Re: Speakers for High Frequency Sound

From: Pooh Bear (rabbitsfriendsandrelations_at_hotmail.com)
Date: 02/12/05 

Date: Sat, 12 Feb 2005 05:13:14 +0000

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

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