Sound is a constant part of our everyday lives; indeed we cannot turn off our own ears from detecting and interpreting the world of sound around us. As musicians, we constantly create sound through our various instruments. However, many musicians do not possess a full understanding of what sound is, or of how it is created and manipulated in the musical world. This post will attempt to cover the basics of sound and acoustics, particularly with respect to musicians.
What is Sound?
Sound can be defined as a vibration in the particles of a medium (typically air) that causes an auditory sensation within the ear. As an object vibrates, the vibration displaces the molecules of air around it, causing a chain reaction of motion through the air. The particles move back and forth from their point of rest in patterns of compression (particles closer together) and rarefaction (particles farther apart from each other). These high and low pressure areas shift through the air as the energy is passed from molecule to molecule.
This pressure variation hits our eardrum, causing it to move in and out in the same way as the particles move. The number of times the particles are displaced back and forth on the eardrum is interpreted by our brain as the frequency, or what we would commonly call the pitch. The more times the molecules vibrate back and forth per second, the higher the frequency of the perceived pitch. We measure this frequency using the unit Hertz (Hz), which is a measurement of cycles per second. A normal human is born with the ability to perceive sounds between 20Hz and 20,000Hz (or 20 kHz), but as we get older, our sensitivity to sound decreases due to damage to our ears and aging processes, particularly with respect to high frequency sounds. In actuality, an adult human probably is sensitive to sounds only up to 16,000Hz – 18,000Hz (16-18 kHz).
The perceived volume of a sound source is a result of how far it vibrates away from its equilibrium and how much it displaces the molecules around it. Greater amplitude of displacement will result in greater eardrum movement. Our brain interprets this as the perceived volume of a sound. Greater energy applied to the eardrum will mean louder sound in our brains.
Now that we understand how sound is created and propagated through the air, we can begin to understand how our instruments function, both in terms of in an acoustic space, and on a recording. These concepts of vibrations, coupled with the physiology of our ear, are the foundation of how we hear sounds, and how we listen to and interpret music. We will delve further into these topics in the next posts, and we will explore other aspects of sound and acoustics, in order to help both the musician and listener understand the world of sound and music.
























One of the most basic skills necessary to start writing your own music is an awareness and familiarity with the ranges of common instruments. Without this knowledge, you might write a passage of music that is unintentionally difficult or tricky or worse, impossible to play.



Learning intervals can be tricky. Even though there are only twelve possibilities within an octave, when you’re first trying to learn it can seem as if the notes blur together into a soup of indistinguishable muck. Minor 3rds, major 6ths, minor 6ths – after a while everything can sound alike and you may need to go lie down for a while!