KABOOM!

I was skiing the other day and heard loud booms. The ski patrol was trying to trigger avalanches by detonating explosives.

I heard similar booms when I was younger but did not give them much thought. Now, however, maybe because I am surrounded by sound at work, I started paying more attention.

As the explosives went off I was surprised because it seemed like I could feel the sound while sitting on the chairlift.

How was this possible?

Sound travels in waves similar to waves we see at a beach. They have a top called a “peak,” and a bottom called a “trough.” A sound’s size is called “amplitude.” The pitch we hear is dependent on the frequency.

My little yappy dog has a high frequency and small amplitude, while the low booms from the ski patrol have a low frequency and large amplitude.

As a large amplitude sound wave travels through the air, it pushes the air forward. Think about seeing “the wave” at sporting events or watching dominoes fall. When we feel the blast we are feeling the force of air actually being pushed forward.

Other sound waves are subtler. For instance, take your hand, put it on your throat and read the next sentence out loud making your voice high and low pitched. The vibrations you feel are your vocal folds, or chords, vibrating due to air coming out of your throat and making sound waves.

If you think about music, there are many instruments with chords that vibrate.

But what about the instruments that do not have chords?

Wind instruments make sound by vibrating air inside them by using different mechanisms. Trombones have a mouthpiece that musicians blow into causing their lips to vibrate. The sound from the vibrating travels down the body and is amplified by the opening at the end. Other wind instruments like a saxophone rely on vibrations from reeds as air is blown past them.

When sound emerges from any item, it travels until it runs into something or has no more energy. If a sound wave hits something, it bounces back and travels in the opposite direction. That is why we can hear echoes so well in areas where there is a lot of room for the sound to bounce from place to place. It is no coincidence opera houses are shaped they way they are.

Try it yourself at the band shell at Memorial Park. You’ll discover that it is a lot easier to hear someone talking while they are inside the shell, than it is if they were talking over by the swings. This is because the sound is echoed out of the shell toward where you are standing in the grass.

This really is only the first note in your favorite song when it comes to sound. We did not even get to the ear, which has a canyon full of interesting scientific intricacies when it comes to hearing.