The Science and Practice of Speaking and Being Heard - February 19, 2016
Danielle, a professional voice coach who deals frequently with the challenges of public speaking, delivered a talk on human acoustics. First we heard some of the history of acoustics, beginning with the architectural techniques the Greeks used to make their actors and orators heard in crowded amphitheatres. Then we moved on to the acoustics of the body itself. Through the body, it’s possible to apply some of the tricks the Greeks used to make their actors boom, and unpack an amphitheatre wherever you might need one.
The ancient Greeks were pioneers in the projection of voice. The amphitheatres constructed between the seventh and fourth centuries BC saw steady adjustments and improvements to every aspect of their design. The amphitheatre of Epidaurus, finished near the end of this period, still stands today and is well-known for its ability to carry sound to its 55th and final row. It seats up to fifteen thousand people—no modest achievement for the pre-microphone age. Usually, modern professional speakers can minister to an audience of up to about fifty or sixty before needing some kind of performance-enhancing technology.
The builders of the amphitheatre had help from the limestone they were using. This rock has the property of absorbing the low frequencies of audience and background noise—below around 500 Hz—while reflecting the higher frequencies of the performers’ voices. On a packed night, the bodies of the spectators themselves would have provided a further dampening effect. At the same time, the circular construction plan and careful positioning of steps and surfaces ensured that sound was channeled to spectators at like volumes regardless of where they were seated.
The acoustic needs of oratory are different from those of music: reverberation can help amplify and extend the effect of musical notes, but in speech this reinforcement can hinder the recognition of ensuing syllables. To accommodate this the Greeks had two types of theatre: amphitheatre and odeon. The odeon had a roof to contain the vibrations of music, while the amphitheatre was open to the sky and behind the stage.
One of the less understood aspects of Greek performance was their equivalent to the modern microphone. Performers in theatre always wore masks, not only to take a new identity but also because the masks themselves were powerful projection devices. Sadly, only replicas remain. But study of the masks suggests that they powerfully amplified sound by creating a space of air between the head and the mask that resonated sympathetically with the actor’s voice, before the vibrations were projected out of the mouth opening in the front. The techniques perfected by the Greek dramatists may have amplified the actor’s natural projection to earsplitting volumes.
Even with all of these aids, there is no doubt that Greek actors had to be incredibly skilled at being heard. With the modern over-reliance on microphones, acoustics has been neglected in everyday contexts. Speakers today can expect to be called to work their craft in all sorts of buildings, very few of which are likely to be of any help in getting their message across. Danielle’s work as a voice coach gives her an insightful perspective on this problem.
Part of the impetus for this talk came from a nagging problem with our meeting arrangements. After the main talk in a Vancouver Public Library meeting room, the Friends in Wonderment retire to a nearby pub to continue their discussions. Unfortunately, the noise of the typical Vancouver pub combined with the clamour of fifteen to twenty Friends can make it very difficult to hear. Maddeningly, the difficulty of being heard tends to make people raise their voices, which increases the general noise level and intensifies the problem.
There is a simple solution to this. It’s a fairly consistent rule in English speech that the consonants carry the meaning while vowels carry volume (and hence pitch, which can carry emotional valence—or in some other languages, additional meaning). By over-articulating their consonants, a speaker can get across more meaning without being louder. Since their speech contributes to the general noise level, this practice benefits everyone else as well.
For example, the Canadian accent has a tendency to drop the ts and ds at the end of a words, as in thought, thawed, bought, bawd, etc. Paying a little extra attention to that final consonant can make a big difference in comprehensibility. As Danielle emphasizes, “speak up” doesn’t have to mean “speak louder.”
But part of the reason we don’t want to speak louder is that we find it wears on the throat. We take it for granted that we can’t amplify our voices without making ourselves hoarse after an hour or two. This hoarseness is not inevitable, however. It comes from putting excessive strain on the throat instead of amplifying the voice in the natural way: by increasing the flow of breath.
The terms for the voice-producing part of the larynx create some confusion as to how they actually work. “Vocal cords” is particularly wrong: it brings to mind the vibrating strings of a guitar or piano. “Vocal folds” is certainly closer and is the more accepted term, but it has to be emphasized that the two folds work together like a valve, holding back air before releasing it once the pressure passes a threshold. (I almost prefer “vocal flaps.”) It’s this cycle, which the lips can imitate by going pphhhhhbbbbbbtttt, that shapes the flow of air coming through the trachea into sound waves.
The arytenoid cartilage controls the tension in the vocal folds. When they’re entirely released, you’re simply breathing. The tenser they get, the more pressure is required to break the seal and the higher the amplitude of the resulting sound waves. When this tension gets too high, however, it puts a strain on the folds. In the short term, this strain can cause inflammation that prevents the folds from working properly. In the long term, it can cause parts of the folds to cease vibrating, producing vocal nodes that substantially alter and weaken the speaker’s voice.
The volume can also be increased by increasing the pressure of air through the larynx. The process to increase this throughput requires engaging the whole body, but it’s ultimately all about breath capacity. When the sufficient amount of air is drawn in on the in-breath, the out-breath will produce the desired volume without any extra strain on the throat. In order to do this, however, most people will have to correct their posture to increase the capacity of their chest cavity. Poor posture pinches the abdomen, preventing the lungs from expanding fully and preventing the diaphragm from extending as far down as it could. Both of these things limit the amount of air that can be taken in in the first place; most of the problems with being heard are the result of this.
Another important aspect of the voice is resonance. When the air is set to vibrating by the vocal folds, these vibrations produce sympathetic vibrations throughout the body, especially in the mouth, face, and sinuses, that modulate the sound before it is finally released.
There’s surprisingly little variation in the lengths of human vocal tracts: they tend to range from 150 to 200 centimetres. Resonance accounts for most of the differences in human voices—the speaker’s habitual muscle positioning, the shape of the roof of the mouth, the arrangement and proportions of other resonance chambers, etc.
Direct resonance is the name given to things that vibrate because they are connected to a vibrating thing. For example, the vibration of the vocal folds causes a direct vibration in the cartilage that emanates through connected tissues. Indirect resonance is resonance produced by vibrations that have traveled through a medium such as air. As the vocal folds produce sound, both types of vibration are produced throughout the body. Primary resonators, the ones in the larynx and higher, produce the main layer of sound; secondary resonators, lower down in the body, enrich the sound.
Sound can be redirected by the shaping of muscles like the soft palate (the part of the roof of the mouth that moves when you swallow or yawn), the mouth, the tongue, and the larynx. One final way to be heard at a greater distance is by speaking through the cheekbones: it produces a more directed sound with a higher overall frequency that is easier to pick out over background noise.
For those interested in learning more about how they might use their voices to greater effect, Danielle offers a free monthly seminar at the Alliance for Arts and Culture. Through her company, Inspired Coaching, Danielle offers in-depth workshops on breath capacity and other aspects of an empowered voice, as well as private coaching and free one-on-one consultations.