Baroque by ear: continuo, sequence and the machine that never stops

The Baroque is the easiest period to recognise and the hardest to date precisely within, because for a century and a half everyone agreed on the same basic machinery. Learn that machinery and you will place a piece between 1600 and 1750 inside two bars. Splitting Bach from Handel from Vivaldi takes a little longer, but it is mostly a matter of temperament, and temperament is audible.

The one tell that does most of the work

Listen underneath. If there is a chord-playing instrument — harpsichord, chamber organ, theorbo — filling in harmony continuously, doubled by a cello, bass viol or bassoon walking the bass line, you are in the Baroque. This is the basso continuo, and it is the structural invention that separates the period from everything before it.

The composer wrote out a bass line and, beneath it, numbers indicating the intervals above each note: figured bass. The keyboard player improvised chords from those figures. So the harmony is present from first bar to last as a physical, audible substrate — something to hold the music up. Renaissance polyphony had no such floor. Classical music dissolved the floor back into the orchestra. For that century and a half, it chugs.

Once the continuo is there, two other traits follow almost inevitably.

Terraced dynamics. A harpsichord cannot get louder by playing harder; its volume changes by changing registration or by adding players. So Baroque dynamics move in blocks: a loud phrase answered immediately by the same phrase quiet, with no fade in between. A gradual swell across eight bars is a Classical or Romantic habit. If you hear a hairpin crescendo, you have probably left the period — or you are listening to a modern-instrument performance imposing later habits on earlier music.

One affect per movement. Baroque aesthetics held that a movement should embody a single emotional state — grief, rage, serenity — and sustain it. So the texture, rhythm and figuration set up in the first bar generally run to the last. This is the source of the period’s characteristic motor rhythm, the unbroken rhythmic drive the Germans call Fortspinnung, “spinning forth”.

Sequence: the engine

The second most useful ear-test after continuo is the sequence — a short figure repeated immediately at a higher or lower pitch, usually two or three times, usually stepwise. Stack that over a circle-of-fifths progression and you have the standard Baroque method of generating length from small material. Vivaldi does it constantly; Corelli made a career of it; Bach does it with more disguise but does it all the same.

Sequences generate a particular listening experience: the sense of being carried forward by a mechanism rather than led by a singer. If a passage feels like machinery rather than melody, suspect Baroque.

The forms

Fugue. One voice states the subject alone. A second enters with the same tune a fifth higher (the answer) while the first carries on with a countersubject. Third and fourth voices follow. Thereafter, entries in related keys alternate with episodes built from sequences. Bach and Buxtehude are the great exponents; a fugue can be for keyboard, for choir, or embedded in an orchestral movement.

Concerto grosso. A small solo group, the concertino, alternates with the full band, the ripieno, and the band keeps returning to the same material, the ritornello. Corelli’s Op. 6 is the prototype, Bach’s Brandenburgs the most extravagant, Handel’s Op. 6 the late summation. The solo concerto, with one soloist, is Vivaldi’s territory and by far the commonest.

Da capo aria. Section A, contrasting section B in a related key, then A again — and the singer ornaments the repeat. This ABA is the fundamental unit of opera seria and of oratorio. Hearing an elaborately decorated reprise is close to a guarantee of a date before 1770.

Suite. A run of short binary-form dances in one key: allemande, courante, sarabande, gigue as the core, with a minuet, bourrée or gavotte optionally inserted before the gigue, and often a French overture to open. Both halves of each dance are repeated, usually with added ornaments on the repeat.

Passion and oratorio. Large-scale sacred narrative for soloists, chorus and orchestra without staging: the Evangelist narrates in recitative, characters sing arias, the chorus is by turns the crowd and the commenting congregation. Bach’s St Matthew Passion (1727) and Handel’s Messiah (1741) are the poles.

The sound of the instruments

Historically informed performance changes the timbre entirely. Strings are gut rather than steel, with shorter, convex bows that bite at the start of a note and taper away — hence the “speaking” articulation and the reluctance to sustain. Oboes are narrow-bore and reedy, nasal by modern standards. Trumpets and horns have no valves, so they play only the notes of a harmonic series, some of which sit audibly out of tune. Pitch is often around A=415 rather than A=440, roughly a semitone flat, which is why a period-instrument recording can sound as if the tape is running slow.

Four composers, four temperaments

The useful test is what happens when the music has nothing to say. Bach fills the gap with counterpoint; Handel fills it with a splendid gesture; Vivaldi fills it with a sequence. Purcell, uniquely, fills it with a harmonic wince — a false relation, where one voice sings a natural against another voice’s sharp, producing the characteristic English sourness.

The traps

Early Baroque is not late Baroque. Monteverdi (1567–1643) sits on the hinge. His madrigals begin in Renaissance polyphony and end with continuo, obbligato instruments and operatic monody. A 1610 piece can sound closer to Palestrina than to Bach; do not assume the fully worked continuo machine before about 1650.

Modern-instrument Bach. A large modern symphony orchestra playing the Air on the G string with a long swelling crescendo is still Baroque music, but every performance tell has been removed. Judge by what is written — continuo line, sequence, motor rhythm — not only by timbre.

Neo-Baroque pastiche. Stravinsky’s Pulcinella, Respighi’s Ancient Airs and Dances, film scores in “harpsichord mode”, and Bach arrangements by Stokowski or Busoni all wear the costume. Tells: harmonies that sidestep unexpectedly, orchestral colours (celesta, muted brass, piano) that did not exist, or a rhythmic irregularity no Baroque composer would write.

Galant transition. The sons of Bach, Pergolesi, and Handel’s late works already thin the texture, shorten the phrases and prefer melody over accompaniment while keeping a continuo. Music from 1730–1760 can legitimately point both ways.

How to spot it in ten seconds

1. Is there a continuo? Harpsichord or organ chords plus a bass instrument, continuously, is a Baroque signature.
2. Does the rhythm ever stop? Unbroken motor rhythm with one texture throughout a movement says Baroque; balanced phrases with full stops say Classical.
3. How do the dynamics change? Loud answered instantly by soft, in blocks, is terraced. Gradual swells point later.
4. Are there sequences? A figure repeated a step down, twice, over circling harmony is close to diagnostic.
5. What are the instruments doing? Gut strings, reedy oboes, wobbly natural horns and flat pitch mean a period ensemble playing pre-Classical repertoire.
6. Is the form a block form? Soloists alternating with a band that keeps returning to the same tune is a ritornello concerto.
7. Is a vocal repeat being ornamented? A decorated da capo puts you before about 1770.
8. Counterpoint or melody? Several lines of equal interest means Bach’s world; one big tune over accompaniment leans Handel, or leans later.
9. Which national accent? French dotted overture rhythms and heavy ornaments; Italian brilliance and sequence; German density; English ground basses and false relations.
10. Check for pastiche. Colours and harmonic swerves that could not exist in 1720 mean someone is imitating, not composing, the Baroque.