What would you consider to be the main focus of your career, or your “specialty”?

The main focus of my research career so far has been to establish a cause-effect understanding of the physics of human voice production, and bridge science and art. I am interested in understanding how changes to the vocal system impact the produced voice, and when voice changes, what physiological changes might have caused this voice change. Without a cause-effect understanding, we have to rely on experience to answer these questions. Some people are more experienced than others and will be better able to help patients or train speakers. However, experience does not always provide answers, and it varies across speakers. It is also difficult to teach experience as teachers and students may not always share the same experience. A causal theory of voice production is essential if we want to move on from art to science. This is particularly important when current clinical practices or pedagogy fail to provide intended results. In this case, science may be able to provide insights as to why they do not work and alternative options.

How did you discover your calling for your specialty? How did it start?

As a PhD student I was fortunate to be involved in a research project on the aeroacoustics of human voice production. This was my point of entry into voice science. I was excited at the prospect of being able to apply my engineering training to understanding the working mechanisms of biological systems. Human voice is special in that, in addition to linguistic meaning, it also conveys important personal information about the speaker such as emotion and personality. Understanding how and why we use voice to convey such information the way we do remains an important drive for my current research.

What do you love the most about your work?

The excitation of discovery and understanding how we use our voice to convey personal information and why we use our voice the way we do.

In your opinion, what qualities do you feel make an "excellent" Vocal Pedagogue? I am not a singer teacher, but I think it is important to be able to identify the root cause of vocal issues and explain them in a language that is easy to understand to students and relates to their experiences. Knowledge of voice science would allow voice teachers to better identify the root cause, and getting to know the student better would help to find the best language to communicate such knowledge to the student.

Can you speak to the importance of having mentors? How have mentors influenced your life/career? Can you tell us about some of your mentors?

Mentors are important in that they provide a broad perspective on what have been done and what important questions still remain unanswered. In my early career I have benefited from Luc Mongeau and Ronald Scherer who introduced me to voice science. I also learned a lot from many of my wonderful colleagues at UCLA, whose support and guidance have significantly influenced my career.

Building Blocks - Questions About Seven Key Areas of Voice

The below topics cover seven key areas of voice. In regard to each topic, what are the most influential tips, insights, or research findings that you would like to share with our audience?

Breathing

The main function of the respiratory system in phonation is to provide the necessary subglottal pressure and sufficient airflow required to sustain phonation for an intended breath duration. It is important to initiate phonation with a suitable lung volume, neither too high nor too low, based on the desired voice production and in coordination with laryngeal adjustments, to avoid high respiratory effort. On the other hand, independent control of the respiratory and laryngeal system is essential to avoid natural tendency to tighten vocal fold adduction when subglottal pressure increases, as this can increase the risk of vocal fold injury.

The Larynx & The Vocal Folds

Vocal control at the larynx is three-dimensional. When we adduct the vocal folds, we not only bring the two vocal folds together (vocal fold approximation) but also change the vocal fold medial surface shape in the vertical dimension. While vocal fold approximation is important to lowering the phonation threshold pressure and initiating phonation, vocal fold medial surface shape in the vertical dimension is essential to the control of voice quality from breathy to pressed, or from head to chest register. Thus, exercises that target the thyroarytenoid muscles to strengthen isolated control of the vocal folds from thick to thin will improve singers’ versatility to produce a variety of voice qualities not only at low pitches but also high pitches or registers.

Acoustics/Resonance

When it comes to acoustics/resonance, what are the most influential tips, insights or research findings that you would like to share with our audience? The vocal tract is anatomically connected to the larynx, and vocal tract adjustments may lead to changes in laryngeal configuration (e.g., tongue movement may affect larynx height). Because of this natural covariation, articulation often modifies not only the resonance but also the voice source. Thus, when voice quality changes with varying articulation, one should keep in mind that the voice quality change may be due to the simultaneous changes in laryngeal configuration rather than articulation alone.

Vocal Registration

When it comes to registration, what are the most influential tips, insights or research findings that you would like to share with our audience? At the laryngeal level, vocal register is largely a thickness effect. Vocal fry and chest-like voices are likely produced with thicker vocal folds, whereas head- or falsetto-like voices are produced by thinner folds. Because thickness often covaries with stiffness in humans, it is not surprising that vocal fry and chest-like voices are more easily produced at low pitches, and head- or falsetto-like voices are more easily produced at high pitches. By gradually varying the vocal folds from thick to thin, one should be able to smoothly transition from a chest-like voice to a head-like voice, thus avoiding register change. This can be achieved through a balanced activation of the thyroarytenoid and cricoarytenoid muscles. When increasing pitch, engage the cricoarytenoid muscles early to avoid voice breaks before it is too late. Use resonance to complement laryngeal adjustments, particularly when the voice source is not strong at high frequencies.

Vocal Health

Maintain a balance between subglottal pressure and vocal fold stiffness. Pressure and stiffness have the largest effects on the contact pressure sustained by the vocal folds during phonation and thus risk of vocal fold injury. The contact pressure increases with increasing subglottal pressure but decreases with increasing stiffness. Thus, when increasing vocal intensity, the increase in subglottal pressure should be accompanied by a simultaneous increase in vocal fold stiffness to avoid excessively high contact pressure, particularly for high intensity vocal production. Vocal fold stiffness in the cover layer is increased by actions of the cricothyroid muscles but decreased by actions of the thyroarytenoid muscles. Thus, when increasing loudness, balance the cricothyroid and thyroarytenoid muscles, and avoid predominantly using the thyroarytenoid muscles alone.

Teaching Methods/Communicating complex ideas about singing

Getting to know the student better often helps to find the best way to communicate complex ideas to the student. Biofeedback provides a tangible target for students to aim for during training and is often helpful. The feedback may be auditory, acoustic (e.g., spectrogram), or physiological (e.g., ultrasound). Current research on solving the inverse problem of voice production (i.e., estimate the amount of lung pressure used, degree of vocal fold adduction, degree of epilaryngeal narrowing, etc., from the produced voice) may provide ambulatory feedback on the laryngeal and vocal tract configurations during phonation, which may find interesting applications in vocal pedagogy.

Final Thoughts (Words of Wisdom, Books, Resources)?

Knowledge of the physics of voice production may not directly improve a singer’s performance. However, when vocal problems occur and current clinical practices or pedagogy fail to provide intended results, such knowledge may be able to provide insights as to why they do not work and alternative options.

Please note that Dr. Zhang is not affiliated with VocalPedagogy.com and we do not give out contact information. We hope you enjoyed the interview!