phoneticize in British English
or phoneticise (fəˈnɛtɪˌsaɪz), phonetize or phonetise (ˈfəʊnɪˌtaɪz)
verb (transitive)1. to represent speech in writing using a system in which individual symbols reflect speech sounds in a regular manner
2. to increase the representation of written language using symbols or letters that correspond more closely or regularly to the sounds of the spoken language