The effect of bone conduction microphone locations on speech intelligibility and sound quality

This paper presents the results of three studies of intelligibility and quality of speech recorded through a bone conduction microphone (BCM). All speech signals were captured and recorded using a Temco HG-17 BCM. Twelve locations on or close to the skull were selected for the BCM placement. In the first study, listeners evaluated the intelligibility and quality of the bone conducted speech signals presented through traditional earphones. Listeners in the second study evaluated the intelligibility and quality of signals presented through a loudspeaker. In the third study the signals were reproduced through a bone conduction headset; however, signal evaluation was limited to speech intelligibility only. In all three studies, the Forehead and Temple BCM locations yielded the highest intelligibility and quality rating scores. The Collarbone location produced the least intelligible and lowest quality signals across all tested BCM locations.     

Personal noise exposures of operators of agricultural tractors

Approximately one million agricultural tractors are used in Turkey for crop production and about one-third of the population lives in rural areas. The objectives of this study were to determine sound pressure levels, A-weighted sound pressure levels, and the permissible exposure time for tractors without cabins, field-installed cabins, and original cabins at ear level of agricultural tractor operators for following machines: plows, cultivators, top soil cultivators, rotary tillers, tool combinations (harrow + roller), mechanical drills, pneumatic drills, chemical applicators, fertilizer applicators, drum mowers, balers, and forage harvesters.Variance analyses showed that type of operation, type of cabins, and operation × cabin interactions were statistically significant (P < 0.01) both for sound pressure levels and equivalent (A-weighted) sound pressure levels. The use of original cabins had a greater effect in decreasing average sound pressures and resulted in more efficient noise insulation, especially at higher center frequencies compared to field-installed cabins whereas field-installed cabins proved to be more favorable compared to tractors without cabins. Sound pressure levels at 4000 Hz center frequency was reduced 2-13 dB and 4-18 dB by using a field-installed cabin and an original cabin, respectively. The measured A-weighted equivalent sound pressure levels were compared to the threshold limit level, and was concluded that depending on the cabin types used, the operators could usually work from 4 to 6 h a day without suffering from noise induced inconveniences while 2-3 h is permissible for plowing and forage harvesting on tractors without cabins. Due to timeliness considerations in agricultural machine operations, a farmer would not be willing to interrupt the operation based on permissible exposure time set by the standards.Based on the findings of this study, particularly an original cabin is recommended to reduce machine-induced noise below the danger limit during agricultural machine operations. Personal protection devices should be used when tractors are operated without cabins, which could reduce A-weighted equivalent sound pressure levels by 10-45 dB(A).     

Objective and subjective evaluation of the acoustic comfort in classrooms

The acoustic comfort of classrooms in a Brazilian public school has been evaluated through interviews with 62 teachers and 464 pupils, measurements of background noise, reverberation time, and sound insulation. Acoustic measurements have revealed the poor acoustic quality of the classrooms. Results have shown that teachers and pupils consider the noise generated and the voice of the teacher in neighboring classrooms as the main sources of annoyance inside the classroom. Acoustic simulations resulted in the suggestion of placement of perforated plywood on the ceiling, for reduction in reverberation time and increase in the acoustic comfort of the classrooms.     

Analysis and prediction of shock-induced near-field acoustics from an exhaust pipe

In this study an acoustic problem of a single shock wave moving through a circular pipe instead of a real pulsating flow with blast waves is considered. Due to the failure of a linear acoustic theory for the problem of interest, the method of computational fluid dynamics is employed to analyze the present problem. For this purpose, the axisymmetric Euler equations are solved by a high-resolution method which consists of a fifth-order weighted essential non-oscillation scheme for spatial discretization and a fourth-order Runge–Kutta method for time integration. In order to reduce the large computational time on a single computer, parallel computation with seven personal computers has been conducted. The detailed flow and sound pressure fields inside and downstream of the pipe are studied. The near-field sound pressure level downstream of the pipe was computed. The sound lobe and its orientation are investigated. In particular, an interesting phenomenon of spatial variation of velocity components associated with the sound lobe is reported. It is found that the spatial variations of the streamwise velocity component and pressure are in phase. However, the spatial variations of the radial velocity component and pressure are out of phase. Moreover, the generation mechanism of acoustics is attributed to the fact of the back-and-forth reflections of upstream-moving expansion waves generated at the pipe wall corner when the shock wave diffracts around the corner. The back-and-forth wave reflections result in the formation of interlacing high- and low-pressure regions that change with time.     

Multi notch adaptive digital filter design for enhancement of speech signals embedded in non-stationary noise

This paper presents a new approach to speech enhancement based on modified least mean square-multi notch adaptive digital filter (MNADF). This approach differs from traditional speech enhancement methods since no a priori knowledge of the noise source statistics is required. Specifically, the proposed method is applied to the case where speech quality and intelligibility deteriorates in the presence of background noise. Speech coders and automatic speech recognition systems are designed to act on clean speech signals. Therefore, corrupted speech signals by the noise must be enhanced before their processing. The proposed method uses a primary input containing the corrupted speech signal and a reference input containing noise only. The new computationally efficient algorithm is developed here based on tracking significant frequencies of the noise and implementing MNADF at those frequencies. To track frequencies of the noise time-frequency analysis method such as short time frequency transform is used. Different types of noises from Noisex-92 database are used to degrade real speech signals. Objective measures, the study of the speech spectrograms and global signal-to-noise ratio (SNR), segmental SNR (segSNR) as well as subjective listing test demonstrate consistently superior enhancement performance of the proposed method over tradition speech enhancement method such as spectral subtraction.     

基于语音识别的IVR系统的设计与实现

语音识别技术在新一代呼叫中心的IVR系统中得到了广泛应用。本文讨论了一个基于语音识别的IVR系统的设计与实现,首先介绍了系统的结构和主要模块,之后介绍了本系统的难点和解决办法。最后从识别率、鲁棒性方面对该系统进行了测试和分析,实验结果表明,该语音识别系统是稳定的实用的。     

基于FLUENT和STAR CCM+的整车气动噪声源对比

为对比FLUENT和STAR CCM+在整车气动噪声源的计算精度,开展某两厢轿车的气动噪声风洞试验并进行数值仿真.研究发现：2个软件得到的整车表面总声压级分布云图较相似,各部件噪声分布特征一致,大小排序相同,但FLUENT得到的总声压级大于STAR CCM+.FLUENT在计算测点总声压级与声压级频谱时优于STAR CCM+,具体体现在：侧窗19个点和车身50个点的能量平均值与试验差值分别仅为0.6 dBA和-0.4 dBA,而STAR CCM+的差值分别为3.1 dBA和1.7 dBA;两者在中低频上差异不大,但FLUENT得到中高频的声压级与试验更加接近.     

Objective evaluation of interior noise booming in a passenger car based on sound metrics and artificial neural networks

Booming sound is one of the important sounds in a passenger car. The aim of the paper is to develop the objective evaluation method of interior booming sound. The development method is based on the sound metrics and ANN (artificial neural network). The developed method is called the booming index. Previous work maintained that booming sound quality is related to loudness and sharpness - the sound metrics used in psychoacoustics - and that the booming index is developed by using the loudness and sharpness for a signal within whole frequency between 20 Hz and 20 kHz. In the present paper, the booming sound quality was found to be effectively related to the loudness at frequencies below 200 Hz; thus the booming index is updated by using the loudness of the signal filtered by the low pass filter at frequency under 200 Hz. The relationship between the booming index and sound metric is identified by an ANN. The updated booming index has been successfully applied to the objective evaluation of the booming sound quality of mass-produced passenger cars.     

Coordinated control of an intelligentwheelchair based on a brain-computer interface and speech recognition

An intelligent wheelchair is devised, which is controlled by a coordinated mechanism based on a brain-computer interface （BCI） and speech recognition. By performing appropriate activities, users can navigate the wheelchair with four steering behaviors （start, stop, turn left, and turn right）. Five healthy subjects participated in an indoor experiment. The results demonstrate the efficiency of the coordinated control mechanism with satisfactory path and time optimality ratios~ and show that speech recognition is a fast and accurate supplement for BCI-based control systems. The proposed intelligent wheelchair is especially suitable for patients suffering from paralysis （especially those with aphasia） who can learn to pronounce only a single sound （e.g.,ah）.     

Optimal design of dynamic absorbers on vibration and noise control of the fuselage

Optimum design of dynamic absorbers for reducing the vibration and the interior noise of an aircraft’s fuselage is studied. Herein, a thin, elastic cylindrical shell is adopted as a simple model of the fuselage. The sound source of the noise in the acoustic field comes from the vibration of the shell. Several dynamic absorbers are then attached to the shell for vibration and noise control. The vibration of the shell and its interior sound pressure, caused by the propellers or the engines are formulated. Optimum design of the absorbers is studied for obtaining the minimum vibration of the fuselage or the minimum noise level in the cylindrical cavity. From the numerical results, the absorbers are found to be effective for vibration and noise control of the fuselage. Some general guidelines on optimum absorber design are also offered in conclusion.     

A型地铁车内噪声分析和优化

为研究轨道车辆轻量化带来的车内振动噪声问题,基于某A型地铁车辆的有限元模型,建立其声学计算模型,以车体板件频率响应的振动位移结果作为声学激励,在车内布置ISO标准场点进行车内噪声分析.结果显示,车内各点声压级在频域上分布极不均匀,且普遍存在几个较大的峰值.分析目标板件的振动,提出几种减振降噪的优化方案.对比各方案发现,增加板件强度后振动和噪声都相应地减小;减振降噪需综合考虑优化后车体的整体强度和动力学性能.     

Analysis and design of networked control systems using the additive noise model methodology

Networked Control has emerged in recent years as a new and exciting area in systems science. The topic has many potential applications in diverse areas ranging from control of microrobots to biological and economic systems. The supporting theory is very rich and combines aspects of control, signal processing, telecommunications, and information theory. In this paper, we give a partial overview of recent developments in Networked Control with an emphasis on the additive noise model methodology. We also point to several open problems in this emerging area. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Procedure and information displays in advanced nuclear control rooms: experimental evaluation of an integrated design

Abstract

In the main control rooms of nuclear power plants, operators frequently have to switch between procedure displays and system information displays. In this study, we proposed an operation-unit-based integrated design, which combines the two displays to facilitate the synthesis of information. We grouped actions that complete a single goal into operation units and showed these operation units on the displays of system states. In addition, we used different levels of visual salience to highlight the current unit and provided a list of execution history records. A laboratory experiment, with 42 students performing a simulated procedure to deal with unexpected high pressuriser level, was conducted to compare this design against an action-based integrated design and the existing separated-displays design. The results indicate that our operation-unit-based integrated design yields the best performance in terms of time and completion rate and helped more participants to detect unexpected system failures.

Practitioner Summary: In current nuclear control rooms, operators frequently have to switch between procedure and system information displays. We developed an integrated design that incorporates procedure information into system displays. A laboratory study showed that the proposed design significantly improved participants’ performance and increased the probability of detecting unexpected system failures.     

Multi-objective efficient design space exploration and architectural synthesis of an application specific processor (ASP)

As the growth of system complexity rapidly increases, the gap between Electronic System Level (ESL) and the Register Transfer Level (RTL) must be filled. Currently, Very Large Scale Integration (VLSI) and System-on-Chip (SoC) designs are multi-objective in nature, requiring simultaneous fulfillment of multiple parameters. Extensive research on Design Space Exploration (DSE) problems and synthesis of an application specific processor (ASP) design have been done until now but none of the prior works have focused explicitly on integrating a fast multi-objective architecture exploration mechanism with the architectural synthesis stages to formalize the design methodology of an application specific processor in case of multiple objectives. This paper proposes a design methodology of a multi-objective application specific processor by integrating an efficient multi-objective (area occupied, execution time and power consumption) exploration approach with the architecture synthesis process, useful for portable devices and many high end applications. The formalized steps of the design methodology for the ASP guarantees the designer an error free approach to design the system with strict limitations on compound operational constraints. The results of implementation of the designed ASP using the proposed design methodology in FPGA and ASIC have also been shown.     

工业控制系统可靠性设计与测试评估技术研究

目前我国的工业控制系统发展迅速,但其可信性较低,为解决这一问题,我们开展了工业控制系统的可靠性设计和测试评估技术研究。研究形成了工业控制系统可靠性设计规范和工业控制系统可靠性测试评估规范,另外还生成了工业控制系统可靠性设计和测试评估的软件操作平台。     

PoliawaC: design and evaluation of an awareness-enhanced groupware client

Presenting the activities of others at the user interface — thereby providing awareness — a is crucial aspect of CSCW systems. However, this problem is often neglected by existing designs. This paper discusses design requirements, introduces a notification design framework and describes the functionality ofPoliAwaC, a groupware client aimed specifically at supporting awarenes.PoliAwaC provides a variety of different graphical notification mechanisms which can be coupled to specific working situations using the AREA model. We also report on the evaluation of the system under real-life conditions in a German federal ministry.     

Analysis and design of chattering‐free discrete‐time sliding mode control

In this paper, the disturbance observer–based chattering‐free discrete‐time sliding mode control (DSMC) approach is proposed for systems with external disturbances. The proposed disturbance observer, which makes full use of the state and input information at the current and last steps, improves the estimation accuracy and achieves accurate compensation for disturbances. Then, with the help of disturbance observer, a new reaching law, which contains not only a nonsmooth term with a dynamically adjusted gain parameter but also a second order difference of the disturbance, is proposed to reduce the range of the quasi‐sliding mode band and eliminate chattering. The proposed DSMC approach realizes the active disturbance rejection and strong robustness. Finally, a simulation example is presented to verify the effectiveness of the proposed method.     

Relational image compression: optimizations through the design of fuzzy coders and YUV color space

For Image Compression and reconstruction method based on Fuzzy relational equations (ICF), two optimizations are proposed. First optimization is to propose an invariant index for the design of appropriate coders in ICF, we call an overlap level of fuzzy sets. Second optimization corresponds to application of YUV color space to the existing ICF. Through the experiment of image compression and reconstruction using 1000 test images extracted from Corel Gallery, the invariance of the overlap level is confirmed. Furthermore, by the experimental comparison of the proposed method (ICF over YUV color space) and the conventional one (ICF over RGB color space) using 1000 test images, it is confirmed that the Peak Signal to Noise Ratio of the proposed method is increased at a rate of 7.1%∼13.2% compared with the conventional one, under the condition that the compression rates are 0.0234∼0.0938.     

Ergonomic design and evaluation of the handle for an endoscopic dissector

The purpose of this study was to design an endoscopic dissector handle and objectively assess its usability. The handles were designed with increased contact area between the fingers and thumb and the eye rings, and the eye rings were modified to have a more perpendicular insertion angle to the finger midline. Four different handle models were compared, including a conventional product. Subjects performed dissection, exclusion, grasping, precision manipulation and precision handling tasks. Electromyography and subjective evaluations were measured. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability. The activity of the first dorsal interosseous muscle was sometimes influenced by the shape of the other parts. The ergonomically designed endoscopic dissector handle used in this study achieved high usability. Medical instrument designs based on ergonomic concepts should be assessed with objective indices.

Practitioner Summary: The endoscopic dissector handles were designed with increased contact area and more suitable insertion angle between the fingers and thumb and the eye rings. Compared to conventional handles, the designated handle reduced the muscle load in the extensor and flexor muscles of the forearm and increased subjective stability.     

一个粘弹性振子的动力学与控制

本文详细分析了一个具有粘弹性项的非线性振子的动力学与控制.首先研究了系统平衡点的稳定性,表明系统存在复杂的无界动力学行为.然后引入时滞速度反馈对这个不稳定系统进行控制.研究结果表明速度反馈控制能镇定此不稳定的粘弹性系统.适当的选择控制增益和控制时滞,控制系统有稳定的平衡点,由Hopf分岔产生的周期解,拟周期解,并能展现出复杂的混沌解.数值模拟验证了结论的正确性.