What are the changes in pronunciation that occu... - SS2 English Structure, speech work Question

The pronunciation of the sibilant changes slightly when the ‘s’/’es’ suffixes are added to words that end in a sibilant. If the sibilant is /s/ or /z/, the suffix is pronounced as /iz/. For example, the plural of "box" is "boxes" and the third person singular of "buzz" is "buzzes." If the sibilant is /ʃ/ or /ʒ/, the suffix is pronounced as /ʃiz/ or /ʒiz/. For example, the plural of "bush" is "bushes" and the third person singular of "judge" is "judges.''