Musical Tremolo Effect and Techniques

In music, tremolo (Italian for "trembling") is a trembling effect applied to vocal or instrumental sound. Depending on the context, tremolo can refer to the rapid repetition of a single note, an oscillation between two different notes, or a periodic variation in volume (amplitude).

Tremolos may be categorized as either measured, where the exact rate of repetition or oscillation is specified by rhythmic notation, or unmeasured, where the rate is not strictly specified and is understood to be performed as rapidly as possible.

Types of Tremolo

Rapid Reiteration and Oscillation

The rapid reiteration of a single note is a characteristic effect on bowed string instruments, achieved by moving the bow back and forth rapidly. However, the technique can be executed on any instrument where it is practicable.

Notation for this effect consists of one or more strokes drawn through the stem of a note, corresponding to the beams that would connect individual repeated notes. On plucked string instruments like the harp, this technique is termed bisbigliando (whispering). On instruments such as the guitar and mandolin, tremolo picking involves the rapid articulation of notes with a plectrum or fingers to sustain notes that would otherwise rapidly decay.

Wind instruments achieve an analogous unmeasured effect via flutter-tonguing, while percussion instruments utilize a roll.

Pitch Alternation and Fingered Tremolo

A rapid alternation between two different pitches constitutes another category of tremolo. On bowed string instruments, this is called a fingered tremolo. It is notated by writing the pitches as a melodic interval, with both notes receiving the rhythmic value of the total duration, connected by beams or strokes indicating speed.

Amplitude Variation and Electronic Effects

A distinct category of tremolo involves a variation in signal amplitude. This can be produced acoustically or via electronic effects in guitar amplifiers and standalone pedals, which rapidly adjust signal volume to create a shuddering effect.

Tremolo is frequently confused with vibrato. In strict acoustic and technical terms, tremolo represents a variation of volume or amplitude, whereas vibrato represents a variation of pitch or frequency.