Zhao, S, Qiu, X, Lacey, J & Maisch, S 2019, 'Configuring fixed-coefficient active control systems for traffic noise reduction', BUILDING AND ENVIRONMENT, vol. 149, pp. 415-427.View/Download from: UTS OPUS or Publisher's site
Zhao, S, Cheng, E, Qiu, X, Burnett, I & Chia-Chun Liu, J 2018, 'Spatial decorrelation of wind noise with porous microphone windscreens.', Journal of the Acoustical Society of America, vol. 143, no. 1, pp. 330-330.View/Download from: UTS OPUS or Publisher's site
This paper explores the wind noise reduction mechanism of porous microphone windscreens by investigating the spatial correlation of wind noise. First, the spatial structure of the wind noise signal is studied by simulating the magnitude squared coherence of the pressure measured with two microphones at various separation distances, and it is found that the coherence of the two signals decreases with the separation distance and the wind noise is spatially correlated only within a certain distance less than the turbulence wavelength. Then, the wind noise reduction of the porous microphone windscreen is investigated, and the porous windscreen is found to be the most effective in attenuating wind noise in a certain frequency range, where the windscreen diameter is approximately 2 to 4 times the turbulence wavelengths (2 < D0/ξ < 4), regardless of the wind speed and windscreen diameter. The spatial coherence between the wind noise outside and inside a porous microphone windscreen is compared with that without the windscreen, and the coherence is found to decrease significantly when the windscreen diameter is approximately 2 to 4 times the turbulence wavelengths, corresponding to the most effective wind noise reduction frequency range of the windscreen. Experimental results with a fan are presented to support the simulations. It is concluded that the wind noise reduction mechanism of porous microphone windscreens is related to the spatial decorrelation effect on the wind noise signals provided by the porous material and structure.
Zhao, S, Dabin, M, Cheng, E, Qiu, X, Burnett, I & Liu, JC-C 2018, 'Mitigating wind noise with a spherical microphone array.', The Journal of the Acoustical Society of America, vol. 144, no. 6, pp. 3211-3211.View/Download from: UTS OPUS or Publisher's site
This paper utilizes a rigid spherical microphone array to reduce wind noise. In the experiments conducted, a loudspeaker is used to reproduce the desired sound signal and an axial fan is employed to generate wind noise in an anechoic chamber. The sound signal and wind noise are measured separately with the spherical microphone array and analyzed in the spherical harmonic domain. The wind noise is found to be irregularly distributed in the spherical harmonic domain, distinct from the sound signal which is concentrated in the first few spherical harmonic modes. This difference is utilized to reduce wind noise without degrading the desired sound pressure level (SPL) by use of a low pass filter method in the spherical harmonic domain. Experimental results with both single-tonal and multi-tonal sound signals demonstrate that the proposed method can reduce wind noise by more than 10 dB in the frequency range below 500 Hz. The SPL of the desired sound signal can be extracted from wind noise with an error within 1.0 dB, even when the sound level is 8 dB lower than wind noise.
Zhao, S, Dabin, M, Cheng, E, Qiu, X, Burnett, I & Liu, JC-C 2017, 'On the wind noise reduction mechanism of porous microphone windscreens.', Journal of the Acoustical Society of America, vol. 142, no. 4, pp. 2454-2454.View/Download from: UTS OPUS or Publisher's site
This paper investigates the wind noise reduction mechanism of porous microphone windscreens. The pressure fluctuations inside the porous windscreens with various viscous and inertial coefficients are studied with numerical simulations. The viscous and inertial coefficients represent the viscous forces resulting from the fluid-solid interaction along the surface of the pores and the inertial forces imposed on the fluid flow by the solid structure of the porous medium, respectively. Simulation results indicate that the wind noise reduction first increases and then decreases with both viscous and inertial coefficients after reaching a maximum. Experimental results conducted on five porous microphone windscreens with porosity from 20 to 60 pores per inch (PPI) show that the 40 PPI windscreen has the highest wind noise reduction performance, and this supports the simulation results. The existence of the optimal values for the viscous and inertial coefficients is explained qualitatively and it is shown that the design of the porous microphone windscreens should take into account both the turbulence suppression inside and the wake generation behind the windscreen to achieve optimal performance.
Zhao, S, Cheng, E, Qiu, X, Burnett, I & Liu, JC-C 2017, 'Wind noise spectra in small Reynolds number turbulent flows.', Journal of the Acoustical Society of America, vol. 142, no. 5, pp. 3227-3227.View/Download from: UTS OPUS or Publisher's site
Wind noise spectra caused by wind from fans in indoor environments have been found to be different from those measured in outdoor atmospheric conditions. Although many models have been developed to predict outdoor wind noise spectra under the assumption of large Reynolds number [Zhao, Cheng, Qiu, Burnett, and Liu (2016). J. Acoust. Soc. Am. 140, 4178-4182, and the references therein], they cannot be applied directly to the indoor situations because the Reynolds number of wind from fans in indoor environments is usually much smaller than that experienced in atmospheric turbulence. This paper proposes a pressure structure function model that combines the energy-containing and dissipation ranges so that the pressure spectrum for small Reynolds number turbulent flows can be calculated. The proposed pressure structure function model is validated with the experimental results in the literature, and then the obtained pressure spectrum is verified with the numerical simulation and experiment results. It is demonstrated that the pressure spectrum obtained from the proposed pressure structure function model can be utilized to estimate wind noise spectra caused by turbulent flows with small Reynolds numbers.
Zhao, S, Cheng, E, Qiu, X, Burnett, I & Liu, JC-C 2016, 'Pressure spectra in turbulent flows in the inertial and the dissipation ranges', JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, vol. 140, no. 6, pp. 4178-4182.View/Download from: UTS OPUS or Publisher's site
Zhao, S, Qiu, X, Cheng, E, Burnett, I, Williams, N, Burry, J & Burry, M 2015, 'Sound quality inside small meeting rooms with different room shape and fine structures', APPLIED ACOUSTICS, vol. 93, pp. 65-74.View/Download from: Publisher's site
Zhao, S, Qiu, X & Burnett, I 2015, 'Acoustic contrast control in an arc-shaped area using a linear loudspeaker array (L)', JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, vol. 137, no. 2, pp. 1036-1039.View/Download from: Publisher's site
Zhao, S, Qiu, X & Cheng, J 2015, 'An integral equation method for calculating sound field diffracted by a rigid barrier on an impedance ground', JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, vol. 138, no. 3, pp. 1608-1613.View/Download from: Publisher's site
Accelerating beams have attracted considerable research interest due to their peculiar properties and various applications. Although there have been numerous research on the generation and application of accelerating light beams, few results have been published on the generation of accelerating acoustic beams. Here we report on the experimental observation of accelerating acoustic beams along arbitrary convex trajectories. The desired trajectory is projected to the spatial phase profile on the boundary which is discretized and sampled spatially. The sound field distribution is formulated with the Green function and the integral equation method. Both the paraxial and the non-paraxial regimes are examined and observed in the experiments. The effect of obstacle scattering in the sound field is also investigated and the results demonstrate that the approach is robust against obstacle scattering. The realization of accelerating acoustic beams will have an impact on various applications where acoustic information and energy are required to be delivered along an arbitrary convex trajectory.
Zhao, S, Cheng, E, Qiu, X, Burnett, I & Liu, JCC 2018, 'Experimental investigations on the wind noise reduction of semi-spherical metal mesh windscreens', 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling, pp. 288-295.View/Download from: UTS OPUS
© 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling. All rights reserved. The accuracy of noise measurements in the presence of flow is affected by wind noise, which is the pseudo sound generated on the microphone by turbulent flow. In outdoor acoustic measurement, porous windscreens are usually installed on the microphones to reduce the wind noise. In strong windy conditions, an additional large secondary shell windscreen is used to further mitigate the wind effect. This paper performs a systematic experimental study of semi-spherical shell windscreens. The effects of the windscreen size, multi-layer windscreens and fabric coverings on both the wind noise reduction and insertion loss are investigated. For single-layer windscreens without coverings, the insertion loss is below 0.4 dB and the maximum wind noise reduction is achieved by the mid-sized windscreen of 20 cm diameter. Covering the single-layer windscreens with a thin and thick cloth is found to introduce additional 1.0 ~ 3.5 dB and 3.0 ~ 7.0 dB wind noise reduction, but also increases the insertion loss to 1.1 ~ 2.2 dB. The multilayer windscreens are found to be superior to the fabric coverings, improving the wind noise reduction while keeping the insertion loss small. The best performance is achieved by the five-layer windscreen, with an 18.2 dB wind noise reduction and a 0.6 dB insertion loss.
Zhao, S, Cheng, E, Qiu, X, Burnett, I & Liu, CC 2017, 'Simulations on the wind noise reduction by spherical shell windscreens', INTER-NOISE 2017 - 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet.View/Download from: UTS OPUS
© 2017 Institute of Noise Control Engineering. All rights reserved. Various windscreens are widely used in outdoor acoustic measurements to reduce the effect of the wind induced pressure fluctuations at the microphones and to improve the measurement accuracy. However, the physical mechanism of the wind noise reduction by windscreens remains unclear yet. In this paper, the wind noise reduction performance of spherical shell windscreens is investigatedwith numerical simulations based on the turbulent modeling in porous media. The effects of both the diameter and the thickness of the spherical shell windscreen on the wind noise reduction performance are investigatedfor both uniform and turbulent incoming flows. It is found that the wind noise at the microphone can be reduced by spherical shell windscreens only when the thickness of the spherical shell windscreen is smaller than 0.1 cmfor uniformincoming flow, and the wind noise reduction increases with the diameter but approaches a constant when the windscreen is largerthan 20 cm.Forturbulentincoming flow, the wind noise reduction performance of the spherical shell windscreen increases with the diameter and reaches the best when the shell thickness is around 1.0 cm.
Zhao, S, Cheng, E, Qiu, X, Lacey, J & Maisch, S 2017, 'A method of configuring fixed coefficient active noise controllers for traffic noise reduction', INTER-NOISE and NOISE-CON Congress and Conference Proceedings, Hong Kong, China.View/Download from: UTS OPUS
© 2017 Institute of Noise Control Engineering. All Rights Reserved. In practical applications of Active Noise Control (ANC) systems on traffic noise reduction, the noise sources to be controlled are usually far away from the system and are continuously moving, hence there are no fixed noise sources for configuring the controller. This paper proposes a method to configure fixed coefficient ANC systems for the scenario of traffic noise reduction. In the tuning process, a pseudo noise source is proposed to be placed near a single channel ANC system to adjust the controller. After the optimal coefficients of the controller are obtained for this situation, the coefficients are fixed and the ANC system is utilized to cancel the actual noise source in the far-field. Simulation results showed that when the noise source is a point source located very far away from the ANC system, moving the pseudo noise source farther away from the single-channel ANC system can effectively increase the noise reduction. However, if the noise source is closer to the single-channel ANC system than the pseudo noise source, the performance deteriorates quickly. When the primary noise originates from a line array of incoherent point sources far from the ANC system, moving the pseudo noise source farther away from the system can effectively increase the noise reduction; however, the performance of the single channel ANC system decreases with frequency and deteriorates when there are many noise sources present simultaneously as in the traffic noise scenario. Experiments were conducted in a laboratory environment for one noise source and three noise sources, and the results are consistent with the simulations.
Alambeigi, P, Zhao, S, Burry, J & Qiu, X 2016, 'Complex Human Auditory Perception And Simulated Sound Performance Prediction', Living Systems and Micro-Utopias: Towards Continuous Designing - Proceedings Of The 21st International Conference On Computer-Aided Architectural Design Research In Asia (CAADRIA 2016), Association for Computer-Aided Architectural Design Research in Asia (CAADRIA) annual conference, CAADRIA, Hong Kong, China, pp. 631-640.View/Download from: UTS OPUS
This paper reports an investigation into the degree of consistency between three different methods of sound performance evaluation through studying the performance of a built project as a case study. The non-controlled office environment with natural human speech as a source was selected for the subjective experiment and ODEON room acoustics modelling software was applied for digital simulation. The results indicate that although each participant may interpret and perceive sound in a particular way, the simulation can pre- dict this complexity to some extent to help architects in designing acoustically better spaces. Also the results imply that architects can make valid comparative evaluations of their designs in an architecturally intuitive way, using architectural language. The research acknowledges that complicated engineering approaches to subjective analysis and to controlling the test environment and participants is difficult for architects to comprehend and implement.
Zhao, S, Cheng, E, Qiu, X, Alambeigi, P, Burry, J & Burry, M 2016, 'A preliminary investigation on the sound field properties in the Sagrada Familia Basilica', 2nd Australasian Acoustical Societies Conference, ACOUSTICS 2016, Conference of the Australian Acoustical Society, AAS, Brisbane, Australia, pp. 797-806.View/Download from: UTS OPUS
This paper reports on a preliminary investigation of the sound field properties inside a large Roman Catholic Church in Barcelona, the Sagrada Familia Basilica, which is a world heritage site although its construction has not been completed. The impulse responses were measured at five sound source positions combined with 14 measurement locations inside the Sagrada Familia Basilica, and the Impulse response to Noise Ratio (INR) were examined to examine the reliability of the measured impulse responses. The room acoustic parameters were calculated and the following five sound field properties in the Sagrada Familia Basilica were analysed: reverberation, spaciousness, loudness, warmth and clarity. The reverberation time (T20) and the Early Decay Time (EDT) were compared with the existing optimal values for small volume churches whereas the middle frequency strength of sound (Gmid), the low frequency strength of sound (G125), the clarity (C80) and the binaural quality index (1 - IACCE) were compared with the optimal values for concert halls. The understanding of the sound field properties in churches, especially in a church of such a large volume as the Sagrada Familia Basilica, is still an open topic and much further research is necessary for a more thorough understanding.
Zhao, S, Cheng, E, Qiu, X, Burnett, I & Liu, JCC 2016, 'Estimation of the frequency boundaries of the inertial range for wind noise spectra in anechoic wind tunnels', Proceedings - 2nd Australasian Acoustical Societies Conference, ACOUSTICS 2016, Conference of the Australian Acoustical Society, AAS, Brisbane, Australia, pp. 1187-1196.View/Download from: UTS OPUS
Wind noise generated by the intrinsic turbulence in the flow can affect the outdoor noise measurements. Various attempts have been made to investigate the wind noise generation mechanism. Wind noise spectra in anechoic wind tunnels can be divided into three frequency regions. In the low frequency region known as the energy-containing range, the wind noise spectrum does not change significantly with frequency. In contrast, in the middle frequency region (or inertial range) the decay rate of the wind noise spectrum curve follows the 7/3 power law, but in the high frequency region (or dissipation range) the decay rate of the wind noise spectrum curve is faster than the -7/3 power law. The boundaries of the -7/3 power law frequency range depend on the Reynolds number; however, no exact value is known according to current literature. This paper proposes a method for predicting the boundary values based on the energy cascade theory. Large eddy simulations of free jet were performed to validate the proposed method and the results were found to be in reasonable agreement with existing experiment measurements obtained in an anechoic wind tunnel. Additional simulations were also conducted with different inflow entrance sizes to further verify the predictions from the proposed method.
Qiu, X & Zhao, S 2015, 'Active control of the directivity of the sound diffraction from barriers', Proceedings of the 22nd International Congress on Sound and Vibration, International Congress on Sound and Vibration, International Institute of Acoustics and Vibration, Florence, Italy.
Active control of the directivity of the sound diffraction from barriers is investigated in this paper where the control sources are located near the top boundary of a barrier to change its spatial diffraction properties. First, an analytical solution for calculating the primary sound field from a point source diffracted from a barrier edge is given based on the Kirchhoff-Helmholtz equation, then the strengths of the secondary point sources near the barrier top boundary are optimized to control the directivity of the diffracted sound through the barrier edge so that the sound pressure is reduced in certain directions behind the barrier. Numerical simulation results show that the proposed directivity control method is feasible and can provide better performance than that of the local control methods in terms of the far field sound reduction. The potential applications of the method include increasing the performance of the current active noise barriers or reducing speech interference from opening ceiling meeting pods in open plan offices.
Zhao, S, Qiu, X, Lu, J & Cheng, J 2015, 'ROBUST TIME DOMAIN ACOUSTIC CONTRAST CONTROL IN AN ARC-SHAPED AREA USING A LINEAR LOUDSPEAKER ARRAY', Proceedings of 22nd International Congress on Sound and Vibration (ICSV), International Congress on Sound and Vibration (ICSV), INT INST ACOUSTICS & VIBRATION, Florence, ITALY.View/Download from: UTS OPUS
Zhao, S, Qiu, X & Lu, J 2014, 'Curving sound field reproduction in free field', 21st International Congress on Sound and Vibration 2014, ICSV 2014, 21st International Congress on Sound and Vibration 2014, pp. 2297-2304.View/Download from: UTS OPUS
Curving sound field reproduction refers to recreating sound propagating along a curving trajectory without disturbing the other side. This kind of sound could bypass the obstacle to reach the region behind the obstacle, which is difficult for conventional sound field reproduction system. Curving sound field reproduction can find applications in various situations, for example, speech signal could be delivered to a person without disturbing another person in front of him/her. This paper investigates the mechanisms for generating sound field based on the wave equation and the spatial sampling theory and the method of using linear loudspeaker arrays to generate such a sound field. A method based on ray acoustics to determine the loudspeaker weights is proposed and the simulation results are in good agreement with the theory. Extension to wideband situation of the method is also investigated and proved to be effective in a broad range of frequencies covering the human speech signal spectrum from 300 Hz to 3400 Hz.