unaspirated

Unaspirated is a phonetic term used to describe a consonant produced without a noticeable burst of air following its release. The concept is most often applied to voiceless stops such as p, t, and k, though it can describe other obstruents as well. An unaspirated stop has little or no audible aspiration and a short voice onset time (VOT). In phonetic transcription, aspirated stops are written with a diacritic or superscript, as pʰ, tʰ, kʰ; unaspirated stops are written simply as p, t, k.

In many languages, aspiration is a salient feature and may be phonemic. Some languages contrast aspirated and unaspirated stops as separate phonemes, while others realize them as allophones depending on context. English provides a familiar example: initial voiceless stops are typically aspirated, as in “pat” or “top.” In certain clusters, however, the same stops are unaspirated; for instance, in “spit” or “stop” the release of the /p/ or /t/ often shows little aspiration.

Acoustically, aspirated and unaspirated stops differ in VOT; aspirated stops have longer VOT, often several tens of milliseconds, whereas unaspirated stops have a VOT close to zero or even negative in some languages. The distinction can influence speech perception, phonotactics, and language teaching, and it is a common focus in cross-language phonetic research and in the development of speech technologies.