STRIDENT
This feature is in fact related to the manner of articulation of phonemes. As you will certainly remember, consonants are produced when a certain type of obstruction is introduced to the passage of air in the mouth. Some consonants are explosive in the sense that the blocked air is suddenly released; some others are fricatives or affricates because the air moves out of the mouth through a narrow opening. In this latter case, sometimes there is a turbulence in the air (like in the case of /s/, /z/, /ʃ/, /ʒ/, /ʧ/, /ʤ/, /f/, and /v/), and sometimes there is no turbulence (like in the case of phonemes other than these). The feature [strident] simply says whether this turbulence exists or not. English liquids, glides, and vowels are [-strident].
Stridency is a feature of fricative (sometimes called spirant) and affricate consonants. Therefore, plosive consonants (i.e., those with the [+abrupt release] feature) are predictably [-strident]:
[+Strident] sounds are categorized into two subtypes based on their place of articulation. /f/ and /v/ are [-sibilant]. However, /s/, /z/, /ʃ/, /ʒ/, /ʧ/, and /ʤ/ are [+sibilant]. In fact, the term sibilant is used for hushers and hissers. During the articulation of [+sibilant] sounds, a groove is formed on the tongue so that the outgoing air takes on a hissing overtone. This hissing sound is not felt during the articulation of /f/ and /v/ (which are [+strident] labiodentals).
