Investigation of vocal jitter and glottal flow spectrum as possible cues for depression and near-term suicidal risk

Among the many clinical decisions that psychiatrists must make, assessment of a patient's risk of committing suicide is definitely among the most important, complex, and demanding. When reviewing his clinical experience, one of the authors observed that successful predictions of suicidality were often based on the patient's voice independent of content. The voices of suicidal patients judged to be high-risk near-term exhibited unique qualities, which distinguished them from nonsuicidal patients. We investigated the discriminating power of two excitation-based speech parameters, vocal jitter and glottal flow spectrum, for distinguishing among high-risk near-term suicidal, major depressed, and nonsuicidal patients. Our sample consisted of ten high-risk near-term suicidal patients, ten major depressed patients, and ten nondepressed control subjects. As a result of two sample statistical analyses, mean vocal jitter was found to be a significant discriminator only between suicidal and nondepressed control groups (p < 0.05). The slope of the glottal flow spectrum, on the other hand, was a significant discriminator between all three groups (p < 0.05). A maximum likelihood classifier, developed by combining the a posteriori probabilities of these two features, yielded correct classification scores of 85% between near-term suicidal patients and nondepressed controls, 90% between depressed patients and nondepressed controls, and 75% between near-term suicidal patients and depressed patients. These preliminary classification results support the hypothesized link between phonation and near-term suicidal risk. However, validation of the proposed measures on a larger sample size is necessary.     

建声条件是决定语言可懂度优劣的主要因素

语言可懂度对专业扩声工程来说是一个重要的特性指标,特别是对公共广播系统工程,语言可懂度特性指标更是系统等级界定的重要依据.决定语言可懂度的因素有很多,那什么是影响语言可懂度的主要因素呢？是建声条件、环境噪声还是系统频响或失真？对同一个扩声系统在多个场所、不同的条件下的语言可懂度进行测量,通过实验的方法来研究和探讨什么是影响扩声系统工程语言可懂度的主要因素,并得出结论.     

Acoustical signal properties for cardiac/respiratory activity and apneas

Traditionally, auscultation is applied to the diagnosis of either respiratory disturbances by respiratory sounds or cardiac disturbances by cardiac sounds. In addition, for sleep apnea syndrome diagnosis, snoring sounds are also monitored. The present study was aimed at synchronous detection of all three sound components (cardiac, respiratory, and snoring) from a single spot. The sounds were analyzed with respect to the cardiorespiratory activity, and to the detection and classification of apneas. Sound signals from 30 subjects including 10 apnea patients were detected by means of a microphone connected to a chestpiece which was applied to the heart region. The complex nature of the signal was investigated using time, spectral, and statistical approaches, in connection with self-defined time-based and event-based characteristics. The results show that the obstruction is accompanied by an increase of statistically relevant spectral components in the range of 300 to 2000 Hz, however, not within the range up to 300 Hz. Signal properties are discussed with respect to different breathing types, as well as to the presence and the type of apneas. Principal component analysis of the event-based characteristics shows significant properties of the sound signal with respect to different types of apneas and different patient groups, respectively. The analysis reflects apneas with an obstructive segment and those with a central segment. In addition, aiming for an optimum detection of all three sound components, alternative regions on the thorax and on the neck were investigated on two subjects. The results suggest that the right thorax region in the seventh intercostal space and the neck are optimal regions. It is concluded that for patient assessment, extensive acoustic analysis offers a reduction in the number of required sensor components, especially with respect to compact home monitoring of apneas.     

Evaluating satellite and climate data-derived indices as fire risk indicators in savanna ecosystems

The repeated occurrence of severe wildfires has highlighted the need for development of effective vegetation monitoring tools. We compared the performance of indices derived from satellite and climate data as a first step toward an operational tool for fire risk assessment in savanna ecosystems. Field collected fire activity data were used to evaluate the potential of the normalized difference vegetation index (NDVI), normalized difference water index (NDWI), and the meteorological Keetch-Byram drought idex (KBDI) to assess fire risk. Performance measures extracted from the binary logistic regression model fit were used to quantitatively rank indices in terms of their effectiveness as fire risk indicators. NDWI performed better when compared to NDVI and KBDI based on the results from the ranking method. The c-index, a measure of predictive ability, indicated that the NDWI can be used to predict seasonal fire activity (c=0.78). The time lag at the start of the fire season between time-series of fire activity data and the selected indices also was studied to evaluate the ability to predict the start of the fire season. The results showed that NDVI, NDWI, and KBDI can be used to predict the start of the fire season. NDWI consequently had the highest capacity to monitor fire activity and was able to detect the start of the fire season in savanna ecosystems. It is shown that the evaluation of satellite- and meteorological fire risk indices is essential before the indices are used for operational purposes to obtain more accurate maps of fire risk for the temporal and spatial allocation of fire prevention or fire management.     

Some algebraic properties of speech signals

Although the set of all recognizable speech signals is not closed under superposition, certain subsets are found experimentally to have vector space properties, and hence may be discriminated by means of annihilation transforms. Experimental results are described for speech phoneme discrimination using time-domain annihilation filters.     

Detection of clinical depression in adolescents' speech during family interactions

The properties of acoustic speech have previously been investigated as possible cues for depression in adults. However, these studies were restricted to small populations of patients and the speech recordings were made during patients' clinical interviews or fixed-text reading sessions. Symptoms of depression often first appear during adolescence at a time when the voice is changing, in both males and females, suggesting that specific studies of these phenomena in adolescent populations are warranted. This study investigated acoustic correlates of depression in a large sample of 139 adolescents (68 clinically depressed and 71 controls). Speech recordings were made during naturalistic interactions between adolescents and their parents. Prosodic, cepstral, spectral, and glottal features, as well as features derived from the Teager energy operator (TEO), were tested within a binary classification framework. Strong gender differences in classification accuracy were observed. The TEO-based features clearly outperformed all other features and feature combinations, providing classification accuracy ranging between 81%-87% for males and 72%-79% for females. Close, but slightly less accurate, results were obtained by combining glottal features with prosodic and spectral features (67%-69% for males and 70%-75% for females). These findings indicate the importance of nonlinear mechanisms associated with the glottal flow formation as cues for clinical depression.     

声学工程的施工与管理

一些与建筑声学密切相关的工程，例如广播电台、电视台、音乐厅、剧院。电影院和礼堂等，要想得到良好的音质效果，除了在设计阶段作出精心设计和计算外，更为重要的是在声学装修阶段，如何去确保设计方案的正确实施。声学工程是一种与建筑及结构有密切联系的综合性的专业，它在工艺上既要达到精细和美观的效果，又要满足设计的各项声学技术指标，其施工难度相对比其它工程要大得多。要实现设计和使用目标，关键在于施工的组织与管理。根据十多年的专业施工实践，总结出以下四项具体做法。1对施Xi项目进行组织设计为了保证每项工程能按质、…     

水下目标声图像特征分析与二次处理

水声环境极其复杂,多途、混响等因素对水中传播的声信号造成的畸变,使得水下目标声成像的分辨率和清晰度受到很大影响。在总结水声目标声图像特征的基础上,深入开展了水声目标图像增强、图像处理的研究,主要内容包括:水声目标图像特征分析、目标图像的二次处理方法、图像处理仿真研究等内容。在图像增强处理的过程中,采用Sobel算子、Prewitt算子、LOG算子和Canny算子。仿真结果显示处理后的水声图像其轮廓比较清晰,图像质量得到了改善,为鱼雷通过图像识别目标要害部位并实施精确打击奠定了基础。     

扬声器胶粘剂接口的声音质量和锥盆处理

【编译者说明】《电声技术》杂志1999年12期刊登了笔者编译的美国扬声器专家Mike Klasco的《扬声器粘合面的声学特性概述》一文。现在,原作者又在美国《AudioXpress》杂志2012年第5期上更广泛深入地谈了这个问题。因1999年刊发的文章实用性强,颇受欢迎,故将新篇也译出,供有兴趣的读者参考。     

Electrical measurements as early indicators of electromigration failure

Detailed results and analysis are given of several electrical parameters measured, at room temperature, at intervals during electromigration stress of A1 4% Cu specimens. The trends of the resistance, second harmonic and electrical noise changes are good indicators of the degradation until near the end of the life when the specimen becomes very variable in its properties.     

基于最小统计量和掩蔽效应的单通道语音增强

利用人耳感知的掩蔽特性，并结合含噪语音能量的最小统计量估计，提出了一种低信噪比下的单通道语音增强算法。该算法对原始语音在Bark频带能量的最小统计量进行估计，从而准确估计含噪语音信噪比，再从感知的角度，在时域和Bark频域上合理调整增强系数，以实现语音增强的目的。实验表明，该增强算法能够在减小语音失真的同时，很好地抑制背景噪声和残余音乐噪声。     

The acoustic properties of SCBA equipment and its effects on speech communication

In assessing system requirements for effective communication in public safety applications, a number of challenges exist. The Self-Contained Breathing Apparatus (SCBA) mask air-delivery system is essential equipment in certain public service activities, mainly firefighting and HAZ-MAT (hazardous materials) operations. It is important that high-quality and reliable communications are maintained when SCBA equipment is employed. An SCBA mask encloses the face and mouth, which alters articulation and distorts the speech spectrum. SCBA system noises such as alarms and air-regulator noise, in addition to environmental noises, add to the deterioration of speech quality in an SCBA-fronted communication system. A digital speech codec adds another potential source of speech distortion and diminished intelligibility when noise-corrupted speech is processed. This article characterizes some of the effects of SCBA equipment on speech quality and intelligibility in the context of a radio communications system and outlines parameters that should be considered in communications system design and interfacing.     

Digital multiplex telephone transmission system using statistical properties of speech

A digital multiplex telephone transmission system is proposed, which should achieve a smaller bandwidth than conventional pulse-code modulation by using the statistical properties of speech waveforms. Each frame of transmitted pulses only contains a coded sample for a channel if the sample differs from the previous one from that channel. The frame can thus contain fewer time slots than there are channels, if there is a high probability of baseband signals changing by less than one quantising level during the frame period.     

评弹演出听闻环境的调查与分析

通过对上海两个典型的评弹书场进行的现场声学参量测试,分析了当前评弹演出环境的现状。根据评弹演奏的特点,针对评弹书场中的主要声学参量进行了研究,提出了其中存在的问题。这项工作将有助于对中国传统民族戏曲表演艺术的最佳演奏和听闻环境的研究。     

维吾尔语音情感声学特征提取与建模研究

在收集较大规模情感语音语料库基础上,分析了维吾尔语语音在韵律特征和音质特征方面的19种语境信息和6种情感特征参数,并利用STRAIGHT算法实现了情感特征参数的提取,最后利用分类回归树（CART）算法针对各个情感特征和中性向其它情感的转换特征进行了建模。实验结果表明,所提取情感特征能准确的区分各个情感类型,为实现中性语音转换成各种目标情感语音奠定了基础。     

TeOx薄膜的结构与声学特性研究

采用射频磁控溅射技术在不同条件、不同基片上制备氧化碲(TeOx)薄膜,并通过X线衍射、傅里叶变换红外光谱、X线光电子能谱等技术对制备的TeOx薄膜的结构和成分进行了分析.研制了TeOx/36°YX-LiTaO3结构的Love波器件,对Love波器件的延时温度系数(TCD)进行研究.结果表明,与36°YX-LiTaO3基片上制作的水平切变声波器件的延时温度系数相比,Love波器件的延时温度系数因TeOx薄膜的沉积而减小,故TeOx薄膜的延时温度系数为负值,其变化量取决于TeOx薄膜的制备条件和薄膜厚度.因此,TeOx/36°YX-LiTaO3结构Love波器件的延时温度系数可通过选择TeOx薄膜的制备条件和膜厚进行优化.     

Quality assessment of speech coding and speech synthesis systems

The concept of speech quality assessment is examined. Quality assessment methodologies for speech waveform coding, source coding, and speech synthesis by rule from the viewpoints of naturalness and intelligibility are reviewed. Both subjective and objective measures are considered     

一种基于听觉掩蔽模型的语音增强算法

本文提出一种基于听觉掩蔽模型的语音增强算法。该算法对应用于语音编码中的听觉掩蔽模型进行了适当的修正，动态地确定第一帧语音信号各个关键频率段的听觉掩蔽阈值，有选择性地进行谱减。计算机仿真表明所提算法优于基本谱减法，不仅信噪比有较大的提高而且有效地减少了主观听觉的失真和残留音乐噪声。     

深圳南山文体中心大剧院音质设计与评价

深圳市南山文体中心大剧院是一座观众厅体积可调的多功能剧院.观众厅具有可调吊顶,可以预设歌舞剧、交响乐和语言三种模式标高.剧院内部根据需要侧墙设有吸声帘幕,舞台上还备有声反射罩.对剧院观众厅做了详细的现场音质测试,并对剧院的音质做出了初步评价.