[TheForge] Re: Tinnitus was Hearing aids

[Mike Spencer]

Bruce wrote:

> The actions you describe are the same ones that will open your
> eustation tubes - the tubes running from the inner ear to the back of
> the throat.

The eustachian tubes connect to the *middle* ear.  In serial  order
from out side to inside, you have:

  Outer ear canal

  Ear drum (tympanum)

  Middle ear, which contains an air space and:

     The hammer (malleus) bone attached to the ear drum

     The anvil (incus) bone between the hammer and stirrup

     The stirrup (stapes) bone connected to the anvil

     Various muscles and ligaments to hold the bones together and

     The opening to the eustachian tube; the "oval window" (connecting
     to the inner ear) in which the footplate of the stirrup sits; and
     the "round window" (also connecting to the inner ear.)

  The inner ear, a spiral helical space in the bone occupied by a
  quite complicated arrangement of bone, specialized cells and fluids
  and intimately connected with the semicircular canals that influence
  sense of balance.

  The acoustic nerve that runs from the inner ear to the brain

The bones of the middle ear (malleus, incus and stapes) act as a
mechanical modulator, somewhat similar to the steel and mica heads on
old wind-up Victrolas.

The footplate of the stapes works something like a hydraulic piston,
pushing (one of the two) fluids of the inner ear back and forth in a
long coiled and tapered passage.  The round window is at the other end
of the passage and acts as a sort of pressure-damping diaphragm so
that the vibrations of the stapes push the fluid back and forth rather
that raising and lowering the hydraulic pressure in the delicate inner
ear. 

On the site that Dan Hayes mentioned:

   http://my.webmd.com/content/Article/48/39169.htm?pagenumber=1

these are listed as the most usual causes of tinnitus.

    1. ear infection 
    2. wax impaction 
    3. noise exposure (like rock concerts) 
    4. TMJ (temporomandibular joint) disorders 
    5. even a side effect of medications such as aspirin,
       ibuprofen, caffeine, or birth control pills 
    
2. would be in the outer ear canal

1. and 4. would be related to the middle ear.

3. and 5. would be related to the inner ear.


So-called "nerve deafness" relates to the inner ear and may refer to
damage to the actual acoustic nerve or, more commonly, damage to the
hair cells or other components of the organ of Corti.  These are the
transducers that convert the amplitude and frequency of mechanical
vibration -- sound -- to signals in the acoustic nerve that encode the
sound in a way that the brain can interpret.

All of that said, the practical matter of using electronics to
compensate effectively for hearing loss lies somewhere between a black
art and a bio-engineering discipline.  I appreciate the practical
pointers from those who've had experience with modern hearing aids.
I'll need the advice soon enough.

FWIW,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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