Qualities of Sound: Loudness, Pitch, Timbre

The three main qualities that are used to describe sound are loudness, pitch, and timbre. Loudness is pretty self-explanatory at a basic level; when you change the volume of your speakers or headphones, you change the loudness of the sound they produce. In the context of a sound wave, loudness is dictated by the amplitude of the wave, a measure of the highest (or lowest) point of a wave. You can explore this by using this resource from my previous post. After clicking oscillate in the top left corner, adjust the amplitude slider in the bottom right. A higher amplitude corresponds to a louder sound, and a lower amplitude corresponds to a quieter sound.

The easiest way to think of pitch is in the context of a musical instrument. In a piano, each key is tuned to a certain pitch and corresponds to a musical note. As you play each note on a piano descending from right to left, the pitch of the notes become lower. Pitch corresponds to the frequency of a sound wave, and my next post will cover this relationship in depth.

My previous post alludes to the concept of timbre (pronounced /'tambər/). I like to describe it as the quality of sound. Timbre is what distinguishes musical instruments; it is why they have a distinct sound even when playing the a note with the same loudness and pitch. The waveform, the shape of a sound wave, is what determines its timbre. This resource from my previous post illustrates this very well. By changing the waveform, you can hear distinct changes in the timbre of the sound without changing the loudness or pitch. Instruments are able to sound unique by producing sound waves with unique waveforms.

Works Cited:
1. Gunther, Leon. The Physics of Music and Color. New York, New York: Springer, 2012.

2."Online Tone Generator." Online Tone Generator. Accessed August 26, 2015.
3."Wave on a String." Wave on a String 1.0.0. Accessed August 26, 2015.