Speakers for High Frequency Sound

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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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William Sommerwerck wrote:

> > Some people can hear an extremely high-pitched sound generated by
> > television CRTs and television cameras. I have long wondered what
> > frequency this sound is.
>
> It's the horizontal scanning frequency, 15,734.25 Hz for American color TV.
> Trust me. You don't need to measure it.
>
> > 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.
>
> If humans can hear it, it can't possibly be at 40kHz, because the best human
> hearing extends to only a bit above 20kHz.

Using a test generator I was able to *sense* rather than hear 22kHz when I was
in my early 20s.

Now I'm 50 - I seem to top out on 'hearing' at about 16kHz. That makes me quite
lucky it seems.

I do believe you can 'educate' your hearing btw. Be interested to hear - lol -
other ppl's comments.


Graham

 

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George Gleason wrote:

> William Sommerwerck wrote:
> >>Some people can hear an extremely high-pitched sound generated by
> >>television CRTs and television cameras. I have long wondered what
> >>frequency this sound is.
> >
> >
> > It's the horizontal scanning frequency, 15,734.25 Hz for American color TV.
> > Trust me. You don't need to measure it.
> >
> >
> I can easily hear it
> and my hearing does not go near 16K

Interesting.

Maybe you're hearing some magnetorestriction related noise in the LOPT ?

Maybe you underestimate your hearing ?


Graham

 

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George Gleason wrote:

> most people do not know how to focus their listening and blank it out
> kind of like what my son does when I ask him if he did his homework

George !

Are you thinking of taking up a new role as a comedian ?

I loved that response.


Graham

 

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pooua@aol.com wrote:

> > my hearing is down 30 dB at 8 K(as high as the test at AES went)
> > when compared to 3K and I can easily hear it
>
> Did AES test your nerve conduction? I have a suspicion that the sound I
> hear is not coming through my eardrums. I am beginning to suspect that
> I hear it through my skull, which means nerve conduction.
>
> Your eardrum may not be able to hear so well, but maybe your ear nerves
> are still able to pick up sounds normally?

I suspect that the brain compensates actually.

I reckon also that the simple desire to use your ears effectively
influences your result significantly.

E.g. George Martin was a famed record producer but was essentially deaf in
one ear !


Graham

 

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Rich Grise wrote:

> On Fri, 11 Feb 2005 17:02:52 -0800, pooua wrote:
>
> > My objectives are to find out what frequencies I can hear, and to match
> > one of the calibrated frequencies from the signal generator against the
> > sound I hear from televisions, so that I can finally know what that
> > frequency from the television is.
>
> The frequency from the television is approximately 15 KHz.
>
> Don't worry about it.
>
> A, there's nothing you can do about it anyway.
> Two, so you can hear TVs. So what?
>
> If you're worried about going deaf in the other ear, go to the otitist,
> which you seem to have claimed you've already done.
>
> If you're looking for something to _block out_ the 15 KHz, that's a whole
> nother discussion. If this is it, I have some other ideas, but you have to
> ask, and then I'll post them under one of my wacko personas. ;-)
>
> Good Luck!
> Rich

I love these quirky posts of yours Rich.

Why not simply suggest he buys a decent TV without a noisy LOPT ?


Graham

 

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On 11 Feb 2005 21:44:36 -0800, pooua@aol.com wrote:

>FWIW, I can hear computer monitors, too, but not as well as
>televisions. That's a good thing, because I work in an office with a
>hundred computer monitors. The room has to be quiet and I have to pay
>attention for me to hear a computer monitor, unless it is going bad.

"When you get old, God dims your vision, to hide the dust."

You raise several interesting topics. Does one really *want*
to be able to hear these things? Does the "going bad" issue
give any clues? Would a small amount of sound absorbtive
material held just outside the ear canal help you?

Your original question seems to have been lost into the
thread, but you can probably get whatever folks here know
about the topic by googling Len Moskowitz's related (?) quest
a few weeks ago, titled "Supertweeters".

Good fortune,

Chris Hornbeck

 

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On Fri, 11 Feb 2005 20:06:40 -0800, play_on wrote:

> On Sat, 12 Feb 2005 00:46:18 GMT, George Gleason
> <g.p.gleason@worldnet.att.net> wrote:
>
>>
>>There is nothing special about hearing this
>>my hearing is down 30 dB at 8 K(as high as the test at AES went) when
>>compared to 3K
>>and I can easily hear it
>>george
>
> Couldn't your hearing be down in the 8k range and still decent in
> higher frequencies? It's been quite awhile since I was tested but I
> remember that I had a dip in the high-midrange area (right where the
> loud guitars and cymbals are!) and then above that I was fine.

Hearing is selective.

The last couple of years of my Dad's life, I was staying with him and Mom,
as sort of "the guy who does everything around the house that they're too
old and feeble to do". Mom's job was basically change Dad's diapers. I
helped haul him out of bed and into his chair, or the car, etc.

But when he was sitting in his chair, with Mom in the couch to his left,
and me on the loveseat to his right, and the TV right in front of him,
with the speakers pointed right at him, he had to turn it up uncomfortably
loud, and Mom and I couldn't talk to each other or anything, or he
couldn't hear the TV. But if I went into the kitchen and poured myself
more than a shot of scotch, he could hear the sound of the overpour well
enough to bitch about it.

People decide what they want to hear.

Good Luck!
Rich

for further information, please visit http/www.godchannel.com

 

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On Fri, 11 Feb 2005 21:35:07 -0800, pooua wrote:

>> How many of you have heard a high-pitched "sound"
>> very much like 15 KHz yoke, even though there is no yoke? This is
>> sometimes called "ringing in the ears", and is what I was thinking of
> when
>> I asked those questions about tinnitus.
>
> Yes, I do have ringing in my ears, but it is fairly quiet. That's one
> way I can distinguish it from the sound of the TV. The TV set sounds
> very loud, so loud that I can hear it 15 feet away through the walls
> and closed windows of buildings, or from about 50 feet away in an open
> space.

This could make for some very interesting experiments. Hear a TV through
walls and closed windows? Or from 50 feet?

I'd really like to see some kind of controlled test there. To me, it
sounds impossible, but I have this dark side, who thinks there's something
more going on. ;-)

So, anyone up for a controlled experiment?

Cheers!
Rich

 

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"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:420D922D.C6377F65@hotmail.com
> George Gleason wrote:
>
>> William Sommerwerck wrote:

>>>> Some people can hear an extremely high-pitched sound generated by
>>>> television CRTs and television cameras. I have long wondered what
>>>> frequency this sound is.

>>> It's the horizontal scanning frequency, 15,734.25 Hz for American
>>> color TV. Trust me. You don't need to measure it.

Agreed.

>> I can easily hear it
>> and my hearing does not go near 16K

It's a matter of intensity.

> Interesting.

Normal.

> Maybe you're hearing some magnetorestriction related noise in the
> LOPT ?

I think that magnetostriction and related vibration in either the
transformers or the deflection yoke is the usual explanation.

> Maybe you underestimate your hearing ?

The mistake appears to be thinking that the limit of HF hearing is one
number that does not vary with the details and nature of the test.

 

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On Fri, 11 Feb 2005 22:18:26 -0500, Arny Krueger wrote:
> <pooua@aol.com> wrote in message
....
>> In any event, there is no
>> physical mechanism that would prevent a human from hearing higher
>> frequencies.
>
> Sure there is. The perception of pitch is based on the activation of hairs
> in a coil-shaped structure in the ear. The finest hairs relate to high
> frequencies, but they don't go on forever. Basically, you run out of
> structure at some point in this part of the ear, and the extent and health
> of this structure sets the highest frequencies that you can perceive. It's
> not uncommon for this structure to be damaged by listening to excessively
> loud sounds.

A cochleal tsunami! =:-O

 

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<pooua@aol.com> wrote in message
news:1108185949.249219.228620@g14g2000cwa.googlegroups.com

>>> In any event, there is no
>>> physical mechanism that would prevent a human from hearing higher
>>> frequencies.

>> Sure there is. [snip] Basically, you run out of structure at some
>> point in this part of the ear, and the extent and health of this
>> structure sets the highest frequencies that you can perceive.

> That would mean there is an upper limit.

Thus, I falsify the claim that "there is no physical mechanism that would
prevent a human from hearing higher frequencies."

That's all I set out to do.

> It does not at all tell us
> that no one could hear higher frequencies than 20 kHz.

That's a different question. There are some pretty obvious ways to find
people who can hear frequencies above 20 KHz. One is to simply jack up the
intensity, and another is to use young people whose ear structures are
simply smaller.

 

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> That's a different question. There are some pretty obvious ways to find
> people who can hear frequencies above 20 KHz. One is to simply jack
> up the intensity, and another is to use young people whose ear structures
> are simply smaller.

Women, and especially black women, are able to hear at higher frequencies than
men.

 

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On Sat, 12 Feb 2005 05:37:51 +0000, Pooh Bear wrote:

>
> Rich Grise wrote:
....
>> If you're looking for something to _block out_ the 15 KHz, that's a whole
>> nother discussion. If this is it, I have some other ideas, but you have to
>> ask, and then I'll post them under one of my wacko personas. ;-)
>
> I love these quirky posts of yours Rich.
>
> Why not simply suggest he buys a decent TV without a noisy LOPT ?

Nah. That's you guys's job! ;-p

Cheers!
Rich

 

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I read in sci.electronics.design that William Sommerwerck
<williams@nwlink.com> wrote (in <110qinrklm6ss4b@corp.supernews.com>)
about 'Speakers for High Frequency Sound', on Fri, 11 Feb 2005:

>If humans can hear it, it can't possibly be at 40kHz, because the best
>human hearing extends to only a bit above 20kHz.

Some young children can hear at least up to 40 kHz. I've done the tests.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http/www.jmwa.demon.co.uk Also see http/www.isce.org.uk

 

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I read in sci.electronics.design that George Gleason
<g.p.gleason@worldnet.att.net> wrote (in <DXbPd.28856$Th1.8953@bgtnsc04-
news.ops.worldnet.att.net>) about 'Speakers for High Frequency Sound',
on Sat, 12 Feb 2005:

>I can easily hear it
>and my hearing does not go near 16K

The normal audiometry test measures your hearing sensitivity at
threshold level. You can see from the Fletcher-Munson (Robinson/Dadson)
curves, that the sensitivity of even an unimpaired ear varies with sound
pressure as well as frequency.

This means that you can hear LOUD sounds at much higher frequencies that
you would expect from your threshold sensitivity curve.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http/www.jmwa.demon.co.uk Also see http/www.isce.org.uk

 

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On 11 Feb 2005 17:42:28 -0800, pooua@aol.com wrote:

>> >I think you are assuming some things that aren't necessarily so. One
>> >very important assumption you are making that is likely to be wrong
>is
>> >that no human can hear very much above 20 kHz. There are a number of
>> >ways that assumption could be wrong. In any event, there is no
>physical
>> >mechanism that would prevent a human from hearing higher
>frequencies.
>
>---
>> Yes, there is. The mass of the tympanic membrane and the
>> sensitivity of the cochlear cilia.
>
>The tympanic membrane (the eardrum) can be bypassed; it is not
>absolutely essential in every case for hearing (indeed, there are
>hearing aids that do exactly that).

---
Yes, but we're talking airborne sound here, aren't we?
---

>I don't know of a way around the cochlear cilia, short of replacing it
>with a functional equivalent (in contrast, the function of the tympanic
>membrane is not absolutely essential to hearing). But, what are the
>limits of the cochlear cilia? Certainly there are animals that can hear
>higher frequencies, and they use the same basic equipment as humans do.

---
Yes, in the sense that Ferraris and Fords are both cars. _But_ we're
not discussing non-human hearing, are we?
---

>> I've done work trying to determine whether the nonlinearity of the
>> auditory system will allow beat notes which occur as a result of
>> exposure to the ear of ultrasonic signals which should result in
>> heterodynes being generated which can be heard, are heard and, so
>far,
>> the results have been negative. That is, if the ear is exposed to a
>> pair of frequencies, both of which are frequencies higher than can be
>> heard, the beat note won't be heard either.
>
>That is interesting in its own way, but I don't believe that is
>directly applicable in this case. The sensitive person may not be
>hearing a beat note.

---
Of course it's applicable. The question you posed was whether there
was any physical limitation on human hearing and I gave the the
tympanic membrane and the cochlear cilia as examples. I further cited
the heterodyne experiment as an example which indicated that if the
low-frequency beat note generated by two ultrasonic signals being
mixed in the ear wasn't being heard, then in all likelihood the
physical structure of the ear was preventing the high frequency
signals from propagating to the point where they could be mixed,
preventing the beat note from being heard.
---

>> >Even so, I probably exaggerated the frequency of the sound. I
>estimate
>> >that the pitch is about double the highest frequency that I heard in
>> >the sound booth at the ENT. The highest frequency they tested was 12
>> >kHz, so I should estimate the sound I hear from a television as 24
>kHz.
>> >It's an ear-piercing shriek, in any event.
>
>---
>> Unless you have perfect pitch, your estimates as to the frequency of
>> what you heard are close to meaningless.
>
>All the more reason to set up a test and measure it directly. I hate
>this guesswork.

---
Then do it. It should be easy enough, just an electret microphone and
an oscilloscope ought to do it. Measure the period of the signal
impinging on the microphone, take its reciprocal, and you'll have its
frequency.
---

>> >I can also hear LCD screens, but that's at a lower pitch, I think,
>and
>> >they are much quieter. I first noticed it when I was in a nature
>park.
>> >It was very quiet outside, so as I raised my digital camera up to
>take
>> >a picture, I could distinctly hear the LCD screen.
>
>---
>> you may have crosstalk between your vision and auditory systems.
>---

>I suppose you would need to run a test to find out for certain?

---
Yes, but _you_ would, not I...
---

>> >Now I am taking a college class in a room that has 3 television sets
>> >suspended from the ceiling. One man saw me putting earplugs in my
>ears,
>> >and asked if I could hear the televisions. It turned out that he is
>> >able to hear some televisions (the one in his college dorm), but he
>> >could not hear the televisions in the classroom. As far as I can
>tell,
>> >I am the only person in the room who hears those televisions.
>
>---
>> It might be instructive to determine whether you can "hear" the
>> monitors with your eyes closed.
>
>I absolutely could hear the monitors with my eyes closed. I would be
>able to hear them in a pitch-dark room. I have been looking down at my
>desk when the instructor has turned them on from his control console,
>and I can definitely hear them when he turns them on. The sound of the
>televisions is distinct and loud, particular in my good ear. As I say,
>I wear earplugs in class to manage the sound.

---
Ok, but I don't understand the point of all of this. Are you merely
relating anecdotes, are you complaining about the sound, are you
looking for some kind of an electronic way to make the noise go away,
or what?

--
John Fields

 

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pooua@aol.com wrote:

>>It's the horizontal scanning frequency, 15,734.25 Hz for American
>>color TV. Trust me. You don't need to measure it.
>
>
> I need to measure it, to be certain that is what I am hearing.
>
>
>>If humans can hear it, it can't possibly be at 40kHz, because
>>the best human hearing extends to only a bit above 20kHz.
>
>
> I think you are assuming some things that aren't necessarily so. One
> very important assumption you are making that is likely to be wrong is
> that no human can hear very much above 20 kHz. There are a number of
> ways that assumption could be wrong. In any event, there is no physical
> mechanism that would prevent a human from hearing higher frequencies.
>
> Even so, I probably exaggerated the frequency of the sound. I estimate
> that the pitch is about double the highest frequency that I heard in
> the sound booth at the ENT. The highest frequency they tested was 12
> kHz, so I should estimate the sound I hear from a television as 24 kHz.
> It's an ear-piercing shriek, in any event.
>
> I can also hear LCD screens, but that's at a lower pitch, I think, and
> they are much quieter. I first noticed it when I was in a nature park.
> It was very quiet outside, so as I raised my digital camera up to take
> a picture, I could distinctly hear the LCD screen.
>
> Now I am taking a college class in a room that has 3 television sets
> suspended from the ceiling. One man saw me putting earplugs in my ears,
> and asked if I could hear the televisions. It turned out that he is
> able to hear some televisions (the one in his college dorm), but he
> could not hear the televisions in the classroom. As far as I can tell,
> I am the only person in the room who hears those televisions.
>
I suspect that for the LCD screens what you are hearing are the power
supplies for the backlight, and not the screen itself. Many of these
have switching frequencies in the approx. 20kHz range, so when you light
up the screen, you hear the squeal.

--
Charlie
--
Edmondson Engineering
Unique Solutions to Unusual Problems

 

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<pooua@aol.com> wrote in message
news:1108170172.822645.33210@c13g2000cwb.googlegroups.com...
> My objectives are to find out what frequencies I can hear, and to match
> one of the calibrated frequencies from the signal generator against the
> sound I hear from televisions, so that I can finally know what that
> frequency from the television is.


Several posts have told you the frequency. To confirm that it is the TV
generating the sound, turn it off and observe that the sound goes away.

J

 

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Neil Henderson <neil.henderson@sbcglobal.netNOSPAM> wrote:
>
>Really? I've never noticed that... got an extremely offensive example I
>could check out? Along those lines, I've noticed that on my own DAW, if you
>run a spectrum analyzer plug-in on any given track, there's often a few
>peaks (not high-level ones, maybe -50 or -60 db IIRC, I'd have to
>double-check to be certain) up in the 30-33k range... do you think this
>could be some kind of harmonic of this monitor leakage?

That would probably be leakage from a VGA monitor, or from a switching
power supply. It might be something inherent in the converters too (probably
leakage from its own internal power supply).
--scott

--
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