Sound
Fundamentals of Music Theory
Music theory is the vocabulary for describing what you already hear, and it is built on four elements: pitch, rhythm, harmony and timbre.
Beginner · 4 sections
Why Learn Theory
Play these two. The tune is identical in both — the same seven notes, in the same order, at the same speed. Something underneath it changed. Say what, in your own words, before you read on.
| If you | Having the words lets you |
|---|---|
| Play with other people | Say "go to the four chord" instead of humming it and hoping |
| Write or record your own music | Find the chord you can already hear in your head, without trial and error |
| Mostly listen | Notice what a piece is doing to you, and recognise the same trick the next time it happens |
Music theory is the vocabulary for describing what you already hear: the set of names, patterns and relationships musicians use to talk precisely about sounds that every listener has been reacting to since childhood.
You heard the difference between those two clips immediately, and you have heard it a thousand times before — a singer alone, then the band coming in behind her. What you may not have had is a way to say which of the several things that changed did the work. That is all a term like "chord" buys you: it turns a feeling you already had into something you can name, repeat on purpose, and ask someone else for.
The comparison with language is exact and worth taking seriously. Nobody learns to speak by studying grammar; grammar is written down afterwards, by people describing what fluent speakers already do. Theory stands in the same relation to music. It arrived late, it is still being revised, and it never invented a single sound.
So this course teaches listening first and naming second. Every section opens with something to play, and the term arrives only after you have heard what it is for.
Fact
Naming something does not change how it sounds. Every phenomenon in this course was audible long before it had a name, and you have been hearing all of them for years.
Convention
Theory is descriptive, not prescriptive. A "rule" in this course is a report of what musicians in some tradition have usually done — which is why every claim here is labelled as a fact, a convention, a tendency or a constraint, and never simply as right.
You already know this
In real music
- Let It Be, The Beatles — the piano plays the same short loop of chords under the whole first verse while the vocal line moves independently above it — the two layers you just heard separated
Play or hum a tune you know by heart on your own instrument. Then play it again and hold any two other notes underneath it while the tune moves. Keep the tune exactly the same both times.
Check 1
Four notes, stepping downwards, stopping before they arrive. Sing the next one. Which note does the line want?
The Four Elements
Four short clips. In the first three, exactly one thing changes and everything else is left alone — play them in order and name the thing that moved. The fourth is the odd one out: nothing about it changes at all, and working out why is the point of it.
| Element | The question it answers | Which clip above | |
|---|---|---|---|
| Pitch | How high or how low is it? | Two heights | |
| Rhythm | When does it happen, and for how long? | Two timings | |
| Harmony | What else is sounding at the same moment? | One note, then three | |
| Timbre | What is making the sound — which instrument, which voice? | One voice only |
The elements of music are the four aspects of sound that music is described in terms of — pitch, rhythm, harmony and timbre — and every piece of music you have ever heard is some combination of the four.
Pitch is how high or low a note is, and rhythm is when it happens and how long it lasts. Those two are enough on their own: a single unaccompanied voice has nothing but pitch and rhythm, and "Happy Birthday" is recognisable when tapped out on one note, or hummed with no sense of time at all, because each element survives the loss of the other.
Harmony is what happens when more than one note sounds at the same moment — the third clip, where a single became , and together. It is the element that changed under the tune in the section before this one, and it is the one that most often produces the reaction people cannot explain.
Timbre is the odd one out: it is the only element that changes nothing about which notes are played. A on a flute and the same on a distorted guitar are the same pitch for the same duration, and no listener would confuse them. It is also why the fourth clip above is so unhelpful — read the fact below it.
Convention
The four are separated because each answers a different question, and a piece can vary one while the others stay recognisably the same — which is what the first three clips above do. They are not sealed off from each other: adding a second pitch under a note is a change of pitch that produces harmony.
Fact
The playback bar at the bottom of this site has one sampled voice, so every example in this course sounds in a single timbre. Timbre is the one element the site cannot demonstrate to you: to hear it you have to play the same note on two different instruments yourself.
Convention
Textbooks list anywhere from four to seven elements, adding melody, form, texture or dynamics. Melody, form and texture each get a chapter of their own later on, and each is built out of the four above rather than standing beside them — a melody, for instance, is pitch and rhythm together in one line. Dynamics is the genuine omission: how loud a sound is cannot be derived from its pitch, its timing, what sounds with it or what is making it, so a list of four leaves it out rather than containing it. It gets a section of its own in chapter 18, and the reason it waits that long is practical — loudness is most worth talking about once there is more than one part to balance.
You already know this
Where this goes
In real music
- We Will Rock You, Queen — the stomp-stomp-clap that opens it is rhythm with no pitch at all, and it carries the song unaided until the guitar arrives at the end
- Peter and the Wolf, Sergei Prokofiev — each character is a different instrument playing in the same orchestra — the duck an oboe, the cat a clarinet, the grandfather a bassoon; timbre is doing all the storytelling
See also
Play one note on your own instrument and hold it. Then change one thing about it and leave the rest alone: play it an octave higher, play it three times quickly instead of once slowly, add a second note underneath it, or play it again with a different tone setting, pickup or mute.
Check 1
A short figure, played twice. Exactly one element is different the second time. Which one?
How This Course Works
Press either of these, then look at the strip along the bottom of the screen. Every control on this site that makes a sound sends it there.
| Beat | What is in it | What it asks of you |
|---|---|---|
| Hear | A play control and a question, with no term above it | Listen, and answer in your own words |
| See | A staff, a table or a diagram of the same thing | Look — and switch the staff off if you do not read one |
| Understand | A one-sentence definition, then two to four short paragraphs | Read, and check the definition against what you heard |
| Connect | What you already knew, where this goes next, and real recordings | Press the replay chip; follow a link if you want it |
| Apply | One task for your own instrument, and a check with an explanation for every answer | Play it yourself, then guess and find out |
The playback dock is the strip fixed to the bottom of every page in this course: one instrument that every play control on the site hands its notes to, so that what you hear and what you see lighting up are always the same instrument.
That is why no chapter draws a keyboard next to its examples. Press any chip, and the dock catches the notes, shows them on the instrument you chose, and keeps them: you can replay the phrase, or step through it one note at a time, long after the button that sent it has scrolled out of sight.
Every section then runs the same five beats in the same order — Hear, See, Understand, Connect, Apply, as the table sets out. The order is deliberate: the sound arrives before the word for it, and the word arrives before you are asked to do anything with it.
Notation is optional here, and that is a promise rather than an encouragement. Nothing in this course is taught only on a staff, and nothing is kept behind a fold.
Convention
Notation is optional in this course, and chapter 4 is not required for any chapter. Chapter 4 teaches reading the staff for its own sake; it is not a prerequisite of anything, no later chapter assumes it, every staff on the site can be switched off, and every definition, table, answer and explanation is written out in words.
Fact
Every play control on this site — the chips above, the small replay chips in Connect, the checks in Apply — sends its notes to the same dock. Whatever sounded last is still there to repeat or step through.
Convention
There is no score, no streak, no percentage and no certificate anywhere in this course. A check can be retried as often as you like, and a wrong answer only changes which explanation you are given.
Press play on any chip, then find the same notes on your own instrument.
Check 1
Chapter 4 teaches you to read the staff. Which of the other chapters require you to have done it first?
Pick Your Instrument
Play these three notes and watch where they light up at the bottom of the screen. Then set the control below to whatever you actually play, and press it again.
| Setting | What the site draws | The tuning it assumes |
|---|---|---|
| Piano | A keyboard: every note in order, each with exactly one place | — |
| Guitar | A six-string fretboard, twelve frets | |
| Ukulele | A four-string fretboard, twelve frets | — standard reentrant tuning: the fourth string sounds above the third, not below it |
| Bass | A four-string fretboard, twelve frets |
Your instrument preference is a single stored setting that tells this site which instrument to draw for you — a keyboard or one of three fretboards — everywhere it would otherwise have to guess.
The setting exists because the same three notes are a different picture on every instrument. On a keyboard, , and are three keys with two gaps between them; on a guitar they are a shape your hand makes across three strings. Being shown the wrong one of those is worse than being shown neither, so the site asks once and then stops asking.
Set it now, on the control above, and it holds for every chapter, every reference page and the dock at the bottom of all of them. Change it whenever you like — there is nothing to confirm and no account to make.
If you play nothing at all yet, leave it on Piano. The keyboard is the diagram this course reaches for when it has to show how notes are spaced, because it puts them in a row and gives each one exactly one home.
Fact
A note has exactly one place on a keyboard and several on a fretted instrument. Within the first twelve frets of a guitar in standard tuning, middle can be played in three different places — on the B string at the first fret, on the G string at the fifth, and on the D string at the tenth — all of them the same pitch.
Fact
The preference is kept in this browser on this device and is sent nowhere. Clearing your site data resets it to Piano, and a different browser or a different machine starts from Piano again.
Convention
This course draws a keyboard by default, and most theory books do the same. That is a convenience — the layout matches the way the notes are counted — and not a claim that the piano is the real instrument or that the others are translations of it.
You already know this
Where this goes
Set the control above to the instrument you play, then press the chip at the top of this section and find those same three notes on the real thing. Play them one at a time, then all together if your instrument allows it.
Check 1
You set the control to Guitar today, then open chapter 5 tomorrow in the same browser. What do the diagrams show you?
Key Takeaways
- Music theory is the vocabulary for describing what you already hear, and it describes music rather than governing it.
- The four elements of music are pitch, rhythm, harmony and timbre, and each one can change while the other three stay exactly as they were.
- Every play control on this site sends its notes to the dock at the bottom of the page, which is the only instrument the course draws.
- Every section runs the same five beats in order: hear the sound, see it written down, understand the term, connect it to what you knew, and apply it on your own instrument.
- Notation is optional throughout this course, and chapter 4 is not a prerequisite for any chapter.
- Setting your instrument once, in this chapter, makes every diagram in every later chapter show the instrument you actually play.
Last updated September 22, 2026
Questions
- Do I need to read music to learn music theory?
- No. Reading the staff is a separate skill from understanding how music works, and this course keeps them apart: chapter 4 teaches reading for its own sake and is not a prerequisite for any other chapter. Every staff on the site can be switched off, and every definition, table, answer and explanation is written out in words.
- What is music theory?
- Music theory is the vocabulary for describing what you already hear — the names, patterns and relationships musicians use to talk precisely about sound. It is descriptive rather than prescriptive: it reports what musicians have done, and it never invented a single sound.
- What are the four elements of music?
- Pitch, how high or low a note is; rhythm, when it happens and how long it lasts; harmony, what else is sounding at the same moment; and timbre, what is making the sound. Each can change while the other three stay as they were, and every piece of music is some combination of the four.
- Do I need an instrument to take this course?
- No. Every example plays through the bar at the bottom of the screen, so you can hear everything with nothing but a browser. An instrument does help: each section ends with one short task on your own instrument, because playing a thing is what moves it from recognised to known.
- Where should I start if I have never studied theory before?
- Here, and then chapter 2 and chapter 3 in order — pitch and rhythm are the two elements everything else is built on. After that the course branches: intervals and scales in chapters 5 to 9, chords and progressions in 10 to 14. Take chapter 4, on reading music, whenever you want it, or not at all.