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Offline DoctorBeaver

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Hearing range
« on: 19/05/2005 10:19:08 »
When a sound is outside of our hearing range, is it that our eardrums don't react to it at all or just that the movements are so small they are imperceptible to us?

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Offline daveshorts

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Re: Hearing range
« Reply #1 on: 20/05/2005 15:06:46 »
I expect the eardrums stop being as sensitive to it, but the real effect will be in the cochlear. In here there is a structure which has the effect of different hairs being sensitve to different frequencies - if you don't have the hairs for the high frequencies (or they get damaged as in older people) you can't hear the pitch.

It is not to do with the size of the vibrations, as this is just to do with the volume of the sound. Outside our hearing range normally means a very high or low pitch.
 

Offline DoctorBeaver

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Re: Hearing range
« Reply #2 on: 20/05/2005 19:30:19 »
Ahhh, so it's similar to the cones or whatever in our eyes not reacting to certain colours?

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Offline daveshorts

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Re: Hearing range
« Reply #3 on: 21/05/2005 20:01:37 »
Yeah pretty much - just a lot more different types an hugely fewer of each type.
 

Offline DoctorBeaver

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Re: Hearing range
« Reply #4 on: 21/05/2005 23:28:34 »
OK - thanks, Dave

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Offline qazibasit

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Re: Hearing range
« Reply #5 on: 23/05/2005 18:13:59 »
well different voices have different sensativity and hearing range voices with a high amplitute have more energy and hence a long range whereas low amplitude waves have low energy which decipates if the source is too far.
 

Offline chimera

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Re: Hearing range
« Reply #6 on: 23/05/2005 20:37:43 »
There's a distinction between the range of frequencies you can hear, and how sensitive to the volume measured in decibels the ear is.

That latter is so sensitive in normal children that it borders on the ability to hear individual atoms smashing into each other, so most of it is ignored by the brain, but we do pick up a lot more than is allowed into our awareness.

Both can be damaged by overexposure to loud sounds, but only the volume-sensitivity is something we actively seem to be able to filter over time, and was known as you may remember to the old Greeks and Egyptians regarding some cataract in the Nile where people were surprised when visitors wondered whether the incessant noise did not drive them crazy. What noise? :)

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Offline DoctorBeaver

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Re: Hearing range
« Reply #7 on: 24/05/2005 12:35:26 »
Filtering of information has long been known about by psychologists. It's the same thing as in a noisy room or bar, if someone says your name you will pick it out from all the background noise even if you had not been specifically listening out for it. Without such filtering the brain would probably blow a fuse trying to cope & there'd be no "processing" power left with which to think.

I've often wondered if dogs' amazing sensitivity to smell (or other animals sensitivity to other sensory input) has been a hindrance to them developing into more intelligent creatures. In the case of dogs, not only is their brain smaller than humans but much more of it must be taken up by processing olfactory input. Did the structure of their brain develop deliberately to have that degree of sensitivity or did that sensitivity evolve as a result of the way their brain evolved? My gut feeling is that it's the former & that its development along those lines stopped development in other ways.
 

Offline DoctorBeaver

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Re: Hearing range
« Reply #8 on: 24/05/2005 12:37:14 »
quote:
Originally posted by DoctorBeaver

I've often wondered if dogs' amazing sensitivity to smell (or other animals sensitivity to other sensory input) has been a hindrance to them developing into more intelligent creatures. In the case of dogs, not only is their brain smaller than humans but much more of it must be taken up by processing olfactory input. Did the structure of their brain develop deliberately to have that degree of sensitivity or did that sensitivity evolve as a result of the way their brain evolved? My gut feeling is that it's the former & that its development along those lines stopped development in other ways.



I think I may post this as a separate thread.
 

Offline m.a.k.

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Re: Hearing range
« Reply #9 on: 19/10/2005 01:14:38 »
excuse me but could tell me if it is normal to hear the mouse sound things that people supposidely can't hear? and also just to say I can hear them, but no one elce can.
 

Offline MooseHole

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Re: Hearing range
« Reply #10 on: 19/10/2005 18:41:09 »
Don't listen to the mice, they're just trying to take your frisbee.
 

Offline m.a.k.

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Re: Hearing range
« Reply #11 on: 19/10/2005 20:49:27 »
sorry ,I mean the antimouse things that annoy them so much that they leave, those,I can hear, and they bug me too
 

Offline m.a.k.

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Re: Hearing range
« Reply #12 on: 19/10/2005 20:50:08 »
ps what frisbee
 

Offline Little scientist

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Re: Hearing range
« Reply #13 on: 06/12/2005 17:19:09 »
The ear drum does come into it, although for noises which are loud enough they bypass the outer and middle ear and stimulate the cochlea directly.

There is also the fact that the auditory nerve doesn't react to frequencies outside these frequencies. There are also no hair cells in the cochlea which are stimulated by frequencies outside those ranges, either cos they weren't there to start with, or they have been damaged.

 

Offline DoctorBeaver

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Re: Hearing range
« Reply #14 on: 06/12/2005 19:25:43 »
Thank you. That explains it very nicely
 

Offline m.a.k.

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Re: Hearing range
« Reply #15 on: 15/12/2005 23:52:59 »
sorry, but could I have that in a lesser degree of large vocabulary
 

Offline Little scientist

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Re: Hearing range
« Reply #16 on: 17/12/2005 09:28:23 »
OK, sorry.

Your ear consists of the funny shaped thing on the side of your head, then a tube, which is ended by your ear drum, behind this are some bones which connect to the hearing organ - cochlea. When a sound reached your ear it goes down the tube, moves your ear drum, which move the bones and  so stimulates the cochlea. The cochlea has got cells connected to a nerve and different pitches of sound make different cells activate 'their' bit of the nerve  so your brain knows whether it is a high or low sound.

If you have a really bad ear infection for example and the bit with the bones was all gunked up, or if the bones were damaged then this couldn't happen. But, you wouldn't be completely deaf that's cos a sound can go straight to the cochlea through your skull, bone transmits sound well.

This is why the outer and middle ear bits aren't completely to blame.

The other part is that if you can't hear a sound outside your hearing range then it can be that your cochlea can't pick those sounds up, which can be because the cells which detect the sound and then stimulate the nerve are damaged, or that there just aren't any for that sound, so they won't stimulate the cells or the nerve.

Hope that answers it a bit better.
 

Offline Soul Surfer

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Re: Hearing range
« Reply #17 on: 18/12/2005 19:06:20 »
The signal processing perfomed by the cochlea is very interesting.  I have in the past tried and failed to sell an innovative algorithm based on the way it works (which is NOT like a fourier transform) but I have failed to displace the vested interests in fourier type processing as used in current data compression but I still hold hopes that it will be rediscovered in a few years time.

One of the interesting features of this algorithm is that it is in fact much more precise and sensitive to impulses and their timing.  you can test this out youself with a pulse/sinewave generator and a good pair of hi fi earphones.

Firstly put a clean sinewave into the earphones at a reasonable volume and turn up the frequency until you can't hear it any more.  If you've got reasonably normal hearing the top frequency you can hear should be around 10,000 - 20,000Hz.

Next put a longish pulse into the earphones at a relatively low repetition rate with a slowish risetime say about 1 millisecond you should hear a series of cliks next reduce the risetime of the pulse the cliks will sound sharper and sharper.  Keep reducing the risetime until they don't sound any sharper  you should find that this fastest risetime you can detect is considerably less than 25 microseconds which is the risetime associated with 20khz.  in other words you can hear frequiencies above the upper limit of your Conmtinuous wave hearing provided they are pulses.

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Offline qazibasit

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Re: Hearing range
« Reply #18 on: 23/12/2005 10:05:07 »
from 20Hz-20KHz is the hearing range.
 

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Re: Hearing range
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