Influence of a wearer's voice on noise dosimeter measurements

In recent years, interest in personal noise exposure has expanded beyond a workplace safety measure to become an effective means of investigating physiological effects of the acoustic environment on an individual. This work investigates the effects of the wearer's voice as a possible dominant sound source on body-mounted noise dosimeters and develops methods to improve the application of dosimeter measurements in medium-level noise environments. Subjects experienced a controlled set of acoustic conditions while wearing a dosimeter. In each condition, sound pressure levels were recorded with and without the subject speaking controlled phrases. Three experimental variables were considered-room type, noise type, and noise level. All three variables had a statistically significant effect upon the contribution of speech to a dosimeter measurement; for example, noise level was shown to cause a change in speech contribution by as much as 5.5 dB between sequential levels. Based upon the analysis, a method of predicting the decibel contribution of a wearer's voice was developed. The results of this study can be used to estimate the effect of a wearer's voice on dosimeter measurements in medium-level noise environments.     

Single point imaging with suppressed sound pressure levels through gradient-shape adjustment

Acoustic noise produced during single point imaging (SPI) experiments was modulated by changes in the spatial encoding gradients. Parameters of both linear and sine-shaped gradient ramps were modified to minimize the acoustic noise levels. Acoustic noise measurements during SPI were measured on three different gradient systems and revealed that for small gradient-bore systems a considerable acoustic noise reduction of more than 20 dB can easily be achieved. SPI in conjunction with an optimized gradient waveform can be a superb alternative to the previously introduced single point ramped imaging with T(1) enhancement (SPRITE) method when sound levels and overheating of gradients are a concern.     

Speakers' comfort and voice level variation in classrooms: laboratory research

Teachers adjust their voice levels under different classroom acoustics conditions, even in the absence of background noise. Laboratory experiments have been conducted in order to understand further this relationship and to determine optimum room acoustic conditions for speaking. Under simulated acoustic environments, talkers do modify their voice levels linearly with the measure voice support, and the slope of this relationship is referred to as room effect. The magnitude of the room effect depends highly on the instruction used and on the individuals. Group-wise, the average room effect ranges from -0.93 dB/dB, with free speech, to -0.1 dB/dB with other less demanding communication tasks as reading and talking at short distances. The room effect for some individuals can be as strong as -1.7 dB/dB. A questionnaire investigation showed that the acoustic comfort for talking in classrooms, in the absence of background noise, is correlated to the decay times derived from an impulse response measured from the mouth to the ears of a talker, and that there is a maximum of preference for decay times between 0.4 and 0.5 s. Teachers with self-reported voice problems prefer higher decay times to speak in than their healthy colleagues.     

滨海公共空间声环境感知评价及影响因素*

滨海公共空间是滨海城市人居环境的重要组成部分,其声环境质量是影响公共空间环境体验的关键因素。本研究以青岛沿海岸线四类滨海公共空间（步道类、广场类、公园类、沙滩类）的声环境为对象,通过问卷调查和实地测量探索滨海公共空间声环境的特征、感知评价及其影响因素。结果表明：（1）滨海公共空间当前环境噪声水平基本不超过国家标准限值55dB(A) ,各类空间声环境客观特征显著不同：公园噪声水平最低,自然声源丰富;广场噪声水平最高,各种城市噪声较多;步道噪声水平较低,但受到交通噪声的影响;沙滩噪声水平较高,但以中低频的海浪声为主,比较稳定。（2）各类滨海公共空间的声源感知以自然声为主,但是广场的自然声源感知较少。此外,声环境的愉悦感评价普遍较高,但在事件感、吵闹度和总体满意度评价上具有显著差异：沙滩声环境总体评价最好,其次是公园,广场和步道的声环境则亟待改善。（3）交通噪声和最大声级Lmax对声环境的负面影响最为显著,此外受访者年龄也是影响滨海公共空间声环境感知评价的关键因素。研究结论可以为滨海公共空间声环境的优化设计提供理论依据。     

Cancellation of Simulated Environmental Noise as a Tool for Measuring Vocal Performance During Noise Exposure

It can be difficult for the voice clinician to observe or measure how a patient uses his voice in a noisy environment. We consider here a novel method for obtaining this information in the laboratory. Worksite noise and filtered white noise were reproduced over high-fidelity loudspeakers. In this noise, 11 subjects read an instructional text of 1.5 to 2 minutes duration, as if addressing a group of people. Using channel estimation techniques, the site noise was suppressed from the recording, and the voice signal alone was recovered. The attainable noise rejection is limited only by the precision of the experimental setup, which includes the need for the subject to remain still so as not to perturb the estimated acoustic channel. This feasibility study, with 7 female and 4 male subjects, showed that small displacements of the speaker's body, even breathing, impose a practical limit on the attainable noise rejection. The noise rejection was typically 30 dB and maximally 40 dB down over the entire voice spectrum. Recordings thus processed were clean enough to permit voice analysis with the long-time average spectrum and the computerized phonetogram. The effects of site noise on voice sound pressure level, fundamental frequency, long-term average spectrum centroid, phonetogram area, and phonation time were much as expected, but with some interesting differences between females and males.     

Acoustic Signal Typing for Evaluation of Voice Quality in Tracheoesophageal Speech

SUMMARY: Because of the aperiodicity of many tracheoesophageal voices, acoustic analysis of the tracheoesophageal voice is less straightforward than that of the normal voice. This study presents the development and testing of an acoustic signal typing system based on visual inspection of a narrow-band spectrogram that can be used by researchers for classification of voice quality in tracheoesophageal speech. In addition to this classification system, a selection of acoustic measures [median fundamental frequency, standard deviation of fundamental frequency, jitter, percentage of voiced (%Voiced), harmonics-to-noise ratio (HNR), glottal-to-noise excitation (GNE) ratio, and band energy difference (BED)] was computed to provide more insight into the acoustic components of tracheoesophageal voice quality. For clinical relevance, relationships between the acoustic signal types and an overall judgment of the voice were investigated as well. Results showed that the four acoustic signal types form a good basis for performing more acoustic analyses and give a good impression of the overall quality of the voice.     

Comparison of fundamental frequency and perturbation measurements among three analysis systems

The need for standardization of procedures in approaches to voice measurement has been recently emphasized. The purpose of this study was to determine the extent to which the acoustic perturbation measurements from three different analysis systems agree when standardized recording and analysis procedures are used. High-quality acoustic voice recordings from 20 patients were analyzed. The results showed that, although fundamental frequency measurements were in strong agreement among the three systems tested, frequency and amplitude perturbation measurements were not in agreement. The underlying approaches to perturbation measurement appeared to be sufficiently different to produce different results. An argument is made for a standardized set of acoustic signals representing normal, dysphonic, and synthesized voices with known characteristics to facilitate testing of new acoustic analysis systems and confirm measurement accuracy and sensitivity.     

Classification of Dysphonic Voice: Acoustic and Auditory-Perceptual Measures

The purpose of this study was (1) to determine the relationship between acoustic measures and auditory-perceptual dimensions of overall voice severity and pleasantness and (2) to evaluate the ability of acoustic and auditory-perceptual measures to discriminate normal from dysphonic voices. Thirty adult dysphonic speakers and six, age-matched normal control speakers were asked to provide oral reading samples of the Rainbow Passage. Acoustic analysis of the speech samples was used to identify abnormal phonatory events associated with dysphonia. The acoustic program calculated long-term average spectral measures, glottal noise measures, and those measures based on linear prediction (LP) modeling. Twelve adult listeners judged overall voice severity and pleasantness from the connected speech samples using direct magnitude estimation (DME) procedures. The acoustic measures accounted for 48% of overall voice severity and 40% of voice pleasantness for dysphonic speakers. The classification performance of the acoustic measures and auditory-perceptual measures was quantified using logistic regression analysis. When acoustic measures or auditory-perceptual measures were considered in isolation, classification was generally accurate and similar across measures. Classification accuracy improved to 100% when acoustic and auditory-perceptual measures were combined. These data provide further support for use of both auditory-perceptual evaluation and acoustic analyses for classifying and evaluating dysphonia.     

船用三通调节阀流-固耦合噪声数值模拟

针对船用PN10DN32三通调节阀噪声声压频谱、声指向性等声学特性规律不明确,噪声声压级是否满足使用要求的问题,基于流-固耦合理论,同时考虑流-固耦合面及流体域内的脉动声学激励源,开展阀门噪声数值模拟研究。分别对三通调节阀在80%及60%开度阀外1 m处的噪声进行数值模拟,分析研究噪声声压频谱特性及声指向性规律。结果表明：80%及60%开度下的噪声声压级分别为49.14 dB(A)、50.79 dB(A),均小于60 d B(A)的噪声限制,满足使用要求。该文为船用三通调节阀噪声数值模拟提供了理论及方法参考。     

Predicting Mutational Change in the Speaking Voice of Boys

SUMMARY: The authors investigated whether acoustic speaking voice analyses can be used to predict the beginning of mutation in 21 male members of a professional boys' choir. Over a period of 3 years before mutation, children were examined every 3 months by ear, nose, and throat (ENT) and phoniatric specialists. At the same time, the voice was evaluated acoustically using analysis features of the Goettingen Hoarseness Diagram (GHD). Irregularity component and noise component, jitter, shimmer, mean waveform correlation coefficient, and fundamental frequency were determined from recordings of the speaking voice. Significant changes of acoustic features appeared 7 and 5 months before mutation onset, which indicates that vocal function is already restricted 6 months before mutation onset. This acoustic voice analysis is therefore suitable to support the care of the professional singing voice.     

Perceptual evaluation of voice quality and its correlation with acoustic measurements

To determine whether a correlation exists between the Grade, Roughness, Breathiness, Aesthenia, Strain (GRBAS) scale (a subjective measure of voice) and the Multi-Dimensional Voice Program (MDVP) scale (an objective measure of voice). A retrospective review of 37 voice patients (12 male/25 female) was conducted. Each voice was perceptually evaluated using the GRBAS scale by an experienced speech pathologist and acoustically analyzed using the MDVP scale. Statistical analysis using a multivariate regression model identified a significant correlation between the noise-related parameters of MDVP and the components of the GRBAS scale. Grade correlated with voice turbulence index (VTI), noise harmonic ratio (NHR), and soft phonation index (SPI). Roughness correlated with NHR only. Breathiness correlated with SPI only. Aesthenia also correlated with SPI only. Of the 19 acoustic variables measured by the MDVP system, only three noise parameters significantly correlated with the GRBAS perceptual voice analysis. Perhaps "noise" is the perceived acoustical quality of the dysphonic voice. A voice quantifying measure such as a "voice index score" could be proposed using the GRBAS scoring and the three clinically relevant MDVP values following further studies.     

Acoustic insulation capacity of Vertical Greenery Systems for buildings

Vertical Greenery Systems (VGS) are promising contemporary Green Infrastructure which contribute to the provision of several ecosystem services both at building and urban scales. Among others, the building acoustic insulation and the urban noise reduction could be considered. Traditionally vegetation has been used to acoustically insulate urban areas, especially from the traffic noise. Now, with the introduction of vegetation in buildings, through the VGS, it is necessary to provide experimental data on its operation as acoustic insulation tool in the built environment. In this study the acoustic insulation capacity of two VGS was conducted through in situ measurements according to the UNE-EN ISO 140-5 standard. From the results, it was observed that a thin layer of vegetation (20–30 cm) was able to provide an increase in the sound insulation of 1 dB for traffic noise (in both cases, Green Wall and Green Facade), and an insulation increase between 2 dB (Green Wall) and 3 dB (Green Facade) for a pink noise. In addition to the vegetation contribution to sound insulation, the influence of other factors such as the mass factor (thickness, density and composition of the substrate layer) and type of modular unit of cultivation, the impenetrability (sealing joints between modules) and structural insulation (support structure) must be taken into account for further studies.     

Multiparametric Evaluation of Dysphonic Severity

SUMMARY: In recent years, the multiparametric approach for evaluating perceptual rating of voice quality has been advocated. This study evaluates the accuracy of predicting perceived overall severity of voice quality with a minimal set of aerodynamic, voice range profile (phonetogram), and acoustic perturbation measures. One hundred and twelve dysphonic persons (93 women and 19 men) with laryngeal pathologies and 41 normal controls (35 women and six men) with normal voices participated in this study. Perceptual severity judgement was carried out by four listeners rating the G (overall grade) parameter of the GRBAS scale. The minimal set of instrumental measures was selected based on the ability of the measure to discriminate between dysphonic and normal voices, and to attain at least a moderate correlation with perceived overall severity. Results indicated that perceived overall severity was best described by maximum phonation time of sustained /a/, peak intraoral pressure of the consonant-vowel /pi/ strings production, voice range profile area, and acoustic jitter. Direct-entry discriminant function analysis revealed that these four voice measures in combination correctly predicted 67.3% of perceived overall severity levels.     

Laryngostroboscopic, Acoustic, and Environmental Characteristics of High-Risk Vocal Performers

Vocal performance often requires excessively high vocal demand. In particular “high-risk” performers, a group of individuals who use their voices at their maximum effort level, are often exposed to unique vocal abuse characteristics which include high environmental and performance demands and inconsistencies of cast performance. Three categories of high-risk performers were studied: musical theater, choral ensemble, and street theater. Musical theater performers produce a Broadway, West End “belting” style voice. Street theater performers use a high-energy pitch varying dialogue in order to imitate a desired character voice. Choral ensemble performance requires group cohesion and blending of four-part harmony. The melodies require sustained vocal durations within each of the respective registers. For each of these studied groups vocal tasks of sustained production of /i/ and /a/ were subjected to analysis. Acoustic measures included fundamental frequency, standard deviation of fundamental frequency, jitter percent, shimmer percent, and noise-to-harmonic ratio. Laryngostroboscopic parameters were assessed during sustained /i/. Environmental acoustic sound field measurements were made using an A weighting and linear weighting sound pressure level. These weightings were used to describe noise levels and vocal output, respectively, within the performance environments. Results of the analysis suggest that high-risk performers are a unique performance type defined by distinctive, acoustic, laryngostroboscopic, and environmental characteristics.     

Acoustic analysis of voice in individuals with amyotrophic lateral sclerosis and perceptually normal vocal quality

Currently, early phonatory changes in amyotrophic lateral sclerosis(ALS) are not well understood. The aim of this study was to compare acoustic parameters of voice in ALS subjects who demonstrated perceptually normal vocal quality on sustained phonation with a control group. We hypothesized that objective analysis of voice would reveal significant differences on specific acoustic parameters of voice compared to the control group. Results revealed statistically significant differences between the two groups on measures related to frequency range and phonatory stability. The findings suggest that early bulbar signs affecting the laryngeal system may be present in patients with ALS before the occurrence of perceptually aberrant vocal characteristics.     

Design aspects of acoustic sensor networks for environmental noise monitoring

An increase in public awareness of noise pollution and the impact of noise on human health has led to the need for enhanced insight in complex noise situations. This insight is commonly obtained either by brief measurements or by evaluation of a simplified acoustic model. Both of these approaches however have limitations in complex noise situations. Noise monitoring can be an appropriate and cost efficient measure to obtain more insight, for it allows to measure at many locations for long periods of time. Monitoring can for example be used to improve the accuracy of models or to assess and respond to changes in the acoustic situation. Several monitoring approaches, for various applications, have been developed or are under development. In the first part of this paper an overview is given of current developments in acoustic monitoring networks and their key aspects. Sensor networks for environmental noise monitoring are here divided into four different categories, distinguished by five aspects: hardware costs, scalability, flexibility, reliability and accuracy. These five aspects determine the range of applications for which a network is suited. In the second part of this paper a monitoring network developed in-house is used to further illustrate the relevance of these aspects. This network was designed to facilitate research into the field of acoustic monitoring networks and is used to experiment with and learn from a broad field of applications.     

Outcome of Resonant Voice Therapy for Female Teachers With Voice Disorders: Perceptual, Physiological, Acoustic, Aerodynamic, and Functional Measurements

Teachers have a high percentage of voice problems. For voice disordered teachers, resonant voice therapy is hypothesized to reduce voice problems. No research has been done on the physiological, acoustic, and aerodynamic effects of resonant voice therapy for school teachers. The purpose of this study is to investigate resonant voice therapy outcome from perceptual, physiological, acoustic, aerodynamic, and functional aspects for female teachers with voice disorders. A prospective study was designed for this research. The research subjects were 24 female teachers in Taipei. All subjects received resonant voice therapy in groups of 4 subjects, 90 minutes per session, and 1 session per week for 8 weeks. The outcome of resonant voice therapy was assessed from auditory perceptual judgment, videostroboscopic examination, acoustic measurements, aerodynamic measurements, and functional measurements before and after therapy. After therapy the severity of roughness, strain, monotone, resonance, hard attack, and glottal fry in auditory perceptual judgments, the severity of vocal fold pathology, mucosal wave, amplitude, and vocal fold closure in videostroboscopic examinations, phonation threshold pressure, and the score of physical scale in the Voice Handicap Index were significantly reduced. The speaking Fo, maximum range of speaking Fo, and maximum range of speaking intensity were significantly increased after therapy. No significant change was found in perturbation and breathiness measurements after therapy. Resonant voice therapy is effective for school teachers and is suggested as one of the therapy approaches in clinics for this population.     

Work-Related Communicative Profile of Voice Teachers: Effects of Classroom Noise on Voice and Hearing Abilities

PurposeVocal instructors during their normal workday are exposed to high noise levels that can affect their voice and hearing health. The goal of this study was to evaluate the voice and hearing status of voice instructors before and after lessons and relate these evaluations with voice and noise dosimetry taken during lessons.MethodsEight voice instructors volunteered to participate in the study. The protocol included (1) questionnaires, (2) pre/post assessment of voice quality and hearing status, and (3) voice and noise dosimetry during lessons. Acoustic measurements were taken of the unoccupied classrooms.ResultsIn six of eight classrooms, the measured noise level was higher than the safety recommendations set by National Institute for Occupational Safety and Health. The background noise level and the reverberation time in the classrooms were in compliance with the national standard recommendations. We did not find a clear pattern comparing pre- and post-measurements of voice quality consistent among genders. In all subjects, the Sound Pressure Levels mean increased, and the standard deviation of fundamental frequency decreased indicating association to vocal fatigue. Previous studies link these changes to increasing vocal fatigue. The audiometric results revealed seven out of eight instructors have sensorineural hearing loss.ConclusionsThe interaction of the acoustic space and noise levels can contribute to the development of hearing and voice disorders for voice instructors. If supported by larger sample size, the results of this pilot study could justify the need for a hearing and voice conservation program for music faculty.