Objective acoustic voice-quality parameters in the computer phonetogram

A phonetogram is a plot of the dynamic range of the voice as a function of fundamental frequency. Traditionally, the phonetogram only records the sound-pressure level (SPL) of the threshold of phonation and the upper limit in SPL the voice can reach with sustained phonation as a function of the fundamental frequency (F₀). In this study, the phonetogram is extended by including acoustic voice-quality parameters. Three additional parameters are tested: jitter, shimmer, and crest factor. For each individual voice, the variation in the three parameters is evaluated over the entire phonetogram area. By averaging individual phonetograms, standard or norm phonetograms are obtained revealing general patterns in voice-quality variation. These patterns reflect the complex relations between F₀, SPL, and the acoustic voice-quality parameters just mentioned. Jitter and shimmer distributions over the phonetogram show that large variations in perturbation values can be expected when production conditions are altered. Highest perturbation values are found for the low F₀ and low SPL phonations. For all voices, a gradual decrease of the crest factor is found with increasing F₀, reflecting the degrading of spectral complexity with F₀. The crest-factor parameter can also be used to mark those areas in the phonetogram where the fundamental dominates the waveform and where flow control is the main SPL regulating mechanism in voice production. The strong quality variations within the phonetogram stress the need for accurate control of F₀ and SPL in objective voice-quality measurement.     

General study of jitter mechanisms for metric-based wireless routing protocols

To ameliorate high collision, a nefarious side effect of route discovery stage of reactive routing protocols in wireless networks, jitter mechanisms are proposed which enforce wireless nodes to postpone their transmission for a random amount of time so as to reduce probability of simultaneous transmission. Although it has been shown that jitter mechanisms can dramatically improve reactive routing protocols, it was not until recently that jitter mechanisms have been subjected to study. In this paper, different random distributions are proposed for jittering mechanisms and also shaping function, with the aim of which a simple routing protocol like AODV becomes sensitive to any arbitrary metric, is defined. Comprehensive simulation of routing metrics and jitter mechanisms have revealed that simple modification of a jitter mechanism, which can be even implemented independent of a routing protocol, greatly improves routes discovered by any routing protocol.     

Jitter tolerance calibration for high-speed serial interfaces

A jitter tolerance calibration test bench suitable for high speed serial interfaces (HSSI) using verilog-AMS is proposed in this paper. The jitter tolerance simulation environment can be easily parameterized in order to be compliant to any HSSI standard specification. As an example, the proposed solution is applied for the jitter tolerance simulation and characterization of the most updated M-PHY ver.3 HSSI standard for mobile applications. A comprehensive method for the calculation of the jitter noise frequency ingredients and the calibration of jitter noise sources is also proposed resulting a jitter tolerance mask compliant with the M-PHY ver.3 specifications. Using the proposed implementation the transistor level and behavioral modules co-simulation time could be significantly minimized.     

激光触发多级多通道开关研究

 研究了200kV激光触发多级多通道开关的运行机理，该开关在直流电压下以四倍频Nd:YAG激光器为触发源进行的实验结果表明：开关触发延迟时间及其抖动随开关电压、激光能量和充气压力上升呈指数下降趋势，对混合气体则随气体密度上升而上升。随透镜焦距的增大延迟时间及其抖动呈上升趋势。该开关实现了多通道放电。     

Acoustic Analysis Findings in Objective Laryngopharyngeal Reflux Patients

OBJECTIVE: The aim of this study was to identify the effects of objective laryngopharyngeal reflux (LPR) on the acoustic parameters of patients by comparing their voice samples with that of control subjects. STUDY DESIGN: Prospective study in two tertiary reference hospitals. METHODS: 48 consecutive patients with symptoms related to LPR and 64 control subjects were included in the study. Suspected LPR patients underwent a 24-hour ambulatory pH monitoring, and 25 (52%) of them were shown to have objective LPR. Acoustical evaluation results of objective LPR patients were compared with that of symptomatic LPR patients and control subjects. RESULTS: All frequency perturbation values obtained from objective and symptomatic LPR patients were higher than the control subjects (P<0.01). Mean fundamental frequency, amplitude perturbation measures, and noise-to-harmonics ratio were not significantly different between groups. CONCLUSION: LPR patients have significantly different frequency perturbation values than control subjects.     

The dual-edge alignment technique with improved spur reduction effects in ring oscillators

In this paper, the technique of dual-edge phase-alignment and its effects on ring oscillators are presented. This technique provides resetting of the built-up jitter at both rising and falling edges of a clean aligning signal named as the reference. Using signals and systems theory, the effect of the technique on the spurs due to the aligning reference signal is completely analyzed. We show that adding properly the dual-edge aligning feature to phase-aligned ring oscillators cause the spurs in the neighborhood of the carrier to disappear. First, the validity of the results obtained from the derived analytical equations is verified through simulations using MATLAB. Then a complete circuit considering realistic models for its components is simulated in TSMC RF CMOS 0.18um process using ADS for further validation.     

Heartbeat-related fundamental frequency and amplitude variation in healthy young and elderly male voices

Modulation of the acoustic amplitude and fundamental frequency of a sustained vowel across the heart cycle was examined via signal-averaging. Ten normal young and ten normal elderly men prolonged phonations of the vowel /a/. Consistent with previous studies, the young men's maximal heart-beat-related frequency and amplitude variations averaged 1.0% and 8.4% of their respective means. Such modulation was estimated to account for 6.6% of the absolute jitter and 11.3% of the shimmer measured in these voice samples. The extent of this systematic variation was significantly greater in the older voices, averaging 2.4% of the mean frequency and 15.4% of the mean amplitude and was estimated to account for approximately 12.9% and 15.8% of their mean absolute jitter and shimmer, respectively. This age-related difference is thought to be a manifestation of involutional changes in laryngeal vascular and soft tissues and in ventilatory biomechanics.     

Influence of Data Acquisition Environment on Accuracy of Acoustic Voice Quality Measurements

Accuracy of acoustic voice analysis is influenced by the quality of recording. Lately, articles have suggested that soundcards perform equivalently to specialized professional-grade data acquisition (DA) systems. The purpose of this study was to investigate the influence of DA environment (DA system and microphone) on acoustic voice quality measurement (VQM) while balancing for gender, age, intersubject and intrasubject variability, and analysis software. More specifically, the relative performance of different hardware environments and the relationship between their technical characteristics and VQM performance was investigated. The discretization error and the effective dynamic range of the different DA environments were measured. We used 3 software systems to record and measure separately 2000 acoustic samples of sustained phonation for fundamental frequency, jitter, and shimmer. Analyses of variance (ANOVA) were performed with these parameters as the dependent variables. The results of the study suggested that professional-grade DA hardware is strongly recommended to provide accurate and valid voice assessment. The fundamental frequency measurement differences across DA environments were highly correlated to the discretization error (r=1.00), whereas jitter and shimmer were highly correlated to the effective dynamic range of the DA environments (r=-0.68 and r=-0.86, respectively).     

一种数据时钟恢复电路的研究与设计

提出了一种支持双数据率的数据时钟恢复电路,对电路中的鉴相器、环路滤波器、压控振荡器等进行了详细的分析研究和设计.基于0.18μm CMOS工艺,在电源电压1.8V下对电路进行仿真.仿真结果显示,电路在2.7 Gb/s和1.62 Gb/s随机流下的抖动峰峰值分别为14 ps和12ps,功耗为80 mW.测试结果显示,时钟恢复电路在2.7 Gb/s和1.62 Gb/s随机流下的抖动峰峰值分别为38 ps和27 ps.