The Physics of Sound and Music: A Beginner’s Guide

Humans have a strong emotional connection to music, even though it is essentially just a series of vibrations. While music evokes significant feelings, every song follows a few principles of physics. When viewed through a physics lens, music becomes both science and art. The physics of sound and music, along with musical instruments and acoustics, contribute to the greater goal of creating a pleasing sound.

The Basic Physics Behind Sound

The physics of sound is explainable by describing how vibrations create sound waves. In scientific terms, sound is caused by vibrations that propagate as mechanical waves. The source of the vibrations, such as a drum, creates those waves by compressing and changing the surrounding air. This process does not take very long, and is why humans hear sounds almost instantly after their creation.

Humans can hear a broad range of sounds, from 20 Hertz to 20,000 Hertz. This range narrows as they age, but what listeners may not know is that their ears pick up different properties of sound waves. These aspects determine how the ear understands the sound, whether it is pleasing or ear-screeching.  The following are some properties of sound waves.

• Frequency: Frequency is the vibrations per second of a sound wave. When it is high, the pitch is high and vice versa. 
• Amplitude: Amplitude is the intensity of those vibrations. The larger the amplitude, the louder the sound human ears hear. 
• Timbre: Timbre consists of overtones and harmonics. It is why many instruments sound different to the human ear. 

A common question is whether sound is possible without vibrations. Since vibrations create sound waves, it is impossible to make one without the other. Sound needs both vibrations and a vessel to carry to the ear. This question contributes to the widespread debate over whether a tree makes a sound when it falls alone in the woods.

The Basic Physics Behind Music

After sound comes the basic physics of music, in which sound waves interact with other elements to create the songs humans know and love. The following are some basic properties of music that give it unique rhythms and sounds. 

• Harmonics and overtones: Multiple harmonics and overtones make up a single musical frequency. The combination of these harmonics is what gives each instrument its timbre.
• Consonance: Consonance is a stable combination of music notes with simple ratios between the notes’ frequencies. 
• Dissonance: Unlike consonance, dissonance is a more tense combination of musical notes with more complex frequency ratios, creating a rough sound.

Musical Scales and Intervals

Musical scales and intervals are fundamental properties of music that require a slightly more in-depth look. Different frequency ratios create musical scales. In fact, Western musicians developed the 12-tone scale based on mathematical relationships between frequencies. A scale is a series of notes separated by specific frequency intervals. These intervals create the melody and harmony that humans often complement musicians on. 

How Instruments Contribute to Sound and Music

Understanding the physics of sound and music can help people grasp how instruments contribute to the scientific aspects of songs. Instruments are separated into different families because each produces sound differently. The following are the instrument families with an explanation of the physics musicians use to create each sound.

The String Family

String instruments produce sound by vibrating a string. They change pitch by utilizing different string lengths, tensions and thickness. The body of a string instrument amplifies the sound, allowing it to carry throughout a music room or from a stage. Some examples of string instruments include the cello and the violin. 

The Wind Family

Wind instruments produce sound by vibrating a section of air. Woodwinds vibrate air via a reed or a musician’s blowing. Brass instruments use the musician’s lips to create vibrations that become sound. To change the pitch during a song, wind instrument players open and close holes or valves. Some examples of woodwinds include clarinets and flutes, while brass instruments include trumpets and tubas. 

The Percussion Family

Musicians playing percussion instruments strike a specific surface to make a sound. They can create music with both definite and indefinite pitches, depending on the song. Definite pitches have a precise frequency that repeats throughout the song, whereas indefinite pitches lack a uniform frequency and add rhythm to a piece. To determine the sound and pitch, musicians must consider the shape, material and size of the percussion instrument. Some percussion instruments include drums and cymbals.

The Importance of Acoustics in Sound and Music

Acoustics are another critical aspect of sound and music, as they enhance the overall listening experience. The study of music’s behavior is called musical acoustics and involves some physics. An instrument creates the original sound, but the sound humans actually hear involves its reflection from the room’s surfaces and features. The reverberation and echo of the space contribute to the overall sound that reaches the ear. 

Designers take acoustics into account when making concert and music halls. That is why the songs sound so much richer in these places. They consider the shape of the room and the materials constructors use to create the hall. The goal is to construct a balanced acoustic environment that provides just the right amount of reverberation to make the sound pleasing to human ears.

The Healing Properties of Music

The physics of sound and music pertain to the actual sound created, but there is also some emerging science about the healing properties of music in the human body. While many people consider music a stress reliever, some studies link it to improvements in patients’ cardiovascular health. Music can decrease blood pressure and heart rate, affecting the autonomic nervous system (ANS) in beneficial ways. Classical music is an effective contributor, especially when the beat is slow and relaxing. 

While this is a different side of science compared to physics, it demonstrates the connection between music as an art form and as an avenue for scientific exploration. Both subjects are necessary to fully understand the complexity of music.

A Deeper Understanding of Music

Music is a combination of art and science, creating something beautiful that humans have enjoyed for a long time. The principles of physics are central to the musical experience, shaping the different sounds listeners hear throughout a piece. Listeners may appreciate music more once they understand the fundamentals of creating it.