In phonetics, preaspiration (sometimes spelled pre-aspiration) is a period of voicelessness or aspiration preceding the closure of a voiceless obstruent, basically equivalent to an -like sound preceding the obstruent. In other words, when an obstruent is preaspirated, the glottis is opened for some time before the obstruent closure. To mark preaspiration using the International Phonetic Alphabet, the diacritic for regular aspiration, , can be placed before the preaspirated consonant. However, Ladefoged and Maddieson prefer to use a simple cluster notation, e.g. instead of .