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Archived from groups: rec.audio.pro,sci.electronics.design,sci.med (More info?)
pooua@aol.com wrote:
> Some people can hear an extremely high-pitched sound generated by
> television CRTs and television cameras.
When they're badly designed / manufactured - yes.
> I have long wondered what frequency this sound is.
Until recent times mostly around 15 kHz.
> So, I am looking around for test equipment to
> help me measure it. I plan to use an audio generator (which I can buy
> for about $200), but I need to find a set of headphones that can
> produce sound at these high frequencies. The low end frequency should
> be about 12 kHz, and I would like to be able to go at least to 50 kHz.
> I am guessing the sound is somewhere around 40 kHz.
Nope.
No human can hear those frequencies - well proven - forget it.
> Incidentally, I just got my hearing checked by my ENT (Ear, Nose,
> Throat doctor). I measured in the 5-to-10 dB range on both the eardrum
> and nerve conduction tests across the entire measured frequency range
> (up to 8 kHz for eardrum, 12 kHz for nerve conduction). My doctor said
> that they want to see values less than 20 dB, so I am well-within the
> safe zone, as far as they are concerned. However, one reason that she
> scheduled this test for me is that I complained that I am going deaf in
> one of my ears. I have almost completely lost my sensitivity to the
> ultra-high pitched sound in that ear. I can hear that sound 100 times
> better from my other ear.
Well - I had a proper hearing test when I was in my mid 20s and the nurse
commented that I had the most perfect hearing she'd ever measured.
I was on the 0dB line all the way to 8 kHz - the highest frequency used for
medical testing it seems.
> People don't realize what a difference it makes to a person's
> perception when the range of hearing differs. I can walk into a room
> with other people, and they think they are in an empty room. If there
> is an operating television in the room, I will be aware of almost
> physical contact.
You have good hearing acuity.
May not necessarily be a result of perfect hearing but a desire to use your
ears as a useful tool.
> Other people can hold a conversation in a normal
> voice, but I have to listen over a sound similar to a dentist's drill
> or a jet engine. After several minutes of that, I often feel dazed. No
> one else even notices anything, except maybe that I am acting a little
> more odd than normal.
You mean you have diffiiculty with large background levels of noise ? Can't
'reject' it ?
Me too. You have high hearing acuity. Your ears are 'wide open' to stimuli.
May ppl simply 'filter out' what they're uninterested in.
Graham
pooua@aol.com wrote:
> Some people can hear an extremely high-pitched sound generated by
> television CRTs and television cameras.
When they're badly designed / manufactured - yes.
> I have long wondered what frequency this sound is.
Until recent times mostly around 15 kHz.
> So, I am looking around for test equipment to
> help me measure it. I plan to use an audio generator (which I can buy
> for about $200), but I need to find a set of headphones that can
> produce sound at these high frequencies. The low end frequency should
> be about 12 kHz, and I would like to be able to go at least to 50 kHz.
> I am guessing the sound is somewhere around 40 kHz.
Nope.
No human can hear those frequencies - well proven - forget it.
> Incidentally, I just got my hearing checked by my ENT (Ear, Nose,
> Throat doctor). I measured in the 5-to-10 dB range on both the eardrum
> and nerve conduction tests across the entire measured frequency range
> (up to 8 kHz for eardrum, 12 kHz for nerve conduction). My doctor said
> that they want to see values less than 20 dB, so I am well-within the
> safe zone, as far as they are concerned. However, one reason that she
> scheduled this test for me is that I complained that I am going deaf in
> one of my ears. I have almost completely lost my sensitivity to the
> ultra-high pitched sound in that ear. I can hear that sound 100 times
> better from my other ear.
Well - I had a proper hearing test when I was in my mid 20s and the nurse
commented that I had the most perfect hearing she'd ever measured.
I was on the 0dB line all the way to 8 kHz - the highest frequency used for
medical testing it seems.
> People don't realize what a difference it makes to a person's
> perception when the range of hearing differs. I can walk into a room
> with other people, and they think they are in an empty room. If there
> is an operating television in the room, I will be aware of almost
> physical contact.
You have good hearing acuity.
May not necessarily be a result of perfect hearing but a desire to use your
ears as a useful tool.
> Other people can hold a conversation in a normal
> voice, but I have to listen over a sound similar to a dentist's drill
> or a jet engine. After several minutes of that, I often feel dazed. No
> one else even notices anything, except maybe that I am acting a little
> more odd than normal.
You mean you have diffiiculty with large background levels of noise ? Can't
'reject' it ?
Me too. You have high hearing acuity. Your ears are 'wide open' to stimuli.
May ppl simply 'filter out' what they're uninterested in.
Graham