Reduce Wind Noise Research Articles

Wind noise due to flow induced around a windscreen in large-scale turbulence

Turbulent wind noise on microphones is a ubiquitous problem for sound measurement and recording outdoors. Windscreens, such as open-cell foam spheres, are effective at reducing wind noise. The unsteady pressure sources induced on the windscreen surface must contribute less noise on average than the stagnation pressure on a bare microphone, or windscreens would not be effective. To quantify this noise reduction mechanism, a model is presented for the unsteady pressure within an impermeable windscreen of arbitrary shape immersed in an initially isotropic turbulent flow. Only turbulent scales larger than the windscreen are considered, which contribute the most intense low-frequency band of the noise spectrum in most practical situations. The inhomogeneous velocity field around the windscreen is modeled in terms of an induced irrotational blocking field that meets the kinematic boundary condition. The interior pressure is expressed as a convolution of the surface pressure field with a filter function in wavevector space. The wind noise wavevector spectrum is then shown to be only a function of the inflow isotropic velocity spectrum and the windscreen shape. Solutions are obtained for the pressure frequency spectrum within a spherical windscreen for a von Kármán turbulence model and compared with prior results in literature.

Multidisciplinary design of door inner belt weatherstrip for simultaneous reduction of wind noise and squeaking in electric vehicles

In electric vehicles (EVs), addressing noise, vibration, and harshness (NVH) has become pivotal, especially concerning external wind noise. To reduce wind noise, a door inner belt weatherstrip needs a high contact load, but this can lead to squeaking noise at the glass/weatherstrip interface. This study demonstrates a multidisciplinary design for the weatherstrip to tackle both issues. By increasing ethylene propylene diene monomer and ethylidene norbornene contents in the thermoplastic vulcanizate (TPV) by about 20 % and 70 %, respectively, the compression set was reduced from 35.4 % to 27.6 %. Concurrently, the TPV’s damping properties improved, with a 25 % increase in loss modulus (323 MPa). Coated flocking surface of weatherstrip significantly reduced the friction coefficient by 80 % (from 1.75 to 0.30). In vehicle evaluations, the newly designed weatherstrip reduced the wind noise by 5 dB(A) and eliminated. This approach highlights the potential of multidisciplinary design in optimizing NVH for next-generation vehicles, including autonomous EVs and urban air mobility.

Building a Virtual Weakly-Compressible Wind Tunnel Testing Facility

Virtual wind tunnel testing is a key ingredient in the engineering design process for the automotive and aeronautical industries as well as for urban planning: through visualization and analysis of the simulation data, it helps optimize lift and drag coefficients, increase peak speed, detect high pressure zones, and reduce wind noise at low cost prior to manufacturing. In this paper, we develop an efficient and accurate virtual wind tunnel system based on recent contributions from both computer graphics and computational fluid dynamics in high-performance kinetic solvers. Running on one or multiple GPUs, our massively-parallel lattice Boltzmann model meets industry standards for accuracy and consistency while exceeding current mainstream industrial solutions in terms of efficiency --- especially for unsteady turbulent flow simulation at very high Reynolds number (on the order of 10 7 ) --- due to key contributions in improved collision modeling and boundary treatment, automatic construction of multiresolution grids for complex models, as well as performance optimization. We demonstrate the efficacy and reliability of our virtual wind tunnel testing facility through comparisons of our results to multiple benchmark tests, showing an increase in both accuracy and efficiency compared to state-of-the-art industrial solutions. We also illustrate the fine turbulence structures that our system can capture, indicating the relevance of our solver for both VFX and industrial product design.

Towards high-quality X-59 sonic thump measurements

Brigham Young University has been studying questions related to NASA X-59 community noise testing. A summary of the key findings and recommendations to date are presented. Among these are weather-resistant ground microphone setups that reduce wind noise, methods for treating the problem of ambient noise contamination on sonic boom metrics and spectra, and the turbulence-induced variability seen over relatively small-aperture arrays. Also discussed are recommendations for data post-processing, e.g., employing a digital pole-shifting filter and zero-padding to improve the fidelity and smoothness of low-frequency spectral data. Finally, the relative merits of various sonic boom metrics are considered. Although Perceived Level has been the most widely-used metric, it is relatively sensitive to ambient noise contamination and turbulence-induced variability. [Work supported by NASA Langley Research Center through the National Institute of Aerospace.]

Numerical simulation of on-road wind conditions for interior wind noise of passenger vehicles

Traditionally vehicles are designed for wind noise under ideal steady wind conditions. But, passenger comfort is affected by high modulation of cabin noise while cruising in traffic due to variations of instantaneous wind speed and direction from driving through large-scale turbulence. In consequence, designing a vehicle for the best performance in a low-turbulence wind tunnel may lead to issues during on-road conditions. To predict the interior noise corresponding to on-road turbulence, a simulation approach is proposed combining an upstream turbulence flow simulation with an SEA vehicle model. This work is an extension of existing well validated procedures for steady wind conditions. Time-segmented transient loads on panels and steady-state structural acoustics transfer functions are combined, producing interior noise results for a series of overlapping time segments. This interior noise prediction, as a function of time, captures the modulation of wind noise results, which are then visualized using a spectrogram, plotting sound pressure level indicated by color as a function of time and frequency bands. Audio signals are also created from the interior noise results, allowing detailed signal analysis from this simulation. This capability enables designers to reduce wind noise modulation in time caused by on-road turbulence, improving speech intelligibility and passenger comfort.

Overview of research-based community noise testing recommendations from Brigham Young University

Brigham Young University has been studying questions related to NASA X-59 community noise testing. A summary of the key findings and recommendations to date are presented. Among these are weather-resistant ground microphone setups that reduce wind noise, methods for treating the problem of ambient noise contamination on sonic boom metrics and spectra, and the turbulence-induced variability seen over relatively small-aperture arrays. Also discussed are recommendations for data post-processing, e.g., employing a digital pole-shifting filter and zero-padding to improve the fidelity and smoothness of low-frequency spectral data. Finally, the relative merits of various sonic boom metrics are considered. Although Perceived Level has been the most widely-used metric, it is relatively sensitive to ambient noise contamination and turbulence-induced variability. [Work supported by NASA Langley Research Center through the National Institute of Aerospace.]

풍잡음 저감용 방풍망 특성에 대한 실험적 연구

An experimental study was carried out to identify the characteristics of a windscreen to reduce wind noise. Five different windscreens were used to measure noise reduction, and the windscreen covered the microphone. They have different shapes, sizes, and pores per inch. First, the capability of each windscreen to block wind was studied, and then the effects of noise source, source magnitude, and wind speed on noise reduction, due to a windscreen, were investigated. The measured noise levels were examined in the 1/3 octave band. In the low frequency range (〈 50 Hz), noise levels were severely distorted for all windscreens. In the high frequency range (〉 6300 Hz), the largest windscreen showed more noise reduction than the other windscreens. In addition, an on-site experiment confirmed that noise measurement was possible for wind speeds up to 5 m/s.

Application of spectral-based wind noise reduction method to acoustical measurements

Wind-induced microphone self-noise is a non-acoustic signal that may contaminate outdoor acoustical measurements, particularly at low frequencies, even when using a windscreen. A recently developed method [Cook etal., JASA Express Lett. 1, 063602 (2021)] uses the characteristic spectral slope of wind noise in the inertial subrange for screened microphones to automatically classify and reduce wind noise in acoustical measurements in the lower to middling frequency range of human hearing. To explore its uses and limitations, this method is applied to multiple acoustical measurements collected in both urban and rural environments. The method can be applied to one-third octave band spectral data with different frequency ranges and sampling intervals. By removing the shorter timescale data at frequencies where wind noise dominates the signal, the longer timescale acoustical environment can be more accurately represented. While considerations should be made about the specific applicability of the method to particular datasets, the wind reduction method allows for simple classification and reduction of wind-noise-contaminated data in large, diverse datasets. [Work supported by U.S. Army SBIR.]

Experimental and Numerical Analyses of Wind-Induced Noise in Two-Way Radios

The generation of wind noise of entrance microphone cavities owing to turbulent airflow is an inherent problem with radio telecommunication systems, such as two-way radios. It will lead to a pressure fluctuation which is highly unpleasant and would degrade a two-way radio communication. This research aims to understand the relationship between noise level and the flow structure of the different parameters to the occurrence of noise during communication using a two-way radio device. A noise measurement is conducted to analyse the sound pressure level (SPL) within a cavity, in which computational fluid dynamic(CFD) is used to investigate the flow behaviour on the various effects of cavity positions at P1, P2, P3, P4, and P5 and wind velocities of 0.75 m/s, 1.49 m/s, 2.24 m/s, 2.99 m/s and 3.75 m/s which corresponding to Reynolds number (Re) of 8694, 17389, 26083, 34777, and 43471 respectively. CFD result showed the presence of separation of the shear layer, the development of vortex shedding, the recirculation region and vorticity were present inside the edges of the cavity. SPL increased with an increase in wind velocity and, the cavity distance of P4. In the cavity position of P5, SPL is decreased due to the wind velocity exceeding the maximum level of a wind tunnel. Therefore, the cavity position of P5 is suitable for reducing wind noise. These parameters are significant for improving the design of two-way radio to reduce the noise during outdoor communication.

Three-Dimensional Simulation of New Car Profile

Aerodynamics has identified remarkable development in the improvement of fuel efficiency, reducing wind noise and increasing engine cooling. Moving body profile controls fuel the consumption rate. This paper discusses a novel car profile consisting of two airfoils Roncz (car profile) and National Advisory Committee for Aeronautics NACA 10 (car sides). They are used to create a streamlined body. Three-Dimensional numerical simulations of the full scale model (half domain) are performed to examine the effect of car profile on the drag coefficient and thus fuel consumption. Simulations are considered over a range of air flow velocities, from 20 to 45 km/h in a step of 5 km/h. The ahmed body is used to validate the results. Results are shown graphically for coefficients of drag and lift and pressure and velocity contours. They show that the design of the car profile is effective.

Origin and mitigation of wind noise on balloon-borne infrasound microbarometers.

High-altitude monitoring of low-frequency acoustic waves (infrasound) on Earth has regained prominence in recent years, primarily driven by improvements in light-weight sensor technology and advances in scientific ballooning techniques. Balloon-borne infrasound monitoring is also being proposed as a remote sensing technique for planetary exploration. Contrary to ground-based infrasound monitoring, the infrasound noise background in the stratosphere as measured by a balloon remains uncharacterized and the efficacy of wind noise mitigation filters has not been investigated. In this study, an analysis of pressure data collected using infrasound microbarometers during the flight of a long-duration zero pressure balloon is presented. A dramatic reduction of background noise in the stratosphere is demonstrated and it is shown that wind noise mitigation filters are not effective at reducing wind noise under these conditions. Results from this study demonstrate stratospheric balloons as a low-noise platform for infrasound monitoring and motivate the development of improved noise mitigation tools.

Mitigating wind noise with a spherical microphone array.

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.

Use of a Deep Recurrent Neural Network to Reduce Wind Noise: Effects on Judged Speech Intelligibility and Sound Quality.

Despite great advances in hearing-aid technology, users still experience problems with noise in windy environments. The potential benefits of using a deep recurrent neural network (RNN) for reducing wind noise were assessed. The RNN was trained using recordings of the output of the two microphones of a behind-the-ear hearing aid in response to male and female speech at various azimuths in the presence of noise produced by wind from various azimuths with a velocity of 3 m/s, using the “clean” speech as a reference. A paired-comparison procedure was used to compare all possible combinations of three conditions for subjective intelligibility and for sound quality or comfort. The conditions were unprocessed noisy speech, noisy speech processed using the RNN, and noisy speech that was high-pass filtered (which also reduced wind noise). Eighteen native English-speaking participants were tested, nine with normal hearing and nine with mild-to-moderate hearing impairment. Frequency-dependent linear amplification was provided for the latter. Processing using the RNN was significantly preferred over no processing by both subject groups for both subjective intelligibility and sound quality, although the magnitude of the preferences was small. High-pass filtering (HPF) was not significantly preferred over no processing. Although RNN was significantly preferred over HPF only for sound quality for the hearing-impaired participants, for the results as a whole, there was a preference for RNN over HPF. Overall, the results suggest that reduction of wind noise using an RNN is possible and might have beneficial effects when used in hearing aids.

Study on hybrid LESâ–“LAA method for wind buffeting noise control of vehicle rear windows

Based on the large eddy simulation (LES) and Lighthill acoustic analogy (LAA) methods, a hybrid simulation technique, so-called LESâ–“LAA, for improving wind buffeting noises generated by opening rear windows of a running vehicle is presented in this article. The wind buffeting noises are simulated by the LESâ–“LAA and experimentally verified. Some factors affecting the wind buffeting noise, such as vehicle speed and window opening scale, are investigated. To decrease the wind buffeting noises, some attempts are made by attaching absorption materials in the compartment and mounting a plexiglass baffle at an appropriate position for reducing wind noise. The results show that the calculation errors on the sound pressure level (SPL) of the LESâ–“LAA are less than 2%. The SPL of wind noise reaches a maximum value at a rear-window opening scale of 42% and is positively correlated to the vehicle speed. The wind buffeting noise of opening windows on both sides is lower than that of opening one. After mounting the baffle, the reduction of interior noise reaches to 27.26 dB. A conclusion is drawn that the proposed LESâ–“LAA method and the buffeting noise control measures are accurate, effective and feasible, which may be directly applied to vehicles and have potential for solving other aeroacoustic engineering problems.

Reducing wind noise in seismic data using Non-negative Matrix Factorization: an application to Villarrica volcano, Chile

Single channel source separation of seismic signals is an appealing but difficult problem. In this paper, we introduce a semi-blind single-channel seismic source separation method to enhance the components of volcanic origin. In this method, the source decomposition scheme is addressed as a Sparse Non-negative Matrix Factorization (NMF) of the time-frequency representation of the single vertical seismic channel. As a case study we present an application using seismic data recorded at Villarrica volcano, Chile, one of the most active in the southern Andes. The analysed dataset is strongly contaminated by wind noise and the procedure is used to separate a component of volcanic origin from another of meteorological origin.

The Development of Modular Electrical Fittings for Transmission Lines in Intelligent Distribution Network

Spacers, for example, this paper introduces the developing process of energy efficient transmission line modular electrical fittings in distribution network. It uses glass fiber composite materials and non-magnetic as the main material which does not produce or produce very little hysteresis and eddy current losses. It has no corona and its energy saving effect is obvious; anti-dancing, high mechanical strength. Refer to the knowledge of aerodynamics to design the structure, not only effectively prevent the connection joint of different materials connected to the wear and tear, and can effectively reduce wind noise, thus reducing friction and shock losses .It not only replaces the expensive and rare metal materials such gold, and provide simple and economical solution for upgrading the distribution network. It meets the transmission line spacers technical indicators, economic and social benefits significantly.

Wind noise reduction using empirical mode decomposition

One common problem of recorded sound outdoors is interfusion of wind noise, which has highly non-stationary characteristics. Although there are a lot of noise reduction methods which produce good results for general kinds of noises, most methods perform worse for wind noise due to its non-stationary nature. Therefore, wind noise reduction need special technique to overcome this non-stationarity. Empirical mode decomposition (EMD) is a relatively new method to decompose a signal into several nonlinear and non-stationary bases which are modeled as amplitude and frequency modulated sinusoids that represent wind noise well. Thus, EMD has a possibility to reduce wind noise from recorded sounds in entirely different way from ordinary methods. In this paper, a preliminary discussion of applying EMD to wind noise reduction is presented. Since EMD decomposes a signal into monocomponent bases, it is easier to treat them as analytic signals via Hilbert transform. Our method utilize this characteristics in order to reduce wind noise. The experiment is performed on female voice superimposed with wind noise and shows it possibility and effectiveness.

Wind noise in hearing aids: I. Effect of wide dynamic range compression and modulation-based noise reduction

Objective: The objectives of this study were: (1) to examine the effect of wide dynamic range compression (WDRC) and modulation-based noise reduction (NR) algorithms on wind noise levels at the hearing aid output; and (2) to derive effective strategies for clinicians and engineers to reduce wind noise in hearing aids. Design: Three digital hearing aids were fitted to KEMAR. The noise output was recorded at flow velocities of 0, 4.5, 9.0, and 13.5 m/s in a wind tunnel as the KEMAR head was turned from 0° to 360°. Study sample: Flow noise levels were compared between the 1:1 linear and 3:1 WDRC conditions, and between NR-activated and NR-deactivated conditions when the hearing aid was programmed to the directional and omnidirectional modes. Results: The results showed that: (1) WDRC increased low-level noise and reduced high-level noise; and (2) different noise reduction algorithms provided different amounts of wind noise reduction in different microphone modes, frequency regions, flow velocities, and head angles. Conclusions: Wind noise can be reduced by decreasing the gain for low-level inputs, increasing the compression ratio for high-level inputs, and activating modulation-based noise reduction algorithms.

Array processing for direction of arrival of infrasound.

Pipe arrays have conventionally been used to detect infrasound. The advantage of this approach is that the arrays have a large aperture over which wind noise can be averaged. In recent years, distributed arrays have been used for the same effect. In addition to reducing wind noise via spatial averaging, these arrays have the ability to process the individual signals from each sensor to estimate direction of arrival (DOA) of acoustic signals and, potentially, the direction of the wind flow. This is especially true for infrasound and low frequency acoustic sources of tactical interest, in the 1–100 Hz range. A frequency‐wavenumber (F‐K) processing technique has been applied to signals from rectangular infrasound arrays to estimate DOA. This approach will be discussed as well as the dependence of accuracy on signal‐to‐noise ratio.

Wind noise minimization for single infrasonic sensors.

One of the main limitations in outdoor infrasound measurements in open areas is the noise generated by turbulent winds. Pipe arrays or arrays constructed using porous hoses are often used to average out the pressure fluctuations from the turbulence. These devices have a limited useful bandwidth, since they also average out the acoustic response at higher frequencies and distort received acoustic waveforms. We have investigated relatively small configurations to reduce wind noise based on our research into low‐frequency wind noise over open outdoor surfaces. Such devices may be useful for temporary arrays for which waveform integrity is more important than wind noise reduction at very low frequencies. In this talk, we present results for infrasonic sensors placed bare on the surface, mounted underneath a flush metal foam flat surface, and under two types of hemispherical dome. For reference, these will be compared to and contrasted with wind noise measurements with barriers and pipe arrays previously repor...