- Explain that sound comes from vibrations and how it travels through air
- Distinguish the four properties of sound and their physical basis
- Read dynamic markings (pp, p, mf, f, ff)
The phone rings, and before the caller says their name you already know it's your grandmother. How? Every voice has its own “fingerprint”. Musicians describe a sound by four properties, and knowing them is the first step to understanding music.
What is sound?
Sound is made by vibration. When a tar string, the skin of a nagara drum or your vocal cords vibrate, they squeeze and stretch the air around them, and this wave reaches our ears. At 20 °C sound travels about 343 metres per second in air. In a vacuum sound cannot travel: an explosion in space is silent. Regular vibrations give a sound with a definite pitch — a musical sound; irregular vibrations make noise (a rustle, for example).
The four properties of sound
| Property | What it depends on | Example |
|---|---|---|
| Pitch (high — low) | the frequency of vibration — vibrations per second (hertz, Hz) | birdsong is high, a big drum is low |
| Duration | how long the vibration lasts | a long balaban note, a short daf stroke |
| Loudness (dynamics) | the amplitude — how strongly it vibrates (decibels, dB) | a whisper ≈ 30 dB, a shout over 80 dB |
| Timbre (tone colour) | the mix of overtones on top of the basic tone | the same note A sounds different on a tar and on a piano |
Musicians write duration with the shapes of notes — you will learn them in the next lessons. The secret of timbre lies in overtones: while a string vibrates along its whole length, it also vibrates in halves, thirds and smaller parts at the same time. These extra faint sounds sit on top of the basic tone, and every instrument has its own mix of them.
Dynamics: the loudness signs of music
| Sign | Italian | Meaning |
|---|---|---|
| pp | pianissimo | very soft |
| p | piano | soft |
| mp | mezzo piano | moderately soft |
| mf | mezzo forte | moderately loud |
| f | forte | loud |
| ff | fortissimo | very loud |
| cresc. (<) | crescendo | gradually getting louder |
| dim. (>) | diminuendo | gradually getting softer |
How much can we hear?
A young person's ear hears sounds from about 20 Hz to 20,000 Hz; with age the upper limit goes down. Musicians tune their instruments to an international standard: the A above middle C = 440 Hz. The lowest note of a piano is about 27.5 Hz, and the highest about 4186 Hz.
Sounds above 20,000 Hz are called ultrasound: bats use it to find their way, and doctors use it for ultrasound scans. Sounds below 20 Hz are infrasound: elephants partly “talk” to each other with such sounds, and earthquakes produce infrasound too.
Murad saw a flash of lightning and heard the thunder 3 seconds later. The speed of sound in air is 343 m/s. Roughly how far away was the lightning?
Show solutionHide solution
Distance = speed × time = 343 m/s × 3 s = 1029 m ≈ 1 km.
Shortcut: divide the seconds by 3 to get roughly the distance in kilometres.
- 1Listen: The Carnival of the Animals
Listen to “The Elephant”, “Aviary” and “The Swan” from Camille Saint-Saëns's The Carnival of the Animals (1886).
- 2Compare the pitch
“The Elephant” is played by the double bass in low notes, “Aviary” by the flute in high ones. How does the composer show each animal's size through pitch?
- 3Describe the timbre
In “The Swan”, describe the cello's timbre in three words (e.g. warm, smooth, singing) and note where the dynamics change.
Key points
- Sound comes from vibration and travels through air at about 343 m/s; it cannot travel in a vacuum.
- Four properties of sound: pitch (frequency), duration, loudness (amplitude) and timbre (overtones).
- A loud sound is not necessarily high: loudness and pitch are different properties.
- Dynamics: pp, p, mp, mf, f, ff; crescendo — getting louder, diminuendo — getting softer.
- People hear about 20–20,000 Hz; the tuning standard is A = 440 Hz.
Check yourself
10 questions. Every correct answer earns XP.