The Physics of Music: How Sound Becomes Symphony

Have you ever wondered why a Sitar sounds different from a Harmonium, even if both the musical instruments are playing the same notes? Welcome to the physics of music — where science and art collide ina beautiful, invisible dance of waves and vibrations. Music surrounds us everywhere, from the gentle hum of a violin string to the booming bass of a speaker. But behind every note, rhythm and harmony lies a fascinating world of physics. Music may feel like pure art, but it is also science in motion—a dance of waves, vibrations, and mathematical patterns that give rise to the music we love. In fact, every sound we hear is a result of simple physical principles.

- Dr. Deepti Sidhaye

What Is Sound?

At its core, sound is a vibration that travels through a medium—usually air—in the form of waves. When one plucks a Sitar string, hit a drum, or sing a note, one creates vibrations in the air. These vibrations travel as waves — not the ocean kind, but compressions and rare-factions of air molecules. In other words, when you pluck a Sitar string, it pushes air particles, creating regions of compression and rarefaction. These pressure variations spread out as waves, eventually reaching our ears. Your ears pick up those waves and translate them into what your brain interprets as sound.

The key properties of a sound wave are:

Frequency (measured in Hertz): How fast the wave vibrates. This determines the pitch of the sound — high notes have high frequencies (treble); low notes have low frequencies ie. deeper tones (bass).

Wavelength: The distance between wave peaks. For sound, wavelength is the distance between two places where the air is squeezed the same way in the repeating pattern.

When the wavelength is short, the pulses are packed close together; the sound is high-pitched like a squeaky whistle. This corresponds to high frequency. When the wavelength is long, the pulses are far apart; the sound is low-pitched like a big drum or a lion’s roar. This corresponds to low frequency. So, wavelength and frequency are inversely proportional to each other.