Effect of Pregnancy on the Speaking Voice

The study aims to investigate the vocal symptoms and acoustic changes in pregnant women pre- and postpartum in comparison to the controls. A total of 25 pregnant women who presented for delivery were enrolled in this study. Twenty-one nonpregnant women were matched as controls. Vocal symptoms such as hoarseness, vocal fatigue, and aphonia were assessed. Acoustic analysis included fundamental frequency (F₀), habitual pitch, relative average perturbation (RAP), shimmer, noise-to-harmony ratio (NHR), and maximum phonation time (MPT). There were no significant differences in the incidence of vocal symptoms in pregnant women versus controls. However, vocal fatigue was more prevalent in the pregnant group. With respect to the acoustic parameters, there was a significant decrease in the MPT at term. The rest of the variables were comparable. Postpartum, the MPT significantly increased and there was an increase in F₀ and a significant decrease in the voice turbulence index (VTI). Pregnant women have more vocal fatigue and a reduction in MPT compared to the controls. Immediately after delivery, there is a significant increase in MPT.     

基于云计算的统一通信警务协同研究与应用

针对统一通信的资金高投入,为了提高统一通信的普及性,提出了托管型统一通信方案;整体方案基于云计算架构,由业务层、呼叫控制层、终端接入层和业务与网络管理层组成,同时分析了统一通信业务,包括基本语音业务、多媒体会议、协同类业务、统一消息、终端业务等;研究了统一通信语音网关,设计中继网关提高组网能力,设计接入网关扩展终端业务;探索了云架构的实现技术,包括P2PSIP技术、虚拟化技术、视频编解码技术等;P2P架构能够使系统动态适应节点失效的情况,提高整个系统的可靠性与鲁棒性;针对线路可提供带宽的不确定性及不稳定性,为保证视频质量,视频会议采用可伸缩视频编码技术;研究成果应用于公安智能警务协同系统,提高了语音系统的用户感知;同时分析了行业现状,展望了未来前景。     

Relationship between subjective voice complaints and acoustic parameters in female teachers'' voices

The aim of the study was to identify the acoustic correlates of female teachers' subjective voice complaints by recording their voices in their working environment. The subjects made recordings during lessons (N = 10) and breaks (N = 11). The subjects were divided into 2 groups: those with few voice complaints (FC group) and those with many voice complaints (MC group). The speech sample made in the breaks was maximally sustained /a/, from which fundamental frequency (F0), jitter, and shimmer were analyzed. The classroom samples were analyzed for F0, sound pressure level (SPL), and F0 time (the active vibration time of the vocal folds). Additionally, an index for assessing voice loading is presented. The results revealed a tendency of the MC group to have higher F0 and lower SPL and perturbation values than the FC group. The index values correlated moderately with the subjective vocal complaints.     

语音编码技术及其硬件实现

压缩编码技术是无线语音通信的关键技术之一。介绍了语音编码技术的基本概念及分类,并选用AMBE多带激励压缩编码算法,通过单片机控制专用语音压缩DSP芯片,提出了一种适合低速无线语音、数据实时通信的系统解决方案,完成了硬件、软件设计,实现了低速率下的语音、数据的同步大气传输。测试结果显示,在语音编码速率为2．4kbps以下时,仍然可以得到音质较好的语音输出。     

线性调频Z变换在舱音背景声的特征频率分析中的应用

舱音背景声特征频率的确定是调查失事飞机事故原因的重要依据之一。基于舱音译码辨听和音频分析的传统方法难以准确获得舱音背景声的特征频率。本文提出采用基于FFT的线性Z变换(CZT)来获取舱音背景声的特征频率的新方法,该方法适用于高采样频率的信号,计算中可以调整频率的分辨率,增加了FFT和频谱分析的灵活性。通过仿真和对用舱音记录器测录的真实舱音背景声计算分析得出:CZT方法是一种适合于确定舱音背景声特征频率的实用、有效方法,用以区分不同舱音在频率上的差别,满足飞机事故原因调查的需要。     

基于人耳听觉模型的自动嗓音评估方法

在嗓音评估系统的长元音谐噪比分析中,针对传统方法在普通傅里叶变换域上进行谐波成分计算并且需要对样本进行人工选择切分的情况,提出了一种新谐噪比计算方法,能够自动切分出长元音中稳定部分,并采用了更贴近人耳听觉模型的时频分析办法,使对长元音的分析能够更稳定更贴近人耳主观听觉.同时由于没有人工干预,使得评估标准更加统一,结果更加客观. 关键词： 嗓音评估 听觉模型 长元音分析 谐噪比计算     

An Exploration of Skin Acceleration Level as a Measure of Phonatory Function in Singing

Two kinds of fluctuations are observed in phonetogram recordings of singing. Sound pressure level (SPL) can vary due to vibrato and also due to the effect of open and closed vowels. Since vowel variation is mostly a consequence of vocal tract modification and is not directly related to phonatory function, it could be helpful to suppress such variation when studying phonation. Skin acceleration level (SAL), measured at the jugular notch and on the sternum, might be less influenced by effects of the vocal tract. It is explored in this study as an alternative measure to SPL. Five female singers sang vowel series on selected pitches and in different tasks. Recorded data were used to investigate two null hypotheses: (1) SPL and SAL are equally influenced by vowel variation and (2) SPL and SAL are equally correlated to subglottal pressure (P(S)). Interestingly, the vowel variation effect was small in both SPL and SAL. Furthermore, in comparison to SPL, SAL correlated weakly to P(S). SAL exhibited practically no dependence on fundamental frequency, rather, its major determinant was the musical dynamic. This results in a non-sloping, square-like phonetogram contour. These outcomes show that SAL potentially can facilitate phonetographic analysis of the singing voice.