About Human Voice
The human voice is a remarkable, cooperative effort of expression whose variation might be thought to surpass any in the animal kingdom. This would be a wrong assumption; the amphibian class – and among them, chiefly frogs — own the distinction of a surpassing variety of voice. We would also be wrong in the assumption that humans, alone, use voice to communicate intelligent thought to one another. Thirdly, humans have managed to teach other animals a relatively small understanding of our vocabulary, even in a variety of languages, such that they show obedience to some vocal commands, but this may be due to our ability to teach more than their ability to learn. The inverse of cross-species communication has, so far, left us far less able to understand their voices.
Those limitations of language aside, for we use the voice for much more than intelligent, spoken language, the human voice is our primary origin of sound and it is almost universally applied to communicate to others. Occasionally, we will even speak to the speaker, alone or in a crowd, as if one side of the brain were communicating to the other for mere pleasure or debate. This is often considered by others as a lapse of judgment. Speaking to one’s self would seem unnecessary. Everything said is already known before it is spoken, but, regardless, everyone does it once in a while. The imperative of vocal expression is that urgent.
Table of Contents
Voice takes a variety of forms. Language, of course, heads the list. But the voice also expresses raw emotions of happiness and sadness, calm and anger, pleasure and distress, trust and fear, doubt and confidence, curiosity and wisdom. It does so in the range of variation of volume from a whisper to a shout, by speaking, crying and singing, by expressions of intelligent coherence and nonsensical sounds and by the relative speed of the string of sounds made. We are so adaptive regardless of cultural and geographic variety, much of these expressions cross language barriers. An American may not understand a Chinese speaking his language, but the former can certainly assess the latter’s expressed emotion, and that is recognized as much by vocal pattern as it is by visual signals.
It was noted first that voice is a complicated, cooperative effort. The broad stroke of that cooperation uses three human components: the lungs, vocal folds in the larynx and a collection of modifiers. The science of voice begins and ends with a simple premise: the requirement of airflow. Air must move through space and through modifying obstacles in order for voice to exist. Without it, the voice would be mute. In a vacuum, no voice is possible.
The voice begins with the lungs which supply the necessary airflow to begin the process. The air flows through the bronchial tubes to the larynx in the throat where the secondary components, the vocal folds, vibrate in response to the relative pressure of the airflow. This vibration creates the audible sound that is voiced. The airflow rises into the mouth where a series of modifiers articulate the sound until it passes through the lips.
Those modifiers, some of which are not subject to manipulation, are, in order of placement and effect, the tongue (and its relative shape, length, attachment at the floor of the oral cavity, and flexibility), the oral cavity (whose shape is bounded by the tongue and floor of the mouth, the inner cheeks, the teeth, the palate, or roof of the mouth), and the lips.
Of these modifiers, only the natural manipulation of the tongue and lips are under variable control to shape the voice. With surgical treatment, either for correction of congenital defects, by virtue of injury, or by personal choice, the other modifiers, or even those able to be controlled, can be manipulated to change or enhance the voice.
The mechanics of voice begin with the lungs, where airflow is thrust under pressure by the same general means as the respiration process. However, to manipulate voice, it is generally required that more pressure be applied than with respiration. Because the voice requires airflow, and the lungs are incapable of producing uninterrupted airflow, voice will be interrupted briefly during its production in order for air to be replenished in the lungs.
Breathing exercises allow the lungs to increase their capacity such that voluntary breathing cycles can be decreased while increasing the amount of air inhaled in each cycle. Such exercises have a variety of benefits; one of them affects voice. So far in the mechanical process, the moving air has no discernible sound other than that heard in normal breathing, or by a gentle breeze. Nor does it express any particular feeling; there is no recognizable intelligence driving it.
The vocal folds (also called vocal chords) in the larynx are the next mechanical component in the production of voice. The vocal folds are a pair of flexible membranes which open and close much like a curtain, but the orientation of the folds is more horizontal than vertical across the larynx. For normal breathing, the vocal folds remain open both for inhaling and exhaling. When vocalizing, the vocal folds both close and vibrate due to the airflow from the lungs.
The relative state of closure varies while vocalizing, but the folds are never completely closed while producing sound. Otherwise, airflow, and thus voice, would cease. The only state of full closure of the vocal folds occurs during eating so that food and liquids are not introduced into the larynx but, rather, into the esophagus. (This is mostly an involuntary action, but, sometimes, while eating, the vocal folds may not successfully close and the reaction is an instantaneous pain in the upper chest because solid objects, even liquid in volume, are not supposed to reach the bronchial tubes.)
During vocalization, the action of the vocal folds is a sudden partial closure while vibrating, thus creating chopped segments or pulses of airflow. The length of the vocal folds, which varies generally between men and women, with longer vocal folds being typical of men, and the tension applied to the folds during their activity is what varies tone and pitch in the voice. The closer together and higher the tension in the folds, the higher the pitch and tone. The opposite condition results in lower pitch and tone. Pitch is the modulation of volume and frequency; tone is the modulation of inflection, expressing emotional variation. At this point, as air passes through the vocal folds, audible sound is produced, but it is not yet modulated to express intelligible sounds such as language.
The closing and opening mechanics of the vocal folds are called, respectively, adduction (closure) and abduction (opening). For example, while breathing the vocal folds are abducted; while vocalizing, the folds are variably adducted, but always mostly closed. The ability to rapidly adduct and abduct the folds is mostly involuntary and genetic, which becomes critical when considering the discussed differences in breathing, vocalizing and eating as noted above. Another aspect of adduction/abduction is that if their relative muscular strength exceeds that of the pressure of airflow from the lungs, voice will cease. This is easily demonstrated by the act of voluntary swallowing, which adducts the vocal folds completely.
Adduction and abduction control whether a unit of speech — a single letter, diphthong or ligature – are voiced or unvoiced, meaning, respectively, that while sound is being produced, the vocal folds are vibrating, or not vibrating. All English vowels and some consonants are voiced, i.e., the folds are vibrating; other consonants are unvoiced. Voiced and unvoiced consonants often occur in pairs, such as “p” (unvoiced) and “b” (voiced). The pairing occurs when, in both cases, the modulators (oral cavity components) are in identical placement; the only difference between the two consonants is the lack of vocal fold vibration (“p”) and vibration (“b”).
The function of the modulators in the oral cavity just above the larynx and vocal folds is to resonate and articulate sound into intelligible segments of spoken word and song. Resonance is produced by the larynx above the vocal folds, the shape of the oral cavity as defined by its sides, roof and floor, the shape of the nasal cavity through the palate, and the skeletal structure of the head. Resonance can be felt in the head and chest; a lower voice will resonate deeper. Resonance does not change with intended meaning or emotion, but it will affect the apparent volume and real distance the sound carries. Articulation is shaped by the tongue, palate, teeth and lips to change sound into its variety of expressions. Articulations of sound are differentiated by the relative position of each modifier and their coordination with one another.
There is also the consideration of the emotive aspect of voice. Singing, as opposed to speaking, is generally considered a more emotive expression as opposed to the literal and logical expression of spoken voice. Even though both speaking and singing use the same mechanics, the position of the larynx must change to accommodate singing. Actually, the act of vocal crying is virtually identical to singing. In speaking, the larynx is positioned vertically in the throat. The singing and crying effort pulls the larynx deeper into the throat while simultaneously pulling the base of the larynx back toward the spine. The effect of this manipulation of the larynx stretches the length of the vocal folds and changes their orientation to a slight angle across the larynx. This effort is mostly voluntary in the respect that speaking and singing are possible for anyone who can vocalize sound. It is the quality of the singing voice which must be trained and it is the training of this manipulation of the position of the larynx which qualifies good and poor singers. The positional shift of the larynx allows the singer to create vibrato, which is the slight modulation of pitch during the singing of a single note, or frequency. This violates the idea of “perfect pitch” in that the pitch does, in fact, vary slightly due to rapid vibratory changes in the vocal folds while sustaining a note, but those changes are so slight, there is almost no change in the frequency, which defines perfect pitch. The emotional result, however, is more satisfying to the singer and more pleasurable for the listener.
Another aspect of emotive vocalization is the quality of sound produced. Untrained public speakers and singers often believe the airflow and pressure originate in the larynx, but the resulting quality of voice is weak and strained. This is why trained speakers and singers are taught that the lungs, supported by the diaphragm beneath them, are the true source of voice. The speaker/singer’s concentration of vocalizing should begin there, not strangled in the throat.
Finally, the emotive character of voice is modulated by the air flow and pressure provided by the lungs and as allowed by the vocal folds. The voice can be modulated in volume and inflection very rapidly for emotional effect. Depending on the language, they vary widely, or they may remain static. Emotion is more expressive if volume and inflection are allowed to vary. The voice can also range quickly from loud and agitated speech to quiet and calm speech. It can vary from fast, clipped speech with staccato consonants to slow, lyrical speech with drawn out vowels to convey emotional shift. Voice can convert from speech to song in a single breath, and back again to convey emotion. All of these techniques are available, limited only by imagination, to convey emotion by voice. It may be possible to achieve without ever saying or singing a single word, but just by creating modulated sound using the mechanics and variable expressions of voice.
Even if man is not as expressive in variation of voice as is the frog, he does have that extended ability to voice speech and song with emotional impact. Anything else is just a figure of speech.
Contact us for results focused speech therapy in Sydney
If you have questions about speech therapy for the voice, contact your local doctor, who will arrange for you to see a speech pathologist. Contact us today!