For this reason, as I am deep in the middle of writing a book that deals in great part with vocal technique, I am trying painstakingly not to offer this book as a The Method but rather as one approach based as much as possible on facts that we know and in certain cases based on analytical extrapolations based on what we do know.
Since I teach CCM (Contemporary Commercial Music) singers as well as opera singers and have done so for as long as I have been teaching, I certainly recognize that there are modes of singing that hold other values more important than absolute acoustic and muscular efficiency. However differences in style and artistic aims do not decry the facts that scientists have dedicated so much of their time trying to pass on information to us that are central to our work. As much as I think that the scientists could do a lot more to help disseminate the information they gather to the voice teachers in ways that are more user-friendly, I think the community of voice teachers is even more lethargic in doing its part to meet the scientists halfway. I do not believe there is a discipline whereby so-called experts hold on to false information as much as we voice teachers do.
There are those who believe that the least the student knows about the workings of the voice the better, that way they are less likely to interfere with its workings. Some truly believe this and it is not as ridiculously condescending as it may appear at first. Singers are tinkers. They like to "mess with the instrument" in an attempt to control it. Smart teachers of all traditions understand that the workings of the voice are fairly automatic and that vocal training is more about getting the instrument in shape to do what it was designed to do without much help from us.
HOWEVER, I do not seize to experience the amazement in students' faces when they get simple information that makes sense. We do not need to give an anatomy lecture to educate the student about what they are responsible for in the process of singing and what happens automatically. Understanding how the voice basically functions make for a confident singer not a complicated one. If the student really understands the process (i.e. what is automatic and what needs their attention) they are less likely to tinker in a manipulative sense, but rather practice to find balance between their responsibilities and the automatic workings of the instrument.
Which brings me to the main topic, vibrato! I will try to be as simple as I can be with this, but I will also try to be thorough:
1. Muscular function relative to pitch occurs thus:
- The singer desires to sing a specific pitch, the brain sends the signal via the two laryngeal nerves (superior laryngeal nerve and recurrent laryngeal nerve) to contract the many muscles of the larynx to create the desired pitch (and quality, as the singer imagines). How well the singer's imagination turns into reality depends on how these muscles have been trained (consciously or unconsciously) over time.
- The nerve impulses from the brain are intermittent. They occur between 5 and 7 times every second depending on the specific person. The impulses are a reminder of the desired muscular function. In between them, the muscles relax. The vibrato is essentially a sequence of A-B-A: A) contraction of muscles to create desired pitch (and quality) B) relaxation of muscles and the pitch drops A) correction of pitch by new nerve impulse.
- It is important to note that the crico-thyroid muscle, which stretches the vocal folds to make them thinner (it works in tandem with the internal thyro-arytenoid muscle [vocalis] which resists the stretch and keeps the folds taut. The vocalis prevents uncontrolled thinning of the folds), is enervated separately by the external branch of the superior laryngeal nerve. The CT is the central pitch-making muscle.
3. Perceived vibrato vs. straight tone:
- Straight tone is part of a continuum relative to the normal vibrant nature of the voice. In other words, a voice functioning with muscular balance will be vibrant. The vibrato pattern is not heard in speech because one specific pitch is not sustained long enough for the ear to perceive the regularity of the nerve impulses. When a tone is sustained, with continuous, consistent breath pressure, the folds go into the regular pattern that bring out the regularity of the A-B-A pattern explained above. However, if the breath pressure is inconsistent, or there is a great imbalance between subglottal pressure and transglottal flow, then the regularity of the pattern might be compromised and the vibrato not perceived. This we judge to be a relatively straighter tone. The vibrato pattern is still perfectly observable in spectrum analysis, but irregularity causes the ear to perceive it as non-vibrant.
- This is an important distinction to make. A vibrato is not learned. It manifests when the voice is functioning in a consistent manner relative to breath pressure/flow. Thus when a singer achieves good vocal habits, the vibrato is simply revealed.
- When a teacher teaches a student good vocal skills and the vibrato manifests, s/he might say: "I just taught the student how to make a vibrato"! But this would be incorrect. The truth is that the teacher taught the student the coordination that reveals the vibrato pattern in a regular manner to the listener's ear.
- Vibrato in the voice confirms learned skills. So in a sense one could superficially say that a vibrato is learned. But this has the effect of separating vibrato from the skills that reveal its innate existence.
- A vibrant voice in singing reveals that the voice has achieved relative balance. From that healthy state, a skilled singer can alter the perception of vibrato to create many effects. A skilled singer can alter the vibrato at will. Classical music expects the voice to function in its natural vibrant, balanced state. Perceived straight tone in the classical tradition is an effect used for special circumstances. In non-classical traditions, the voice is expected to be in a vibrato-less state that imitates the less regular patterns of every day speech. Vibrato is then perceived as an added effect instead of the fact that perceived vibrato is the hallmark of a balanced voice in singing.
- It is important to distinguish the importance of reducing the natural vibrato of the voice in acoustic circumstances whereby the natural vibrato would cause musical problems. The motets of Giovanni Gabrieli, for instance, were written for the Basilica di San Marco di Venezia. The echo effect of singing in cathedral of any size makes the voice's natural vibrato excessively problematic.
- Choruses that included children's voices (boy's voices for the most part), as was the case in the renaissance and in the Catholic Baroque (including the Anglican tradition) would require modifications relative to their voices. Children are perfectly capable of accomplishing a perceived vibrato, however it is more rare because the respiratory training that maintains consistent breath pressure at will is not normally developed in young children. The adult voices of such choirs would have to make concessions both in terms of power and the perception of the vibrato if the chorus is to have a homogenized sound.
- The operas of the baroque period and the works of Bach would have no such restrictions. The adult voices (Bach's choir , especially the castrati would have developed such amazing breath control as to make vibrato a normality, not an anomaly. It is important to note that because a straight tone requires an inferior coordination relative to efficiency, music that requires great virtuosity such as the fioratura passages and long lines required in such works as the solo madrigals of Monteverdi and the solo works of Bach, Vivaldi and Handel, would necessitate the kind of efficiency of a vibrant voice. A voice producing a perceivable straight tone also alters the resonance of the voice causing it to be less powerful relative to balance with an orchestra, even of modest size. Modern performance practice, having establish a preference for straight-tone globally for Early Music, would seek solutions for orchestra balance that would make the natural inferiority of straight-tone singing viable. It is also important to note that an inspired musician singing early music in straight-tone can be extremely convincing. That also does not decry the natural inefficiency of perceived straight-tone singing. It is important to add here that conductors might decide in a Draconian manner to eliminate vibrato when poorly train singers exhibit bleats and wobbles (next post).
- We cannot currently go back in time to verify what the practices might have been. But it is unlikely from a scientific point of view that any music requiring extreme virtuosity would logically inspire straight-tone singing.
- It is also important to realize that the voice is the only instrument that produces an inherent, "natural" vibrato. Other instruments produce an induced, or forced vibrato, mostly attempting to imitate the nature of the voice. It is conceivable that some composers dealing with children's voices and the vibrato-less nature of instruments might require their adult singers to suppress the natural vibrancy of the voice. All of that is speculation and subject to musical tastes. Researchers with a preference for straight-tone can make a good argument why one should approach certain works with a perception of straight-tone. A good case can also be made for vibrato as being functionally necessary for extremely virtuosic vocal music. The main point however is that vibrato is an inherent part of the human voice that is revealed (not imposed) through balancing the instrument toward its most efficient state for acoustic singing without artificial amplification.