A new formant-tracking algorithm using phoneme information is proposed. Conventional formant-tracking algorithms obtain formant tracks by analyzing the acoustic speech signal using continuity constraints without any additional information. The formant-tracking error rate of the conventional methods is reportedly in the range of 10%-20%. In this paper, we show that if text or phoneme transcription of speech utterances is available, the error rate can be significantly reduced. The basic idea behind this approach is that given the phoneme identity, formant-tracking algorithms can have a better clue of where to look for formants. The algorithm consists of three phases: 1) analysis, 2) segmentation and alignment, and 3) formant tracking by the Viterbi searching algorithm. In the analysis phase, formant candidates are obtained for each analysis frame by solving the linear prediction polynomial. In the segmentation and alignment phase, the text corresponding to the input speech utterance is converted into a sequence of phoneme symbols. Then, the phoneme sequence is time aligned with the speech utterance. A hidden Markov model (HMM) based automatic segmentation algorithm is used for forced-time alignment. For each phoneme segment, nominal formant frequencies are assigned at the center of each phoneme segment. Then nominal formant tracks for the entire utterance are obtained by interpolating the nominal formant frequencies. In order to compensate for the coarticulation effect, different interpolation methods are used depending on the phonemic context. The interpolation process makes the formant-tracking algorithm robust to possible segmentation errors made by the HMM-based segmentation algorithm. As a result, the proposed formant-tracking algorithm does not require highly accurate alignment/segmentation. Finally, a set of formants is chosen from the formant candidates in such a way that the resulting formant tracks come close to the nominal formant tracks while satisfying the continuity constraints. The algorithm is tested using natural speech utterances and the performance is compared against formant tracks obtained by the conventional method using continuity constraints only. The new algorithm significantly reduces the formant-tracking error rate (5.03% for male and 3.73% for female) over the conventional formant-tracking algorithm (13.00% for male and 15.82% for female).

In this paper, we introduce a new European project named OrienTel. The aim of OrienTel is to enable the project's participants to design and develop multilingual interactive communication services for the Mediterranean and the Middle East, ranging from Morocco in the West to the Gulf states in the East, including Turkey and Cyprus. These multilingual applications will be largely speech-based and will typically be implemented on mobile and multi-modal platforms such as cellular GSM or UMTS phones, personal digital assistants (PDAs) or combinations of the two. Applications of the kind targeted are unified messaging, information retrieval, customer care, banking, WAP and service portals. To achieve this aim, the consortium will produce various surveys of the OrienTel region, compile a set of 22 linguistic databases, conduct research into ASR-related problems the OrienTel languages hold and develop demonstrator applications bearing evidence of OrienTel's multilingual orientation.

A spoken dialogue system capable of maintaining a humanmachine conversation over a telephone must simultaneously maintain many dialogue sessions with different callers and third-party servers running applications over the Internet. There are three main issues to be addressed. First, the caller’s identity has to be passed between each dialogue turn. Secondly, the dialogue state and connections to third party servers have to be continuously maintained. Thirdly, the system interfaces have to follow some standards, especially Internet protocols. We use session tickets and session object hashes to address these issues. Each dialogue turn is encoded in a session data object and VXML page. The session tickets contain the session ID and security-related information passed between the VoiceXML interpreter and document server. The session object hash stores the third party connection handle, which is retrieved for subsequent dialogue turns.

A new formant tracking algorithm using phoneme dependent nominal formant values is tested. The algorithm consists of three phases: (1) analysis, (2) segmentation, and (3) formant tracking. In the analysis phase, formant candidates are obtained by solving for the roots of the linear prediction polynomial. In the segmentation phase, the input text is converted into a sequence of phonemic symbols. Then the sequence is time aligned with the speech utterance. Finally, a set of formant candidates that are close to the nominal formant estimates while satisfying the continuity constraints are chosen. The new algorithm significantly reduces the formant tracking error rate (3.62%) over a formant tracking algorithmusing only continuity constraints (13.04%). We will also discuss how to further reduce the tracking error rate. INTRODUCTION In the Bell Labs' Text-To-Speech (TTS) system [1], a limited number of acoustic units is stored in the inventory table. Therefore, it is important to be able to...

In this paper we present an overview of the German version of the Bell Labs text-to-speech system, a high-quality concatenative synthesis system with extensive text analysis capabilities. We discuss problems of text analysis, and our solutions to these problems, including: the integration of text normalization tasks into linguistic text analysis; the capability to morphologically analyze compounds and unseen words; name analysis and pronunciation. We briefly describe the prosodic components of the text-to-speech system and their underlying duration and intonation models. Finally, the phonetically motivated structure of the acoustic inventory is presented.