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Science Series Part 1: What Is Sound?

Emily Martinson, Au.D., Ph.D.

Nerd Alert: This week’s blog post is on physics!  Feel free to run away, or hide underneath something heavy.  I promise I won’t tell your high school science teacher.

For those of you who remain, let’s talk science!

Before we can discuss how we hear, we have to first understand what sound itself is, and how it works.  Most of us think of sound as anything that we hear, but in reality, sound doesn’t have anything to do with hearing at all.

Sound is, at its most simplistic definition, a vibration made up of waves (more on that later- stay tuned for our next Science Series post on sound waves).  Let’s take, for example, a trumpet.  When you blow into the trumpet, you are producing a vibration in the form of sound waves.

For sound to travel from the trumpet to the ear, however, there needs to be a medium, which is a substance to travel through.  When it comes to sound, that is usually air, but can also be water.  Without a medium, sound cannot travel, and therefore cannot be heard.  In our trumpet example, the medium is the air.  Vibrations from the trumpet cause a vibration in the air leading to the ear.

Interestingly, the need for a medium is the reason why in space you cannot hear sound: there is no air for it to travel through.  Keep that in mind during your next space flight!