What Are Acoustics? (Attempt #1)

So this is it. My last post regarding World Book Student. Today, the question is, "What are acoustics?" To link to the final subsection of the article, click here. I learned that acoustical research was first started by Lord Rayleigh, a British physicist, in 1878. Acoustical research is still continuing to expand and reach new areas. For instance, Georg von Bekesy showed how the ear distinguishes between sounds. This happened only about 70 or so years ago. Now, we have things such as Active Noise Cancelation, or ANC, and Active Structural Acoustic Control, or ASAC. On the topic of ANC, I saw a machine in my therapist's office in the waiting room. It was producing a sound simmilar to white noise. I figured it was something to help you relax, because white noise is usually related to sleeping. Well, it now makes sense, because the machine was creating a white noise. It was not for relaxation, however. It was to block out any sound from the office. Even more intriguing, it only blocks out sounds from the office. When in the office, you can hear much of what is going on in the waiting room. Also, now I know that white noise is not to trick the brain into falling asleep, but rather to block out noise. I found out many information today and I was able to make a few strong connections, but I was unfortunately not able to answer my question. To answer this I will have to find a new source. One final thanks to World Book, you have been a great source and a great help. For the works cited, please refrence "How Are Sound Waves Created?"