Voice projection is the strength of speaking or singing

Singing

Singing is the act of producing musical sounds with the voice, and augments regular speech by the use of both tonality and rhythm. One who sings is called a singer or vocalist. Singers perform music known as songs that can be sung either with or without accompaniment by musical instruments...

 whereby the voice

Voice

Voice may refer to:* Human voice* Voice control or voice activation* Writer's voice* Voice acting* Voice vote* Voice message-In film:* Voice , a 2005 South Korean film* The Voice , a 2010 Turkish horror film directed by Ümit Ünal...

 is used loudly and clearly

Enunciation

In phonetics, enunciation is the act of speaking. Good enunciation is the act of speaking clearly and concisely. The opposite of good enunciation is mumbling or slurring. See also pronunciation which is a component of enunciation. Pronunciation is to pronounce sounds of words correctly....

. It is a technique which can be employed to demand respect and attention, such as when a teacher

Teacher

A teacher or schoolteacher is a person who provides education for pupils and students . The role of teacher is often formal and ongoing, carried out at a school or other place of formal education. In many countries, a person who wishes to become a teacher must first obtain specified professional...

 is talking to the class, or simply to be heard clearly, as an actor

Actor

An actor is a person who acts in a dramatic production and who works in film, television, theatre, or radio in that capacity...

 in a theatre

Theatre

Theatre is a collaborative form of fine art that uses live performers to present the experience of a real or imagined event before a live audience in a specific place. The performers may communicate this experience to the audience through combinations of gesture, speech, song, music or dance...

.

Breath technique is essential for proper voice projection. Whereas in normal talking

Manner of articulation

In linguistics, manner of articulation describes how the tongue, lips, jaw, and other speech organs are involved in making a sound. Often the concept is only used for the production of consonants, even though the movement of the articulars will also greatly alter the resonant properties of the...

 one may use air from the top of the lungs, a properly projected voice uses air properly flowing from the expansion of the diaphragm

Thoracic diaphragm

In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...

. In good vocal technique, well-balanced respiration is especially important to maintaining vocal projection. The goal is to isolate and relax the muscles controlling the vocal folds

Vocal folds

The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx...

, so that they are unimpaired by tension

Muscle tone

In physiology, medicine, and anatomy, muscle tone is the continuous and passive partial contraction of the muscles, or the muscle’s resistance to passive stretch during resting state. It helps maintain posture, and it declines during REM sleep.-Purpose:Unconscious nerve impulses maintain the...

. The external intercostal muscles are used only to enlarge the chest cavity, whilst the counterplay between the diaphragm and abdominal muscles is trained to control airflow.

Stance is also important, and it is recommended to stand up straight with the feet shoulder width apart and the upstage foot (right foot if right-handed etc) slightly forward. This improves balance and breathing.

In singing, voice projection is often equated with resonance

Resonance

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

, the concentrated pressure through which one produces a focused sound. True resonance will produce the greatest amount of projection available to a voice by utilizing all the key resonators found in the vocal cavity. As the sound being produced and these resonators find the same overtones, the sound will begin to spin as it reaches the ideal singer's formant

Formant

Formants are defined by Gunnar Fant as 'the spectral peaks of the sound spectrum |P|' of the voice. In speech science and phonetics, formant is also used to mean an acoustic resonance of the human vocal tract...

at about 2800 Hz. The size, shape, and hardness of the resonators all factor into the production of these overtones and ultimately determine the projective capacities of the voice.