CHAPTER 4 - Other Resources
There are two different types of vibrato: amplitude (or volume) and pitch. These are produced on the clarinet by a variety of methods. Amplitude vibrato may come from the diaphragm, glottis, or throat, while pitch vibrato originates with the jaw or lip. Confusion exists in method books, and among clarinetists, because the method of production is often used to describe vibrato, rather than the type of sound. To add to this state of chaos, Rehfeldt says that jaw vibrato is more common than amplitude vibrato in practice, while Drushler claims the opposite to be true!26 It seems to the author that pitch vibrato is more intriguing for the composer, because it is much richer and varied in sound potential.
Pitch vibrato is achieved by the clarinetist through fluctuations of jaw (or lip) pressure on the reed. There will be slight timbre differences in the sound, because the reed is being pinched, but the perception of these will be directly related to the depth of the vibrato (how wide the pitch range is above and below the primary pitch) and the speed of the vibrato (how many cycles in time).
Amplitude vibrato is produced by fluctuations in air pressure past the reed. The difference in amplitude (or loudness) of these fluctuations is severely limited.
Since most clarinetists today do not employ vibrato, it would be best for composers to notate it when desired. Rate of vibrato should be displayed ( six to eight pulsations per second is a reasonable upper limit), indicated in the following manner (Example #55).
Example #55 (click on music for mp3)
Depth (pitch) can also be indicated (as Paul Zonn does in Revolution ).
Example #56 (click on music for mp3)
Another example of vibrato depth, which is meant to expand a microtonal trill, is found in an etude by the author (Example #57). Other possibilities are below the first example.
Example #57 (click on example for mp3)
A spectrogram displays the increasing strength of pulses just above the fundamental, a strong 2 nd partial throughout, and a frequency band of increasing strength and size from the 3 rd partial higher through 20,000 hz.
Microtonal trill to vibrato (0-7 seconds)
Microtonal trill to vibrato (7-14 seconds)
Pitch vibrato is also possible to produce in a gradual progression from air only, to sound (or the opposite) (Example #60). The pulsations of air sound similar to the sound that a stylus might make when it reaches the end of a phonograph record.
Example #60 (CD4-Examples, Track 17)
for information on how to see/hear more examples of vibrato, click here