声纹鉴定的应用研究

利用KAY5500语图仪的各项功能及这些功能对语音研究的作用,研究语音的声学特征,探讨语音同一认定的原理、方法,及声谱图反映出的表征语音声学特性的各声纹特征在声纹鉴定中价值。     

声纹鉴定中的音强特征研究

目的 确定声纹鉴定中的音强特征的应用价值.方法 将10名条件相近、普通话较标准的男性发音人的语音样本输入VS-99型语音工作站,分别对每个人所发的相同音节韵母的宽带声纹图谱进行分析比对.结果 不同人发出的相同音节,其音强分布一般不同,有时还会出现明显的差异,主要表现在韵母总体音强按频率分布状态、韵母总体音强按时间分布状...     

声纹鉴定的证据属性分析

声纹是指用声学仪器显示出来的携带语言信息的声波频谱图,人们比照指纹形象地把声波频谱图称为声纹。声纹鉴定技术是根据声纹学的科学原理,运用声谱仪(亦称“声谱分析仪”)认定人身异同的一种科学鉴定技术。在刑事司法领域,通过声学仪器对犯罪人与嫌疑人声纹进行比较鉴定,可以得出认定是否同一的结论。声纹鉴定是将现代科技手段用于司法实践,为迅速发现犯罪、查明证实犯罪嫌疑人起到了独特的作用。     

不同手机及不同通信网络通话录音质量评析

目的为送检手机通话录音质量的审查提供理论依据。方法提出一种定量化的语音检材质量评价标准,并对不同手机及不同通信网络下的录音进行质量评价。该标准基于主流鉴定设备,涵盖了声学语谱图共振峰个数及数值、基频参数、区域平均频谱等分析方法以及声纹比对测试。结果实验结果显示,不同条件下得到的通话录音质量存在一定的差异性,会对声纹图谱鉴定产生一定影响,但并不会造成本质性差异。结论语音同一认定中,对基于移动通信网络获取的检材录音应考虑到通话语音质量的差异性对检验的影响,并在鉴定分析中加以评估和克服。     

电子伪装语音的变声规律研究

本文以目前社会上流行的两款不同类别的电子伪装语音器材为对象,对多名实验对象变声前、后的声学特征(基频、共振峰、声调、能量和过零率等)进行了深入的实验分析。实验结果和分析表明,变声相对于原声,其声学特征变化是有规律的,根据这一声学特征变化规律,对变声语音逆变声就能得到与原声符合很好的恢复语音,这为深入开展对经过电子伪装的语音进行同一人鉴定奠定了基础。     

电子伪装语音的变声规律研究

本文以目前社会上流行的两款不同类别的电子伪装语音器材为对象,对多名实验对象变声前、后的声学特征（基频、共振峰、声调、能量和过零率等）进行了深入的实验分析。实验结果和分析表明,变声相对于原声,其声学特征变化是有规律的,根据这一声学特征变化规律,对变声语音逆变声就能得到与原声符合很好的恢复语音,这为深入开展对经过电子伪装的语音进行同一人鉴定奠定了基础。     

正常、大声两种说话状态下语音的声学差异及对声纹鉴定的影响

本文主要通过对正常、大声两种说话状态下的普通话中三个单元音[a]、[i]、[u]的声强、时长、基频、谐波振幅差值、共振峰等声学参数的分析,综合比较了各参数的变化规律,发现大声说话时的语音并非正常语音的简单放大,二者不仅在声强上存在差别,同时在频率域上也发生了重要变化。同一人不同状态下发音的频谱特征差异性较大,同种状态下发音的相似性、可比性较强,为此,声纹鉴定中应尽量选取状态相同的语音进行比对。     

白噪声不同信噪比对语音基音和共振峰的影响研究

目的研究不同强度白噪声对语音特征提取的影响,总结变化规律,为带噪语音的声纹鉴定提供参考。方法对TIMIT连续语音语料库中的录音样本加载不同强度白噪声,使用语音工作站提取纯净语音、不同信噪比带噪语音的基频、共振峰,研究分析白噪声对语音特征参数的影响。结果低噪环境下,语音共振峰相对稳定,增大噪声强度,共振峰出现偏移或者无法检出现象;各阶共振峰抗噪能力不同,低阶共振峰抗噪声能力强,稳定度高,高阶共振峰抗噪能力弱,稳定性差,低阶共振峰抗噪能力优于高阶共振峰;基音在各种噪声强度下稳定度高,具备较强鲁棒性。结论信噪比降低会引起共振峰频率偏移,甚至丢失共振峰;噪声对高阶共振峰影响大于低阶共振峰;基频在噪声环境下具备较高的抗干扰能力,声纹鉴定中应重点分析噪声对语音特征的影响。     

听辨在声纹鉴定中的作用

目的对言语特征进行研究,扩大声纹鉴定的应用范围。方法分析当前声纹鉴定的技术方法,汇总听辨结合的几种方法,找出听辨结合的关键点。结果对以往的鉴定经验和教训进行归纳总结,改进现有的鉴定模式和理念,使其贴近实战、贴近案件需求。     

正常、大声两种说话状态下语音的声学差异及对声纹鉴定的影响

本文主要通过对正常、大声两种说话状态下的普通话中三个单元音[a]、[i]、[u]的声强、时长、基频、谐波振幅差值、共振峰等声学参数的分析,综合比较了各参数的变化规律,发现大声说话时的语音并非正常语音的简单放大,二者不仅在声强上存在差别,同时在频率域上也发生了重要变化。同一人不同状态下发音的频谱特征差异性较大,同种状态下发音的相似性、可比性较强,为此,声纹鉴定中应尽量选取状态相同的语音进行比对。     

Root Morphology and Anatomical Patterns in Forensic Dental Identification: A Comparison of Computer‐Aided Identification with Traditional Forensic Dental Identification*

Abstract: An online forensic dental identification exercise was conducted involving 24 antemortem–postmortem (AM–PM) dental radiograph pairs from actual forensic identification cases. Images had been digitally cropped to remove coronal tooth structure and dental restorations. Volunteer forensic odontologists were passively recruited to compare the AM–PM dental radiographs online and conclude identification status using the guidelines for identification from the American Board of Forensic Odontology. The mean accuracy rate for identification was 86.0% (standard deviation 9.2%). The same radiograph pairs were compared using a digital imaging software algorithm, which generated a normalized coefficient of similarity for each pair. Twenty of the radiograph pairs generated a mean accuracy of 85.0%. Four of the pairs could not be used to generate a coefficient of similarity. Receiver operator curve and area under the curve statistical analysis confirmed good discrimination abilities of both methods (online exercise = 0.978; UT‐ID index = 0.923) and Spearman’s rank correlation coefficient analysis (0.683) indicated good correlation between the results of both methods. Computer‐aided dental identification allows for an objective comparison of AM–PM radiographs and can be a useful tool to support a forensic dental identification conclusion.     

Testing the reliability of frontal sinuses in positive identification

The use of frontal sinus radiographs in positive identification has become an increasingly applied and accepted technique among forensic anthropologists, radiologists, and pathologists. From an evidentiary standpoint, however, it is important to know whether frontal sinus radiographs are a reliable method for confirming or rejecting an identification, and standardized methods should be applied when making comparisons. The purpose of the following study is to develop an objective, standardized comparison method, and investigate the reliability of that method. Elliptic Fourier analysis (EFA) was used to assess the variation in 808 outlines of frontal sinuses by calculating likelihood ratios and posterior probabilities from EFA coefficients. Results show that using EFA coefficient comparison to estimate the probability of a correct identification is a reliable technique, and EFA comparison of frontal sinus outlines is recommended when it may be necessary to provide quantitative substantiation for a forensic identification based on these structures.     

红外光谱法用于安钠咖中咖啡因和苯甲酸钠快速定性和定量分析

目的建立安钠咖样品中咖啡因和苯甲酸钠快速定性和定量分析的红外光谱方法。方法采用高纯度咖啡因和苯甲酸钠混合制样的方法制备定性和定量建模样品,通过分析混合样品的红外光谱图,确定安钠咖样品中咖啡因和苯甲酸钠的特征吸收峰。采用偏最小二乘法(partial least squares,PLS)建立红外光谱定量模型。结果通过分析17个咖啡因和苯甲酸钠混合样品(咖啡因纯度范围10%~80%)的红外光谱图,确定了咖啡因的特征吸收峰为1698、1650、1237、972、743、609cm-1;苯甲酸钠的特征吸收峰为1596、1548、1406、845、708、679cm-1。将所有特征吸收峰均检出作为阳性判断依据时,48个安钠咖缴获样品中咖啡因和苯甲酸钠的阳性检出率均为100%。咖啡因PLS定量模型的线性范围为10%~80%,决定系数(R2)为99.9%,交叉验证均方差(root mean square error of cross validation,RMSECV)为0.68%,预测均方差(root mean square error of prediction,RMSEP)为0.91%;苯甲酸钠PLS定量模型的线性范围为20%~90%,R2为99.9%,RMSECV为0.91%,RMSEP为1.11%。配对样本t检验结果显示,高效液相色谱法和红外光谱法的测定结果差异无统计学意义。采用所建立的红外定量方法分析48个安钠咖缴获样品,咖啡因的纯度为27.6%~63.1%,苯甲酸钠的纯度为36.9%~72.3%。结论采用红外光谱法对安钠咖样品中的咖啡因和苯甲酸钠进行快速定性和定量分析,可提高检验鉴定效率、降低检验成本。     

Indication and limitations of using palatal rugae for personal identification in edentulous cases

To explore the availability and the limitations of using the palatal rugae pattern in forensic practice for personal identification in edentulous cases, we set up an experiment, which involved 48 patients who had both old and new complete dentures and we observed their rugae. First, we made 48 pairs of maxillary casts from their old and new dentures and a further 50 maxillary casts from complete dentures at random, to use as variables. All the initial impressions taken from the mucosal surfaces of complete dentures were made from alginate impression materials, and the maxillary casts were made from hard dental plaster. Secondly, all 146 casts were trimmed so that all the areas except for the rugae area were removed. Subsequently, 50 examiners were given the 48 casts from the old dentures and were then asked to compare them with the other 98 casts for possible matches. The case numbers, which matched correctly, were recorded. The median percentage of correct matches among the 50 examiners was 94%, despite variations in their experience with forensic identification, and this accuracy does not differ significantly from that in dentate cases, as described in previous publications. The median percentage of correct matches among the 48 cases was 90%. Analyzing the incidence of obtaining a correct match in each case revealed that there were three major misleading shapes that could give rise to a low rate of correct matches; (1) severely low and poorly demarcated eminences of rugae, (2) change of palatal height, and (3) non-complex rugae pattern. These features are mainly due to the shape of the edentulous palate itself and rarely due to the dentures, and could lead to difficulties in finding unique points for use in matching rugae patterns. The results suggest that an appropriate selection of cases, taking into consideration the above misleading shapes, may establish an increased rate of accuracy for identification with this method, thereby bringing the percentage of correct matches closer to 100% in edentulous cases, which is also the percentage of correct matches previously reported in dentate cases.     

The Culprit in Target-Absent Lineups: Understanding Young Children’s False Positive Responding

Young children (4- to 7-years old; N = 59) and adults (N = 53) were shown a series of targets that were either familiar (i.e., popular cartoon characters) or unfamiliar (unknown human faces) to assess whether children’s false positive responding with target-absent lineups is driven by social factors to a greater degree than cognitive factors. Although children were able to produce correct identification rates with virtually 100% accuracy for the cartoon characters, they produced a significantly lower correct rejection rate compared to adults. Children also produced a significantly lower correct rejection rate for the human faces compared to adults. These data are discussed for understanding children’s identification evidence.     

The Reliability of Visually Comparing Small Frontal Sinuses*

Abstract: Several studies have investigated frontal sinus comparison for personal identification. One study addressed the statistical reliability of correct identification using automated digital methods and resulted in a 96% accuracy rate. Missed matches with the digital methods generally involved small, less featured sinuses. This study investigates the hypothesis that human examiners may be able to more accurately identify correct matches than digital methods, even when the comparisons involve small frontal sinuses. Participants were provided two sets of 28 radiographs and were instructed to identify matching radiographs and list the radiographs that did not have a corresponding match. Overall, error rates were low, with correct associations identified at a rate of 0.983. No incorrect associations (“false positives”) were made. Correct association rates were highest among participants “experienced” examining radiographs. Results support previous assertions that frontal sinus radiographs are a reliable means of personal identification even when the frontal sinuses are small.     

Identification Accuracy of Children versus Adults: A Meta-Analysis

Identification accuracy of children and adults was examined in a meta-analysis. Preschoolers (M = 4 years) were less likely than adults to make correct identifications. Children over the age of 5 did not differ significantly from adults with regard to correct identification rate. Children of all ages examined were less likely than adults to correctly reject a target-absent lineup. Even adolescents (M = 12–13 years) did not reach an adult rate of correct rejection. Compared to simultaneous lineup presentation, sequential lineups increased the child–adult gap for correct rejections. Providing child witnesses with identification practice or training did not increase their correct rejection rates. Suggestions for children's inability to correctly reject target-absent lineups are discussed. Future directions for identification research are presented.     

Reliability of Craniofacial Superimposition Using Three‐Dimension Skull Model

Craniofacial superimposition is a technique potentially useful for the identification of unidentified human remains if a photo of the missing person is available. We have tested the reliability of the 2D‐3D computer‐aided nonautomatic superimposition techniques. Three‐dimension laser scans of five skulls and ten photographs were overlaid with an imaging software. The resulting superimpositions were evaluated using three methods: craniofacial landmarks, morphological features, and a combination of the two. A 3D model of each skull without its mandible was tested for superimposition; we also evaluated whether separating skulls by sex would increase correct identifications. Results show that the landmark method employing the entire skull is the more reliable one (5/5 correct identifications, 40% false positives [FP]), regardless of sex. However, the persistence of a high percentage of FP in all the methods evaluated indicates that these methods are unreliable for positive identification although the landmark‐only method could be useful for exclusion.     

似然比在法庭说话人确认中的应用

本文把成功应用于DNA检验的证据评估方法（似然比）应用于法庭语音证据评估之中,提取语音的LPC作为识别特征,并使用45人电话对话录音中元音/a/作为样本进行了测试。结果表明该方法不仅能正确识别说话人,而且能根据当前嫌疑人样本和问题语音样本的差异,量化该语音样本作为证据的力度,为法庭提供科学合理的证据评估结果和科学解释。同时,自动特征提取的引入比起人工提取共振峰特征,提高了工作效率,识别系统性能也获得大幅提升。     

HLA-A基因座多态性在亲子鉴定中的应用研究

首次将HLA A基因座的聚合酶链反应 寡核苷酸探针 (PCR SSOP)杂交分型技术应用于亲子鉴定案例分析 ,以获得HLA A基因座多态性用于法医学鉴定分析的基础数据。HLA A基因座基因分型的等位基因检出率 ( 2 4个 )和非父排除率 ( 73 3 % )均高于血清学检测方法 ;正常家系分析结果符合孟德尔遗传规律。对 3 9个亲子鉴定例的成员进行HLA A基因检测 ,9例排除 ( 2 3 1% ) ;未排除的 3 0例的亲子关系概率在 65 2 %～ 99 5 %之间。用PCR SSOP技术对HLA基因座基因分型不仅可以应用于亲子鉴定和法医学个人识别 ,还可以应用于器官移植配型及人类遗传学研究。