Head voice can be used in relation to the following: The term goes back at least as far as the Roman tradition of rhetorical instruction.
AD 95) recommends teaching students ut quotiens exclamandum erit lateris conatus sit ille, non capitis ("that when the voice has to be raised the effort comes from the lungs and not from the head," Inst.
The first recorded mention of the term in a musical context was around the 13th century, when it was distinguished from the throat and the chest voice (pectoris, guttoris, capitis—at this time it is likely head voice referred to the falsetto register) by the writers Johannes de Garlandia and Jerome of Moravia.
[3] 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.
[3] In particular, the use of the term head register has become controversial since vocal registration is more commonly seen today as a product of laryngeal function.
According to an early 20th-century book written by David Clippinger, all voices have a head register, whether bass or soprano.
[6] A recent book by a former teacher at Oberlin College Conservatory of Music and a vocal pedagogy teacher, Richard Miller, states that in the "tenore lirico," the higher part of the singing voice above the secondo passaggio at G4 extending upwards is referred to as "full voice in head," or voce piena in testa, effectively stating the head register begins at G4 in the "tenore lirico," not at E4.
This view is more consistent with modern understandings of human physiology and in keeping with stroboscope videos of laryngeal function during vocal phonation.
These internal phonatory sensations produced by laryngeal vibrations are called "resonance" by singers and teachers of singing.
[1] Resonances and registration aside, the term "head voice" is commonly used to mean "high notes that are not falsetto or strained".