Vocal resonance may be defined as "the process by which the basic product of phonation is enhanced in timbre and/or intensity by the air-filled cavities through which it passes on its way to the outside air."[1] Throughout the vocal literature, various terms related to resonation are used, including: amplification, filtering, enrichment, enlargement, improvement, intensification, and prolongation. Acoustic authorities would question many of these terms from a strictly scientific perspective. However, the main point to be drawn from these terms by a singer or speaker is that the result of resonation is to make a better sound, or at least suitable to a certain esthetical and practical domain.
The voice, like all acoustic instruments such as the guitar, trumpet, piano, or violin, has its own special chambers for resonating the tone. Once the tone is produced by the vibrating vocal cords, it vibrates in and through the open resonating ducts and chambers. Since the vocal tract is often associated with different regions of the body, different resonance chambers might be referred to as: chest, mouth, nose/"mask", or head[clarification needed].
In a more symbolic/perceptual way, rather than physical, the various terms applied can represent vocal "colors" in a continuous scale: from dark (chest) resonance to bright (head-nasal) resonance. We may call this spectrum a resonance track. In the lower range, the chest/dark color predominates; in the middle range, the mouth-nasal resonance is dominant; and in the higher range, the head-nasal resonance (bright color) predominates. The objective of using such images by several teachers and coaches is to achieve command of all the "colors of the spectrum". That, ultimately, may allow a greater scope of emotional expression. The emotional content of the lyric or phrase suggests the color and volume of the tone and is the personal choice of the artist.
Head resonance should not be confused with head register or falsetto. It is used primarily for softer singing in either register throughout the range. [clarification needed]
Mouth resonance is used for a conversational vocal color in singing and, in combination with nasal resonance, it creates forward placement or mask resonance.
Chest resonance adds richer, darker, and deeper tone coloring for a sense of power, warmth, and sensuality. It creates a feeling of depth and drama in the voice.
Nasal (mask resonance) is present at all times in a well-produced tone[citation needed], except perhaps in pure head tone or at very soft volume. Nasal resonance is bright and edgy and is used in combination with mouth resonance to create forward placement (mask resonance). In an overall sense, it adds overtones that give clarity and projection to the voice.
There are some singers who are recognized by their pronounced nasal quality; whereas others are noted for their deep, dark, and chesty sound; and still others are noted for their breathy or heady sound; and so on. In part, such individuality depends on the structure of the singer's vocal instrument, that is, the inherent shape and size of the vocal cords and of the vocal tract.
The quality or color of a voice also depends on the singer's ability to develop and use various resonances by controlling the shape and size of the chambers through which the sound flows. It has been demonstrated electrographically in the form of "voice-prints" that, like fingerprints, no two voices are exactly alike.[2]
Sympathetic and forced vibration
In a technical sense, resonance is a relationship that exists between two bodies vibrating at the same frequency or a multiple thereof. In other words, the vibrations emanating from one body cause the other body to start vibrating in tune with it. A resonator may be defined as a secondary vibrator which is set into motion by the main vibrator and which adds its own characteristics to the generated sound waves.[3]
There are two kinds of resonance: sympathetic resonance (or free resonance) and forced resonance (or conductive resonance)[4] The essential difference between both types is what causes the resonator to start vibrating. In sympathetic resonance, there is no need of a direct physical contact between the two bodies. The resonator starts functioning because it receives vibrations through the air and responds to them sympathetically, as long as the resonator's natural frequencies of vibration coincide with the exciting oscillations. In forced resonance, the resonator starts vibrating because it is in physical contact with a vibrating body, which "forces" the resonator to replicate its oscillations.[5]
Both types of resonance are at work in the human voice during speaking and singing. Much of the vibration felt by singers while singing is a result of forced resonance. The waves originated by the airflow modulated by the vibrating vocal folds travel along the bones, cartilages, and muscles of the neck, head, and upper chest, causing them to vibrate by forced resonance. There is little evidence that these vibrations, sensed by tactile nerves, make any significant contribution to the external sound.[6]
These same forced vibrations, however, may serve as sensation guides for the singer, regardless of their effect on the external sound. These sensations may provide evidence to the singer that their vocal folds are forming strong primary vibrations which are being carried from them to the head and chest. Thus these vibratory sensations can supply sensory feedback about the efficiency of the whole phonatory process to the singer.
In contrast, the sound a person hears from a singer is a product of sympathetic resonance. Air vibrations generated at the level of the vocal folds in the larynx propagate through the vocal tract (e.g., the ducts and cavities of the airways). In other words, the voice's resultant glottal wave is filtered by the vocal tract: a phenomenon of sympathetic resonance.[7] The vocal resonator is not a sounding board comparable with stringed instruments. Rather, it's a column of air traveling through the vocal tract, with a shape that is not only complex, but highly variable. Vennard says:
Thus it may vibrate as a whole or in any of its parts. It should not be too hard to think of it as vibrating several ways at once. Indeed most vibrators do this, otherwise we would not have timbre, which consists of several frequencies of different intensities sounding together. Air is fully as capable of this as any other medium; indeed, the sounds of many diverse instruments are carried to the ear by the same air, are funnelled into the same tiny channel, and can still be heard as one sound or as sounds from the individual sources, depending upon the manner in which we give attention.[5]
Factors affecting resonators
There are a number of factors which determine the resonance characteristics of a resonator. Included among them are the following: size, shape, type of opening, composition and thickness of the walls, surface, and combined resonators. The quality of a sound can be appreciably changed by rather small variations in these conditioning factors.[6]
In general, the larger a resonator is, the lower the frequency it will respond to; the greater the volume of air, the lower its pitch. But the pitch also will be affected by the shape of resonator and by the size of opening and amount of lip or neck the resonator has.[3]
A conical shaped resonator, such as a megaphone, tends to amplify all pitches indiscriminately. A cylindrical shaped resonator is affected primarily by the length of the tube through which the sound wave travels. A spherical resonator will be affected by the amount of opening it has and by whether or not that opening has a lip.[6]
Three factors relating to the walls of a resonator will affect how it functions: the material it is made of, the thickness of its walls, and the type of surface it has. The resonance characteristics of a musical instrument obviously will vary with different materials and the amount of material used will have some effect.[3]
Of special importance to singing is the relationship of the surface of a resonator to its tonal characteristics. Resonators can be highly selective, meaning that they will respond to only one frequency (or multiples of it), or they can be universal, meaning that they can respond to a broad range of frequencies. In general, the harder the surface of the resonator, the more selective it will be, and the softer the surface, the more universal it will become. "[A] hard resonator will respond only when the vibrator contains an overtone that is exactly in tune with the resonator, while a soft resonator permits a wide range of fundamentals to pass through un-dampened but adds its own frequency as on overtone, harmonic or inharmonic as the case may be."[5]
Hardness carried to the extreme will result in a penetrating tone with a few very strong high partials. Softness carried to the extreme will result in a mushy, non-directional tone of little character. Between these two extremes lies a whole gamut of tonal possibilities.[3]
The final factor to be mentioned is the effect of joining two or more resonators together. In general, the effect of joining two or more resonators is that the resonant frequency of each is lowered in different proportions according to their capacities, their orifices, and so forth. The rules governing combined resonators apply to the human voice: for the throat, mouth and sometimes the nose all function in this manner.[3]
The vocal resonators in detail
Chest anatomy
There are seven areas that may be listed as possible vocal resonators. In sequence from the lowest within the body to the highest, these areas are the chest, the tracheal tree, the larynx itself, the pharynx, the oral cavity, the nasal cavity, and the sinuses.[6]
The chest
The chest is not an effective resonator, despite numerous voice books and teachers referring to “chest resonance”. Although strong vibratory sensations may be experienced in the upper chest, it can make no significant contribution to the resonance system of the voice, simply by virtue of its structure and location. The chest is mostly connected to the upstream structures of the airways, such as the lungs and trachea (e.g., under the vocal folds). There, it has a high degree of vibrational absorption, with little or no acoustical function to reflect sound waves back toward the larynx.[3]
The tracheal tree
throat diagram
The tracheal tree makes no significant contribution to the resonance system, except for a negative effect around its resonant frequency. The trachea and the bronchial tubes combine to form an inverted Y-shaped structure known as the tracheal tree. It lies just below the larynx, and, unlike the interior of the lungs, has a definite tubular shape and comparatively hard surfaces. The response of the tracheal tree is the same for all pitches except for its own resonant frequency. When this resonant frequency is reached, the response of the subglottic tube is to act as an acoustical impedance or interference which tends to upset the phonatory function of the larynx. Research has placed the resonant frequency of the subglottal system or tracheal tree around the E-flat above "middle C" for both men and women, varying somewhat with the size of the individual.[8]
The larynx
Due to its small size, the larynx acts as a resonator only for high frequencies. Research indicates that one of the desirable attributes of good vocal tone is a prominent overtone lying between 2800 and 3200 hertz, with male voices nearer the lower limit and female voices nearer the upper. This attribute is identified as brilliance, or more frequently as ring or the singer's formant, as fully described by Sundberg.[9] There are several areas in or adjacent to the larynx which might resonate such a high pitch. Among them are the collar of the larynx, the ventricles of Morgagni, the vallecula, and the pyriform sinuses. The larynx is not under conscious control, but whatever produces "ring" can be encouraged indirectly by awareness on the part of the student and the teacher of the sounds which contain it.
The pharynx
The pharynx is the most important resonator by virtue of its position, size, and degree of adjustability. It is the first cavity of any size through which the product of the laryngeal vibrator passes; the other supraglottal cavities have to accept whatever the pharynx passes on to them. Greene states:
"The supraglottic resonators being in the main muscular and moveable structures must be voluntarily controlled to produce conditions of optimal resonance either by varying degrees of tension in their walls, or by alterations in the size of their orifices and cavities during the articulatory movements."[citation needed]
The oral cavity
The oral cavity is the second most effective resonator.[5][7] The shape and placement of the tongue drastically changes the shape of this resonator. The size of the resonator is also decided by the jaw's degree of opening or closing of the mouth. Finally, the lips shape a final filter on the sound, completing the final step of the "oral resonance."
The nasal cavity
The nasal cavity is the third most effective resonator.[5][7]
The sinuses
In spite of being traditionally referred to as resonators by many singers and teachers, the sinuses consist of small closed air pockets, not acoustically connected to the vocal tract, and with no proven role in voice resonance.[5][7] One could argue that head surface and deeper nerves close to the sinuses may detect passive vibrations entailed by the voice generated and transmitted across the vocal tract. These sensations might support the preservation of the image of the sinuses as effective resonators.
Related Research Articles
In speech science and phonetics, a formant is the broad spectral maximum that results from an acoustic resonance of the human vocal tract. In acoustics, a formant is usually defined as a broad peak, or local maximum, in the spectrum. For harmonic sounds, with this definition, the formant frequency is sometimes taken as that of the harmonic that is most augmented by a resonance. The difference between these two definitions resides in whether "formants" characterise the production mechanisms of a sound or the produced sound itself. In practice, the frequency of a spectral peak differs slightly from the associated resonance frequency, except when, by luck, harmonics are aligned with the resonance frequency, or when the sound source is mostly non-harmonic, as in whispering and vocal fry.
The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the definition used among those who study laryngeal anatomy and physiology and speech production in general. Phoneticians in other subfields, such as linguistic phonetics, call this process voicing, and use the term phonation to refer to any oscillatory state of any part of the larynx that modifies the airstream, of which voicing is just one example. Voiceless and supra-glottal phonations are included under this definition.
The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound production in which the vocal folds are the primary sound source.
An overtone is any resonant frequency above the fundamental frequency of a sound. In other words, overtones are all pitches higher than the lowest pitch within an individual sound; the fundamental is the lowest pitch. While the fundamental is usually heard most prominently, overtones are actually present in any pitch except a true sine wave. The relative volume or amplitude of various overtone partials is one of the key identifying features of timbre, or the individual characteristic of a sound.
Resonance is the phenomenon, pertaining to oscillatory dynamical systems, wherein amplitude rises are caused by an external force with time-varying amplitude with the same frequency of variation as the natural frequency of the system. The amplitude rises that occur are a result of the fact that applied external forces at the natural frequency entail a net increase in mechanical energy of the system.
The field of articulatory phonetics is a subfield of phonetics that studies articulation and ways that humans produce speech. Articulatory phoneticians explain how humans produce speech sounds via the interaction of different physiological structures. Generally, articulatory phonetics is concerned with the transformation of aerodynamic energy into acoustic energy. Aerodynamic energy refers to the airflow through the vocal tract. Its potential form is air pressure; its kinetic form is the actual dynamic airflow. Acoustic energy is variation in the air pressure that can be represented as sound waves, which are then perceived by the human auditory system as sound.
Singing is the act of creating musical sounds with the voice. A person whose profession is singing is called a singer, artist or vocalist. Singers perform music that can be sung with or without accompaniment by musical instruments. Singing is often done in an ensemble of musicians, such as a choir. Singers may perform as soloists or accompanied by anything from a single instrument up to a symphony orchestra or big band. Different singing styles include art music such as opera and Chinese opera, Indian music, Greek music, Japanese music, and religious music styles such as gospel, traditional music styles, world music, jazz, blues, ghazal, and popular music styles such as pop, rock, and electronic dance music.
Head voice is a term used within vocal music. The use of this term varies widely within vocal pedagogical circles and there is currently no one consistent opinion among vocal music professionals in regard to this term. Head voice can be used in relation to the following:
A resonator is a device or system that exhibits resonance or resonant behavior. That is, it naturally oscillates with greater amplitude at some frequencies, called resonant frequencies, than at other frequencies. The oscillations in a resonator can be either electromagnetic or mechanical. Resonators are used to either generate waves of specific frequencies or to select specific frequencies from a signal. Musical instruments use acoustic resonators that produce sound waves of specific tones. Another example is quartz crystals used in electronic devices such as radio transmitters and quartz watches to produce oscillations of very precise frequency.
The syrinx is the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal folds of mammals. The sound is produced by vibrations of some or all of the membrana tympaniformis and the pessulus, caused by air flowing through the syrinx. This sets up a self-oscillating system that modulates the airflow creating the sound. The muscles modulate the sound shape by changing the tension of the membranes and the bronchial openings. The syrinx enables some species of birds to mimic human speech.
Helmholtz resonance, also known as wind throb, refers to the phenomenon of air resonance in a cavity, an effect named after the German physicist Hermann von Helmholtz. This type of resonance occurs when air is forced in and out of a cavity, causing the air inside to vibrate at a specific natural frequency. The principle is widely observable in everyday life, notably when blowing across the top of a bottle, resulting in a resonant tone.
Acoustic resonance is a phenomenon in which an acoustic system amplifies sound waves whose frequency matches one of its own natural frequencies of vibration.
Twang is an onomatopoeia originally used to describe the sound of a vibrating bow string after the arrow is released. By extension, it applies to the similar vibration produced when the string of a musical instrument is plucked, and similar sounds. The term came to be applied to a nasal vocal resonation, and was historically used to describe "a disagreeable resonance". Later, however, the term came to be more broadly associated with regional dialects, to the extent that in some locations, "a twang is a desirable commodity".
Kenneth Noble Stevens was the Clarence J. LeBel Professor of Electrical Engineering and Computer Science, and professor of health sciences and technology at the research laboratory of electronics at MIT. Stevens was head of the speech communication group in MIT's research laboratory of electronics (RLE), and was one of the world's leading scientists in acoustic phonetics.
An acoustic guitar is a musical instrument in the string family. When a string is plucked, its vibration is transmitted from the bridge, resonating throughout the top of the guitar. It is also transmitted to the side and back of the instrument, resonating through the air in the body, and producing sound from the sound hole. While the original, general term for this stringed instrument is guitar, the retronym 'acoustic guitar' – often used incorrectly to indicate the steel stringed model – distinguishes it from an electric guitar, which relies on electronic amplification. Typically, a guitar's body is a sound box, of which the top side serves as a sound board that enhances the vibration sounds of the strings. In standard tuning the guitar's six strings are tuned (low to high) E2 A2 D3 G3 B3 E4.
Chest voice is a term used within vocal music. The use of this term varies widely within vocal pedagogical circles and there is currently no one consistent opinion among vocal music professionals in regard to this term. Chest voice can be used in relation to the following:
Bass traps are acoustic energy absorbers which are designed to damp low-frequency sound energy with the goal of attaining a flatter low-frequency (LF) room response by reducing LF resonances in rooms. They are commonly used in recording studios, mastering rooms, home theatres and other rooms built to provide a critical listening environment. Like all acoustically absorptive devices, they function by turning sound energy into heat through friction.
Vocal pedagogy is the study of the art and science of voice instruction. It is used in the teaching of singing and assists in defining what singing is, how singing works, and how proper singing technique is accomplished.
Speech science refers to the study of production, transmission and perception of speech. Speech science involves anatomy, in particular the anatomy of the oro-facial region and neuroanatomy, physiology, and acoustics.
Oral skills are speech enhancers that are used to produce clear sentences that are intelligible to an audience. Oral skills are used to enhance the clarity of speech for effective communication. Communication is the transmission of messages and the correct interpretation of information between people. The production speech is insisted by the respiration of air from the lungs that initiates the vibrations in the vocal cords. The cartilages in the larynx adjust the shape, position and tension of the vocal cords. Speech enhancers are used to improve the clarity and pronunciation of speech for correct interpretation of speech. The articulation of voice enhances the resonance of speech and enables people to speak intelligibly. Speaking at a moderate pace and using clear pronunciation improves the phonation of sounds. The term "phonation" means the process to produce intelligible sounds for the correct interpretation of speech. Speaking in a moderate tone enables the audience to process the information word for word.
References
↑ McKinney, James (1994) The Diagnosis and Correction of Vocal Faults, Nashville, TN: Genovex Music Group.
1 2 3 4 Greene, Margaret Cicely Langton; Lesley Mathieson (2001). The Voice and its Disorders (6thed.). London; Philadelphia: Whurr; John Wiley & Sons. ISBN978-1-86156-196-1.
1 2 3 4 Sundberg, Johan(1989). The Science of the Singing Voice, Northern Illinois University Press, ISBN0875805426
↑ Van den Berg, J.W. (December 1963). "Vocal Ligaments versus Registers". The NATS Bulletin. 19: 18.
↑ Sundberg, Johan(1974). Articulatory interpretation of the "singing formant". J Acoust Soc Am. 1974 Apr;55(4):838–844.
Further reading
Large, John (February–March 1972). "Towards an Integrated Physiologic-Acoustic Theory of Vocal Registers". The NATS Bulletin. 28: 30–35.
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