Ehrmm... resonation???rifftrax wrote:If you're saying that somehow a 25.1khz wave can bounce around in my ear-hole and somehow 'produce' a sub-harmonic then I'm really interested to hear the theory behind that.
No, that was me saying that. And I could be wrong, just thinking up loud of what could cause it....Meffy wrote:I don't recall saying anything about "surface reflection." You extrapolated that.
ok, thanks for that bit of inforifftax wrote:(and remember, I'm 26... I'm not a teenager)
If the threshold of perceivability is 116dB, would you call that "no problem" ??rifftax wrote:a variety of ages can hear well beyond 20khz with no problem.
I have been experiencing this for the past entire year that I've worked for the company full-time. They bought me a test bench with the appropriate equipment to do these measurements about 3 months into getting hired there. This is something I've really had ample time to study quite in depth (literally, I am surrounded by ultrasonic devices at work 24/7, or least all 40 hours per week I am there). They are everywhere being activated all the time constantly for quality control checks, etc. I have spent countless hours recording, analyzing and presenting data from spectrograms and meters and all I can pin-point is that I am definitely hearing the output very clearly from a ultrasonic device that produces a 25khz tone, and it does sound different from a 19khz tone or a 16khz tone.BertKoor wrote:I'd investigate the phenomena indeed, and think of possible causes. Like I just did in my first post, and I just read some confirmation of their likeliness. Plus the unlikeliness that you have ruled it out completely and systematically, since you're too eager to see confirmation of your own theory.
Ah, my mistake. I retract that comment. Think what's under surfaces. That's about as far into that as I can go, since that product is still current and likely to be updated before long with new technology on the transducer end of things.BertKoor wrote:No, that was me saying that. And I could be wrong, just thinking up loud of what could cause it....Meffy wrote:I don't recall saying anything about "surface reflection." You extrapolated that.
A resonance is simply a reinforcement of a particular frequency resulting in increased amplitude of the wave. A "standing wave" in the ear would only cause certain frequencies to be reinforced and others to null at different points. When you're dealing with a pure tone the perceived level would be completely static if you didn't move your head (which is indeed exactly my experience as well).BertKoor wrote:Ehrmm... resonation???rifftrax wrote:If you're saying that somehow a 25.1khz wave can bounce around in my ear-hole and somehow 'produce' a sub-harmonic then I'm really interested to hear the theory behind that.
NB: I don't know how old you are, and how old all of your colleagues are. But if you're below 20 it's not totally impossible you can hear a 25kHz frequency. I think nobody ever doubted that. It's just that you haven't ruled out all other possibilities.
I can do that. Might take some time as I don't know if we have transducers that would cover between 20khz and 25khz but I'm sure I can figure something out.BertKoor wrote:Please make that perceivability threshold plot I asked for, ok?
Trouble is that its not all of us can hear above 20khz. Lucky (maybe) for some. I say maybe because it can be a source of problems for people. Switch mode PSUs are everywhere and some say they can hear the whistle. Meffy had similar with line output transfomers. I used to have this at work with CRT computer monitors, some would complain of the whistle. There is also something called TAOS hum that some can hear. If the title of your thread said "I can hear above 20khz" then it would be different. Youre doing an investigation of yourself, not the public as it dosnt apply to most so it beacomes a curiosity rather than something you can put to work or exploit into a product/service..rifftrax wrote:I have been experiencing this for the past entire year that I've worked for the company full-time. They bought me a test bench with the appropriate equipment to do these measurements about 3 months into getting hired there. This is something I've really had ample time to study quite in depth (literally, I am surrounded by ultrasonic devices at work 24/7, or least all 40 hours per week I am there). They are everywhere being activated all the time constantly for quality control checks, etc. I have spent countless hours recording, analyzing and presenting data from spectrograms and meters and all I can pin-point is that I am definitely hearing the output very clearly from a ultrasonic device that produces a 25khz tone, and it does sound different from a 19khz tone or a 16khz tone.BertKoor wrote:I'd investigate the phenomena indeed, and think of possible causes. Like I just did in my first post, and I just read some confirmation of their likeliness. Plus the unlikeliness that you have ruled it out completely and systematically, since you're too eager to see confirmation of your own theory.
Believe me, I'm not just willy-nilly throwing up a post of "OMG GUISE I JUST DISCOVERED THIS" after my first day on the job. I've been dealing with this stuff day in and day out for countless hours before deciding to even mention it to anyone.
Pretty much everyone in my office can hear the 116db 25.1khz tone emitted by a particular transducer I've done the most testing with. Serious. I shit you not. This includes a 33 year old chick and people up to around 40.UltraJv wrote:Trouble is that its not all of us can hear above 20khz. Lucky (maybe) for some. I say maybe because it can be a source of problems for people. Switch mode PSUs are everywhere and some say they can hear the whistle. Meffy had similar with line output transfomers. I used to have this at work with CRT computer monitors, some would complain of the whistle. There is also something called TAOS hum that some can hear. If the title of your thread said "I can hear above 20khz" then it would be different. Youre doing an investigation of yourself, not the public as it donst apply to most so it beacomes a curiosity rather than something you can put to work.
I do it all the time. It's a hobby of mine.rifftrax wrote: You've already made up your mind too. When was the last time you tested an ultrasonic transducer at 25khz? Seriously, I'd like to know.
I said I dont doubt that they sense the pressure, yes but it dosnt mean anything in a useful context. Music conveys infomation, a tone dosnt have much information - where is the proof that information is conveyed? The military and commerce looked into this years ago with the idea of using ultrasonic transducers to allow music/sound in specific areas only to stop music annoying others outside a perimeter. It never materialsed into anything useful.rifftrax wrote:Pretty much everyone in my office can hear the 116db 25.1khz tone emitted by a particular transducer I've done the most testing with. Serious. I shit you not. This includes a 33 year old chick and people up to around 40.UltraJv wrote:Trouble is that its not all of us can hear above 20khz. Lucky (maybe) for some. I say maybe because it can be a source of problems for people. Switch mode PSUs are everywhere and some say they can hear the whistle. Meffy had similar with line output transfomers. I used to have this at work with CRT computer monitors, some would complain of the whistle. There is also something called TAOS hum that some can hear. If the title of your thread said "I can hear above 20khz" then it would be different. Youre doing an investigation of yourself, not the public as it donst apply to most so it beacomes a curiosity rather than something you can put to work.
That's why I'm saying this is kind of significant.
I swear I can feel my microwave oven when I'm just a few feet away from it.BertKoor wrote:'Mway, yeah... If you put it right next to my ear and set it to 116dB I can vaguely sense something's coming out of it. But I certainly can tell weather it's switched on or off!'
Now thats not my definition of "no problem hearing 25kHz".
Please make that perceivability threshold plot I asked for, ok?
You obviously never talked to xoxosUltraJv wrote: I said I dont doubt that they sense the pressure, yes but it dosnt mean anything in a useful context. Music conveys infomation, a tone dosnt have much information - where is the proof that information is conveyed? The military and commerce looked into this years ago with the idea of using ultrasonic transducers to allow music/sound in specific areas only to stop music annoying others outside a perimeter. It never materialsed into anything useful.
Commercially useful I meantspaceman wrote:You obviously never talked to xoxosUltraJv wrote: I said I dont doubt that they sense the pressure, yes but it dosnt mean anything in a useful context. Music conveys infomation, a tone dosnt have much information - where is the proof that information is conveyed? The military and commerce looked into this years ago with the idea of using ultrasonic transducers to allow music/sound in specific areas only to stop music annoying others outside a perimeter. It never materialsed into anything useful.
what does it have to do with you thinking that its a fact that you could prove something was likely?rifftrax wrote:That's pretty cute. What does this have to do with the fact that if you were to come to my work I could prove without a shadow of a doubt that you too could likely hear 25.1khz?
your ears are a transducer system. how did do you get a spectrogram through them?You're totally right, and those subharmonics would have clearly shown up on the spectrograms I was running.
well, that definitely proves that no scientist who ever measured human hearing response knew what they were doing, then.I actually know how to use the equipment at my test bench though.
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