Fujisaki Model Research Articles

Exuberant cellular reaction of the optic nerves in experimental Creutzfeldt-Jakob disease

We report here on the exuberant glial reaction in the optic nerves affected by prion diseases. Optic nerves from CJD- and GSS-, and scrapie-infected mice and hamsters showed severe pathology. These lesions were qualitatively indistinguishable from each other but were more intense in the Fujisaki model than in the hamsters inoculated with Echigo-1. Exuberant cellular reaction comprised of macrophages containing numerous mitochondria, abundant rough endoplasmic reticulum, and secondary lysosomes filled with digested myelin debris, electron-dense material and occasionally, entire myelin-bound vacuoles were readily observed in both models. Macrophages actively digesting myelin fragments and containing lyre-like bodies and paracrystalline inclusions were frequently noted. Some macrophages extended long filopodia to form labyrinth-like structures, and within a few macrophages, concentric arrays of cisterns and channels sequestrated part of the cytoplasm. An analogous network of narrow cisterns was seen to surround whole segments of the myelinated fibers.

Evaluating the Quality of an Integrated Model of German Prosody

The perceived quality of synthetic speech strongly depends on its prosodic naturalness. Departing from earlier works by Mixdorff on a linguistically motivated model of German intonation based on the Fujisaki model, an integrated approach to predicting F0 along with syllable duration and energy was developed. The current paper first presents some statistical results concerning the relationship between linguistic and phonetic information underlying an utterance and its prosodic features. These results were employed for training the MFN-based integrated prosodic model predicting syllable duration and energy along with syllable-aligned Fujisaki control parameters. The paper then focusses on the method of perceptual evaluation developed, comparing resynthesis stimuli created by controlled prosodic degrading of natural speech with stimuli created using the integrated model. The results indicate that the integrated model generally receives better ratings than degraded stimuli with comparable durational and F0 deviations from the original. An important outcome is the observation that the accuracy of the predicted syllable durations appears to be a stronger factor with respect to the perceived quality than the accuracy of the predicted F0 contour.

Comparing the naturalness of several approaches for generating F0 contours in German text-to-speech systems

Generating near-to-natural F0 contours is an important issue in text-to-speech synthesis and contributes vastly to the quality of synthetic speech. In earlier studies by the authors, a model of German intonation was developed that is based on the quantitative Fujisaki model. A typical F0 contour is described as a sequence of major rises and falls, which are modeled by onsets and offsets of accent commands connected to accented syllables. The current paper addresses perception experiments comparing the intonational naturalness of a Fujisaki-model-based TTS and four other German TTS systems with comparably high segmental quality. Natural speech samples were used as a reference. Three of the TTS systems had PSOLA, and one LPC segmentals. Two types of experiments were conducted with 20 subjects: (1) a pair comparison of 15 isolated sentences, (2) a ranking test based on a news passage of about 15 sec produced with each of the systems. Preliminary results from experiment (1) show, that on a naturalness scale from 0 to 5, the natural speech samples reach a maximum score of 4.5, with values of 2.8 for the best synthesis, the LPC-based one. The system with Fujisaki-model-based intonation leads the group of PSOLA systems, which is closely clustered at a mean of 2.4.

Classification of Thai tone sequences in syllable-segmented speech using the analysis-by-synthesis method

Tone classification is important for Thai speech recognition because tone affects the lexical identification of words. An analysis-by-synthesis algorithm for classifying Thai tones in syllable-segmented speech is presented that uses an extension to Fujisaki's (1983) model for tone languages that incorporates tonal assimilation and declination. The classifier correctly identifies all of the tones in 89.1% of the test utterances.

Automatic extraction of fundamental frequency control rules by statistical analysis

This paper aims at the improvement of the naturalness of Japanese synthetic speech and proposes a method of extracting automatically the rules for controlling the voice fundamental frequency (written as F0). The proposed method is composed of two steps. (1) The F0 time-series pattern of a sufficient amount of speech data is represented by parameters under Fujisaki's model. (2) The F0 control rule that estimates the parameter values from the language information is extracted by statistical analysis. The proposed method is applied to 200 Japanese sentences read by a speaker, and the relation between the language information and the parameter values is derived by analyzing the obtained F0 control rules. The following properties are identified. (1) The phrase command diminishes when the number of morae in the preceding phrase decreases. (2) The accent component is reduced when the number of morae in the higher-pitched part of the accented phrase is larger. Relation (2) is a refinement of knowledge already obtained by the analysis of a small number of samples. Thus, it is shown that adequate F0 control rules can be extracted automatically by the proposed method. © 1997 Scripta Technica, Inc. Syst Comp Jpn, 28(3): 91–100, 1997

Analysis and synthesis of German F0 contours by means of Fujisaki's model

This paper presents the adaptation of Fujisaki's quantitative model to the analysis of German intonation and its application to F 0 synthesis by rule. The parameter values of the model are determined by an automatic approximation of naturally produced F 0 contours. The algorithm is not primarily based on mathematical criteria but is subject to constraints that emerge from a linguistic interpretation of the model. The potential sources of variation of the parameter values are examined using statistical methods. A set of rules is formulated that capture the effects of both linguistic and speaker-dependent features. The rules generate artificial intonation contours which in turn can be related to linguistic features such as sentence mode or word accent. Acceptability of the rule-generated intonation patterns as well as the adequate modelling of linguistic prosodic properties are evaluated perceptually by both phonetically trained subjects and prosodically “naive” listeners. In general, utterances resynthesized with rule-generated F 0 contours are judged highly acceptable and natural by both groups of listeners. Detailed judgements with respect to word accent and sentence mode are obtained that help to improve several specific rules and contribute to a more adequate description of German intonation.

Text‐to‐speech system for English and Japanese

A real‐time text‐to‐speech system for English and Japanese has been developed. This system consists of a language processing module, a phonetic acoustic processing module, and a synthesis module. Full general English and Japanese sentences can be converted to speech. The Japanese software and English software are independent except for the synthesis module. The features of this system are as follows. (1) The synthesis module is a phoneme‐based cascade‐parallel formant synthesizer with high observed intelligibility (73.5% for the 119 Japanese monosyllables). (2) This system has a 3000‐morphene English dictionary and 40 000‐word Japanese dictionary with a high‐speed search algorithm. (3) A large speech database was collected for the development of Japanese prosody rules. (4) For the precise control of pitch contour, the Fujisaki model was adopted. (5) One of the two systems developed can stand alone; the other requires a personal computer with a high‐speed DSP board. (6) In the development of this system, some powerful interactive tools have also been developed for varying speech parameters in real time.

Self-Reproducing Flat Pomeron in the Eikonal Approximation

where ac (t) is the trajectory function of the branch point of the cut in the complex angular momentum plane, non-zero r with ac (t) = 1 ± r v't corresponds to a pair of colliding Regge cuts and vanishing r to a fixed cut at J = 1. However, in Fujisaki's model the property of the discontinuity of the cut is not determined uniquely so that the asymptotic behavior of the contribution from the self-reproducing Pomeranchuk cut is indefinite as far as the logarithmic dependence on energy is concerned. In this paper it is shown that in the framework of eikonal approximation a flat pomeron (a(t) =1) of simple pole type (no logarithmic factor in the asymptotic behavior) is a unique solution of the selfreproducing condition provided that the Pomeranchuk trajectory is linear. We consider the elastic scattering of equal mass spinless particles. We assume that the contribution from primordial pomeron to the amplitude is given by