基于单字音特征提取的说话人识别方法

证实普通话可以分解为辅音音素和单元音音素通过过度音的连接,提出一种单字音特征提取方法。该方法在传统的帧特征提取基础上,对相关帧进行二次处理,得到单字语音中的多个代表帧,将代表帧进行拼接作为单字的特征矢量。这种特征提取方法能更好地表现说话人单字发音中相邻语音帧之间的连续性。仿真实验表明该方法在说话人识别系统的应用中达到较高的识别率,使识别时间进一步缩短。     

一种用于方言口音语音识别的字典自适应技术

基于标准普通话的语音识别系统在识别带有方言口音的普通话时,识别率会下降很多。针对这一问题,论文介绍了一种“字典自适应技术”。文中首先提出了一种自动标注算法,然后以此为基础,通过分析语音数据,统计出带有方言口音普通话的发音规律,然后把这个规律编码到标准普通话字典里,构造出体现这种方言发音特征的新字典,最后把新字典整合于搜索框架,用于识别带有该方言口音的普通话,使识别率得到显著提高。     

云南民族口音汉语普通话语音识别研究

该文根据云南境内少数民族同胞说普通话时明显带有民族口音的语言使用现状,介绍了一个以研究非母语说话人汉语连续语音识别为目的的云南少数民族口音汉语普通话语音数据库,并在其基础上开展了发音变异规律、说话人自适应和非母语说话人口音识别研究,是汉语语音识别中用户多样性研究的重要补充。     

一种联合语种识别的新型大词汇量连续语音识别算法

提出了一种联合语种识别的新型大词汇量连续语音识别(Large vocabulary continuous speech recognition, LVCSR)算法,并构建了实时处理系统. 该算法能够充分利用语音解码过程中收集的音素识别假设,在识别语音内容的同时识别语种类别.该系统可以应用于多语种环境,不仅可以以更小的系统整体计算开销替代独立的语种识别模块,更能有效应对在同一段语音中混有非目标语种的情况,极大地减少由非目标语种引入的无意义识别错误,避免错误积累对后续识别过程的误导.为将语音内容识别和语种识别紧密整合在一个统一语音识别解码过程中,本文提出了三种不同的算法对解码产生的音素格结构进行调整(重构):一方面去除语音识别中由发音字典和语言模型引入的特定目标语种偏置,另一方面在音素格中包含更加丰富的音素识别假设.实验证明, 音素格重构算法可有效提高联合识别中语种识别的精度.在汉语为目标语种、汉英混杂的电话对话语音库上测试表明,本文提出的联合识别算法将集外语种引起的无意义识别错误减少了91.76%,纯汉字识别错误率为54.98%.     

利用语音非线性特征改进说话人识别的性能

分析说话人发音过程中的非线性现象,通过计算38个汉语音素的最大Lyapunov指数验证语音内含混沌性.从不同侧面讨论语音非线性特征量的物理意义和计算方法,包括Lyapunov指数、二阶熵和相关维数,并将这些非线性特征用于说话人识别.在Gauss混合模型的说话人识别系统中,基于MFCC参数得到识别结果的基础上,用最大Lyapunov指数、二阶熵和相关维数再进行说话人的二次辨认,提高说话人识别的性能.实验结果表明非线性特征参数中包含有说话人特征的信息,因此可用于改进基于MFCC的识别性能.     

利用音素顺序分类法的与说话人无关的语音识别系统

本文提出一种包括英语和汉语在内,对有限单词并与说话人无关的语音识别系统。该系统是利用一系列的语音参数来描述待识别的语音信号,并与词汇表中相应的各参考语音多数比较判别。为了增加识别率,把各种语音信号接音素及其顺序分类。对于汉语类的语音信号,则进一步按汉语的“四声”声调划分子类。本文讨论了按此种分类方法生成参考语音参数表的方法和过程。本系统分类比较细,虽然这将导致要求计算机内存容量增加,但由于在同一语音类别中参考词汇数目相对地减少,这对提高识别速度和识别率均有利。     

普通话发音训练多级音素模板综合评价方法

提出了一种应用于普通话声韵母发音评价的多级音素模板综合评分法,该方法在单模板匹配的基础上,通过寻找汉语音素发音过程中的浊化、摩擦、爆破等特征,形成多个子模式,进行多模式匹配,最后给出加权评分。实验结果表明多级音素模板综合评分法有效地改善了汉语发音中几组相似音之间的区分度。也介绍了MFCC等语音特征提取、DTW模板匹配算法、基于聚类的模板训练以及综合加权评价机制的实现方法。     

母语与非母语语音识别声学建模

为了兼容母语与非母语说话人之间的发音变化,提出一种新的声学模型建模方法。分析中国人受母语影响产生的英语发音变化,利用中国人英语发音数据库自适应得到语音模型,采用声学模型融合技术构建融合2种发音规律的识别模型。实验结果证明,中国人英语发音的语音识别率提高了13.4%,但标准英语的语音识别率仅下降1.1%。     

发音特征在维汉语音识别中的应用

采用传统谱特征作为输入进行语音识别通常会受到声学环境差异的影响。为此,提出汉语和维语音素和音位的对应规则,并将这种规则应用于基于发音特征的语音识别系统。训练神经网络多层感知器,获取语音信号各类发音特征的后验概率,将其与美尔频率倒谱系数(MFCC)拼接后送入隐马尔科夫模型进行声学模型训练。将不同发音特征分别与传统MFCC特征进行组合并给出测试结果。实验结果表明,当汉语声带状况和送气发音特征与传统MFCC组合时,以及维语的发音方式和声带状况特征与MFCC组合之后,系统误识率较低。     

基于UBM的发音质量评价算法

将已经成功应用到说话人识别/确认领域中的高斯混合模型和全局背景模型(UBM)引入语音发音质量评价领域,提出一种新的评价英语发音质量的算法。该算法训练出标准发音的全局背景模型。UBM模型描述与音素无关的特征分布,定义段时长归一化的相似度比例对数为音素的发音质量分数,综合得到整句发音的评分结果。实验证明,在实验室自行采集的非母语语音数据库上,该算法评分与专家评分的相关性达到了0.700,优于其他评分算法。     

Multilingual recognition of non-native speech using acoustic model transformation and pronunciation modeling

This article presents an approach for the automatic recognition of non-native speech. Some non-native speakers tend to pronounce phonemes as they would in their native language. Model adaptation can improve the recognition rate for non-native speakers, but has difficulties dealing with pronunciation errors like phoneme insertions or substitutions. For these pronunciation mismatches, pronunciation modeling can make the recognition system more robust. Our approach is based on acoustic model transformation and pronunciation modeling for multiple non-native accents. For acoustic model transformation, two approaches are evaluated: MAP and model re-estimation. For pronunciation modeling, confusion rules (alternate pronunciations) are automatically extracted from a small non-native speech corpus. This paper presents a novel approach to introduce confusion rules in the recognition system which are automatically learned through pronunciation modelling. The modified HMM of a foreign spoken language phoneme includes its canonical pronunciation along with all the alternate non-native pronunciations, so that spoken language phonemes pronounced correctly by a non-native speaker could be recognized. We evaluate our approaches on the European project HIWIRE non-native corpus which contains English sentences pronounced by French, Italian, Greek and Spanish speakers. Two cases are studied: the native language of the test speaker is either known or unknown. Our approach gives better recognition results than the classical acoustic adaptation of HMM when the foreign origin of the speaker is known. We obtain 22% WER reduction compared to the reference system.     

Study on pharyngeal and uvular consonants in foreign accented Arabic for ASR

This paper investigates the unique pharyngeal and uvular consonants of Arabic from the point of view of automatic speech recognition (ASR). Comparisons of the recognition error rates for these phonemes are analyzed in five experiments that involve different combinations of native and non-native Arabic speakers. The most three confusing consonants for every investigated consonant are discussed. All experiments use the Hidden Markov Model Toolkit (HTK) and the Language Data Consortium (LDC) WestPoint Modern Standard Arabic (MSA) database. Results confirm that these Arabic distinct consonants are a major source of difficulty for Arabic ASR. While the recognition rate for certain of these unique consonants such as // can drop below 35% when uttered by non-native speakers, there is advantage to include non-native speakers in ASR. Besides, regional differences in pronunciation of MSA by native Arabic speakers require the attention of Arabic ASR research.     

Within-word pronunciation variation modeling for Arabic ASRs: a direct data-driven approach

Pronunciation variation is a major obstacle in improving the performance of Arabic automatic continuous speech recognition systems. This phenomenon alters the pronunciation spelling of words beyond their listed forms in the pronunciation dictionary, leading to a number of out of vocabulary word forms. This paper presents a direct data-driven approach to model within-word pronunciation variations, in which the pronunciation variants are distilled from the training speech corpus. The proposed method consists of performing phoneme recognition, followed by a sequence alignment between the observation phonemes generated by the phoneme recognizer and the reference phonemes obtained from the pronunciation dictionary. The unique collected variants are then added to dictionary as well as to the language model. We started with a Baseline Arabic speech recognition system based on Sphinx3 engine. The Baseline system is based on a 5.4 hours speech corpus of modern standard Arabic broadcast news, with a pronunciation dictionary of 14,234 canonical pronunciations. The Baseline system achieves a word error rate of 13.39%. Our results show that while the expanded dictionary alone did not add appreciable improvements, the word error rate is significantly reduced by 2.22% when the variants are represented within the language model.     

基于praat软件的俄语读音分析

用语音合成与分析软件praat分析了中国学生俄语读音的一些特点。通过对语音信号的波形图、语图谱、基音、共振峰、音高、音强等声学特性的分析,研究了中国学生在音素、音节、重音、音调、节奏、语调等方面存在的差异,为纠正其不良的发音、读句习惯提供技术帮助。     

Automatic pronunciation scoring of words and sentences independent from the non-native’s first language

This paper describes an approach for automatic scoring of pronunciation quality for non-native speech. It is applicable regardless of the foreign language student’s mother tongue. Sentences and words are considered as scoring units. Additionally, mispronunciation and phoneme confusion statistics for the target language phoneme set are derived from human annotations and word level scoring results using a Markov chain model of mispronunciation detection. The proposed methods can be employed for building a part of the scoring module of a system for computer assisted pronunciation training (CAPT). Methods from pattern and speech recognition are applied to develop appropriate feature sets for sentence and word level scoring. Besides features well-known from and approved in previous research, e.g. phoneme accuracy, posterior score, duration score and recognition accuracy, new features such as high-level phoneme confidence measures are identified. The proposed method is evaluated with native English speech, non-native English speech from German, French, Japanese, Indonesian and Chinese adults and non-native speech from German school children. The speech data are annotated with tags for mispronounced words and sentence level ratings by native English teachers. Experimental results show, that the reliability of automatic sentence level scoring by the system is almost as high as the average human evaluator. Furthermore, a good performance for detecting mispronounced words is achieved. In a validation experiment, it could also be verified, that the system gives the highest pronunciation quality scores to 90% of native speakers’ utterances. Automatic error diagnosis based on a automatically derived phoneme mispronunciation statistic showed reasonable results for five non-native speaker groups. The statistics can be exploited in order to provide the non-native feedback on mispronounced phonemes.     

一个面向语音识别的云南民族口音普通话语音数据库

介绍了一个以语音识别为目的的云南民族口音普通话语音数据库。当前，语音识别技术要走向实用必须解决用户情况多样性带来的鲁棒性问题，通常把这个问题简要地归结为“男女老幼”和“南腔北调”。作为民族文化大省的云南，共有25个少数民族，广大少数民族同胞在说普通话时明显带有地方民族口音，云南民族口音普通话语音识别研究是用户情况多样性研究的重要内容，而为之建立云南民族口音普通话语音数据库是该研究的重要基础和先决条件。