Hearing loss - the simulation

ever wonder how the deaf/hearing impaired ppl hear the sound? well i do...
The following method is just my guessing of how they hear sounds..

1. total deaf..
this is easy... just closed our ears completly and go do it in a sound proof room.

2. partial loss of hearing ..
for a complete n better explaination, pls visit http://en.wikipedia.org/wiki/Hearing_impairment . For short... we can use an equlizer of a stereo set.
set the equilizer to the middle on all channels... play a music... and listen to it. This condition should be able to represent our normal hearing....
now... reduce any channels to the lowest level. sure we can still hear the music but the sound is not as nice as before.... and this can be used to represent the condition of partial loss hearing.

Can a technology help? sure.... although the result will not be as good as the natural one. Why not? well.., human can hear from from 20 to 20,000 hz (http://hypertextbook.com/facts/2003/ChrisDAmbrose.shtml). which means we need a channel for each frequency.
The most advanced hearing aid may cover up to 30 channels (i'm not sure if it s exist). Sounds useless? not really, to comunicate we need only less 10 main frequencies. Some languages may need more frequencies and some need less. These frequencies are needed to produce & pickup letters which we are all knows, a right combination of letters will produce word.

The "power" of sound is reprensented by decibels a.k.a dB (http://trace.wisc.edu/docs/2004-About-dB/).
Our normal conversation is about 40-50 db. Can we accept more than 50 dB? sure... but it may injure our hearing.

Now Back to the our topic. For hearing impaired people, mostly they cant hear any sound below 60 dB. What make it? well... there numbers of reasons which i'mnot going to talk about it now. So, basicly the hearing aids will give the user the capability to hear (bring up) up the needed level.

How do we know about our hearing capability? There are some ways to test it (http://www.ehealthmd.com/library/hearingloss/HL_tests.html). Some of them need a cooperation from the tester.. some don't. Which method is best? Well.... BEST is a funny word... they actualy exist only with in our specific targets... so, if we dont have any target then BEST simply don't exist. I guess you know what i'm trying to say.