Extended vocal technique
Vocalists are capable of producing a variety of extended technique sounds. These alternative singing techniques have been used extensively in the 20th century, especially in art song and opera. Particularly famous examples of vocal extended technique can be found in the music of Luciano Berio, George Crumb, Arnold Schoenberg, and Salvatore Sciarrino.
Timbral techniques
=Spoken
Spoken text is frequently employed. The term “parlando” is a similar direction which is somewhat out of date.
=Sprechgesang
Sprechgesang is a combination singing and speaking. It is usually heavily associated with Arnold Schoenberg (particularly his Pierrot Lunaire which uses sprechgesang for its entire duration) and the Second Viennese School. Schoenberg notated sprechgesang by placing a small cross through the stem of a note which indicates approximate pitch. In more modern music “sprechgesang” is frequently simply written over a passage of music.
Vocal tremolo
A vocal tremolo is performed by rapidly pulsing the air expelled from the singer’s lungs while singing a pitch. These pulses usually occur from 4-8 times per second.
Vocal trill
A vocal trill is performed by adding singing vibrato while performing a vocal tremolo.
Inhaling
Vocal sounds or even words can be produced while a singer is inhaling. This can creat a strained or even humorous effect.
Yodelling
Yodelling is performed by rapidly alternating between a singers chest and head voice.
Non-Vocal Sounds
Besides producing sounds with the mouth singers can be required to clap or snap their fingers. This is usually notated by writing the appropriate word over a not. These gestures are sometimes written on a separate one line staff as well.
Artificial Timbral changes
Gases
Inhaled helium is occasionally used to drastically change the timbre of the voice. When inhaled helium changes the resonant properties of the human vocal track resulting in a very high squeaky voice. Tn Salvatore Martirano’s composition L’s GA the singer is required to in hail from a helium mask. Conversely an unnaturally low voice can be achieved by asking the singer to inhale the harmless gas sulfur hexafluoride.
Artificial vocal enhancement
Amplification, possibly with electronic distortion of the voice is frequently used in contemporary composition. Through the use of various electronic distortion techniques the possibilities are nearly unlimited. I good example of this can be found in much of the music written and performed by Laurie Anderson. Another interesting example of artificial vocal enhancement is found in Robert Newell’s Spirals in which the composers asks singers to use megaphones.
=Piano
There are a number of pieces with require a singer to lean over a (sometimes amplified) piano and sing directly into the strings. If the strings are not dampened the effect is to start audible sympathetic vibrations in the piano. By far the most famous piece to use this technique is Ancient Voices of Children by George Crumb.