Finger substitution

Finger substitution is a playing technique used on many different instruments, ranging from stringed instruments such as the violin and cello to keyboard instruments such as the piano and pipe organ. It involves replacing one finger which is depressing a string or key with another finger to facilitate the performance of a passage or create a desired tone or sound. The simplest type of finger substitution is when a finger replaces another finger during a rest; the more difficult type is to replace one finger with another while a note is being played.

On stringed instruments such as the violin, cello, and double bass, finger substitution is used for a variety of reasons. For complex, rapid passages, finger substitution is sometimes used to make a fingering pattern more consistent and easy to remember. In slow-moving music with expressive sustained bowed notes, finger substitution may be used so that a particular finger can be used for vibrato, to add emphasis to a note, or to introduce a subtle glissando effect (especially in Tango music and certain Romantic styles). One of the difficulties with finger substitution is maintaining correct intonation; when a finger replaces another finger to perform the same pitch, there is the risk that the intonation of the replaced finger may not match that of the initial note.

When a string player does finger substitution, they usually take care to hide the switching of the fingers by doing the replacement during a bow change or a rest. Finger substitution is more difficult with bowed (arco) passages than with pizzicato passages, because the notes are sustained much longer with the bow; if the substitution is not done carefully, an arco passage is more likely to result in unwanted shifting noises. In some cases, as with Romantic era music, Roma music, or Tango pieces, players may deliberately leave in the short glissando that occurs with finger substitution, using this as an expressive effect or ornament. When cello or double bass players are playing a high-register passage in thumb position, the thumb may be replaced with a finger if there is a sustained note which would otherwise have to be played with the thumb, because the vibrato with the thumb sounds different from finger vibrato. The bony side of the thumb cannot produce the same type of vibrato as the fleshy pads of a fingertip.

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