Sound is generated and travels through the collision of molecules, regardless of state. If the pressure keeps changing repeatedly within certain speed ranges, you’ve got sound. Sound can be messy. It spreads out, bends around corners and bounces off objects. As sound spreads out, it gets drastically weaker. If you know how this happens, you’ll find it easier to control the bouncing.
Sound has distinct properties that need to be understood. Different references regard them differently. But perhaps it will be most important to learn about the two most basic properties — amplitude and frequency. These are typically the first that we perceive. The video* below will be helpful in explaining amplitude and frequency:
Another physical property of sound which you might be curious about is the speed of sound.
As implied in the video above, the actual speed of a disturbance depends on different factors:
While the above video references are extremely useful in explaining some physical properties of sound, for the sake of this course, we will refer to list below as prescribed by Prof. Steve Everett:
- Pitch (or Frequency)
- Loudness (or Amplitude)
He explains each one in this video:
It’s a lot to take in. But understanding these six attributes can be helpful in understanding the succeeding parts of this course.
* Period and wavelength refer to the same properties as amplitude and frequency, respectively, but will typically not be referred to in this course.
Everett, S. (n.d.). The six properties of sound. [Video file]. Retrieved from http://www.coursera.org.
[khanacademymedicine]. (2014, January 5). Relative speed of sound in solids, liquids, and gases. [Video file]. Retrieved from https://www.youtube.com/watch?v=yF4cvbAYjwI&t=10s.
[khanacademymedicine]. (2014, January 3). Speed of sound. [Video file]. Retrieved from https://www.youtube.com/watch?v=UgE2GIQwUCw.
[khanacademymedicine]. (2014, January 1). Sound properties. [Video file]. Retrieved from https://www.youtube.com/watch?v=-_xZZt99MzY/