Vocal Tract Model Synthesis (Article)
Vowels are synthesized using vocal tract solid models, demonstrating functions of the vocal tract and vocal cords waves. The models were shaped based on 3D MRI and stereolithography (Rapid Prototyping), and glottal waves are generated using Rosenberg-Klatt waveform with 1/f fluctuation of its cycle. Male and female models are used to produce vowels. Voice qualities are well enough to identify the persons whom MR images were taken from. (posted 9:11 PM, February 9, 2015)

The Role of the First Formant in Training the Male Singing Voice (Article)
Awareness of the acoustic registration events caused by changing interactions between the lower harmonics of the voice source and the first formant of the vocal tract can assist both teacher and student in working out a smooth, comfortable transition through the passaggio into the upper range of the male voice. This paper explains how knowledge and anticipation of these events, and of the passive vowel modifications that accompany them, can form the basis for effective pedagogic strategies. A relatively stable tube (vocal tract) length is necessary for timbral consistency and balance across the fundamental frequency range, since this can stabilize the general location of all formants and especially the singer’s formant cluster. However, upon ascending the scale, untrained males instinctively tend to activate muscles that shorten the tube in order to preserve the strong first formant/second harmonic (F1/H2) acoustic coupling of open timbre, resulting in “yell” timbre. If tube length and shape are kept stable during pitch ascent, the yell can be avoided by allowing the second harmonic to pass through and above the first formant. This results in the timbral shift referred to as covering or “turning over,” a shift which enables avoidance of the laryngeal muscular adjustments associated with pressed phonation. The variety of first formant locations, vowel by vowel, where these shifts occur creates opportunities for developing effective strategies for training the male passaggio. (posted 5:31 PM, November 2, 2014)

More About Resonant Voice: Chasing the Formants But Staying Behind Them (Article)
To achieve a more resonant voice, a formant is not placed directly on a harmonic, but rather slightly above a harmonic. Stated conversely, the harmonic chases the formant, but never quite catches up with it. The advantage of this maneuver is a strengthening of all harmonics, not just a single one. (posted 2:34 PM, August 27, 2014)

What Makes a Voice Acoustically Strong? (Article)
A voice is acoustically strong if the glottal flow can be reduced from a high value to a low value in a short time interval. The total collapse of flow per second is called the maximum flow declination rate. It can be increased by increasing lung pressure, by increasing vibration at the bottom of the vocal fold, or by narrowing the acoustic tube immediately above the vocal folds. In practice, a combination of these control strategies is probably utilized by singers. (posted 2:34 PM, August 27, 2014)

The F0-F1 Crossover Exercise (Article)
The author has a long-term goal to understand and appreciate proven exercises and vocalizes used by singing teachers. One such exercise is the downward glide in pitch on a vowel [u] or [o], beginning on about D5 and ending one to two octaves lower. (posted 2:34 PM, August 27, 2014)

Resurrection from the Coffin (Article)
The author suggests that the Favorable Vowel Chart included in the writings of Berton Coffin over thirty years ago, needs to be resurrected, employing new theories of vowel modification and voice registers. (posted 2:34 PM, August 27, 2014)

Another Incremental Step in Reviving and Revising Coffin's Favorable Vowel Chart (Article)
In a previous issue the author proposed a new way of looking at pitch-vowel interaction in singing as promulgated by Berton Coffin. In a yearly update, Dr. Titze writes that the basic goal of understanding why certain vowels are favored at certain pitches has not changed. (posted 2:34 PM, August 27, 2014)

How Are Harmonics Produced at the Voice Source? (Article)
In summary, harmonics in the glottal waveform are produced by adducing the vocal folds sufficiently so that they can collide. This changes the waveform from a simple oscillatory shape that has only one frequency. Alternately, or in conjunction with collision, the vocal tract can be engaged to feed back an acoustic wave to the glottal flow. (posted 2:34 PM, August 27, 2014)

Source-Vocal Tract Interaction in Female Operatic Singing and Theater Belting (Article)
Contrasting operatic and musical theatre voice production, the authors seek “to explain the female opera-belt contrast in terms of source-vocal tract interaction.” The study shows that despite aesthetic differences, many of the technical approaches overlap between these otherwise markedly different genres. (posted 2:34 PM, August 27, 2014)