Ingressive Vocal Fry
Ingressive or inhaled vocal fry is a very particular technique used for the singing of very low pitches. When well performed, this register (also called Pulse register) can help bass singers extend their range by up to an octave. The author discovered his ability to perform these ultra low notes with surprising power while imitating the computer-enhanced voice of a hauntingly low bass on the radio. Subsequent attempts to use the technique while singing proved quite successful and consistently enabled the singing of pitches far lower than most basso profundos, right to the bottom of the piano (27Hz). Although the technique would not necessarily be utilized in a solistic, melodic fashion, it is quite effective when used in choral singing.
Some of the acoustic characteristics of the technique include a high rate of glottal closure as well as very rapid closure, both of which ensure a spectrum very rich in upper partials. Consequently, these notes are much more audible than if they were sung in regular chest voice, if this were possible. Because this technique uses a slight but constant inhalation gesture (i.e. very little air is actually entering) and glottal closure is so high, it is possible to sustain a sound or phrase for far longer periods of time than what would normally be possible. Although these pitches are very low, the effect of the fundamental frequency and first harmonics on the sound is almost negligible and most of the perceptive acoustic information is extracted from upper frequencies.
Here are some examples of the author using this technique:
1) Vowel series [a-e-i-o-u] sung on a double low G (49Hz)
2) Descending A Major scale to 27 Hertz (last note on piano)