The maximum time an individual can sustain a sung tone, after having filled the lungs maximally. In the literature, maximum phonation time (MPT) is often reported as having been measured on the vowel / i / (eee) at spontaneous, comfortable pitch and loudness.

However, MPT may vary markedly with pitch, vowel, effort, register, and so forth. Furthermore, MPT may differ dramatically among individuals all of whose larynges are otherwise considered normal. Hence, MPT is a useful measure primarily when it is very abnormal (less than seven seconds), and also when production constraints are more specific than “comfortable pitch and loudness.” At our practice, we routinely measure MPT at average/anchor frequency, during spontaneous speech.