In phonetics, the hook (Vietnamese: dấu hỏi) is a diacritic mark placed on top of vowels in the Vietnamese alphabet. In shape it looks like a a tiny question mark without the dot underneath. For example, a capital A with a hook is "Ả", and a lower case "u" with a hook is "ủ". It functions as a tone marker. Vowels with this symbol are pronouned with a falling then rising tone. Phonetics (from the Greek word phone = sound/voice) is the study of speech sounds (voice). ... A diacritic mark or accent mark is an additional mark added to a basic letter. ... The Vietnamese alphabet (quốc ngữ or national script) is the current writing system for the national language of Vietnam. ...
Diacritic marks can be combined with IPA letters to transcribe modified phonetic values or secondary articulations.
One modification is the use of subscript parentheses around the phonation diacritics to indicate partial phonation; a single parenthesis at the left or right of the voicing indicates that it is partially phonated at the beginning or end of the segment.
For traditional diacritics, the IPA uses the name of the symbol from a certain language, for example, é is acute, based on the name of the symbol in English and French.