Listening to Natural and Synthesized Speech while Driving: Effects on User Performance

The effects of message type (navigation, E-mail, news story), voice type (text-to-speech, natural human speech), and earcon cueing (present, absent) on message comprehension and driving performance were examined. Twenty-four licensed drivers (12 under 30, 12 over 65, both equally divided by gender) participated in the experiment. They drove the UMTRI driving simulator on a road consisting of straight sections and constant radius curves, thus yielding two levels of low driving-workload. In addition, as a control condition, data were collected while participants were parked. In all conditions, participants were presented with three types of messages. Each message was immediately followed by a series of questions to assess comprehension. Navigation messages were about 4 seconds long (about 9 words). E-mail messages were about 40 seconds long (about 100 words) and news messages were about 80 seconds long (about 225 words). For all message types, comprehension of text-to-speech messages, as determined by accuracy of response to questions, and by subjective ratings, was significantly worse than comprehension of natural speech (79 versus 83 percent correct answers; 7.7/10 versus 8.6/10 subjective rating). Driving workload did not affect comprehension. Interestingly, neither the speech used (synthesized or natural) nor the message type (navigation, E-mail, news) had a significant effect on basic driving performance measured by the standard deviations of lateral lane position and steering wheel angle.     

Dealing with Prosody in a Text-to-Speech System

The task of assigning appropriate intonation to syntheticspeech is one that requires knowledge of linguistic structure as well ascomputational possibilities. This paper surveys the basic challengesfacing the designer of a text-to-speech system, and reviews some of theperspectives on these problems that have been developed in thelinguistic literature.     

基于智能手机的语音导航教学辅助系统设计

利用Microsoft Speech SDK语音开发包和提供的TTS组件技术,在VS.NET2008开发环境下,采用C#语言开发适用于智能手机的语音导航教学辅助系统的设计方案。首先介绍了系统开发平台的选型根据,其次对系统体系结构和系统功能进行详细论述,最后给出了系统关键技术及实现方法。该系统的开发方法在适合视障人士的应用领域中具有一定指导意义和实际的应用价值。     

Close Shadowing Natural Versus Synthetic Speech

Close shadowing experiments involving natural and synthetic stimuli are described. Preliminary results show that speakers are able to follow natural stimuli with an average delay of 70 ms whereas this delay typically exceeds 100 ms for stimuli produced by text-to-speech systems. A complementary experiment shows that this contrast is mainly due to the inappropriate or impoverished prosody generated by actual text-to-speech systems.     

中文文语转换在电话语音系统中的应用

传统电话语音系统中采用音一音组合方式实现语音输出，即事先将要输出的信息用人工朗读录制成语音文件，在用户查询时播放该语音文件．这样，语音文件的录制和存储就成为系统的瓶颈．而利用文语转换技术。将任意的中文文本信息经过文本分析、音元拼接等过程，转换为语音文件，再通过电话进行播放的方法可以很好地提高系统的效率．文中重点论述了以汉字音节为基本单元的语音库建立过程，以及根据语音文件的音频格式进行波形拼接等关键性问题．     

汉语文本-可视语音转换的研究

本文通过对发音者可见器官动作的研究 ,从视觉方面抽取汉语发音的 2 6个基本口形 ,并利用 MPEG- 4所规定的面部动画参数 (FAP)来描述这些口形 ,从而获得了符合国际标准的描述汉语发音的视觉参数 .另外 ,我们研究了这些参数在连续语流中的变化及协同发音对口形的影响 ,基于已有的汉语文语转换系统 (Sonic)和二维网格人脸模型(Plane Face)实现了一个汉语文本 -可视语音转换系统 (TTVS)     

The Effect of Lexical Complexity on Intelligibility

Most intelligibility tests are based on the use of monosyllabictest stimuli. This constraint eliminates the ability to measurethe effects of lexical stress patterns, complex phonotacticorganizations, and morphological complexity on intelligibility.Since these aspects of lexical structure affect speechproduction (e.g., by changing syllable duration), it is likelythat they affect the structure of acoustic-phonetic patterns.Thus, to the extent that text-to-speech systems fail to modifyacoustic-phonetic patterns appropriately in polysyllabic words,intelligibility may suffer. This means that while most standardintelligibility tests may accurately estimate theintelligibility of monosyllabic words, this estimate may notgeneralize as well to predict the intelligibility of words withmore complex lexical structures. The present study was carriedout to measure how words varying in lexical complexity differ inintelligibility. Monosyllabic, bisyllabic, and polysyllabicwords were used varying in morphological complexity(monomorphemic or polymorphemic). Listeners transcribed thesestimuli spoken by two human talkers and two text-to-speechsystems varying in speech quality. The results indicate thatlexical complexity does affect the measured intelligibility ofsynthetic speech and should be manipulated in order toaccurately predict the performance of text-to-speech systemswith unrestricted natural text.     

Schwa-Deletion in Hindi Text-to-Speech Synthesis

We describe the phenomenon of schwa-deletion in Hindi and how it is handled in the pronunciation component of a multilingual concatenative text-to-speech system. Each of the consonants in written Hindi is associated with an inherent schwa vowel which is not represented in the orthography. For instance, the Hindi word pronounced as [namak] (salt) is represented in the orthography using the consonantal characters for [n], [m], and [k]. Two main factors complicate the issue of schwa pronunciation in Hindi. First, not every schwa following a consonant is pronounced within the word. Second, in multimorphemic words, the presence of a morpheme boundary can block schwa deletion where it might otherwise occur. We propose a model for schwa-deletion which combines a general purpose schwa-deletion rule proposed in the linguistics literature (Ohala, 1983), with additional morphological analysis necessitated by the high frequency of compounds in our database. The system is implemented in the framework of finite-state transducer technology.     

A field evaluation of the Italian “Automated reverse directory assistance” service

The paper describes a field evaluation of the automated reverse directory assistance service presently in use in Italy in which information about names and addresses is provided by a TTS system. A simulation of the service using a natural voice was also run to get comparative data. Both services were accessed from an office room and a call-box on the street. Different evaluation metrics, such as intelligibility, task completion, task correctness, transaction success, and user's reactions were used. The aim of the work was to evaluate TTS synthesis in real world use and to make a comparison between laboratory data and data on system performance in a real application. Such a comparison suggested that in laboratory tests more attention should be dedicated to simulate more closely the conditions that can be predicted in real world use, by including important aspects that are generally not taken into consideration in laboratory tests and that are likely to have a large influence on TTS system performance such as environmental noise, prosody, and task complexity. The results also underline the importance of field evaluations to get an overall view of the usability of a service in real applications and with users who are as similar as possible to actual users.     

语音欺骗检测方法的研究现状及展望

语音欺骗是指通过录音、语音合成（Text-to-speech, TTS）、语音转换（Voice conversion, VC）等手段,将一段非法的、未经过自动说话人验证（Automatic speaker verification, ASV）系统认证的声音进行“修改仿冒”,以达到通过ASV系统检测的目的。随着人工智能和语音欺骗技术的发展,ASV系统在安全性方面遇到了严峻的挑战。检测输入ASV系统的语音的真实性,防止欺骗语音通过ASV的验证以提高ASV系统的安全性,是近年来语音领域研究的一个热点问题。国内外学者的最新研究从声学特征选取、识别模型选择等角度出发,探索了不同的语音欺骗方法对ASV系统的影响,并深入研究了相应的语音欺骗检测技术,在一定程度上提高了ASV系统的防欺骗性能。本文介绍了语音欺骗的基本方法,给出了语音欺骗检测的框架和典型声学特征,分两大类别总结了语音欺骗检测的主要方法和最新进展,梳理了目前语音欺骗检测中仍然存在的若干技术问题,并对语音欺骗检测技术的发展方向进行了展望。