Singing

Singing is the act of producing musical sounds with the voice, and augments regular speech by the use of both tonality and rhythm. A person who sings is called a singer or vocalist. Singers perform music known as songs that can either be sung a cappella (without accompaniment) or accompanied by musicians and instruments ranging from a single instrumentalist to a full symphony orchestra or big band. Singing is often done in a group of other musicians, such as in a choir of singers with different voice ranges, or in an ensemble with instrumentalists, such as a rock group or baroque ensemble. Nearly anyone who can speak can sing, since in many respects singing is a form of sustained speech. Singing can be informal and done for pleasure; for example, singing in the shower or karaoke; or it can be very formal, as in the case of singing during a religious ritual such as a Mass or professional singing typically done on stage or in a recording studio. Singing at a high amateur or professional level usually requires time, dedication, instruction, and regular practice. Professional singers usually build their careers around one specific musical genre, such as classical or rock, and they typically take voice training provided by a voice teacher or vocal coach throughout their career.

In its physical aspect, singing has a well-defined technique that depends on the use of the lungs, which act as an air supply, or bellows; on the larynx, which acts as a reed or vibrator; on the chest and head cavities, which have the function of an amplifier, as the tube in a wind instrument; and on the tongue, which together with the palate, teeth, and lips articulate and impose consonants and vowels on the amplified sound. Though these four mechanisms function independently, they are nevertheless coordinated in the establishment of a vocal technique and are made to interact upon one another. During passive breathing, air is inhaled with the diaphragm while exhalation occurs without any effort. Exhalation may be aided by the abdominal, internal intercostals and lower pelvic muscles. Inhalation is aided by use of external intercostals, scalenes and sternocleidomastoid muscles. The pitch is altered with the vocal cords. With the lips closed, this is called humming.
The sound of each individual's singing voice is entirely unique not only because of the actual shape and size of an individual's vocal cords but also due to the size and shape of the rest of that person's body. Humans have vocal folds which can loosen, tighten, or change their thickness, and over which breath can be transferred at varying pressures. The shape of the chest and neck, the position of the tongue, and the tightness of otherwise unrelated muscles can be altered. Any one of these actions results in a change in pitch, volume, timbre, or tone of the sound produced. Sound also resonates within different parts of the body, and an individual's size and bone structure can affect the sound produced by an individual.

Singers can also learn to project sound in certain ways so that it resonates better within their vocal tract. This is known as vocal resonation. Another major influence on vocal sound and production is the function of the larynx which people can manipulate in different ways to produce different sounds. These different kinds of laryngeal function are described as different kinds of vocal registers. The primary method for singers to accomplish this is through the use of the Singer's Formant; which has been shown to match particularly well to the most sensitive part of the ear's frequency range.

Vocal registration refers to the system of vocal registers within the human voice. A register in the human voice is a particular series of tones, produced in the same vibratory pattern of the vocal folds, and possessing the same quality. Registers originate in laryngeal function. They occur because the vocal folds are capable of producing several different vibratory patterns. Each of these vibratory patterns appears within a particular range of pitches and produces certain characteristic sounds. The term "register" can be somewhat confusing as it encompasses several aspects of the human voice. The term register can be used to refer to any of the following：
- A particular part of the vocal range such as the upper, middle, or lower registers.
- A resonance area such as chest voice or head voice.
- A phonatory process (phonation is the process of producing vocal sound by the vibration of the vocal folds that is in turn modified by the resonance of the vocal tract)
- A certain voca timbrelor vocal "colour" A region of the voice which is defined or delimited by vocal breaks.

In linguistics, a register language is a language which combines tone and vowel phonation into a single phonological system. Within speech pathology the term vocal register has three constituent elements: a certain vibratory pattern of the vocal folds, a certain series of pitches, and a certain type of sound. Speech pathologists identify four vocal registers based on the physiology of laryngeal function: the vocal fry register, the modal register, the falsetto register, and the whistle register. This view is also adopted by many vocal pedagogists.
Vocal resonation is 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. Various terms related to the resonation process include amplification, enrichment, enlargement, improvement, intensification, and prolongation, although in strictly scientific usage acoustic authorities would question most of them. The main point to be drawn from these terms by a singer or speaker is that the end result of resonation is, or should be, to make a better sound. 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.
Chest voice and head voice are terms used within vocal music. The use of these terms varies widely within vocal pedagogical circles and there is currently no one consistent opinion among vocal music professionals in regards to these terms. Chest voice can be used in relation to a particular part of the vocal range or type of vocal register; a vocal resonance area; or a specific vocal timbre. Head voice can be used in relation to a particular part of the vocal range or type of vocal register or a vocal resonance area

History and development
The first recorded mention of the terms chest voice and head voice was around the 13th century, when it was distinguished from the "throat voice" (pectoris, guttoris, capitis — at this time it is likely that head voice referred to the falsetto register) by the writers Johannes de Garlandia and Jerome of Moravia. The terms were later adopted within bel canto, the Italian opera singing method, where chest voice was identified as the lowest and head voice the highest of three vocal registers: the chest, passagio and head registers. This approach is still taught by some vocal pedagogists today. Another current popular approach that is based on the bel canto model is to divide both men and women's voices into three registers. Men's voices are divided into "chest register", "head register", and "falsetto register" and woman's voices into "chest register", "middle register", and "head register". Such pedagogists teach that the head register is a vocal technique used in singing to describe the resonance felt in the singer's head.

However as knowledge of human physiology has increased over the past two hundred years, so has the understanding of the physical process of singing and vocal production. As a result, many vocal pedagogists, such as Ralph Appelman at Indiana University and William Vennard at the University of Southern California, have redefined or even abandoned the use of the terms chest voice and head voice. In particular, the use of the terms chest register and head register have become controversial since vocal registration is more commonly seen today as a product of laryngeal function that is unrelated to the physiology of the chest, lungs, and head. For this reason, many vocal pedagogists argue that it is meaningless to speak of registers being produced in the chest or head. They argue that the vibratory sensations which are felt in these areas are resonance phenomena and should be described in terms related to vocal resonance, not to registers. These vocal pedagogists prefer the terms chest voice and head voice over the term register. This view believes that the problems which people identify as register problems are really problems of resonance adjustment. This view is also in alignment with the views of other academic fields that study vocal registration including: speech pathology, phonetics, and linguistics. Although both methods are still in use, current vocal pedagogical practice tends to adopt the newer more scientific view. Also, some vocal pedagogists take ideas from both viewpoints.
The contemporary use of the term chest voice often refers to a specific kind of vocal coloration or vocal timbre. In classical singing, its use is limited entirely to the lower part of the modal register or normal voice. Within other forms of singing, chest voice is often applied throughout the modal register. Chest timbre can add a wonderful array of sounds to a singer's vocal interpretive palette. However, the use of overly strong chest voice in the higher registers in an attempt to hit higher notes in the chest can lead to forcing. Forcing can lead consequently to vocal deterioration

Classifying singing voices
In European classical music and opera, voices are treated like musical instruments. Composers who write vocal music must have an understanding of the skills, talents, and vocal properties of singers. Voice classification is the process by which human singing voices are evaluated and are thereby designated into voice types. These qualities include but are not limited to: vocal range, vocal weight, vocal tessitura, vocal timbre, and vocal transition points such as breaks and lifts within the voice. Other considerations are physical characteristics, speech level, scientific testing, and vocal registration. The science behind voice classification developed within European classical music has been slow in adapting to more modern forms of singing. Voice classification is often used within opera to associate possible roles with potential voices. There are currently several different systems in use within classical music including: the German Fach system and the choral music system among many others. No system is universally applied or accepted.

However, most classical music systems acknowledge seven different major voice categories. Women are typically divided into three groups: soprano, mezzo-soprano, and contralto. Men are usually divided into four groups: countertenor, tenor, baritone, and bass. When considering voices of pre-pubescent children an eighth term, treble, can be applied. Within each of these major categories there are several sub-categories that identify specific vocal qualities like coloratura facility and vocal weight to differentiate between voices.

It should be noted that within choral music, singers' voices are divided solely on the basis of vocal range. Choral music most commonly divides vocal parts into high and low voices within each sex (SATB, or soprano, alto, tenor, and bass). As a result, the typical choral situation affords many opportunities for misclassification to occur. Since most people have medium voices, they must be assigned to a part that is either too high or too low for them; the mezzo-soprano must sing soprano or alto and the baritone must sing tenor or bass. Either option can present problems for the singer, but for most singers there are fewer dangers in singing too low than in singing too high.

Within contemporary forms of music (sometimes referred to as Contemporary Commercial Music), singers are classified by the style of music they sing, such as jazz, pop, blues, soul, country, folk, and rock styles. There is currently no authoritative voice classification system within non-classical music. Attempts have been made to adopt classical voice type terms to other forms of singing but such attempts have been met with controversy. The development of voice categorizations were made with the understanding that the singer would be using classical vocal technique within a specified range using unamplified (no microphones) vocal production. Since contemporary musicians use different vocal techniques, microphones, and are not forced to fit into a specific vocal role, applying such terms as soprano, tenor, baritone, etc. can be misleading or even inaccurate.

Vocal pedagogy is the study of the teaching of singing. The art and science of vocal pedagogy has a long history that began in Ancient Greece and continues to develop and change today. Professions that practice the art and science of vocal pedagogy include vocal coaches, choral directors, vocal music educators, opera directors, and other teachers of singing.
Vocal pedagogy concepts are a part of developing proper vocal technique. Typical areas of study include the following:
# Human anatomy and physiology as it relates to the physical process of singing
- Vocal health and voice disorders related to singing
- Breathing and air support for singing
- Phonation
- Vocal resonation or Voice projection 
- Vocal registration : a particular series of tones, produced in the same vibratory pattern of the vocal folds, and possessing the same quality, which originate in laryngeal function, because each of these vibratory patterns appears within a particular range of pitches and produces certain characteristic sounds.
- Voice classification
# Vocal styles: for Classical singers, this includes styles ranging from Lieder to opera; for pop singers, styles can include "belted out" a blues ballads; for jazz singers, styles can include Swing ballads and scatting.
- Techniques used in styles such as sostenuto and legato, range extension, tone quality, vibrato, and coloratura

Vocal technique
Singing when done with proper vocal technique is an integrated and coordinated act that effectively coordinates the physical processes of singing. There are four physical processes involved in producing vocal sound: respiration, phonation, resonation, and articulation. These processes occur in the following sequence:
- Breath is taken
- Sound is initiated in the larynx
- The vocal resonators receive the sound and influence it
- The articulators shape the sound into recognizable units

Although these four processes are often considered separately when studied, in actual practice they merge into one coordinated function. With an effective singer or speaker, one should rarely be reminded of the process involved as their mind and body are so coordinated that one only perceives the resulting unified function. Many vocal problems result from a lack of coordination within this process.

Since singing is a coordinated act, it is difficult to discuss any of the individual technical areas and processes without relating them to the others. For example, phonation only comes into perspective when it is connected with respiration; the articulators affect resonance; the resonators affect the vocal folds; the vocal folds affect breath control; and so forth. Vocal problems are often a result of a breakdown in one part of this coordinated process which causes voice teachers to frequently focus in intensively on one area of the process with their student until that issue is resolved. However, some areas of the art of singing are so much the result of coordinated functions that it is hard to discuss them under a traditional heading like phonation, resonation, articulation, or respiration.

Once the voice student has become aware of the physical processes that make up the act of singing and of how those processes function, the student begins the task of trying to coordinate them. Inevitably, students and teachers will become more concerned with one area of the technique than another. The various processes may progress at different rates, with a resulting imbalance or lack of coordination. The areas of vocal technique which seem to depend most strongly on the student's ability to coordinate various functions are:
- Extending the vocal range to its maximum potential
- Developing consistent vocal production with a consistent tone quality
- Developing flexibility and agility
- Achieving a balanced vibrato

Developing the singing voice
Singing is a skill that requires highly developed muscle reflexes. Singing does not require much muscle strength but it does require a high degree of muscle coordination. Individuals can develop their voices further through the careful and systematic practice of both songs and vocal exercises. Vocal pedagogists instruct their students to exercise their voices in an intelligent manner. Singers should be thinking constantly about the kind of sound they are making and the kind of sensations they are feeling while they are singing. Vocal exercises have several purposes, including warming up the voice; extending the vocal range; "lining up" the voice horizontally and vertically; and acquiring vocal techniques such as legato, staccato, control of dynamics, rapid figurations, learning to sing wide intervals comfortably, singing trills, singing melismas and correcting vocal faults.

Vocal music is music performed by one or more singers, with or without instrumental accompaniment, in which singing provides the main focus of the piece. Vocal music is probably the oldest form of music, since it does not require any instrument besides the human voice. All musical cultures have some form of vocal music and there are many long standing singing traditions throughout the world's cultures.
Music which employs singing but does not feature it prominently is generally considered as instrumental music. For example, some blues rock songs may have a simple call-and-response chorus, but the emphasis in the song is on the instrumental melodies and improvisation. Vocal music typically features sung words called lyrics, although there are notable examples of vocal music that are performed using non-linguistic syllables or noises, sometimes as musical onomatopoeia. A short piece of vocal music with lyrics is broadly termed a song.

Health Benefits
Scientific studies suggest that singing can have positive effects on people's health. A preliminary study based on self-reported data from a survey of students participating in choral singing found perceived benefits including increased lung capacity, improved mood, stress reduction, as well as perceived social and spiritual benefits. However, one much older study of lung capacity compared those with professional vocal training to those without, and failed to back up the claims of increased lung capacity.Singing may positively influence the immune system through the reduction of stress. One study found that both singing and listening to choral music reduces the level of stress hormones and increases immune function. A multinational collaboration to study the connection between singing and health was established in 2009, called Advancing Interdisciplinary Research in Singing (AIRS) 

Source：
http://en.wikipedia.org/wiki/Singing