A tremelo can be defined as being a ‘trembling’ or ‘quivering’ effect - this usually takes one of two forms. One is where a single note is rapidly bowed repeatedly and the other is a a fast oscillation between two notes (rather like a trill) - with the gap between the two notes being wider than a trill.
A tremelo might be rhythmically even, or unmeasured (which can also be written as tremolando). The unmeasured version would be used where a composer or arranger instructs the notes to be simply played as quickly as possible - this technique is used often when adding strings to pop and rock tracks and can add a feeling of tension to a piece of music. Tremeloes can also be given an accent at the beginning (which means the first note of the tremelo is emphasised to give it a ‘kick’) - this can convey a feeling of tension even further and is particularly effective with a full string section rather than writing for single strings.
In string arranging, a tremolando can also be used very quietly - and if the whole of the string section are playing this way at the same time, it can give a rumbling feeling of something imminently about to happen - so instead of having a chord held, it can lend a sense of anticipation and of course add all important variety to a string arrangement.
Tags: Orchestrating for strings, rapid bowing, scoring for violins, string arranger, String Arranging, tense strings, tremolando, Tremolo, tremoloes, using string orchestra to create tension, writing for string section, Writing for stringed instruments
[...] to a piano part inevitably leads to ‘un pianistic writing’, but another reason is that tremolos (or tremolandos) are exceedingly hard to play on a keyboard instrument. They are sometimes written [...]