The Note System
A note is a pitch with a name on it. Something vibrates, the speed of that vibration is what you hear as high or low, and seven letters are enough to name all of them. On a piano, a guitar, a flute or your own voice, the notes are the same notes.
- 7 letters
- 12 notes
- every instrument
Where you run into this
- Every instrument
- Reading music
- Ear training
A note is a speed you can name.
In short
A note is a frequency: how many times per second something vibrates, counted in hertz. Four hundred and forty times per second is the A that orchestras tune to. Halve that number and you get a lower A, double it and you get a higher one, and both are called A. Between one A and the next sit twelve notes. Seven of them carry the letters A to G, and the five in between borrow a name from a neighbour with a sharp or a flat, which is why one pitch can be called C sharp or D flat depending on where you came from.
Every note and its frequency
Twelve notes, and here they all are with the number that belongs to each one. Press any of them, then change the octave and watch every number double while every letter stays put.
How high a note is
Move the frequency and listen. Low numbers rumble, high numbers whistle, and every time you double the number you land on the same letter one octave up.
Two notes an octave apart sound like one thing in two sizes. That is not a figure of speech. The higher one vibrates exactly twice as fast, and your ear files that away as the same note rather than a new one. Every naming system in every musical culture starts from that one fact.
How it works
Twelve notes, seven letters, five in-between names, repeating for as long as you can still hear them. Instruments differ only in how they lay those notes out: frets along a string, holes down a tube, keys in a row, or nothing at all when you sing. The piano is the map on this site because it shows the pattern most plainly, with the black keys grouped in twos and threes so every C is findable. The notes themselves belong to no instrument.
This page is the vocabulary the rest of the site depends on. Intervals count letter names, chords are letters stacked, keys are collections of them.
Where you run into this
- A tuner, which names the note you played and tells you how far off you are
- Sheet music, where the lines and spaces are those same seven letters
- Any instrument you pick up, because the layout changes and the notes do not
- Tuning down a guitar or transposing a song, which moves every frequency and keeps every name
Our own examples
A lesson you press your way through: find the A everyone tunes to, halve it, double it, and watch the number change while the letter stays. Then a frequency you can move by hand, so hertz stops being a number and becomes a sound.
Keep going
Everything in sound and hearing
- The Note System
- What Is an Interval
- Tension and Expectation