In linguistics
Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

, voicelessness is the property of sounds being pronounced without the larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...

 vibrating. Phonologically, this is a type of phonation
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...

, which contrasts with other states of the larynx, but some object that the word "phonation" implies voicing
Voice (phonetics)
Voice or voicing is a term used in phonetics and phonology to characterize speech sounds, with sounds described as either voiceless or voiced. The term, however, is used to refer to two separate concepts. Voicing can refer to the articulatory process in which the vocal cords vibrate...

, and that voicelessness is the lack of phonation.

The International Phonetic Alphabet
International Phonetic Alphabet
The International Phonetic Alphabet "The acronym 'IPA' strictly refers [...] to the 'International Phonetic Association'. But it is now such a common practice to use the acronym also to refer to the alphabet itself that resistance seems pedantic...

 has distinct letters for many voiceless and modally voiced
Modal voice
Modal voice is the vocal register used most frequently in speech and singing in most languages. It is also the term used in linguistics for the most common phonation of vowels...

 pairs of consonants (the obstruent
An obstruent is a consonant sound formed by obstructing airflow, causing increased air pressure in the vocal tract, such as [k], [d͡ʒ] and [f]. In phonetics, articulation may be divided into two large classes: obstruents and sonorants....

s), such as [p b], [t d], [k ɡ], [q ɢ] [f v], [s z].
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