Reform and Practice of Immersive Teaching in Environmental Acoustics

Environmental Acoustics is a professional course that educates students majoring in Acoustics.Affected by practical equipment and other factors,the teaching effect of knowledge points relevant to subjective auditory perception contained in the course is poor.Taking the course of Spatial Hearing and 3D Stereo as an example,this study develops a virtual simulation experiment system for the topic of subjective hearing perception in order to carry out the reform and practice of immersive teaching.Combined with the virtual simulation experiment project with high sense of presence,students are supported by the actual auditory perception effect in the whole learning process and have achieved good learning effect.

Acoustical environment of urban area related to the city development

The relationship between urban development and noise pollution was analyzed. The analysis, based on a wide range of measurements and statistical data,revealed the changes of the ambient noise resulting from city development. In conclusion, some fundamental measures for improving the acoustical environment were suggested, such as the division of cities into functional areas and the development of a well designed road network. In addition, the town planning, architecture and the implementation of appropriate regulations could also help to reduce noise levels was suggested as well.

Modeling and simulation of torpedo acoustic homing trajectory with multiple targets

The characteristics of a torpedo＇s acoustic homing trajectory with multiple targets were studied. The differential equations of torpedo motion were presented based on hydrodynamics. The Fourth order Runge-Kutta method was used to solve these equations. Derived from sonar equations and Snell＇ s law, a simple virtual underwater acoustic environment was established for simulating the torpedo homing process. The Newton iteration method was used to calculate homing range and ray tracing was approximated by pieccwise line, which takes into consideration distortions cause by temperature, pressure, and salinity in a given sea area. The influence of some acoustic warfare equipment disturb the torpedo homing process in certain circumstances, including decoys and jammers, was alsotaken into account in simulations. Relative target identification logic and homing control laws were presented. Equal consideration during research was given to the requirements of rcal-timeactivity as well as accuracy. Finally, a practical torpedo homing trajectory simulation program was developed and applied to certain projects.

Noise Action Plans for the Acoustic Protection of Urban Areas around the Athens International Airport （A.I.A.） Strategic Noise Maps 2006 ＆ 2011

Athens International Airport ＂Eleftherios Venizelos＂ （AIA） is considered a pioneer international Public-Private Partnership, being the first major int. airport constructed with the participation of the private sector with the BOOT method （Build, Own, Operate, and Transfer）. AIA＇s 1st day of operation was in March 2001 and the aircraft traffic on 2006 reached 191.000 movements ＆ 15.1 million passengers. According to the European Directive 49/2002 and the Joint Ministerial Decision 13586/724-28/3/06, Athens International Airport （AIA） is included in the category of＂large airports＂ and it consequently comes under the authority of the above mentioned legislation on the evaluation and management of environmental noise. A complete Study on Aircraft Noise [1], according to the European Directive 49/2002 [2] and Joint Ministerial Decision 13586/724-28/3/06 was undertaken under the auspices of the Ministry of Environment, Energy ＆ Climate Change, the Hellenic Civil Aviation Authority, and AIA S.A. In this article the following results are presented： （1） The 2006 Strategic Noise Map （SNM） of both indicators Lden and Lnight based on the ECAC.CEAC Doc 29 methodology ＂Report on Standard Method of Computing Noise Contours around Civil Airports＂, 1997 [3], （2） A statistical analysis of predicted vs measured noise levels based on the existing Noise Monitoring System, （3） Effects from the removal of marginally accepted chapter 3 aircraft, （4） A complete evaluation of results regarding calculation of area/land uses and number of individuals living in residences inside blocks exposed in various levels of noise, and （5） A full evaluation of Noise Action Plans （NAP） regrouping existing and foreseen actions FOR 2006 ＆ 2011 scenarios, especially regarding among others, noise abatement procedures, a comprehensive noise insulation legal framework.

Acoustic and Vibration Environment Prediction Technology of Instrument Cabin Based on Multi-Source Data

Noise characteristic is one of the important factors to be considered during the design of a launch vehicle system.In this paper,the acceptance conditions for the external noise environment of the instrument cabin are given based on multi-source data,including the measured data of the launch vehicle lift-off noise,the mechanical environment of the launch vehicle equipment,and the external noise environment of the instrument cabin deduced from empirical formula.Then an acoustic and vibration transfer model is established based on the response data of the instrument equipment used to conduct measurements in the noise test reverberation room.By using an external noise environment and a transfer model,the response of the instrument and equipment for the acceptance condition can be obtained.The acoustic and vibration prediction technology introduced in this paper can provide technical support in the environmental prediction analysis of heavy launch vehicles for the future.

Quiet in the nest:The nest environment attenuates song in a grassland songbird

The nest environment may limit the ability of nest-bound birds to hear sounds from the outside world.In vocal learning species,such as humans and songbirds,it is vital for young animals to hear the voices of conspecific animals early in life.In songbirds,nest structure varies considerably across species,and the resulting impact on sound transmission may have consequences for vocal learning in nestlings.In this study,we tested the hypothesis that the nest environment attenuates song of Savannah Sparrows(Passerculus sandwichensis),grassland songbirds that build nests on the ground under cover of dense vegetation.We recorded live Savannah Sparrows singing at variable distances from 21 nests.We recorded songs using one microphone inside the nest(the typical position of a nestling)and another placed 1 m directly above the nest(a typical position of an adult).We found a substantial reduction in signal-to-noise ratio,where songs recorded inside the nest were an average of 11 dB lower than songs recorded directly above the nest.We estimate that the attenuation imposed by the nest reduced the maximum acoustic environment from 117.7 m(for recordings above the nest),to 78.6 m(for recordings within the nest),which is analogous to listening from a position 39.1 m farther away from the singer.Previous research estimated that song transmits up to 100 m in this species,so any adult male within 100 m of a young bird was previously considered a potential vocal tutor.By reducing the nestling acoustic environment from 100 m to 78.6 m,the number of male tutors available to nestlings is reduced by an average of 27%.Given the growing evidence that song learning begins very early in life,future research on vocal development should account for how the structural properties of the natal environment affect the songs that nestlings hear.

Simulation Evaluation of Outdoor Noise Environment in Buildings

Green campus design has become an essential strategy to enhance campus life and learning.However,noise pol-lution remains a troubling aspect that impacts teaching and learning processes,even causing harm to the health of students and teachers.Therefore,acoustic environment quality design is crucial.This article focuses on the expansion project of a school campus in Shenzhen.We simulated and analyzed the outdoor noise environment separately for the proposed teach-ing building,as well as the existing buildings like the dining hall,teaching building,and laboratory building.The results showed that the proposed teaching building was mainly affected by surrounding noise,with the worst outdoor noise being in classrooms adjacent to the teaching building in the south and the basketball court at the west of the classroom,with maximum noise values reaching 73 dB and 66 dB,respectively.In the future,these rooms should be renovated to achieve an excellent indoor soundproof environment.

Enriched Acoustic Environment as a customized treatment for tinnitus: A non-controlled longitudinal study

Tinnitus is a heterogeneous hearing disorder with no cure at present,but some treatments,such as a combination of counselling and sound therapy,can alleviate the discomfort it causes.The sound therapy efficiency depends on both the type of sound stimulus and the time of exposure.This study describes the fundamentals of a personalized sound therapy that stimulates the auditory system with either continuous or sequential sounds whose spectra are adjusted to the hearing levels of the participants.This sound therapy is called Enriched Acoustic Environment and is assessed in a sample of 137 participants with tinnitus.Tinnitus-related distress relief was clinically relevant and statistically significant for 90%of these patients.This was quantified as a mean decrease of 24.3 points on the Tinnitus Handicap Inventory.31%of participants were treated with sequential stimuli and achieved greater relief of distress(29.4 points on their Tinnitus Handicap Inventory score)compared to those treated with continuous sound(69%).According to these results,sequential sound seems to be optimal compared to continuous sound.

ACOUSTICAL EVALUATION OF SIX‘GREEN’OFFICE BUILDINGS

To explain the reactions of the building occupants to their acoustical environments,meetings with the designers,walk-through surveys,and detailed acoustical measurements were done.The objective was to determine how design decisions affect office acoustical environments,and how to improve the acoustical design of‘green’office buildings.Design-performance criteria were established.Measurements were made of noise level,reverberation time,speechintelligibility index(SII),and noise isolation.Noise levels were atypically low in unoccupied buildings with no mechanical ventilation,but excessive in areas near external walls next to noisy external noise sources—especially with windows open for ventilation—and in occupied buildings.Reverberation times were excessive in areas with large volumes and insufficient sound absorption.Speech intelligibility was generally adequate,but speech privacy was inadequate in shared and open-office areas,and into private offices with the doors open for ventilation.Improvement of the acoustical design of‘green’buildings must include increasing the external-internal noise isolation and that between workplaces,and the use of adequate sound absorption to control reverberation and noise.

ACOUSTICAL IMPROVEMENTS WITH NATURAL AIR VENTILATION IN THE LIU INSTITUTE FOR GLOBAL ISSUES AT THE UNIVERSITY OF BRITISH COLUMBIA

Low speech privacy in shared and private offices in one of the early generation of a“green”building resulted in occupants’dissatisfaction.This problem is experienced in Liu institute with a natural-ventilation system.Such a system requires low air-flow resistance which is achieved by large openings which will result in noise transmission between various spaces within the building.The poor acoustical quality in this building resulted in occupants’noise complaints which were further investigated by way of relevant acoustical measurements.CATT-Acoustic software was utilized to modify the acoustical quality of the building without any disturbance to the occupants.The optimized design of the transfer box above the office door was selected based on CATT-Acoustic predictions.The acoustical measurements were conducted after installation of the transfer box above the office door.The measurements’results agreed with the predictions which led to improved speech privacy to an acceptable level between the office and the corridor in Liu Institute.More work should be done to improve the acoustical quality of natural-ventilated building to conform to ANSI standards.1 The results of this study strongly support including acoustics in“green”building designs with natural ventilation to avoid users’complaints.

Based on the Characteristics of Respondents and the Voice of the Urban Neighborhood Public Space Business Facilities Noise Environment Evaluation Research

Comfort is one of the important indicators evaluation of voice. In order to understand the urban neighborhood public space environment of comfort,this paper is to explore characteristics of consumer society on the public space environment evaluation of the effect,and using the questionnaire survey method,to evaluate the Harbin city neighborhood area public space as the typical case analysis. Based on one of the main sound source in neighborhood public space,environment,business facilities environment as the breakthrough point,it is to consider neighborhood public space environment evaluation and social characteristics.

Optimisation design and verification of the acoustic environment for multimedia classrooms in universities based on simulation

The acoustic environment of the classroom is one of the most important factors influencing the teaching and learning effects of the teacher and students.It is critical to ensure good speech intelligibility in classrooms.However,due to some factors,it may not be easy to achieve an ideal classroom acoustic environment,especially in large-scale multimedia classrooms.In a real renovation project of 39 multimedia classrooms in a university,seven typical rooms were selected,and the acoustic environment optimisation design and verification for these multimedia classrooms were performed based on simulation.First,the acoustic and sound reinforcement design schemes were determined based on the room acoustics software ODEON.Next,the effects of the optimisation design were analysed,and the simulated and measured results were compared;the accuracy of using the reduced sound absorption coefficients,which were determined empirically,was also examined.Finally,the recommended reverberation times(RTs)in multimedia classrooms corresponding to speech intelligibility were discussed,the effectiveness of the speech transmission index(STI)as a primary parameter for classroom acoustic environment control was considered,and the acoustic environment under the unoccupied and occupied statuses was compared.The results revealed that although there are many factors influencing the effect of classroom acoustic environment control,an adequate result can be expected on applying the appropriate method.Considering both the acoustic design and visual requirements also makes the classroom likely to have a good visual effect in addition to having a good listening environment.

Capturing uncertainties of the underwater acoustic environment based on an ocean-acoustic coupled model

Considering the uncertain effects of temporal and spatial changes in the marine en- vironment on the underwater acoustic environment, we established an ocean-acoustic coupled numerical model and performed a parallel calculation. This model incorporated acoustic calcu- lations into the dynamic ocean, thereby achieving a dynamic forecasting and assessment of the acoustic environment. Furthermore, we adopted the ensemble prediction method to predict the vertical structure of temperature in a classic cross-section, the sound speed of the cross-section of the investigated sea area, and transmission losses. We gave the prediction errors of the sound speed profile as well as the 90% probability interval of transmission losses and the uncertainty histograms of the sound speeds, transmission losses, and sonar ranges at different depths and frequencies. The results reflected the influence of marine temporal and spacial variations on the uncertainties of the underwater acoustic environment, and the results also quantified the uncertainties of the underwater acoustic environment parameters. The experimental results indicate that the method used in this study is able to delineate and quantify the uncertainties of the underwater acoustic environment caused by marine dynamic changes.

Parametric array differential Pattern time delay shift coding underwater acoustic communication in the under-ice environment

In order to meet the demands of underwater acoustic communication in under ice environment,a differential Pattern time delay shift coding underwater acoustic communication method based on parametric array is introduced in this paper.The under ice underwater acoustic channel is characterized by heavy multipath transmission.Under this model,a parametric array emission method of Pattern signal is derived and the system performance is analyzed.A broadband low frequency sound waves with narrow beam-pattern,which will reduce the interface reflections and suppress the effects of multipath transmission,can be obtained by the emission method.The Songhua River under ice trial results show that there is an anti-multipath property and a higher data rate in the under-ice acoustic channel in proposed approach.