Every sound you hear – a pan, a guitar, a voice, a clap – is made in the same way: something vibrates. Music is where art meets science and technology. In this post you will learn how sound travels, what makes one note higher, louder or brighter than another, how rooms and microphones change what we hear, and about the many careers open to people who love music.
What is sound?
When an object vibrates, it pushes and pulls on the air particles next to it. They bump into their neighbours, and a sound wave of squeezed (compressed) and stretched-out air travels outwards. When the wave reaches your ear, it makes your eardrum vibrate, and your brain hears a sound. Sound needs a medium – a solid, a liquid or a gas – to travel through, so it cannot travel through a vacuum such as outer space. In air at room temperature it travels at about 343 metres per second.
Watch: SciShow Kids explains what sound is.
Frequency, amplitude and timbre
Scientists draw sound as a wave. Its properties match the elements of music you already know:
| Property of the wave | What it is | What you hear | Element of music |
| Frequency | How many vibrations happen each second, measured in hertz (Hz) | Higher frequency = higher pitch | Pitch (melody) |
| Amplitude | The size of the vibration – how far the particles move | Bigger amplitude = louder sound | Dynamics |
| Waveform (wave shape) | The mix of the main frequency with weaker extra frequencies called harmonics (overtones) | Different shapes = different tone colours | Timbre |
| Duration | How long the vibration lasts | Long or short notes | Rhythm (duration) |
The A above middle C, which orchestras tune to, vibrates 440 times a second (440 Hz). Going up an octave doubles the frequency: the next A up is 880 Hz, and the A below is 220 Hz. Human hearing covers roughly 20 Hz to 20 000 Hz, although the top limit falls as we get older.
Try it: sound wave lab
Move the sliders and watch the wave. Then use “Play” to compare an octave, soft and loud, or all four waveforms.
TRY ITSound wave lab
Change the waveform, the frequency and the loudness and watch the drawing change. Then press Play to hear it. A higher frequency squeezes more waves into the same time; a louder sound makes a taller wave.
Press Play to listen. Nothing plays until you press the button. Start with your volume low.
Start with your volume low. Square and sawtooth waves sound buzzy because they contain many extra frequencies called harmonics.
How instruments make their sounds
Every instrument has something that vibrates, and usually something that makes the sound louder and richer (a resonator, such as the body of a guitar).
| What vibrates | Examples | How the pitch changes |
| A string | guitar, cuatro, violin, piano, sitar | Shorter, tighter or thinner strings vibrate faster and sound higher |
| A column of air | flute, recorder, clarinet, trumpet | A shorter column of air sounds higher – that is what holes, keys and valves change |
| The vocal folds | the human voice | Tighter, thinner folds vibrate faster for higher notes |
| A stretched skin (membrane) | tassa, tabla, djembe, drum kit | A tighter or smaller skin sounds higher – tassa players heat the skin to tighten it |
| A solid object | steelpan, xylophone, bell, triangle | Smaller notes, or thinner parts of the metal or wood, sound higher |
| An electronic circuit | synthesiser, electric keyboard | The circuit or computer program sets the frequency |
The science of the steelpan
A steelpan is tuned steel. The panmaker sinks the top of an oil drum into a bowl, marks out the note areas, shapes and heats the metal, then tunes each note with a hammer. Each note area is tuned so that its main frequency and some of its overtones (often the octave above) are in tune – skilled work that combines craft and physics. Smaller note areas give higher pitches, which is why the tenor pan has many small notes while the bass pans have a few large notes and use whole drums.
Watch: from oil drum to steel pan. This is a longer documentary, so watch one section at a time.
Acoustics: sound in a space
Acoustics is the study of how sound behaves in a room or space. When sound hits a hard surface it bounces back (reflects); when it hits a soft surface it is partly absorbed. Many reflections blending together are called reverberation (reverb), while a single reflection that you hear separately is an echo. The way a sound dies away after a note is played is its decay.
- Hard surfaces – concrete walls, tiled floors and glass reflect sound, so the room sounds “live”, with a long reverb. Too much reverb can blur fast notes and words.
- Soft surfaces – carpets, curtains, cushioned seats and even a full audience absorb sound, so the space sounds “dry”.
- Outdoors there are few reflections, and sound fades quickly with distance, so performers often need a sound system.
- Performers adjust – in a large, echoing church you may sing a little slower and make the consonants clearer; for ten listeners in a small room you play more softly than for a hundred in a hall.
Music technology: from microphone to speaker
A sound system (public-address or PA system) makes sound louder and sends it to an audience. The signal travels along a chain:
- Microphone – changes sound waves into an electrical signal. In a dynamic microphone, the sound moves a thin diaphragm attached to a coil of wire near a magnet, which produces a tiny electric current.
- Mixing console (mixer or mixing desk) – combines the signals from many microphones and instruments, and lets the sound engineer adjust the volume, tone (EQ) and effects of each one.
- Amplifier – makes the weak signal strong enough to drive the speakers.
- Loudspeakers – change the electrical signal back into sound waves: a cone moves in and out, pushing the air.
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Watch: how microphones work, in about a minute.
Today a computer or phone can be a whole studio. A digital audio workstation (DAW) records, edits and mixes music; notation software lets you write scores that play back; and MIDI keyboards and synthesisers send note information to the computer. Much of today’s soca, dancehall and pop is produced this way, often in small home studios. Always respect copyright: get permission before you use other people’s recordings or samples.
Careers in music
Music skills lead to many careers in Trinidad and Tobago, across the Caribbean and around the world. These include the careers listed in the CSEC Music syllabus:
| Area | Careers |
| Performing | performer (singer, instrumentalist, steel band player), accompanist, conductor or band leader |
| Creating | composer, songwriter, arranger (for example, a steel band arranger for Panorama), producer of programmes and records |
| Technology | sound engineer, live sound technician, disc jockey (DJ), music producer |
| Making and repairing | instrument repair technician, piano tuner, panmaker and pan tuner |
| Teaching and health | music educator (school or private teacher), music therapist |
| Business and media | music journalist or critic, music retailer, entertainment lawyer, artist manager, cultural officer |
| Research | music librarian, researcher (publishing), ethnomusicologist (who studies the music of different cultures) |
Many music careers are entrepreneurial: musicians often run their own small businesses – teaching students, playing at weddings and events, selling recordings online, or running a studio or sound-system company. Skills that help in every music career include reading music, using technology, teamwork, reliability, and basic business skills such as pricing your work and managing money.
Activity: sound science and career research
- Make a simple instrument: stretch elastic bands of different thicknesses over an open box, or fill glass bottles with different amounts of water and tap them. Which makes the highest pitch, and why?
- Clap once in different places around your school – a classroom, a stairwell, the hall, outdoors. Describe the reverberation in each place, and decide which would be best for a concert.
- Choose one music career. Find out what the job involves, the training needed, and a Caribbean person who works in that field. Present your findings in a short talk or on a poster.
Quick check
1. What must happen for any sound to be made?
Show answer
Something must vibrate, and the vibrations must travel through a medium, such as air, to the ear.
2. What is frequency, and what does it control?
Show answer
The number of vibrations per second, measured in hertz (Hz). It controls pitch: the higher the frequency, the higher the pitch.
3. A note has a frequency of 220 Hz. What is the frequency of the note an octave higher?
Show answer
440 Hz – going up an octave doubles the frequency.
4. Why do a flute and a violin sound different when they play the same note at the same loudness?
Show answer
Their waveforms are different: each has its own mix of harmonics (overtones), which gives it its timbre.
5. Put these in order from the performer to the audience: amplifier, microphone, loudspeaker, mixing console.
Show answer
Microphone → mixing console → amplifier → loudspeaker.
6. Name four careers in music.
Show answer
Any four, for example: performer, composer or arranger, sound engineer, music teacher, music therapist, panmaker or pan tuner, DJ, entertainment lawyer, ethnomusicologist.
Previous: Performing Music: Choosing a Piece, Posture, Breathing, Vocal Technique and Effective Practice
Next: Back to the Music History and Theory notes – all lessons
Syllabus link: T&T Lower Secondary (NCSE) Visual and Performing Arts curriculum – Music, Forms 1–3: Timbre 3.1.36 (how instruments are played and how the different sounds are produced) and 3.3.31 (analyse musical pieces with different timbres); Music curriculum Connections to Science (pitch, duration and intensity of sound; reverberation and decay) and to Technology Education (computers, keyboard synthesisers, amplifiers, microphones and mixing boards). CSEC® Music syllabus (CXC 31/G/SYLL 17): Section 2: Listening and Appraising – Music Literacy and Perception, General Objectives 5–6 (technology and the quality of sound) and Specific Objective 10 (careers that use listening and appraising skills); Section 3: Performing, Specific Objectives 11 and 14 and Content 11 (acoustics and sound control; careers that use performing skills); Aim 6 (entrepreneurial and technological skills) and the syllabus list of Career Choices.
Attributions to media used in this post:
Sine wave amplitude wavelength.svg – Badseed, using work by Josemontero9 and José Luis Gálvez – CC BY-SA 3.0 (via Wikimedia Commons)
Waveforms.svg – Omegatron – CC BY-SA 3.0 (via Wikimedia Commons)
Ellie Mannette.jpg – Jake Lambuth – CC BY-SA 4.0 (via Wikimedia Commons)
A dynamic (XLR) microphone – WEISRE DM-701.jpg – BRONSKIARCHIVE – CC BY-SA 4.0 (via Wikimedia Commons)
Mixing console (Unsplash).jpg – Abigail Keenan akeenster – CC0 (via Wikimedia Commons)
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