Most of us can tell within seconds whether a song is happy or sad, old or new, played on a guitar or a violin. We hear far more than we can name. Music history starts by giving names to what the ear already notices, so we can compare a Bach fugue, a blues and a gamelan piece without reading a note of notation. In this course, music is sound organized in time, and we follow four ways that organization works: rhythm, melody, harmony and form.

Rhythm: music in time

Rhythm is how music moves through time. Its steady pulse is the beat, the thing you tap your foot to, and tempo is the speed of that beat, from slow funeral marches to fast dance tunes. Beats usually fall into repeating groups. Meter is the grouping of beats into a repeating pattern of strong and weak. A march goes ONE two, ONE two. A waltz goes ONE two three.

Rhythm can also play against the beat. Syncopation is the accenting of notes that fall off the main beats, which gives music a feeling of surprise or lift. Ragtime, jazz and much Latin American music depend on it. When two or more different rhythms run at the same time, such as three against two, musicians speak of polyrhythm, which is central to many West African traditions you will meet in the next level.

Melody: the tune

Every musical sound has a pitch, how high or low it is. Pitch depends on how fast a vibration repeats. When one note vibrates exactly twice as fast as another, the two sound like versions of the same note: an octave is the distance between two pitches where one vibrates twice as fast as the other. Every tradition divides the octave into smaller steps, but not all divide it the same way, a point that matters when we turn to Arab and Indian music.

A melody is a series of single pitches heard as one line, the part you hum. Melodies have shape. They rise and fall, move by small steps or big leaps, and build toward a high point. A melody often breaks into phrases, like sentences in speech, that end at resting points.

Harmony: notes together

When several pitches sound at once, harmony appears. A chord is three or more pitches sounded together. Some combinations sound stable and restful; others sound tense and seem to want to move. Musicians call this contrast consonance and dissonance, and much Western music works by building tension with dissonance and then releasing it. What counts as harsh changes with time and place. Intervals that medieval theorists treated as rough became the sweet center of later harmony.

Closely related is texture, the way lines combine. Monophony is a single melody with no accompaniment, like one person singing alone or a choir singing in unison. Homophony is a melody supported by chords, like a singer with a strummed guitar. Polyphony is two or more independent melodies sounding at once, as in a round such as "Row, Row, Row Your Boat."

Timbre: the color of sound

A flute and a trumpet playing the same note at the same loudness still sound different. Timbre is the tone color that lets us tell instruments and voices apart. It comes from the mix of fainter, higher vibrations, called overtones, that ride above the main pitch.

Form: the shape of the whole

Form is the overall structure of a piece, built from repetition, contrast and variation. Musicians label sections with letters. Binary form has two parts, AB. Ternary form goes out and back, ABA. Strophic form repeats the same music for each new verse of words, as in most hymns and folk ballads. Popular songs usually alternate verses with a returning chorus. In call and response, a leader sings or plays a phrase and a group answers it, a pattern heard in African, African American, church and work music around the world.

Listening for form is the most useful habit a new listener can build. Ask: when does something come back? When does something new arrive? What has changed when the opening returns?

Worked example: one tune, many shapes

The tune English speakers know as "Twinkle, Twinkle, Little Star" began as a French song, "Ah! vous dirai-je, maman," printed in the 1760s. Around 1781 to 1782 Mozart wrote twelve variations on it for piano. Listening to them is a short course in everything above.

The theme states the melody plainly in homophony: tune on top, simple chords below, steady meter, phrases that rise and fall back to rest. In the first variation the melody hides inside quick running notes, so the rhythm changes while the harmony stays. Another variation moves the busy part into the left hand. One shifts into a minor key, and the same tune suddenly sounds grave. Near the end the tempo slows to a lyrical adagio, and the last variation speeds up and switches to a triple meter for a bright finish.

The form is theme and variations: A, then A changed again and again. Your ear keeps recognizing the tune because its skeleton, the order of its harmonies and the shape of its phrases, survives each disguise. That is what listening for form means. Try it next with any song you like: mark when the chorus returns and notice what the arrangement adds the second time.