The glottal stop or glottal plosive is a type of consonantal sound used in many spoken languages, produced by obstructing airflow in the vocal tract or, more precisely, the glottis. The symbol in the International Phonetic Alphabet that represents this sound is ʔ.
As a result of the obstruction of the airflow in the glottis, the glottal vibration either stops or becomes irregular with a low rate and sudden drop in intensity.
Features of the glottal stop:
It has no phonation at all, as there is no airflow through the glottis. It is voiceless, however, in the sense that it is produced without vibrations of the vocal cords.
Glottal stop (letter)
In the traditional romanization of many languages, such as Arabic, the glottal stop is transcribed with the apostrophe or the symbol , which is the source of the IPA character ʔ. In many Polynesian languages that use the Latin alphabet, however, the glottal stop is written with a rotated apostrophe, (called ‘okina in Hawaiian and Samoan), which is commonly used to transcribe the Arabic ayin as well (also ) and is the source of the IPA character for the voiced pharyngeal fricative ʕ. In Malay the glottal stop is represented by the letter (at the end of words), in Võro and Maltese by .
Other scripts also have letters used for representing the glottal stop, such as the Hebrew letter aleph and the Cyrillic letter palochka , used in several Caucasian languages. The Arabic script uses hamza , which can appear both as a diacritic and as an independent letter (though not part of the alphabet). In Tundra Nenets, it is represented by the letters apostrophe and double apostrophe . In Japanese, glottal stops occur at the end of interjections of surprise or anger and are represented by the character .
In the graphic representation of most Philippine languages, the glottal stop has no consistent symbolization. In most cases, however, a word that begins with a vowel-letter (e.g. Tagalog aso, "dog") is always pronounced with an unrepresented glottal stop before that vowel (as in Modern German and Hausa).