Science of Sound
This module covers the following concepts:
Sound is made when an object vibrates the air (or other medium) around it. When these vibrations reach our ear, our brain interprets them as “sound.”
When sound causes air molecules to vibrate, it compresses and expands the air, forming pockets of high and low pressure. We call them sound waves because the air pressure goes up and down in a repeating pattern.
When a sound wave meets a new material, it is reflected, diffused, absorbed, or transmitted. As sound travels in an environment without obstacles, the sound pressure level will decrease.
Sound frequency is a measure of how quickly the pressure changes, and is measured in Hertz (Hz). Objects that vibrate faster produce higher frequency sounds, and objects that vibrate slower produce lower frequency sounds.
Sound amplitude measures the amount of energy in a sound wave, and is measured in decibels sound pressure level (dB SPL). Sounds with higher amplitude have a greater amount of sound pressure.
Phase is the fraction of a complete wave cycle elapsed as measured from a specified reference point and often expressed as an angle. Sound is cancelled (eliminated) when two sounds are presented at 180 degrees out of phase.
Sound is everywhere, all the time. You don’t even stop to think about it until your favorite song comes on the radio or you hear the school bell ring! Let’s explore how amazing sound is.- Don Finan Ph.D.
