Sound weapons

Sound is very powerful, so powerful that sound weapons already exist.

Here is a short video showing the capacities of a sound weapon

How hearing aid works

This is the principle of hearing aid (the machine for hearing handicapped) and how to work.

The URL address is 'https://www.youtube.com/watch?v=4q1Jpcp8yD4'

it is very important to know how sound recording even started so here is a breif video enjoy!
https://www.youtube.com/watch?v=Xo9d-kUsuS0