Page "Phonetic complement" Paragraph 22

Chinese never developed a system of purely phonetic characters.

Instead, about 90 % of Chinese characters are compounds of a determinative ( called a ' radical '), which may not exist independently, and a phonetic complement indicates the approximant pronunciation of the morpheme.

However, the phonetic element is basic, and these might be better thought of as characters used for multiple near homonyms, the identity of which is constrained by the determiner.

Due to sound changes over the last several millennia, the phonetic complements are not a reliable guide to pronunciation.