o to increase the frequency of sound waves. It increases the sound waves to a level of frequency that humans cannot hear so you won't be able to hear many things though the wall other then low noises like pounding.
Explanation:
I am in construction class as well as a student teacher for other construction type programs trust me :D
<span>Wave energy is an idea that Robert Hutchings Goddard introduced in his “Further Developments” to his research "A Method of Reaching Extreme Altitudes" </span>
