The accuracy of the widely used and International Phonetic Association-sanctioned Chao five-point scale of tonal transcription is examined quantitatively. Perceptually transformed acoustic data are used from two Chinese dialects with complex tone systems, and a measure derived of the conformability of the data using their likelihoods. It is shown that some tones conform well to the model, but others do not, with tonal pitch targets lying equidistant between the Chao integers. It is concluded that the Chao model is probably not an accurate reflection of the distribution of tonal pitch targets.
Bibliographic reference. Rose, Phil (2014): "Transcribing tone — a likelihood-based quantitative evaluation of chao's tone letters", In INTERSPEECH-2014, 101-105.