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December 16, 2007, 03:28:36 PM
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Topic: How would a trumpet sound without its harmonics past 20khz  (Read 2858 times)
Reply #30
« on: March 18, 2004, 06:38:28 PM »
Robert Livingston Offline
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cheesy
I regularly operate and repair SONAR equipment in the shop ... and yes ... you can hear clicks from the 200KHz transducer. In no way do I suspect that you could hear 200KH (10 times the hearing range). It's probably the shape of the burst envelope that deforms the potted casting with the energy being output from the piezoelectric element inside.
Then too, how do you explain the psycho effects of making a person want lo leave a room with high levels of supersonic sound. {Remember the gadgets used to drive out mice from supermarkets but also drive out customers if the're left on during the day.}
What are the effects of non-symetrical ultrasonic audio? What if it has a modulation envelope and becomes integrated?
I can understand how you could lose the perception of pitch at higher frequencies, considering the spiral shape of the inner ear. At lower ranges there could be longitudinal travel along the spiral as well as lateral across it, creating standing nodes at specific hair/nerve bundles inside. At higher frequencies there would be greater spiral length losses and theretoo frequency perception loss.
Impulse desensitization also seems to be plausable if there are hair bundles "TeePee shaped" with a specialized strand to "cap" at the top. The impulse energy would dislodge the bundle and create a short term loss of specific frequency perception until the hair bundle "re-forms"
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Chipo
Reply #31
« on: March 20, 2004, 12:52:53 AM »
DeluXMan Offline
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Quote from: Robert Livingston
cheesy
I regularly operate and repair SONAR equipment in the shop ... and yes ... you can hear clicks from the 200KHz transducer. In no way do I suspect that you could hear 200KH (10 times the hearing range). It's probably the shape of the burst envelope that deforms the potted casting with the energy being output from the piezoelectric element inside.


Wow!  Cool work!   Cool

Good ideas and questions.  I guess the key here is that with high db levels there is a point where the sense of touch takes over for hearing, once the sound is loud enough to start pushing things around.  
At relatively high levels we feel the sound in our bodies, essential to the full enjoyment of rock music, and to some extent we can feel it in the ears at that level too.  At extreme levels sound actually hurts, independently of whether we can hear it or not.  The extra dbs of energy in the ultra-sonic impulse might cause more trama and subsequent pain for example.  I did my testing at a relatively low db listening level.  It would be fun to experiment with different listening levels.
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=DeluX-Man=
Reply #32
« on: March 21, 2004, 11:03:59 AM »
Andrew Rose Offline
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WWW

Excellent and informative topic here - somehow I can't see this sort of discussion going on in certain forums of auido discussion. Thing is, how does all this help me get the vocals out of my recordings? cheesy  cheesy  cheesy

(Currently restoring Blind Willie McTell recordings from 1931-33 ready for CD reissue - not too many ultrasonic harmonics there to worry about... Cool )
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Reply #33
« on: March 21, 2004, 05:56:27 PM »
Havoc Offline
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Nobody around that has access to some decent mics that go up that far? Just looked at the B&K site (prompted by a question at the AA site) and saw they had capsules going to 140kHz. So with a AD sampling at 192kHz we could capture a few more harmonics and make up our minds? And open an even bigger can of worms....

Quote
Then too, how do you explain the psycho effects of making a person want lo leave a room with high levels of supersonic sound. {Remember the gadgets used to drive out mice from supermarkets but also drive out customers if the're left on during the day.}


These are not that much up in frequency. And I also fear that the earlier examples of those gadgets were not very well controlled and radiated also at the limit of hearing or had some modulation that made them "hearable" if there had not been so much other noise around.

At the lab we had some optical modulators (using ultrasound being injected in quartz.  to modulate the light going through the quartz). This was at about 10MHz, but the output was modulated in the audio range around 1-6kHz. Power was not very high (couple of watt) but nobody ever experienced anything. And we spend 5 days a week from 6 to 10 hours inide the room where 3 of those things were permanatly operating. Often hours within a meter of 2 of them.

These are completly different situations I agree, but I think it shows that to pin down a cause needs more firm knowledge.

Quote
When i did the same thing with a 5kHz. fundimental i could hear no increase in level in my ear that's only good up to about 10kHz., even though there was an increase of 6db in level each time the harmonics were switched in! I guess there is no subjective increase if you can't hear the harmonics! Oh well, good to know.


Yes, but did your speakers increased their output as well?

Quote
Excellent and informative topic here - somehow I can't see this sort of discussion going on in certain forums of audio discussion.


You mean this kind of questions are not posed at the audioasylum? Surely they must have some opinion about it D)
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Expert in non-working solutions.
Reply #34
« on: March 21, 2004, 10:03:27 PM »
AndyH Offline
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Havoc, they did warn you, at the lab, about those long purple things your grandchildren would be growing?
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Reply #35
« on: March 22, 2004, 02:56:08 PM »
Havoc Offline
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Havoc, they did warn you, at the lab, about those long purple things your grandchildren would be growing?


Aubergines? I doubt it, the family is very bad in gardening Smiley
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Expert in non-working solutions.
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