Obstruent Obstruent An obstruent is a speech sound such as , , or that is formed by "obstructing" airflow. Obstruents contrast with sonorants, which have no such obstruction and so resonate. All obstruents are consonants, but sonorants include both vowels and consonants. Obstruents are subdivided into plosives (oral stops), such as , with complete occlusion of the vocal tract, often followed by a release burst; fricatives, such as , with limited closure, not stopping airflow but making it turbulent; and affricates, which begin with complete occlusion but then release into a fricative-like release, such as . Obstruents are prototypically voiceless, but
Formant Formant In speech science and phonetics, a formant is the spectral shaping that results from an acoustic resonance of the human vocal tract. However, in acoustics, the definition of a formant differs slightly as it is defined as a peak, or local maximum, in the spectrum. For harmonic sounds, with this definition, it is therefore the harmonic partial that is augmented by a resonance. The difference between these two definitions reside in whether "formants" characterise the production mechanisms of a sound or the produced sound itself. In practice, the frequency of a spectral peak can differ from the associated resonance