A Phonological Processor for Italian

Rodolfo Delmonte Centro Linguisfico Interfacol~ UniversirA degli Studi di Venezia Ca' Ga.rzoni-Moro - S. Marco 3417 ABSTRACT A computer program for the automatic translation of any text of Italian into naturally fluent synthetic speech is pre- sented. The program, or Phonological Processor (hence FP) maps into prosodic structures the phonological rules of Italian. Structural information is provided by such hierarchical pros- odic constituents as Syllable (S), Metrical Foot (HF), Phono- logical Word (PW), Intonational Group (IG). Onto these struc- tures, phonological rules are applied such as the "letter-to- sound" rules, automatic word stress rules,internal stress hier- archy rules indicating secondary stress,external sandhi rules, phonological focus assignment rules, logical focus assignment rules. The FP constitutes also a model to simulate the reading process aloud, and the psycholinguistics and cognitive aspects related will be discussed in the computational model of the FP. At present, Logical Focus assignment rules and the computation- al model are work in progress still to be implemented in the FP. Recorded samples of automatically produced synthetic speech will be presented at the conference to i11ustrate the functioning of the rules. O. Introduction The FP which we shall describe in detail in the following pages, is the terminal section of a system of speech synthesis by rule without vocabulary restrictions, implemented at the Centre of Computational Sonology of the University of Padua. From the linguistic point of view the FP is a model to simu- late the operations carried out by an Italian speaker when reading aloud any text. To this end, the speaker shall use the rules of his internal grammar to translate graphic signs into natural speech. These rules wi11 have to be implemented in the FP, together with a computational mechanism simulating the psychological end cognitive functions of the reading process. I. The Phonologlcal Rules At the phonological level the FP has to account for low level or segmental phenomena, and high level or suprasegmental ones. The former are represented by three levels of structure, that is S, MF, PW and are governed by phonological rules which are meant to render the movements of the vocal tract and the coarticulatory effects which occur regularly at word level and at word boundaries. The latter are represented by one level of structure, the IG, and are governed by rules which account for long range phenomena like pitch contour formation, intonation centre assignment, pauses. In brief, the rules that the FP shall have to apply are the following: i. transcription from grapheme to nphoneme", including the most regular coarticulatory and allophonic phenomena of the It~dian language; ii. automatic word stress assignment, including all the most frequent exceptions to the rules as well as individuation of homographs, which are very common in Italian; iii. internal word stress hierarchy, with secondary stres/es assignment, individuation of unstressed dipththongs, triph- thongs, hiatuses; iv. external sandhi rules, operating at word boundaries and re- sulting in stress retraction, destressing, stress hierarchy modification, elision by assimilation and other phenomena; v. destressing of functional words listed in …

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