Post-alveolar fronting explained

We have indicated elsewhere (see Fronting) that, as well as velar consonants being fronted, post-alveolar consonants can also be affected. Fronting of /ʃ ʒ ʧ ʤ/ is known as post-alveolar fronting (or sometimes palato-alveolar fronting). Like velar fronting, it can occur in syllable-initial or syllable-final position.

Consider the word jam /ʤæm/ being realized as /væm/. Here, the initial voiced post-alveolar fricative /ʤ/ has been substituted by a consonant made further forwards in the mouth, the voiced labio-dental fricative /v/. This is, therefore, an example of syllable-initial post-alveolar fronting. As with velar fronting, the substituting sound typically mirrors the same voicing as the substituted post-alveolar sound, i.e. voiced /ʤ/ is substituted with voiced /v/. In addition, the substituting /v/ reflects some of the manner of production. In this case, the fricative /v/ retains the friction of the affricate /ʤ/. In sum, voiceless post-alveolars are typically fronted by voiceless fricatives, and voiced post-alveolars are typically substituted by voiced fricatives.