If you need to convert between speech pitches and hertz, note that a speech pitch of 60.000 corresponds to 261.625 Hz. Meanwhile, when a speech pitch value rises by one unit, the corresponding hertz value is multiplied by the twelfth root of 2, defined by the Sound Manager constant twelfthRootTwo . These frequencies correspond to approximate pitch values in the ranges of 30.000 to 40.000 and 55.000 to 65.000, respectively. You can determine the current speech pitch on a speech channel by calling the GetSpeechPitch function, described on page 4-75 . You can change the current pitch by calling the SetSpeechPitch function, described on page 4-76 .
Pitch is the listener's subjective interpretation of speech's average frequency.
The speech pitch specified is a baseline value corresponding to a particular frequency, from which the actual frequency of generated speech varies with the rises and falls of the intonation of speech. When a person speaks, there is a tune to the speech. Often you are more aware of the singsong quality, or change in the range of speech pitch, of a language that you don't know rather than one that you speak. The synthesizer must generate this tune in order to sound more human-like. Speech pitch is always described by a set of numbers that specify the range of pitch of the tune a synthesizer generates.