住宅建筑中相邻房间的侧向传声预测

侧向传声作为建筑中声传递的组成部分,对住宅的整体隔声效果具有重要的影响,通过将建筑中相邻房间的各建筑构件划分为若干子系统,应用统计能量分析(Statistical Energy Analysis,SEA)理论,从系统的声功率平衡的角度建立侧向传声的预测模型,在描述各路径的传声规律的同时确定主要传声路径。研究结果表明:当外围护结构为重质结构,且为匀质单一材料构造时,(1)在低频处,全程通过两相邻房间的侧墙或楼板的非通过隔墙的侧向路径成为主要侧向传声路径;(2)在中高频,各侧向路径的声压级差趋于一致,此时的建筑隔声性能取决于通过隔墙的直接路径上的声传递;(3)采用重质隔墙可以缩小侧向传声影响的频率范围。本研究为改善住宅的声环境质量及建筑隔声设计提供了理论依据。      

High frequency vibration energy transfer in a system of three plates connected at discrete points using statistical energy analysis

Vibration energy transfer in a system of three plates separated by a small distance and connected at a few discrete points, like solar panels in a spacecraft, is investigated. Coupling loss factors are obtained experimentally using the power injection technique. The system is then subjected to the acoustic excitation in a reverberant chamber. The measured responses of the inner plate are significant. But the measured responses of the inner plates are higher than the responses estimated based on the coupling loss factors obtained. When the system is subjected to mechanical excitation the measured responses of the inner plate closely match with the estimated responses. The difference is perhaps due to the sound radiated from the outer plates not being considered for the calculation, requiring further studies.     

Prediction of sound flanking transmission through two adjacent rooms within a residence building

Flanking transmission has significant effects on the overall sound insulation of two adjacent rooms within a residence building. This study investigates the mechanism of the sound flanking transmission by dividing it into several subsystems with the statistical energy analysis method. The sound energy equations of these subsystems are obtained first, and then,the sound transmissions on each flanking path are predicted and the dominant sound transmission path is determined by solving these equations and calculating the total loss factors of the subsystems and coupling loss factors between subsystems. With respect to a masonry building with heavy-weight homogeneous structure, the results show that:(1) the flanking transmission paths instead of the separating wall may become the dominant ones at low frequencies;(2) all sound transmissions on the flanking paths tend to be consistent at medium and high frequencies, so the sound insulation between two adjacent rooms depends on the direct path of the separating wall;(3) heavy-weight separating walls can be used to reduce the frequency range of the flanking transmission.     

SEA and contribution analysis for interior noise of a high speed train

This paper presents a detailed Statistical Energy Analysis (SEA) and contribution analysis of the interior noise of a high-speed train through extensive simulations and measurements. The SEA model was developed based on the actual geometrical parameters of a benchmark high-speed coach. Sound transmission loss levels of the structural components of the car body, which are required in the SEA model, were tested in a dedicated acoustic laboratory following international standard ISO 140-3:1995. Modal densities of these structural components were derived from measured frequency response functions using the modal counting method. Damping loss factors were obtained using the half-power bandwidth method and the vibration attenuation method. By considering the relationship between sound radiation and power transmission, coupling loss factors between structures and cavities were estimated. Source inputs to the SEA model were derived from field experiment data. Interior noise due to those sources was predicted using the SEA model and the prediction was generally in good agreement with measurement. Contribution analysis was then performed using this validated model through parametric study, and this analysis was further examined experimentally. In conclusion, for the coach that was investigated in this paper, the key factors for interior noise are sidewall vibration, bogie area noise, and floor sound transmission loss. Based on this and other engineering considerations, an interior noise control strategy can be defined.     

Theoretical models for investigation of sound transmission through isolation layers in staircase systems

The behaviour patterns of staircase dynamic response to structure-borne sound are given through analysis of two-dimensional models. Typical models of this kind include angular discontinuities which represent the intersection line between the horizontal slabs and the stair's slope. Numerical examples illustrate the effect of elastic isolation layers on the solid-borne transmission loss between the stairs and the other parts of the building, the strong coupling between the stairs and the building caused by substitution of the elastic isolation layers by rigid sound bridges, the dependence of the dynamic response of the staircase on frequency, and the coupling between the longitudinal and flexural waves due to the aforementioned angular discontinuities of the staircase system.     

SOUND TRANSMISSION THROUGH ELASTOMERIC BULB SEALS

The sound barrier performance of elastomeric vehicle weather seals was investigated. Experiments were performed on a single bulb seal specimen using a reverberation room method. The seal wall velocity was measured using a laser Doppler vibrometer. The sound pressure near the velocity measurement location was measured simultaneously, which allowed the sound intensity on both sides of the seal and the sound transmission loss to be determined. The vibration response and the sound transmission loss of the bulb seal were then computed using finite element analysis. Acoustic-structure interactions were considered for a partially coherent spatially distributed pressure excitation. The experimental data obtained using the reverberation room method allowed the validation of the numerical models. The resonance frequency due to the mass-air-mass mode of vibration was accurately predicted. The model was then used to numerically investigate the influence of various design parameters. It was found that the elastic modulus significantly affects the bulb seal resonance frequency, and that the loss factor of the material has major effects on the sound transmission loss around resonance.     

Non-resonant sound transmission through double walls using statistical energy analysis

Although SEA is a suitable framework for predicting sound transmission through double walls it has been found that the standard method of computing the non- resonant coupling loss factor from a room to cavity underestimates the coupling. A revised model for computing this coupling loss factor is presented which gives much better agreement with measured data. This allows better predictions to be made of sound transmission through lightweight double walls.     

The sound transmission loss of a single panel measured with the two-microphone and the conventional method-comparison with the statistical energy analysis model

The sound transmission loss of a single metal panel obtained with the sound intensity technique and the conventional method have been compared with the theoretical model of Statistical Energy Analysis (SEA). This method of comparison with a theoretical model is useful in order to explain small systematic deviations between the results of both experimental methods.It happens that the difference between the so-called residual reactivity level and the measured reactivity gives a good estimate of the accuracy of the intensity measurement. Even in very simple cases this quantity can disturb the measuring results due to the complex sound field close to the sound radiating panel. By correcting the sound transmission loss results with the well known Waterhouse correction and by choosing an appropriate probe distance to the sound radiating construction, good agreement is obtained between the results of both experimental methods as well as with the SEA model.     

Untersuchung zur anwendbarkeit impulsförmiger anregung für ein meßverfahren zur bestimmung von körperschallanregung und -übertragung

A procedure has been developed for measuring the structure-borne sound sensitivity of building structures to stationary excitation. This procedure has the advantage that it can be conducted with simple sound pressure and vibration measurements. The precision and reproducibility of the measurement procedure have been tested. This method permits the measurement of the vibratory point forces due to structure-borne sound sources in buildings or other systems.In order to determine the structure-borne sound sensitivity and the vibratory point forces to transient excitation, impulses were tested and compared with the results obtained with stationary excitation.     

预测声屏障插入损失的抛物方程法及其初始声场研究

Salomons建立的抛物方程(CNPE)方法可以预测非均匀环境中的声屏障插入损失。但是该方法在声屏障与声源距离较近时会产生较大误差。文中通过理论分析发现产生该问题的原因在于CNPE方法所使用的Gauss初始场仅适用于小仰角(10°以内)范围内的声波。为解决Gauss初始场引起的问题,推导了可以用于较大仰角声波的更高阶数的Gauss初始场。通过数值仿真对比了不同阶数的初始场在CNPE方法中的效果。结果表明:4阶初始场是最适合CNPE方法的初始场,将该初始场与CNPE方法相结合,可以准确预测当声屏障与声源距离较近时的插入损失.      

Temporal processing in the aging auditory system.

Measures of monaural temporal processing and binaural sensitivity were obtained from 12 young (mean age = 26.1 years) and 12 elderly (mean age = 70.9 years) adults with clinically normal hearing (pure-tone thresholds < or = 20 dB HL from 250 to 6000 Hz). Monaural temporal processing was measured by gap detection thresholds. Binaural sensitivity was measured by interaural time difference (ITD) thresholds. Gap and ITD thresholds were obtained at three sound levels (4, 8, or 16 dB above individual threshold). Subjects were also tested on two measures of speech perception, a masking level difference (MLD) task, and a syllable identification/discrimination task that included phonemes varying in voice onset time (VOT). Elderly listeners displayed poorer monaural temporal analysis (higher gap detection thresholds) and poorer binaural processing (higher ITD thresholds) at all sound levels. There were significant interactions between age and sound level, indicating that the age difference was larger at lower stimulus levels. Gap detection performance was found to correlate significantly with performance on the ITD task for young, but not elderly adult listeners. Elderly listeners also performed more poorly than younger listeners on both speech measures; however, there was no significant correlation between psychoacoustic and speech measures of temporal processing. Findings suggest that age-related factors other than peripheral hearing loss contribute to temporal processing deficits of elderly listeners.     

Prediction of total loss factors of structures,I: Theory and experiments

A method for calculating the total loss factors of a complex structure has been derived by using Statistical Energy Analysis (SEA). The derived formulae have been simplified on the assumption that coupling between substructures except for the measured substructure is very weak. In two limiting situations, “damping addition” formulae have been obtained. The formula has been applied to predict the total loss factors of a steel box and these results are compared with actual experimental measurements. The agreement between estimated and measured values was in most cases quite good.     

南海北部海域内波环境下声传播损失起伏统计特性

浅海内波会引起声传播能量随时间的起伏变化,进而影响水声设备的工作性能.本文利用2015年南海北部一次浅海声场起伏实验数据,对比分析了浅海线性内波和孤立子内波条件下的声传播损失统计特性.在孤立子内波条件下,声传播损失起伏明显加剧,可达11 dB,且分布明显展宽,相对于线性内波的环境,声传播损失起伏可增加5 dB.从简正波...     

THE ROLE AND EXPERIMENTAL DETERMINATION OF EQUIVALENT MASS IN COMPLEX SEA MODELS

The application of statistical energy analysis to vibro-acoustic systems of complex geometry has been made practicable by the introduction of the concept of equivalent mass/equivalent volume. Although previous research at the ISVR has shown that these parameters can be directly measured, it has recently been found that the published formulae for carrying out this calculation are not sufficiently accurate. This is because it has been previously incorrectly assumed that the measurement on the subsystem of interest is unaffected by the presence of other attached subsystems. The paper derives the correct expressions for equivalent mass/equivalent volume for the general case of N -connected subsystems. By utilizing these derived expressions, the paper then proceeds to show that the coupling loss factors can be obtained directly in terms of the measured input power and vibration velocity/sound pressure. The paper concludes by showing that the power balance equations can, by utilizing the above expressions, be framed in terms of the subsystem velocities/sound pressures rather than in terms of subsystem energies.     

Sound transmission loss of foam-filled honeycomb sandwich panels using statistical energy analysis and theoretical and measured dynamic properties

Comparisons between the experimental and predicted sound transmission loss values obtained from statistical energy analysis are presented for two foam-filled honeycomb sandwich panels. Statistical energy analysis (SEA) is a modeling procedure which uses energy flow relationships for the theoretical estimation of the sound transmission through structures in resonant motion. The accuracy of the prediction of the sound transmission loss using SEA greatly depends on accurate estimates of: (1) the modal density, (2) the internal loss factor, and (3) the coupling loss factor parameters of the structures. A theoretical expression for the modal density of sandwich panels is developed from a sixth-order governing equation. Measured modal density estimates of the two foam-filled honeycomb sandwich panels are obtained by using a three-channel spectral method with a spectral mass correction to allow for the mass loading of the impedance head. The effect of mass loading of the accelerometer is corrected in the estimations of both the total loss factor and radiation loss factor of the sandwich panels.     

Determination of the sound energy level of a gunshot and its applications in room acoustics

In some cases an impulsive noise source such as a gunshot can be a preferred alternative when investigating building acoustics, including sound insulation measurements, when compared to conventional steady state noise sources. A gun equipped with blank cartridges is an impulsive noise source that is lightweight and small enough to be easily transported. The differences in the noise characteristics between individual cartridges for the same gun are usually small, so the impulsive source can be replicated to a high degree. This paper is focused on the practical application of the sound exposure levels produced by a gunshot with a known sound energy level in the rooms under investigation. In this way, the equipment and methods required by the conventional method are simplified significantly. Furthermore, reverberation times need not be measured, since the equivalent absorption area can be directly obtained from the measured sound exposure levels. Using Green’s theorem, the roles of the sound source and measuring microphone were exchanged, which simplified the determination of sound insulation as it was easier to change the position of the gun than the microphone. The results obtained using the impulsive noise source were in good agreement with those obtained using the conventional method. Above 100 Hz, their difference in any frequency band of interest was less than 1 dB.     

Evaluating the maximum playback sound levels from portable digital audio players

To assess the maximum sound levels that may be experienced by young people in Canada from modern digital audio players, this study measured nine recent models of players and 20 earphones. Measurement methodology followed European standard BS EN 50332. Playback levels ranged from 101 to 107 dBA at maximum volume level. Estimated listener sound levels could vary from 79 to 125 dBA due to the following factors: (i) earphone seal against the ear, (ii) player output voltage, (iii) earphone sensitivity, and (iv) recorded music levels. There was a greater potential for high sound levels if intra-concha "earbud" earphones were used due to the effect of earphone seal. Simpler measurement techniques were explored as field test methods; the best results were obtained by sealing the microphone of a sound level meter to the earphone using a cupped hand and correcting for the free field response of the ear. Measurement of noise levels 0.25 m from the earphone showed that a bystander is unlikely to accurately judge listener sound levels.     

Frequency shifts of sound field maxima under the effect of intense internal waves

Numerical simulation is carried out to study frequency shifts of a low-frequency sound field maxima under the effect of solitary internal waves (solitons) propagating along an acoustic track in the presence of mode coupling. The frequency shifts are measured by the correlation method. Simulation data obtained with allowance for mode coupling and data obtained in the adiabatic approximation are compared and analyzed.     

Noise control measures in the new Singapore International Airport

This paper describes some of the noise control measures incorporated in the passenger terminal building at the new Singapore International Airport at Changi. As the acoustics adviser to the Changi Airport Development Division of the Public Works Department, the overall consultant of this multi-billion dollar project, the author reviews some of the special steps taken to incorporate some of the latest acoustics techniques in this airport.These include the establishment of norms for various factors such as permissible background noise levels to each of the rooms, offices, arrival and departure halls, etc. Specifications called for include optimum sound absorption and reverberations times, airborne sound insulation for internal and external building partitions and structureborne sound insulation, as well as a sophisticated sound reinforcement system.Because of the stringent requirements following some of these specifications, the factor of the skill and workmanship of the contractors involved in the erection of the partitions had to be allowed for. As a result, all suppliers and contractors were requested to send their building proposals for testing. This was done in the newly established Acoustics Laboratory of the National University of Singapore at Kent Ridge. Some of the tests carried out, based on International Standards ISO R140 and ASTM E90 on sound transmission loss and ISO R354 and ASTM C423 on sound absorption, are evaluated.     

Line source and site characterizations for defining the sound transmission loss of building facades

An analytical model is presented for defining the sound transmission loss of building facades exposed to noise from line sources. The model describes the non-diffuse sound field incident upon the facade in terms of both source and site parameters. The effects of facade orientation relative to the line source and the sound propagation with distance are introduced as a single term in the definition of the facade sound transmission loss. This term defines a mean angle of incidence for the exterior sound field that is equivalent to a point source location relative to a point on the facade. Numerical results are presented illustrating the magnitudes of these effects and it is shown that alternative methods for conducting field measurements of building facade sound transmission loss may be related by using this model.