The Dilu dialect (spoken in Mengshan, Guangxi) shows, disparity in the categorization of phonation types in phonetic and phonological analyses. While the phonological analysis proposes that Dilu operates with two phonation types, i.e. creaky and modal, phonetic facts show a three-way distinction, i.e. creaky, male modal and female modal. In this paper acoustic features are investigated for modal and creaky voices in Dilu. In particular, the parameters of Open Quotient (OQ) and Speed Quotient (SQ) are examined. We discuss whether it is necessary and possible for female and male modal voices to collapse into one category to serve the purpose of phonological transcription. Finally, based on an independent five-level tone scale, we propose a tone transcription system for languages that have various phonation types.