The perceptual property of sounds that allows us to order them

Sound Wave

In my previous articles, I have told you that a musical note is a sign that we use in musical notation to represent the relative duration and pitch of a musical sound or tone. You have learned about note values which represent the duration of that musical tone. Now let’s learn about pitch concept.

Musical Tone

A musical tone is a steady periodic sound which is characterized by its duration, pitch, loudness and timbre. Sometimes we use the term tone to refer to musical notes. But in reality musical notes can be more complex than tones. Because they may have aperiodic elements such as vibrato etc.

Production of Sound Waves

To understand musical notes,  you need to understand sound waves. To produce a sound, we need a sound source (a vibrating object) and a medium. For music, vibrating object can be anything from an instrument part to vocal cords of a person. When the object vibrates back and forth, it creates a disturbance that is transmitted through the medium.

For example, let’s say the medium is air. When the object vibrates forward, it pushes back the air molecules and thus they push the other molecules too. These molecules gather to create a compression zone. When the object vibrates back, it creates a vacuum zone called rarefaction. Because all molecules affect each other, this disturbance is transmitted throughout the air. Then they create an audible wave. This sound wave has certain properties such as frequency, amplitude, speed, texture, etc. But here I’ll write about pitch. This is why you need to understand frequency first. Because frequency is the property of sound that determines the pitch.


Frequency is the number of occurrences of an event per unit time. The repeating event here is the vibrations that create a sound wave. If an object vibrates fast, it creates more frequent sound waves. So the frequency of the sound will be high. If it vibrates slowly, it creates less frequent sound waves, thus the frequency will be low. The unit of frequency is hertz (symbol Hz)


Pitch is a perceptual concept that allows us to order musical sounds or tones according to their frequencies. This is how we tell a note is higher or lower than others. Pitch is an important concept in music. All notes have specific frequencies thus pitches. This is how we perceive them, identify them and distinguish them from others. Different voices or instruments produce different ranges of tones. For example, women have higher voices than men or a bass guitar has a lower range of tones than an electric guitar.

Comparison between the pitches of a bass guitar and a whistle

In this figure, you can see the difference of frequencies of a bass guitar and a whistle. When you pluck the strings of a bass guitar, they vibrate less. This is why they produce lower frequency or lower pitched tones. But a whistle produces high pitched tones.

Note that when we say a note is high or low, we refer to its pitch, not volume or loudness of that note. It is entirely a different concept which is related to the amplitude property of sound waves.




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