tremolo

Tremolo comes from Italian tremare, 'to tremble, to shake,' derived from Latin tremere ('to tremble, to quake'), which traces back to the Proto-Indo-European root *trem- meaning 'to shake.' The same root gives English 'tremble,' 'tremor,' and 'tremendous' (originally meaning 'causing trembling through fear'). In music, tremolo specifically names the rapid repetition of a single note (or alternation between two notes) rather than pitch variation — the string player who moves the bow rapidly back and forth on a single note produces a tremolo, as does the pianist who alternates rapidly between two registers. The technique predates the word's formal musical usage: medieval lutenists and viol players used rapid repetition as an expressive device long before it was codified in notation.

The confusion between tremolo and vibrato is persistent and instructive. Vibrato is a fluctuation in pitch — the slight oscillation above and below the central pitch that gives a singer's or string player's tone its warmth and expressiveness. Tremolo is a fluctuation in volume or a rapid repetition of pitch. In practice, both techniques are sometimes called by the wrong name, and the confusion goes back centuries: early music treatises used the terms inconsistently, and the organological literature has never fully standardized the distinction. On the guitar, what is called the tremolo arm (or whammy bar) actually produces vibrato — pitch oscillation — while the tremolo picking technique produces true tremolo — rapid note repetition. The misapplication is so widespread that both uses are now standard.

The orchestral tremolo on strings is among the most atmospherically powerful effects in the classical vocabulary. A sustained tremolo in the strings creates a shimmer or a sense of hovering, of suspended animation. Composers from Gluck to Wagner used it to create supernatural or mysterious atmospheres; Beethoven used it in the opening of his Ninth Symphony to suggest something emerging from primordial silence; Sibelius used it to create the icy, hovering quality that characterizes his atmospheric landscapes. The tremolo is ideal for these purposes because it occupies musical time without clearly articulating rhythm — it fills space without defining it, which creates the sense of suspension or unease that composers have exploited for three centuries.

In the twentieth century, tremolo migrated into popular and electronic music in transformed ways. The tremolo arm on an electric guitar produces pitch vibrato (confusingly); tremolo pedals and effects units produce amplitude modulation — rhythmic fluctuation in volume — that owes its lineage to the orchestral tremolo. Surf music, psychedelic rock, and country all developed distinctive tremolo sounds using amplitude modulation, and the effect became one of the defining textures of certain genres. The term drifted furthest from its Latin origin in electronic contexts, where 'tremolo' can name almost any rapid oscillation in a signal, whether of pitch, volume, or timbre.