameras and some clever software make a great
burglar "alarm" - 140dB that tracks their head. Betcha that'd make you
leave a room, fast.
Just take a high speed drill to your eardrums. Such a boobytrap invariably
nails the owner more than anybody else.
It sure would be a lot less work and yield the same results.
think harder.
Cheers
Terry |
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