MadSci Network: Anatomy

Re: Why are some people born mute?

Date: Thu Jun 15 16:28:18 2000
Posted By: Paulette Caswell, Grad student Education, etc., AMICUS, Inc. Ed. Svcs.
Area of science: Anatomy
ID: 955133617.An

Hello to all of you in Ms. Swann's science class!  And thank you all for your 
compliments on the Mad Scientist website -- the website designers are doing their 
very best, and it is good to know that their efforts are appreciated!

Now, you want to know why some people are "born mute."  Actually there are two 
different answers to this question.  

1.) Some people are not able to speak because they are born with problems in 
their throats or vocal cords, or they have nervous system problems that affects 
their control of their tongue, breathing, or mouth movements.  This is called 
"physically mute."

2.) Since you are talking in your class about "sounds," there is another form of 
"mute" that happens to people who are born profoundly (very very seriously) deaf 
in both ears.  "Deafness" is simply damage to very tiny microscopic little cells, 
called "hair cells" in a very tiny shell-shaped bone located in your inner ear 
(it's behind the "ear" you see on the side of your head, under your skull bone).  

When those little tiny "hair cells" are damaged, sound comes into their ears, but 
it cannot be converted to electronic signals that their brains can use to 
understand sounds.  It is like typing on a keyboard to a computer, but if those 
keys don't work, you can keep on typing all day long and the computer will never 
get the "input."  

You can only speak clearly what you can hear clearly. So, people who are born 
profoundly deaf in both ears cannot hear ANY of the sounds of human speech, even 
with "hearing aids."  As a result, they cannot pronounce the sounds of human 
speech well, and they are called "mute."

But these people are NOT really "mute" at all!  Born-deaf people have perfectly 
normal voices, and throats, and vocal systems. They can laugh, make sounds, cry, 
scream, and make many other sounds.  And with very intensive speech training, 
they can learn to make voice sounds, even though they can't hear what they are 
saying, but it is not a "perfect" voice, and it might not be understandable to 
other people.  

The term "deaf-mute" is no longer used, because everyone knows now that deaf 
people are NOT "completely silent" (unless they want to be).

Fortunately, there is a new device, called the cochlear implant (CI), that 
replaces the function of the damaged "hair cells" for a born-deaf person.  The CI 
has a microphone that listens to sounds, and sends the sounds to a "sound 
processor."  The sound processor converts the sound vibrations to electronic 
signals.  These electronic signals are sent through a magnet on the outside of 
the deaf person's head, to another magnet under the skin behind the ear.  The 
"inside" magnet sends the electronic signals to a group of wires, called an 
"array," that is in the cochlea.  The "array" transmits (sends) the electronic 
signals to the auditory nerves, and the deaf person's brain gets the signals that 
it needs.  After that, the deaf person can hear almost everything, and then, 
because they can HEAR speech sounds, their brain learns to adjust itself to 
PRONOUNCE speech sounds.  Born-deaf people with CIs, especially those who receive 
a CI at a very early age, and learn to use a CI well, are definitely NOT "mute," 
and their speech is clear and understandable to everyone.

For more information, you can look at the following websites:

** For cochlear implants, go to http:// .  You can even request free information on this 
website and they will send you a really COOL videotape with a lot of graphics 
about how the ear works, and also printed information with a lot of very nice 

** For information on how deaf children are learning to speak clearly with their 
cochlear implants, go to http:// .  They also have free information, and free videotapes, 
that you can order, which shows born-deaf children speaking normally and hearing 
normally with cochlear implants.

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