So this might be a better explanation than bone conduction for ultrasonics detection, which seems to disappear when headphones are used?
Thanks. Interesting verbage.
I'm confused by the references to water and head in water with spl's up in the 177 range vs 115 in air.. Are they speaking about the response of a mike underwater with better coupling?
The limits of 115dB are maximums. I didn't see an integrated number. I don't know if it is the same idea as within hearing... For single impulse, we were allowed 144dB for under 200 milliseconds (IIRC) for a single 8 hour period. If it scales the same with U/S, that would set the long term threshold pretty low..
Interesting paper, they basically say nothing's been done since the 60's..
This quote is also interesting..
""In respect of hearing damage by noise, the concept of intended protection requires detailed knowledge of the noise dose (level and duration) required to produce a hearing damage response over the range of susceptible individuals. There have been no useful studies of the dose-response relation for VHF or ultrasonic noise.
So until somebody actually does research, we'll use these numbers until we know for certain....😕
"need more inpuuut"..
jn aka "j5"
interesting hearing limits vs age testing. I would say I punished my hearing quite well at concerts in my youth, right through until maybe 10 years or so ago, yet at 39 I still hear something past 16-17khz at moderate volume, and that puts me better than the top 10 percentile for my age group, which surprises me.
ive not ever spent years on end on work sites (though i've done some including sheet metal work and making fiberglass filled baffles for car tunnels, but we were provided earplugs. being primarily working for myself, or in kitchens, ive probably been saved there, but all the same I wouldnt have thought so many my age had that much hearing damage.
especially if we take this forum for example, where so many people in their 40-60's claim to hear subtle differences in the RF spectrums... or at least clear differences -130dB down well above 20khz
@ kindhornman: I wasnt so much thinking hearing directly VHF through bone conduction, more that the skull and fleshy bits might cause reflections/refractions to bounce around in the skull and produce lower harmonics.
ive not ever spent years on end on work sites (though i've done some including sheet metal work and making fiberglass filled baffles for car tunnels, but we were provided earplugs. being primarily working for myself, or in kitchens, ive probably been saved there, but all the same I wouldnt have thought so many my age had that much hearing damage.
especially if we take this forum for example, where so many people in their 40-60's claim to hear subtle differences in the RF spectrums... or at least clear differences -130dB down well above 20khz
@ kindhornman: I wasnt so much thinking hearing directly VHF through bone conduction, more that the skull and fleshy bits might cause reflections/refractions to bounce around in the skull and produce lower harmonics.
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Thanks qusp, I was wondering how you were referencing the bone conduction for high frequencies. As far as upper frequency hearing I still have fairly good hearing in the upper ranges and I am a dinosaur at 57 years old. Last time I was checked the audiologist told me not to tell my wife that my hearing was so good so she would think I just didn't hear her! I also complained about the leakage into the booth as I could hear things that I knew were coming from out in the street, low frequency traffic noises.
Actually check out my link to Audio Spotlight, they know exactly what is happening. The sound was beamed as they say, the wiggle words around stereo are ammusing.
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I did look and just reviewed it again. I still don't understand from their description why the audible part of the sound does not happen until it hits a barrier. If the air were generating the IM products the longer wavelengths would be radiating from the beam. If the reflection from the surface causes the IM (energy increases at the reflection) then it would make sense. Am I missing something?
I haven't reviewed the theory in years but in the demo I heard putting your head in the beam in free space gave the audible experience. The effect has been known for years, the beam forming is not intuitive and massive DSP is needed to generate the driving signals.
-- The back door to the ear drum is via the nose/mouth -sinus - path.... or Eutach.tube. Used to equalize air pressure on the ear drum. It could also be a possible path for sound.
BTW - who IS the oldest person reading this stuff here? Can't be me (I hope)?
THX-RNMarsh
BTW - who IS the oldest person reading this stuff here? Can't be me (I hope)?
THX-RNMarsh
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In most chatrooms I am confidently assured of being the oldest. But KOJ is about ten years older (not that he bothers with us here).
When a mutual acquaintance introduced me to Keith, it was for the purpose (he thought) of scaring me straight. That is, in the sense that if I kept up my obsessive electronics activities, I might become someone comparable to him.
Clearly I didn't keep it up sufficiently.
When a mutual acquaintance introduced me to Keith, it was for the purpose (he thought) of scaring me straight. That is, in the sense that if I kept up my obsessive electronics activities, I might become someone comparable to him.
Clearly I didn't keep it up sufficiently.
I am 71, and still able to hear differences in audio reproduction that most of you ignore!. '-)
[B said:
Holy Cow. Man you are really, really, really Old. 71 qualifies you to be a Geezer. Geezer status is good. I know... because I'm 93.
-RNM
I was tested a few years ago by an ear specialist for a 'balance' problem. I came out better than average for my age.
I still hear 'crap' from most sources, and I hear 'quality' when it is there.
I used to have very hi extended frequency response, but of course that is gone.
My poor business partner, Carl,70, is just about deaf, and uses a hearing aid.
My other business partner, Hal, is 72 years old, and last week he called me with great enthusiasm that his friend brought over some quality vinyl and he and his friend were awed by the sound quality. Of course, he is using a Blowtorch with a Vendetta built in, and a $1000 dollar Ortofon cartridge, so he has a chance to appreciate what vinyl playback can sound like. '-)
I still hear 'crap' from most sources, and I hear 'quality' when it is there.
I used to have very hi extended frequency response, but of course that is gone.
My poor business partner, Carl,70, is just about deaf, and uses a hearing aid.
My other business partner, Hal, is 72 years old, and last week he called me with great enthusiasm that his friend brought over some quality vinyl and he and his friend were awed by the sound quality. Of course, he is using a Blowtorch with a Vendetta built in, and a $1000 dollar Ortofon cartridge, so he has a chance to appreciate what vinyl playback can sound like. '-)
Wow! I now know the feeling a fourth-world citizen has when seeing a fridge for the first time ....🙄
jan
jan
JD,
trailer-park citizens see a lot of fridges, they're just no longer functional (for the originally intended use).
trailer-park citizens see a lot of fridges, they're just no longer functional (for the originally intended use).
Hello Scott, I have a couple of these in my junkbox.....diaphrams that have arced through.
Any idea of the processing involved ?.
Dan.
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