How Do Hearing Aids Amplify and Filter Sound?

[Unstoppable13]

Well we have to describe how hearing aids amplify sound. I need a understanding of the physics behind it how its works, no stuff about transistors and how its built. So like how does it amplify sound. ie change amplitude, wave length. etc

Also how they remove unnecessary noises.

If you can explain how they work it would be greatly appreciated. Also if you could post links to sites which relate to this because it would aid to my understanding of them.

 

[mgb_phys]

They are basically just a microphone, an amplifier and a speaker, just a rock concert in a smaller box.

Sound waves make the membrane of a microphone move a little bit, this creates a small electric current, an amplifier (transistors and stuff) uses battery power to make a bigger electric current which it uses to make a speaker membrane vibrate a larger amount.
Digital ones also have a computer which turns the incoming sound into numbers, does some maths to remove certain frequencies and amplify other frequnecies more and then generate an output signal that goes to the speaker