Help file - Dafydd Gibbon, 2007-12-03
The term "all-prosodic" is borrowed from the description of the YorkTalk parametric synthesiser. In the present context, it means that the only parameters which can be controlled are prosodic parameters, according to a particular model (see below). No syntactic parsing is involved, no calculation of stress positions, out-of-vocabulary (OOV) words are not accepted, and the grapheme-to-phoneme conversion is entirely lexicon-based.
The Parametric All-Prosodic MBROLA PHO file generator requires two inputs:
Definitions and processing strategy
The input sentence is processed as follows:
pitchi = baseline + onset * slopeiThat is, the pitch of phonemei, the phoneme at position i in the sentence, is defined as the baseline added to the product of the onset (initial pitch), and the declination. The declination is the slope raised to the power of i, the position of phoneme i in the sentence. If slope < 1, the declination falls asymptotically towards the baseline, but never quite reaches it. The model is closely related to the so-called linear model of Pierhumbert & Liberman (1984):
pitchi = (pitchi-1 - baseline) * slope + baselineNote that the term "linear" is misleading in any sense of the term, first, because the function is asymptotic, second, because the baseline, onset (not specified in the Pierrehumbert & Liberman model) and declination components are either global constants or vary independently of the preceding pitch).
OutputThe output of the Parametrised All-Prosodic MBROLA PHO file generator is a PHO file with the following specifications: