many languages, both phonologically and historically, the glottal consonants do not behave like other consonants. Phonetically, they have no manner or place of articulation other than the state of the glottis: glottal closure for , breathy voice for , and open airstream for . Some phoneticians have described these sounds as neither glottal nor consonantal, but instead as instances of pure phonation, at least in many European languages. However, in Semitic languages they do appear to be true glottal consonants. Supra-glottal phonation In the last few decades it has become apparent that phonation may involve the entire larynx, with as many as six valves and muscles working either independently or together. From the glottis upward, these articulations are: glottal (the vocal cords), producing the distinctions described above ventricular (the 'false vocal cords', partially covering and damping the glottis) arytenoid (sphincteric compression forwards and upwards) epiglotto-pharyngeal (retraction of the tongue and epiglottis, potentially closing onto the pharyngeal wall) raising or lowering of the entire larynx narrowing of the pharynx Until the development of fiber-optic laryngoscopy, the full involvement of the larynx during speech production was not observable, and the interactions among the six laryngeal articulators is still poorly understood. However, at least two supra-glottal phonations appear to be widespread in the world's languages. These are harsh voice ('ventricular' or 'pressed' voice), which involves overall constriction of the larynx, and faucalized voice ('hollow' or 'yawny' voice), which involves overall expansion of the larynx. The Bor dialect of Dinka has contrastive modal, breathy, faucalized, and harsh voice in its vowels, as well as three tones. The ad hoc diacritics employed in the literature are a subscript double quotation mark for faucalized voice, , and underlining for harsh voice, . Examples are, Other languages with these contrasts are Bai (modal, breathy, and harsh voice), Kabiye (faucalized and harsh voice, previously seen as ±ATR), Somali (breathy and harsh voice). Elements of laryngeal articulation or phonation may occur widely in the world's languages as phonetic detail even when not phonemically contrastive. For example, simultaneous glottal, ventricular, and arytenoid activity (for something other than epiglottal consonants) has been observed in Tibetan, Korean, Nuuchahnulth, Nlaka'pamux, Thai, Sui, Amis, Pame, Arabic, Tigrinya, Cantonese, and Yi. European language examples In languages such as French and Portuguese, all obstruents occur in pairs, one modally voiced and one voiceless: [b] [d] [g] [v] [z] [ʒ] → [p] [t] [k] [f] [s] [ʃ].