American English Phonetics

11. Fricatives and affricates

The articulation of a fricative involves the formation of a narrowing at some point in the speech tract such that friction is produced when the airstream is forced through the narrow opening, to produce a hissing or hushing kind of sound.

An affricate can be described as a sound that begins as a stop and ends as a fricative; it is a stop whose release is slowed down, such that considerable friction is heard.