Aerodynamic and acoustic characteristics of the adult AfricanAmerican voice

Laryngeal aerodynamic and acoustic characteristics of African American voice production were examined from vowel samples produced by ten adult female and ten adult male speakers. The data were compared with that for a control group consisting of ten adult female and ten adult male White speakers, matched for age, height, and weight. All measures were analyzed using Cspeech 4.0. Aerodynamic measurements, extracted from a glottal airflow waveform, included maximum flow declination rate, alternating glottal airflow, minimum glottal airflow, and airflow open quotient. Acoustic measures included fundamental frequency and sound pressure level. No significant mean differences between the African American and White speakers were found, except for maximum-flow declination rate. The White speakers produced significantly higher declination rates than the African American speakers. The factor of sex for the African American speakers was statistically significant for the measures of maximum-flow declination rate, alternating glottal airflow, open quotient, and fundamental frequency, consistent with the functioning of the White speakers. The results suggest that during vowel production, where the vocal tract is in a fairly static position, acoustic and aerodynamic characteristics for African American and White Speakers are comparable.     

Effects of vocal training on the acoustic parameters of the singing voice

Vocal training (VT) has, in part, been associated with the distinctions in the physiological, acoustic, and perceptual parameters found in singers' voices versus the voices of nonsingers. This study provides information on the changes in the singing voice as a function of VT over time. Fourteen college voice majors (12 females and 2 males; age range, 17–20 years) were recorded while singing, once a semester, for four consecutive semesters. Acoustic measures included fundamental frequency (F₀) and sound pressure level (SPL) of the 10% and 90% levels of the maximum phonational frequency range (MPFR), vibrato pulses per second, vibrato amplitude variation, and the presence of the singer's formant. Results indicated that VT had a significant effect on the MPFR. F₀ and SPL of the 90% level of the MPFR and the 90–10% range increased significantly as VT progressed. However, no vibrato or singers' formant differences were detected as a function of training. This longitudinal study not only validates previous cross-sectional research, ie, that VT has a significant effect on the singing voice, but also it demonstrates that these effects can be acoustically detected by the fourth semester of college vocal training.     

The accent method of voice therapy: Effect of accentuations on FO, SPL, and airflow

The effect of the increased flow rate (ΔU) in response to the Accent Method exercises on fundamental frequency (FO) and sound pressure level (SPL) was studied in three subjects (professionally trained, trained, and untrained in this method). In all the subjects, the rhythmic accentuated exercises produced a variable degree of increase in FO (ΔFO) and SPL (ΔSPL). The professionally trained subject showed greater ΔFO and ΔSPL in response to the ΔU in the fastest tempo, which requires higher skills. Both trained subjects showed a greater correlation between ΔU and both ΔSPL and ΔFO, as well as between ΔFO and ΔSPL, as compared to the untrained subject. The effects of the accentuated exercises on FO and SPL in response to the increased airflow rate (ΔU) thus appear to demonstrate the treating effectiveness of the Accent Method.     

基于无线传输的车载温湿度测量系统设计

为了克服传统温湿度静态点测量的局限性大、灵活性差的问题,设计了一种基于无线传输的车载温湿度测量系统;用户通过计算机来无线遥控小车,可以进行人体无法进入或带有危险性质场所的温湿度测量;使用了DHT11数字式温湿度传感器进行温湿度的测量,并利用NRF905收发模块实现了数据的无线传输;上位机采用Labview图形化开发工具,控制面板上可以进行温湿度历史数据的查询,以曲线、数字、量程三种不同的形式显示实时温湿度数据,当温湿度超过预警值时能够报警,同时能实时显示小车运动轨迹;整个系统人机界面简洁,系统工作稳定,适应性强。     

使用者的社会因素对地下商业街主观响度和声舒适度影响的调查研究

前人研究表明主观响度和声舒适度由实际环境中的众多因素决定,而不是仅受声压级的影响。本文在对地下商业街声场和声源特性进行调查与分析的基础上,针对使用者的社会因素对主观响度和声舒适度的影响,在哈尔滨的几个典型地下商业街进行了大量问卷调查,并运用相关统计方法对结果进行了分析。研究表明,收入和职业与主观响度存在相关性,相关系数在0.1～0.4之间,学历、收入和职业与主观声舒适度亦存在相关性,相关系数在0.1～0.6之间。虽然性别对主观响度和主观声舒适度无显著性影响,但是女性对这两者的主观感觉评分范围比男性宽。年龄段与主观响度和声舒适度的相关性不显著,但是不同地下商业街有的年龄段对主观响度和声舒适度的感受有区别。职业对于主观声舒适度的影响的本质是源于收入和学历对于主观声舒适度的作用,并且收入对于主观声舒适度的影响要大于学历的影响。这些结果可以增加对地下商业街声景的了解,并且为建立地下商业街声景预测模型提供了基础。     

工程车用空调器的设计及主要生产工艺

本特种工程车用空调器采用蒸气压缩制冷原理,即利用液态制冷剂吸热汽化产生制冷效应,利用车上的发动机作为驱动源,通过皮带传动带动压缩机工作,使制冷剂在系统内产生循环,通过换热器与空气进行热交换,从而实现车室的降温要求。制冷剂采用新型环保制冷剂R134 a,整机结构紧凑、性能可靠、换热效率高。     

The design and instrumentation of an experimental rig to investigate acoustic methods for the detection and location of underground piping systems

A major UK initiative, entitled ‘Mapping the Underworld’, is seeking to improve our capability of locating buried utility service infrastructure without resorting to extensive excavations. One of the four projects aims to develop and prove the efficacy of a multi-sensor device for remote buried utility service detection, location and, where possible, identification. An essential technology to be combined into the device is low-frequency acoustics, and suitable techniques for detecting buried infrastructure, in particular buried plastic water pipes, have been proposed. In order to develop and test these techniques, an experimental rig has been built. It is the design and instrumentation of this rig along with the rationale for the chosen design which is the main focus of this paper. Preliminary measurements have been made on the rig, to determine the most appropriate acoustic excitation method and to confirm that the rig is behaving as anticipated. The results of these investigations are also reported.     

专家控制技术在船舶机舱监测报警系统中的应用研究

为提高船舶自动化程度,实现无人机舱,将专家控制技术应用到机舱监测报警系统中;详细阐述了专家控制系统的结构、原理,从受控对象、专家控制器、规则库、推理机四方面介绍了建模过程;并结合结构功能、知识表示、传感数据预处理完成了智能机舱监测报警系统的建立;最后通过大连海事大学开发的DMS-2015轮机模拟器对专家控制型机舱监测报警系统进行了验证,结果表明,该系统的应用,使机舱故障报警更加精确,故障排除更加方便,大大降低了轮机员工作值班的疲劳强度,而且为船舶机舱监测报警提供了一个新思路。     

两种非等温送风恒温恒湿机的实验研究

恒温恒湿机的用途之一是通过给机电设备机房降温,完成对电子设备的降温.去掉中间的降温媒介,直接对电子设备发热截面进行吹风降温,可以减掉机房照明和维护结构的发热量,从而节省电能.对于各部位发热量不同的设备发热截面,可以通过非等温送风型恒温恒湿机,实现从冷却设备到被冷却设备的点对点降温.对于两台发热量不同的电子设备,可以应用...     

敞开式低温陈列柜送风系统的优化设计研究

从敞开式低温陈列柜内部风机的布置入手,通过改变风机的数量和送风量,测试风幕特性和柜性能,来优化送风系统的设计。研究表明,采用双风机替代原单风机配置后,陈列柜风幕各层的送风速度分布更趋合理,柜内温度场均匀性提高22.29%,融霜水量减少9.26%,功率消耗减少2.53%,提高了陈列柜的运行性能。     

The effect of voice lessons on the clinical and perceptual skills of graduate students in speech-language pathology

Two groups of 10 speech-language pathology graduate students were each given 7 weeks of singing lessons to determine whether voice lessons could have an effect on their clinical and perceptual skills. Pre-, mid-, and posttests to measure various skills were designed and implemented. With use of paired sample statistical testing, statistically significant results were obtained. In addition, the subjective responses of the students show that the lessons were effective in improving pitch perception, breath control, and legato production or easy onset. This study supports efforts to integrate curricula in vocal performance and speech-language pathology.     

The effect of uvulopalatopharyngoplasty on the nasality of voice

We prospectively studied the effect of uvulopalatopharyngoplasty (UPPP) on several speech and vocal parameters in 15 patients. Preoperative, 1-month postoperative, and 6-month postoperative assessments were made. Specific parameters included maximum phonation time, mean speaking fundamental frequency, mean frequency perturbation, intensity, and nasalance. Psychoacoustic analysis included pitch, quality, rate, resonance, and loudness. The primary outcome measure was the nasality of voice. At the 1-month postoperative assessment, one patient exhibited mild hypernasality by psychoacoustic analysis and a mildly elevated measured nasalance. At 6 months, both the psychoacoustic hypernasality and the measure nasalance had normalized. Consequently, no subjects exhibited hypernasality at the final assessment. Although abnormalities by psychoacoustic analysis were exhibited by 3 subjects at the 6-month postoperative assessment, none could be attributed to the surgery, but rather to concurrent illnesses. This study adds further data and support that UPPP done in standard fashion does not result in significant changes in voice either by measured parameters or by clinical assessment. Although this study does not obviate the need for preoperative counseling of patients about the potential effect of UPPP on voice, they can be counseled that the risk of hypernasality after UPPP is low.     

Influence of body position on breathing and its implications for the evaluation and treatment of speech and voice disorders

This paper examines how breathing differs in the upright and supine body positions. Passive and active forces and associated chest wall motions are described for resting tidal breathing and speech breathing performed in the two positions. Clinical implications are offered regarding evaluation and treatment of breathing behavior in clients with speech and voice disorders.     

风速对空气源热泵翅片管换热器结霜特性影响

针对风速对空气源热泵翅片管室外换热器结霜特性的影响进行了实验研究.实验结果表明,结霜量随风速的增加不是成线形增长,在风速为1.3m/s时结霜量最小.霜层厚度随着风速的增加反而减小,而翅片管换热器的最大换热量随着风速的增加而增加.     

The interaction of formant frequency and pitch in the perception of voice category and jaw opening in female singers

This study represents a first step toward understanding the contribution formant frequency makes to the perception of female voice categories. The effects of formant frequency and pitch on the perception of voice category were examined by constructing a perceptual study that used two sets of synthetic stimuli at various pitches throughout the female singing range. The first set was designed to test the effects of systematically varying formants 1 through 4. The second set was designed to test the relative effects of lower frequency formants (F1 and F2) versus higher frequency formants (F3 and F4) through construction of mixed stimuli. Generally, as the frequencies of all four formants decreased, perception of soprano voice category decreased at all but the highest pitch, A5. However, perception of soprano voice category also increased as a function of pitch. Listeners appeared to need agreement between all four formants to perceive voice categories. When upper and lower formants are inconsistent in frequency, listeners were unable to judge voice category, but they could use the inconsistent patterns to form perceptions about degree of jaw opening.     

基于uClinux的嵌入式水声信号采集存储系统设计

为了减少水声学研究和水声工程设计试验的时间、成本等,针对水声信号和系统工作环境的特点,设计并实现了一种基于嵌入式uClinux操作系统的水声信号采集存储系统。发挥了处理器对外部设备优秀的控制能力和uClinux操作系统出色的稳定性两大优势,使系统稳定、可靠、低功耗、便捷地工作。通过海试验证了数据的有效性,证明系统具有实用价值。     

基于PID控制的空调器性能测试装置研制

介绍了PID控制技术在空调器性能测试室内温湿度控制中的应用,设计了一个空调器性能测试系统,并基于VB编程技术,在Win2000/WinXP操作系统上,开发了系统数据采集,显示数据处理功能的测控系统。试验证明,该系统稳定、可靠,能满足国家标准的规定。     

Phonatory control in male singing: A study of the effects of subglottal pressure, fundamental frequency, and mode of phonation on the voice source

This article describes experiments carried out in order to gain a deeper understanding of the mechanisms underlying variation of vocal loudness in singers. Ten singers, two of whom are famous professional opera tenor soloists, phonated at different pitches and different loudnesses. Their voice source characteristics were analyzed by inverse filtering the oral airflow signal. It was found that the main physiological variable underlying loudness variation is subglottal pressure (Ps). The voice source property determining most of the loudness variation is the amplitude of the negative peak of the differentiated flow signal, as predicted by previous research. Increases in this amplitude are achieved by (a) increasing the pulse amplitude of the flow waveform; (b) moving the moment of vocal fold contact earlier in time, closer to the center of the pulse; and (c) skewing the pulses. The last mentioned alternative seems dependent on both Ps and the ratio between the fundamental frequency and the first formant. On the average, the singers doubled Ps when they increased fundamental frequency by one octave, and a doubling of the excess Ps over threshold caused the sound pressure level (SPL) to increase by 8–9 dB for neutral phonation, less if mode of phonation was changed to pressed. A shift of mode of phonation from flow over neutral to pressed was associated with a reduction of the peak glottal permittance i.e., the ratio between peak transglottal airflow to Ps. Flow phonation had the most favorable relationship between Ps and SPL.     

Test-retest study of the GRBAS scale: Influence of experience and professional background on perceptual rating of voice quality

Perceptual evaluation was performed by means of the GRBAS scalefor a series of nine pathological voice samples that were presented twice to a group of 23 judges, consisting of experienced and inexperienced otolaryngologists (ENTs) and speech-language pathologists (S/LPs). The time interval between ratings was 14 days. Test-retest reliability was moderate. The best agreement between the observers was obtained for the G (grade) parameter and the worst for the S (strained) parameter. Considering the medians of the GRBAS ratings, no significant influence was measured for level of experience or professional background. Yet, based on means, the results show that professional background has a greater impact on perceptual rating than experience.     

Backing effects on the underwater acoustic absorption of a viscoelastic slab with locally resonant scatterers

Backing effects on the underwater acoustic absorption of a viscoelastic polymer slab embedded with locally resonant scatterers are reported. The polymer slab is embedded with two layers of locally resonant scatterers, i.e. Al spheres coated by soft silicon rubber. Theoretical absorption coefficients of the polymer slab under different backings using a layer multiple scattering method show good agreement with the experimental results, which supports unambiguously the experimental observation. Then relations between the resonance modes and the low-frequency absorption peaks of the composite slab are clarified to address the absorption mechanisms. It shows that the mass of the steel backing affects evidently the low-frequency absorption, the absorption peak shifts to lower frequency range while increasing the backing mass.