Sound - Two Definitions

Did you ever hear the old philosophical question -

..."If a tree falls in the forest but no one is there to hear it, does it make a Sound?"...

It seems a silly question - of course it makes a sound! Just ask the squirrels who are now deaf! (never mind that you'll need to know squirrel sign language since they're deaf now...or dead since the tree likely just fell on them…).

No squirrels were actually harmed in the taking of this photo from Google… LOL!

Well the truth is, the answer depends on how you define Sound. For some, Sound is defined as a function of the listener - Sound is “the sensation experienced by the listener”. So without the listener, there's no sound! Others define it as a function of physics - “a mechanical energy wave passing through a medium”.

The point is that it’s really both. 

What’s important to understand here is that what we hear is not entirely what’s being played. There are lots of reasons for this that we’ll cover in the class but it boils down to a few key things:

  • No two people hear the same way. Our bodies are different, our ears are different and of course, our minds are different.
  • Sound as “the sensation experienced by the listener” has nothing to do with our ears at all! Its entirely about our brain and our interpretation of what we hear. This is as much personal as it is cultural and a product of our environment. In fact, a single person won’t hear sound the same in two different places in the same room! How on earth can we all hear things the same?
  • The physics of “a mechanical energy wave passing through a medium” never changes. IE, what’s being played is not different - we are. IE the reason we don’t hear things the same is not due to the sound itself at all.

I'll let you choose which one you like the best although for the purposes of this course, we'll default to the Physics definition. That way, we can all agree on what actually IS being played and our individual perception won’t cloud things.

So as you read this section, keep these two definitions in mind.

Here’s a pretty cool video to get you excited about Sound Waves. Did you know you can actually SEE them?

And in this one, not only can you see sound, you can see how certain sounds create specific shapes in the universe.

How does it work?

During the reading of the chapter, these are the things to be paying attention to (IE, you might see this on a quiz...)

- What kind of wave is Sound? Hint: don’t say "sound wave" - that’s not going to cut it.

- What are the TWO parts of that wave? Hint: There are only two and we’re not talking about…...

- What are the 3 characteristics of Sound? Hint: each one has at least 2 terms that are used to define them...

- How do we measure these characteristics of Sound? Inches? Pounds? Hint: There are specific terms that matter here.

- What are the two states of Sound? Hint: It’s either a “prisoner” or...

- Think about the tree in the forest. Since it may or may not make a sound depending on which philosophy you believe, in which situation would it make a sound or not?

- How loud is conversation? Jet engines? Whispers? Think about the decibel rating that matches each...

- How well do humans hear? What is the range (generally)?