József Domokos

A rule-based approach to build a text-to-speech system for Romanian

We present in this article our approach for building a text-to-speech system for Romanian. Main stages of this work were: voice signal analysis, region segmentation, construction of acoustic database, text analysis, unit and prosody detection, unit matching, concatenation and speech synthesis. In our approach we consider word syllables as basic units and stress indicating intrasegmental prosody. A special characteristic of current approach is rule-based processing of both speech signal analyse and text analyse stages.

Romanian phonetic transcription dictionary for speeding up language technology development

This paper intends to present a machine readable Romanian language pronunciation dictionary called NaviRo. The dictionary contains 138,500 unique words from the DexOnline dictionary together with their phonetic transcriptions in speech assessment method phonetic alphabet. The development of the pronunciation dictionary and the performed validation tests are also described in the paper. NaviRo pronunciation dictionary is freely available on the project website (http://users.utcluj.ro/~jdomokos/naviro) in plain text, Hidden Markov Model Toolkit and Festival speech synthesis system dictionary format. There are also available for download the used grapheme and phoneme sets and the audio samples for the used phonemes. The use of these resources is completely unrestricted for any research purposes in order to speed up Romanian language speech technology research.

Performance Analysis of Remote Desktop Virtualization based on Hyper-V versus Remote Desktop Services

Abstract The fast spread of computer networks and broadband Internet access, and also the development of different operating systems, makes possible to use different virtualization techniques and virtual machines. The release and spread of virtualization platforms makes possible the development of cost-effective information systems that can provide in addition dynamic resource management and simplified system administration. In this paper we present a comparative performance analysis of Remote Desktop Virtualization based on Hyper-V versus Remote Desktop Services. We introduce system architecture for the two tested scenario and test environment including detailed hardware description. The main conclusions of the paper are that despite the higher acquisition and maintenance costs, the Remote Desktop Services outperforms the Hyper-V based Remote Desktop Virtualization in memory, CPU and also storage management.

Achievements in the field of voice synthesis for Romanian

This article presents some of the voice synthesis methods designed and implemented at the research center of Technical University of Cluj-Napoca, methods that include: the phonemes-based and diphones-based LPC synthesis, the multipulse MPE synthesis, the NSM synthesis method, the RR_PSOLA variant of TD-PSOLA, a method based on syllables concatenation, and a corpus-based method. Also there are presented some voice synthesis systems that were realised: the ROMVOX system, SprintVox system, LIGHTVOX system and HTS system.

An approach to lexical stress detection from transcribed continuous speech using acoustic features

This paper presents a first approach to the unsupervised learning and prediction of primary lexical stress starting from continuous speech data and its orthographic transcript. The approach is intended to be used in the development of text-to-speech synthesis systems for under-resourced languages. Our method is based on syllable nuclei approximation and stress detection using simple acoustic features. The evaluation is performed on 3.5 hours of speech uttered by a Romanian female speaker and results show an accuracy of 47.20% at word level and 58.61% at syllable level.

Romanian Language Voice Browsing for Web Applications Using Grapheme Level Acoustic Modeling

The aim of this article is to present a demonstrative Web application with Romanian language continuous speech recognition based multimodal interface. The scope of the paper also includes the presentation and testing of the capabilities of a context dependent grapheme based acoustic model for the Romanian language. The article describes the system architecture, the Web application development and the speech database used for the acoustic feature vector construction and acoustic model training. Further the task grammar is presented. At the end recognition results are presented in both offline and online operating mode. The used speech corpora together with the transcriptions are freely available for academic use on the NaviRo project website: http://users.utcluj.ro/~jdomokos/naviro/.

Algorithm for detection of voice signal periodicity

This article presents an original algorithm for detecting the periodicity of voice signal. Main characteristics of current algorithm are: precise determination of each period from a voiced segment of speech, accurate detection of pitch interval boundaries, marking the glottal peak of each period. The algorithm uses time domain analysis of the signal, from this resulting its rapidity and efficiency.

Text conditioning and statistical language modeling for Romanian language

In this paper we present a synthesis of the theoretical fundamentals and some practical aspects of statistical (n-gram) language modeling which is a main part of a large vocabulary statistical speech recognition system. There are presented the unigram, bigram and trigram language models as well as the Good-Turing estimator based Katz back-off smoothing algorithm. There is also described the perplexity measure of a language model used for evaluation. The practical experiments were made on Romanian Constitution corpus. There are also presented the text normalization steps before the language model generation. The results are ARPA-MIT format language models for Romanian language. The models were tested and compared using perplexity measure. Finally some comparisons were made between Romanian and English language modeling and conclusions are drawn.

Voice synthesis application based on syllable concatenation

This article presents a voice synthesis application based on syllable concatenation. The system is dedicated for Romanian language, so it was need to work on special rules to decompose Romanian text into syllables. Also for preserving initial prosody of text, accentuation of syllables inside word had to be determined. Then we have recorded a vocal database with the most frequent syllables of Romanian language. A unit matching algorithm matches linguistic units from the input text and acoustic units from database. Acoustic units are then concatenated and converted into sound by mean of a synthesizer.

WEB Application for Romanian Language Phonetic Transcription.

Abstract This paper presents a Romanian language phonetic transcription web service and application built using Java technologies, on the top of the Phonetisaurus G2P, a Word Finite State Transducer (WFST)-driven Grapheme-to-Phoneme Conversion toolkit. We used NaviRO Romanian language pronunciation dictionary for WFST model training, and MIT Language Modeling (MITLM) toolkit to estimate the needed joint sequence n-gram language model. Dictionary evaluation tests are also included in the paper. The service can be accessed for educational, research and other non-commercial usage at http://users.utcluj.ro/~jdomokos/naviro/.