Sound Waves

We speak of sound as being high and low, and short and long, to differentiate between pitch and duration of a sound wave. The physical means to changing pitch and duration varies with each instrument, including our voice and hands (rhythm).

  • Pitch = high & low tones

  • Duration = long & short time

A sound wave has a definite volume that can be greater in pitch, or longer in duration. We translate this volume when we hear it (not the volume that we turn up or down, but a physical one). To reproduce a wave on our instrument, we must begin this vibration, either through a mouthpiece, our vocal chords, or striking a drum or piano key. The sound wave then must move through either an instrument's body, our voices' throat, down a piano string, or into the body of a percussive instrument like a drum, triangle, vibraphone, etc.


slide whistle

Now, the sound wave is trapped into a pitch. This is either a big volume or a smaller one. It is determined by the diameter and length of a string, the width or depth of a drum, or the shortness or length of a wind instrument, as well as our throat, as we sing or blow.

We may raise (or shorten) the wave's pitch by choosing a shorter, thinner string, by striking a smaller, thinner percussion instrument, by removing fingers from a horn's keys, or by tightening our vocal chords (brass instrumentalists also tighten their lips). This raises its pitch, because the sound wave's volume is compressed to fit smaller dimensions.

The opposite is true to lower the pitch of a sound wave. We're decompressing the wave to fit into larger dimensions, such as a longer, wider drum; a longer, thicker string; a longer, wider wind instrument; or relaxing our lips or vocal chords.

With both of these pitch variations, we're allowing the sound wave to resonate its vibration within the physical material it travels along. Notice that if an instrument shortens and/or thins, the wave raises in pitch, but if an instrument lengthens and/or widens, the pitch is lower. That's where practicing comes in to play, as we learn the proper divisions to shorten or lengthen our instrument for the next sound (note).


"Although we can't see a sound wave, we can hear and feel it."

The pitch of a sound wave has a time length, or duration that we may control to create rhythm. This happens at the beginning of our striking a piano key or drum, or blowing through a mouthpiece or our vocal chords. The sound wave begins its path until it finishes, or we stop it.

Practice involves training our mouth and fingers when to activate or deactivate, at the precise moment. Learning is difficult sometimes, since more than one finger activates more than one key. Also, our vocal chords must begin or end despite their position in tightening or relaxing. Percussionists must strike different instruments, in order, as well. Likewise, brass players' fingers and lips are caught in action, trying to lengthen or shorten a note's duration. This mostly happens in quick succession!

Therefore, it's useful to understand a sound wave, so we may use its pitch and duration as a brush stroke, if you will. Our artistry will improve the more we learn to control the physical dimensions that a wave travels along.

Sound waves emerge through vibration and depth. The faster the vibration and the shorter the depth, the more compressed that the wave sounds.

Furthermore, whenever a wave is less compressed, it requires more energy to keep its duration active. So, we have to blow/breathe harder to support the pitch and duration. Similarly, pianos and drums compensate their strikes with larger hammers/mallets to help carry the less compressed waves (lower tones).

Beginning musicians may compress/decompress these sound waves too much or too little, resulting in sounds that are a little too high or low (sharp or flat). It helps to listen to the notes' relation to one another. This is how different instruments sound good together, as they closely match each others' sound waves (play in tune).

Although we can't see a sound wave, we can hear and feel it. We hear higher tones better, and lower tones vibrate everything they hit. Both higher and lower waves' duration may be the same, but the amount of energy to maintain each duration is different.


Finally, the amplitude, or loudness of a sound wave takes energy. Lower waves need more energy to increase loudness. We test the limits of the material that the sound waves travel through. The wave's pitch and duration remains the same, except we use more force.

In summary, pitch, duration, and loudness of sound is what we control to make music.

Recommended reading: Page 9

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