Why Does the Beat Bend? Stolen Time, Paid Back

The word names a deliberate departure from strict time, in which a performer lingers on some notes and hurries others to shape a phrase. It is not an error, an inability to keep time or a licence to play however one feels, and it is expected in a great deal of music where the score gives no indication of it, since the convention is understood rather than written. The metaphor in the name is precise, since time taken from one place is understood to be given back in another, so the phrase as a whole occupies roughly the duration it would have had. Whether that repayment is obligatory is the substance of a long argument.

Two quite different practices go by the same name:

• •An earlier form where the melody bends while the accompaniment keeps strict time
• •A later form where everything bends together and the whole texture breathes
• •The earlier form was described explicitly by Mozart and attributed to Chopin
• •The later form dominates most performance now and is what most listeners expect
• •The earlier form is far harder to execute, requiring independence between the hands
• •Recordings from the early twentieth century preserve players doing the earlier one

Recordings made between the 1890s and the 1930s document performing conventions that written sources describe imprecisely, and what they contain is startling to a modern listener. Pianists routinely play the hands out of alignment, sounding the melody note after the bass rather than with it, as a standard expressive device rather than as an accident. Tempo fluctuates far more freely than any modern performer would attempt. Arpeggiation of chords is constant. Several of these players studied with pupils of the composers whose music they perform, which gives the recordings evidential weight. Performance practice changed sharply in the mid twentieth century towards literal accuracy, and these recordings are the main evidence for what was lost.

Notation is remarkably poor at recording this aspect of performance, which is why the practice has to be learned rather than read. Written markings indicating a broadening or a holding back exist and are sparse, covering the most significant moments and leaving everything smaller unmarked. Metronome marks give a single figure for a passage whose whole point is that the speed varies. Composers who wrote detailed instructions about dynamics and articulation frequently wrote nothing about this at all, on the assumption that any competent performer knew what to do. The result is that a score looks far more rigid than the music it records, and a performance that follows it literally sounds wrong to anybody who knows the convention.

The practice is criticised as often as it is praised, and the criticisms identify specific failures rather than objecting to flexibility in principle. Applied without a sense of the underlying pulse, it becomes formless, since the expressive effect depends on the listener retaining a sense of where the beat would have been. Applied constantly, it stops registering as departure and simply becomes the tempo. Applied to every phrase identically, it turns into a mannerism. Taken without repayment, it slows the music progressively, which is why a piece can arrive at the end considerably slower than it started. The distinction between shaping a phrase and simply being unable to play in time is audible and is what makes the technique difficult.

Stretching some notes and compressing others is an expected convention rather than a licence, and the name implies time taken is given back. An earlier practice bent the melody over a strict accompaniment, while the later one bends everything together, and recordings from before 1930 preserve the earlier approach along with much else that has disappeared. The effect depends on the listener still sensing where the beat would have been.