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Sound is displaced air. Below 20 vibrations per second, you feel it as pulse. Above 20, you hear pitch. Rhythm and pitch are the same phenomenon at different speeds.

A frequency slider sweeps from 1Hz (a click) through 20Hz (a buzz) up to 440Hz (a note). You hear the exact moment rhythm becomes pitch.

Name every interval (m2, M2, m3, M3, P4, tritone, P5, m6, M6, m7, M7, P8). Hear each one. Measure them in semitones. Interval quality. Inversion (M3 inverts to m6). The tritone as the most unstable interval — and why V7→I resolves (the tritone inside V7 resolves outward to the tonic).

Theory: Ch 5 (Introduction to Intervals, quality, inversion, augmented/diminished)

8c taught passing tones. This lesson completes the vocabulary. Neighbor tones (step away, step back). Suspensions (hold a note from the previous chord into the new one — the clash resolves downward). Pedal point (a drone, which the learner has been doing since 8b). Appoggiatura (leap to a dissonance, resolve by step). Anticipation (arrive at the next chord’s note early). Each type creates a different kind of tension.

Theory: Ch 10 (Non-Chord Tones, all types)

Four cadence types: authentic (V→I), plagal (IV→I, the “amen”), deceptive (V→vi, the surprise), half (ending on V, unresolved). Then form: verse-chorus, AABA (standards), ABAC, the 12-bar blues as formal structure (the bridge to the Blues track). Sentence (1+1+2 bar phrase) vs period (antecedent-consequent). Phrases that ask questions and phrases that answer them.

Theory: Ch 7.4 (Cadences), Ch 12 (Form in Popular Music), Ch 13 (Phrases in Combination)

Walking bass (stepwise motion through chord tones — this is where strudel’s stepwise functions shine). Son clave (3+3+2 rhythm, habanera, reggaeton). Alberti bass (arpeggiated accompaniment pattern). Block chord patterns. Afterbeats and offbeats (reggae, polka). The 3+3+3+3+2+2 grouping. Each texture creates a different genre feel from the same harmony.

Theory: Ch 14 (Accompanimental Textures, including son clave and world rhythms)

The reveal — every strudel transform the learner knows IS a classical composition technique. rev = retrograde. fast(2) = diminution. slow(2) = augmentation. add(note(N)) = transposition. .off() = canon. Name them. Show Bach using the same operations on paper. Build a melody through motivic development: state a motive, then develop it using transforms the learner has been using since EDM.5.

Theory: Ch 11 (Melodic Analysis: motive, inversion, augmentation, diminution, retrograde, extension, ornamentation)

The strudel visualization suite. Piano roll for pitch, scope for waveform, spiral for harmonic relationships, spectrum for frequency content, punchcard for rhythm. Each visualization reveals something the ear might miss.

Strudel’s tonal system. chord() for chord symbols, .voicing() for automatic voice leading, addVoicings() for custom dictionaries, anchor() for bass note control. Build jazz voicings that lead themselves.

Advanced pattern manipulation. stepwise for walking bass and scalar motion. {} for polymètre (different lengths running simultaneously). mask/sew/stitch for boolean pattern gating. Pattern factories for generative composition.

Secondary dominants — borrowing the V chord from another key to tonicize a non-tonic chord. V/V, V/vi, V/ii. The moment a chord “points” somewhere other than home. How game composers use tonicization for dramatic color shifts.

Theory: Ch 17 (Secondary Dominants)

Mode mixture — borrowing chords from the parallel key. ♭VI and ♭VII in major (the “epic” sound). Picardy 3rd (ending a minor piece on a major chord). Why so many game soundtracks hover between major and minor.

Theory: Ch 19 (Mode Mixture)

The most dramatic chords in tonal music. The Neapolitan (♭II as a predominant — instant gravitas). The three augmented 6th chords (Italian, French, German) and their chromatic approach to V. Boss-fight harmony.

Theory: Ch 20–21 (Neapolitan & Augmented Sixth Chords)

Changing keys mid-piece. Pivot chord modulation (a chord that belongs to both keys). Common-tone modulation (one note bridges two distant keys). Direct modulation (the “truck driver” key change). How Zelda dungeons modulate to signal progression.

Theory: Ch 22–23 (Modulation, Enharmonic Modulation)

Form beyond verse-chorus. Binary (A-B, Baroque dance). Ternary (A-B-A, da capo). Rondo (A-B-A-C-A, recurring theme). Sonata form (exposition-development-recapitulation, the grandest structure in Western music). How RPG overworld themes use rondo form.

Theory: Ch 24–25 (Binary, Ternary, Rondo, Sonata)

Four-part writing — soprano, alto, tenor, bass. Voice ranges. The four types of motion (parallel, contrary, oblique, similar). Why parallel 5ths and octaves are avoided. Doubling rules. Connect chords so each voice moves as little as possible.

Theory: Ch 26–27 (Voice Leading Triads & Seventh Chords)

Non-chord tones in four-part context. Suspension chains (4-3, 7-6, 2-3). Chromatic voice leading with secondary dominants and mode mixture. Pedal point as structural device. The art of making four independent lines sound like one harmony.

Theory: Ch 28–29 (Chromatic Harmony in 4 Parts)

Species counterpoint — the systematic method. Species 1 (whole notes, consonance only). Species 2 (half notes, passing tones). Species 3 (quarters, neighbor tones). Species 4 (syncopation, suspensions). Species 5 (florid, combining all). Each species maps to strudel techniques the learner already knows.

Theory: Ch 30 (Species Counterpoint)

The pinnacle of counterpoint. Two-voice invention (subject + countersubject, invertible counterpoint). Fugue exposition (subject, real/tonal answer, countersubject entries). Stretto (overlapping entries). Episodes and modulation. .off() IS canon. rev IS retrograde. The learner has been writing counterpoint since EDM.5.

Theory: Ch 30 (Fugue, Invention)