These kinds of workouts are officially referred to as, semi-occluded phonations. They are popular with singing techniques and with voice therapists. Their purpose are three-fold:
1). They balance the sub-glottal and supra-glottal air pressure (above and below) the vocal folds and thus help the singer to create more efficient phonation and balance with the increased velocity of air required for singing. Inherently, speech vocal mode is not efficient compared to phonations used in singing, so the semi-occluded vocal tract exercises increase the efficiency of the relationship between the singer's respiration and vocal folds.
2). Semi-occluded vocal tract exercises establish a resonant track. They help the singer to get into a seamless passage through the vocal bridges (breaks), thus preparing the voice for good bridging from the lower vocal registers to the higher registers, namely, (chest to head voice).
3). Semi-occluded phonations create cricoid tilt, which is one of the main characteristics of the most important vocal mode and physiological configuration for singing, vocal twang. Vocal twang first and foremost, insures that the vocal folds achieve excellent compression/closure and vocal twang amplifies the voice in the 2000-3800 Khz frequency range, thus making the voice more projected and louder.
To call these semi-occluded vocal tract postures warm-ups do not give them justice. They do far more than just warm up the voice and are the first part of the three part, "Foundation Building Routine" taught in the beginning to all TVS students.
THE VOCALIST STUDIO
Robert J. Lunte I 800.269.9040
www.skype.com : "rjlseagull"