An obstruent (/ˈɒbstruːənt/) is a speech sound such as [k], [d͡ʒ], or [f] that is formed by obstructing airflow. Obstruents contrast with sonorants, which have no such obstruction and so resonate.^[1] All obstruents are consonants, but sonorants include vowels as well as consonants.

Subclasses

Obstruents are subdivided into:

• plosives (oral stops), such as [p, t, k, b, d, ɡ], with complete occlusion of the vocal tract, often followed by a release burst;
• fricatives, such as [f, ɸ, θ, s, ʃ, x, v, β, z, ʒ, ɣ], with limited closure, not stopping airflow but making it turbulent;
• affricates, which begin with complete occlusion but then release into a fricative-like release, such as [t͡ʃ] and [d͡ʒ].^[2]

Voicing

Obstruents are often prototypically voiceless, but voiced obstruents are common. This contrasts with sonorants, which are prototypically voiced and only rarely phonemically voiceless.^[3]