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ears

moktan

Well-Known Member
Joined
Jan 24, 2008
Messages
910
Points
93
Location
Kalimpong
Most of us would go to great lengths to protect our expensive audio gear from the vagaries of commercial voltages, dust etc...but having read a few chapters of Master Handbook of ACOUSTICS by F. Alton Everest, I would like to restate what we have known all along..the most crucial link in the audio chain are our ears..(though unlike stuff for which we have to render financial accountability according to economic systems that are not under our immediate control or comprehension, the ear..at least your first pair is for free)
in a nut shell, this book which as you would expect for a tome of this scope, just touches cursorily on the biology of hearing.. but that sketchy info was, at least for me, enough to start 'seeing' my ear in a new light..
the ear basically comprises of the outer ear, the middle ear and the inner ear..not to mention the brain which actually hears things..
out of the three 'zones' the first two are quite well understood ..
the outer ear, of which the protruding pinna is a conspicuous part, is the vibration gathering device, a kind of a catchment for vibrations ("the external ears are no mere crinkly decorations but complex channels or convolutions which add a slight, reflected sound or echo to any sound that one hears...This slight, added echo will vary with the different angles from which sounds originate. For example, if one hears a sound above , the tiny echo added by the ears crinkles will differ from the one that they add to a sound coming from below or to one from behind .
Now, this minute echo will enter the ear a fraction of a second after the main sound does. Then that part of the brain that cares for ones hearing will analyze this main sound and its accompanying delayed echo. And by this analysis one is immediately made aware of the direction from which the sound came. So quickly does all this take place that one is not even conscious of it. Further, when one hears a sound coming from the right, then the right ear hears it just before the left ear does and vice versa. This too plays a part in the ability to know the direction from which a sound originates)

- in a sense the ear affixes directionality to the sound from a vibrational perspective..as the book says 'the direction of sound of the sound is superimposed on the sound content itself'..

(an experiment: if we listen with one ear to random noise..a 7.2kHz noise seems to come from a source at level to the ear, an 8kHz noise seems to come from above and 6.3kHz from below..which means the directional information is extracted from the sound spectrum itself)

the ear canal, to which the sonic information (be it your wife's rant or a sublime Parker's Mood is conveyed as variations in air pressure) is another marvel..acoustically the middle ear is comparable with a pipe organ of 2.5cm length and .7cm diameter..which means that the air that is trapped in it resonates for frequencies of about 3000Hz..thus making the ear most sensitive to midrange frequency where most of the relevant sound information resides...(in addition to this, when sound wave hits the face it gets diffracted, this diffraction also increases the sound pressure at the mid frequencies)

the middle ear:
this comprises of a liquid..hence the air vibrations of the ear canal have to be transferred into the vibrations of the liquid..(the middle ear also has a hot line to the outer atmospheric pressure via the Eustachian tube, which also function as a drainage when the middle ear gets infected)..the sound vibrations in the air of the ear canal vibrate the ear drums which initiate the action of the ossicles -the three bone lever arrangement comprising of the incus, mallus and stapes- a mechanical impedence device that renders an optimal transfer of vibration from the air medium to the liquid of the middle ear...
note:
the ears have built-in protection against extremely loud noises. Though, a sudden nearby explosion can result in excessive vibrations that could cause irreparable damage to the intricate hearing apparatus. But if a very loud sound develops gradually, quick-acting muscles can turn down the volume. The eardrums membrane is tightened to reduce its vibrations, and middle-ear muscles twist the auditory ossicles. Thus the stirrup does not transmit such great vibrations through the oval window into the inner ear.

the inner ear...this is the business end of the ear where it gets complicated for the novice..though one may want to look up Georg von Bksy
on wiki...along with the problem of how the workings of the organ of Corti visa vi its communication with the brain...

after this it gets complicated so will expect the experts to carry from here..

moral of the story: take good care of the ears, it is more complicated, ingenious and intricate than you could possible imagine...at least I couldn't...
imagine that is...i can still hear though..
 
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suri

New Member
Joined
Mar 15, 2009
Messages
2,287
Points
0
Location
kannur
Most of us would go to great lengths to protect our expensive audio gear from the vagaries of commercial voltages, dust etc...but having read a few chapters of Master Handbook of ACOUSTICS by F. Alton Everest, I would like to restate what we have known all along..the most crucial link in the audio chain are our ears..(though unlike stuff for which we have to render financial accountability according to economic systems that are not under our immediate control or comprehension, the ear..at least your first pair is for free)
in a nut shell, this book which as you would expect for a tome of this scope, just touches cursorily on the biology of hearing.. but that sketchy info was, at least for me, enough to start 'seeing' my ear in a new light..
the ear basically comprises of the outer ear, the middle ear and the inner ear..not to mention the brain which actually hears things..
out of the three 'zones' the first two are quite well understood ..
the outer ear, of which the protruding pinna is a conspicuous part, is the vibration gathering device, a kind of a catchment for vibrations- by the way the ear affixes directionality to the sound from a vibrational perspective..as the book says 'the direction of sound of the sound is superimposed on the sound content itself'..

(an experiment: if we listen with one ear to random noise..a 7.2kHz noise seems to come from a source at level to the ear, an 8kHz noise seems to come from above and 6.3kHz from below..which means the directional information is extracted from the sound spectrum itself)

the ear canal, to which the sonic information (be it your wife's rant or a sublime Parker's Mood is conveyed as variations in air pressure) is another marvel..acoustically the middle ear is comparable with a pipe organ of 2.5cm length and .7cm diameter..which means that the air that is trapped in it resonates for frequencies of about 3000Hz..thus making the ear most sensitive to midrange frequency where most of the relevant sound information resides...(in addition to this, when sound wave hits the face it gets diffracted, this diffraction also increases the sound pressure at the mid frequencies)

the middle ear:
this comprises of a liquid..hence the air vibrations of the ear canal have to be transferred into the vibrations of the liquid..(the middle ear also has a hot line to the outer atmospheric pressure via the Eustachian tube, which also function as a drainage when the middle ear gets infected)..the sound vibrations in the air of the ear canal vibrate the ear drums which initiate the action of the ossicles -the three bone lever arrangement comprising of the incus, mallus and stapes- a mechanical impedence device that renders an optimal transfer of vibration from the air medium to the liquid of the middle ear...

after this it gets complicated so will expect the experts to carry from here..

moral of the story: take good care of the ears, it is more complicated, ingenious and intricate than you could possible imagine...at least I couldn't...
imagine that is...i can still hear though..
that - really - is a good synopsis of the function of the hearing mechanism! -
 

moktan

Well-Known Member
Joined
Jan 24, 2008
Messages
910
Points
93
Location
Kalimpong
and hear! hear!..
If an engineer were to duplicate its (the ears) function, he would have to compress into approximately one cubic inch a sound system that included an impedance matcher, a wide-range mechanical analyzer, a mobile relay-and-amplification unit, a multichannel transducer to convert mechanical energy to electrical energy, a system to maintain a delicate hydraulic balance, and an internal two-way communications system. Even if he could perform this miracle of miniaturization, he probably could not hope to match the ears performance.Sound and Hearing, by S. S. Stevens, Fred Warshofsky ..
 

moktan

Well-Known Member
Joined
Jan 24, 2008
Messages
910
Points
93
Location
Kalimpong
so what are the ways and means by which you can protect your hearing??

(1)

"If you now are a tobacco user, stop using tobacco. The nicotine in tobacco causes constriction of inner-ear arteries. This, in turn, reduces blood flow and consequently the flow of nourishment that the inner ear needs in order to play its vital role in your life"
 

gobble

Well-Known Member
Joined
Sep 23, 2008
Messages
5,468
Points
113
Location
Bangalore
and hear! hear!..
If an engineer were to duplicate its (the ears) function, he would have to compress into approximately one cubic inch a sound system that included an impedance matcher, a wide-range mechanical analyzer, a mobile relay-and-amplification unit, a multichannel transducer to convert mechanical energy to electrical energy, a system to maintain a delicate hydraulic balance, and an internal two-way communications system. Even if he could perform this miracle of miniaturization, he probably could not hope to match the ears performance.Sound and Hearing, by S. S. Stevens, Fred Warshofsky ..
Great Stuff Moktan!! Let me give you another example of how nature excels! For years now, I have been taking one glance into my partially empty fuel tank of the scooter to determine if I need to fill 220/- worth of petrol or 200/- or 150/- etc. And I always fill it almost exactly to the upper level marker with just a one or two second glance. Even after the price of petrol has changed over the last 3 years, the eye-brain network estimates the right amount to fill, in rupees - in an instant!

Now imagine the effort required to program a man made invention that is not just a level marker, but computes in advance how many rupees worth of petrol is needed to fill up the tank within 2 seconds. Imagine the carbon cost of manufacturing such a device as well! :clapping:

Cheers
 

suri

New Member
Joined
Mar 15, 2009
Messages
2,287
Points
0
Location
kannur
Now imagine the effort required to program a man made invention that is not just a level marker, but computes in advance how many rupees worth of petrol is needed to fill up the tank within 2 seconds. Imagine the carbon cost of manufacturing such a device as well! :clapping
hi gobble - damn the carbon footprint - i want this device! with whatever it needs for daily/weekly updates to the system re the petrol price!

regds suri
 
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