Journal articles on the topic 'Rotating Sound Sources'
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1
Yost, William, Xuan Zhong, and Anbar Najam. "Rotating sound sources and listeners: Sound source localization is a multisensory/cognitive process." Journal of the Acoustical Society of America 137, no. 4 (April 2015): 2200–2201. http://dx.doi.org/10.1121/1.4920001.
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Yost, William, and M. Torben Pastore. "Sound source localization in two-dimensions: Rotating sources and listeners." Journal of the Acoustical Society of America 145, no. 3 (March 2019): 1873. http://dx.doi.org/10.1121/1.5101771.
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Hansen, Niels Chr, and David Huron. "Twirling Triplets: The Qualia of Rotation and Musical Rhythm." Music & Science 2 (January 1, 2019): 205920431881224. http://dx.doi.org/10.1177/2059204318812243.
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While musicologists have long noted that triplet rhythms evoke sensations of rotation in listeners, no theory has been proposed to account for this apparent association. To investigate this phenomenon, 33 excerpts of “spinning, rotating, twirling, or swirling” music were crowd-sourced from an online discussion forum. Analysis revealed a prominence of fast, repeated, isochronous patterns using stepwise pitch movement, with significantly more compound meters than generally found in Western music. Inspired by ecological acoustics, an Ecological Theory of Rotating Sounds (ETRoS) is proposed to explain these associations. The theory maps patterns of loudness fluctuations to trajectories of rotating sound sources. Two experiments tested the theory. In Experiment A, listeners rated how much binary, ternary, quaternary, and quinary figures (of 2–5 notes) evoked sensations of rotation. Experiment B used a two-alternative forced-choice paradigm pitting ecological quaternary stimuli (strong-medium-weak-medium) against unecological stimuli with permuted stress values more typical of Western music (strong-weak-medium-weak). Results indicate that perceived rotation increases with tempo and is poorly evoked by binary rhythms. Loudness patterns consistent with rotating trajectories were perceived as more rotating than unecological patterns—but only when pitch was also moving. Altogether, moderate support is provided for an acoustic-ecological account of rotating sounds.
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Ocker, Christof, and Wolfram Pannert. "Three-dimensional acoustic energy flow from rotating sound sources." Acta Acustica 5 (2021): 48. http://dx.doi.org/10.1051/aacus/2021042.
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A detailed study of the three-dimensional sound fields around a monopole point source in subsonic and supersonic rotation is investigated. We calculate the sound pressure, the acoustic velocity, as well as the instantaneous and time-averaged acoustic intensity fields with the advanced time approach. The advanced time approach is applied for sound sources at subsonic and supersonic rotation and yield comparable results as those obtained from the spherical harmonic series expansion method or the solution of the retarded time equation. Further, the direction of the time-averaged acoustic energy flow is derived from the acoustic intensity vectors. It is shown, that the direction of the energy flow path differs from the radial direction and depends on the rotational direction and rotational velocity. Those findings are useful, for example, to improve the acoustic absorption performance of sound absorbers and acoustic liners around turbomachines.
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Xiao-Xia Guo, Xiao-Xia Guo, Rui-Qi Zhang Xiao-Xia Guo, Shu-Hao Liu Rui-Qi Zhang, Chen Wan Shu-Hao Liu, Zhen-Yu Wang Chen Wan, and Rong-Rong Han Zhen-Yu Wang. "Visualization of Rotating Machinery Noise Based on Near Field Acoustic Holography." 電腦學刊 33, no. 4 (August 2022): 215–23. http://dx.doi.org/10.53106/199115992022083304018.
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<p>In order to solve the problem of fast identification of the noise source of rotating machinery, the time-space complex envelope model of monopole sound source is studied, and a modulation method of the complex envelope is proposed. A method combining near-field acoustic holography technology and complex envelope information is proposed to reconstruct the sound field and realize the identification of rotating machinery noise sources. Using the overall fluctuation of the signal to identify the noise source of the rotating machinery greatly reduces the amount of calculation, and speeds up the positioning speed while ensuring the positioning accuracy. According to the sound field radiation characteristics of rotating machinery noise, different measurement distances, different sampling points numbers and different reconstruction distances are selected to reconstruct the sound field. The simulation data analysis results show that the near-field acoustic holography technology can still obtain high sound field reconstruction accuracy under the condition of large reconstruction distance, and does not require high sampling points numbers. Using the envelope information extracted by envelope modulation technology to reconstruct the sound field can accurately identify the number and geometric distribution of sound sources. This technology not only speeds up data processing, but also ensures the accuracy of sound field reconstruction.</p> <p> </p>
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Xu, Kunbo, Yun Shi, Weiyang Qiao, and Zhirong Wang. "The Methodological and Experimental Research on the Identification and Localization of Turbomachinery Rotating Sound Source." Energies 15, no. 22 (November 17, 2022): 8647. http://dx.doi.org/10.3390/en15228647.
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The localization and quantification of turbomachinery rotating sound sources is an important challenge in the field of aeroacoustics. In order to compensate the motion of a rotating sound source, a rotating beamforming technique is developed and applied in a flow duct, which uses a wall-mounted microphone array placed circularly parallel to the fan, to detect the broadband noise source of the aeroengine fan. A simulation of three discrete rotating sound sources with a non-constant rotational speed is pursued to verify the effectiveness in reconstruction of the correct source positions and quantitative prediction of the source amplitudes. The technique is ulteriorly experimentally implemented at an axial low-speed fan test rig facility. The fan test rig has 19 rotor blades and 18 stator vanes, with a design speed up to 3000 rpm. The method can accurately identify the radial and circumferential positions of the three rotating sound sources in the simulation case, large side-lobes appear near the main-lobe of the sound source due to the geometric influence of the microphone array. A noticeable feature of beamforming images for axial flow fan is that the sound sources appear to be concentrated in the tip region rather than distributed along the span.
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Carley, Michael. "Series expansion for the sound field of rotating sources." Journal of the Acoustical Society of America 120, no. 3 (September 2006): 1252–56. http://dx.doi.org/10.1121/1.2221410.
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Sales, G. D., K. J. Wilson, K. E. V. Spencer, and S. R. Milligan. "Environmental ultrasound in laboratories and animal houses: a possible cause for concern in the welfare and use of laboratory animals." Laboratory Animals 22, no. 4 (October 1, 1988): 369–75. http://dx.doi.org/10.1258/002367788780746188.
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Many laboratory animals are known to be sensitive to sounds (ultrasounds) beyond the nominal upper limit (20 kHz) of the human hearing range. Sources of sound in laboratories and animal houses were examined to determine the extent of ambient ultrasound. Of 39 sources monitored, 24 were found to emit ultrasonic sounds. Many of these (e.g. cage washers and hoses) also produced sound in the audible range. Running taps, squeaky chairs and rotating glass stoppers created particularly high sound pressure levels and contained frequencies to over 100 kHz. The oscilloscopes and visual display units investigated provided particular cause for concern as they emitted sounds that were entirely ultrasonic and therefore were apparently silent. Ambient ultrasound therefore appears to be common in laboratories and animal houses. It is suggested that its effect on laboratory animals should be investigated and guidelines on acceptable levels be formulated.
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Xue, W. F., J. Chen, J. Q. Li, and X. F. Liu. "Acoustical feature extraction of rotating machinery with combined wave superposition and blind source separation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, no. 9 (September 1, 2006): 1423–31. http://dx.doi.org/10.1243/0954406jmes189.
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As the result of vibration emission in air, machine sound signal carries affluent information about the working condition of machine and it can be used to make mechanical fault diagnosis. The fundamental problems with fault diagnosis are the estimation of the number of sound sources and the localization of sound sources. The wave superposition can be employed to identify and locate sound sources, which is based on the idea that an acoustic radiator can be approximated and represented by the sum of the fields due to a finite number of interior point sources. But, in practice, a large number of measurements must be used in order to achieve a desired resolution, which makes the reconstruction process very time-consuming and expensive. In this paper, a combined wave superposition method has been developed reconstruct to acoustic radiation from machine acoustical signals. This method combines the advantages of both the wave superposition and Helmholtz equationleast squares methods, and it allows for reconstruction of the acoustic field from an arbitrary object with relatively few measurements, thus significantly enhancing the reconstruction efficiency. After sound source localization, the blind source separation (BSS) is proposed to extract acoustical feature from the mixed measuring sound signals. In a semi-anechoic chamber, a cross-planar microphone array, which consists of 29 microphones, was successfully applied to obtain the two-dimensional mapping of the sound sources. The location, the sound pressure, and the properties in frequency domain of the sound sources can be found through this method precisely. The experimental results demonstrate that the methods presented can potentially become an acoustical diagnosis tool.
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Tóth, Bence, János Vad, and Gábor Kotán. "Comparison of the Rotating Source Identifier and the Virtual Rotating Array Method." Periodica Polytechnica Mechanical Engineering 62, no. 4 (July 16, 2018): 261–68. http://dx.doi.org/10.3311/ppme.11194.
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The aim of this paper is to present two acoustic beamforming methods developed for rotating sources, namely the Rotating Source Identifier (ROSI) and the Virtual Rotating Array method (VRAM). These were applied onto a series of simulated test cases, and their behaviour was analysed. Both methods were able to localise the source reliably. However, the source strength was found to depend on the number or microphones when VRAM was applied. This phenomenon was quantified and an approximate formula was given providing the minimum number of microphones required to reach a certain amplitude error. Beamwidth and side lobe suppression were found to agree between the two methods, meaning that the way rotation is handled does not significantly affect the point spread functions. The computational cost of ROSI was two to three orders of magnitude higher than that of VRAM. The results show that both methods are applicable for the beamforming analysis of rotating sound sources. However, in case of VRAM, the number of microphones has to be chosen carefully to obtain reliable amplitude results.
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Krause, Ralph, Christian Friebe, Michael Kerscher, and Christof Puhle. "Investigations on noise sources on a contra-rotating axial fan with different modifications." E3S Web of Conferences 111 (2019): 02076. http://dx.doi.org/10.1051/e3sconf/201911102076.
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An Acoustic Camera was applied to examine modifications of fan blade designs regarding their noise emissions. A so-called rotational beamforming algorithm allows for the detection of sound sources on the rotating blades by using a virtual rotation of the microphones. Depending upon the frequency different sources could be localized. Both the leading and the trailing edge were modified. This paper shows the performed modifications and tests with the Acoustic Camera. It also presents first results and gives an outlook on future work.
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Jekosch, Simon, and Ennes Sarradj. "An Extension of the Virtual Rotating Array Method Using Arbitrary Microphone Configurations for the Localization of Rotating Sound Sources." Acoustics 2, no. 2 (May 15, 2020): 330–42. http://dx.doi.org/10.3390/acoustics2020019.
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The characterization of rotating aeroacoustic sources using microphone array methods has been proven to be a useful tool. One technique to identify rotating sources is the virtual rotating array method. The method interpolates the pressure time data signals between the microphones in a stationary array to compensate the motion of the rotating sources. One major drawback of the method is the requirement of ring array geometries that are centred around the rotating axis. This contribution extends the virtual rotating array method to arbitrary microphone configurations. Two different ways to interpolate the time signals between the microphone locations are proposed. The first method constructs a mesh between the microphone positions using Delaunay-triangulation and interpolates over the mesh faces using piecewise linear functions. The second one is a meshless technique which is based on radial basis function interpolation. The methods are tested on synthetic array data from a benchmark test case as well as on experimental data obtained with a spiral array and a five-bladed fan.
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Jekosch, Simon, and Ennes Sarradj. "An Inverse Microphone Array Method for the Estimation of a Rotating Source Directivity." Acoustics 3, no. 3 (June 22, 2021): 462–72. http://dx.doi.org/10.3390/acoustics3030030.
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Microphone arrays methods are useful for determining the location and magnitude of rotating acoustic sources. This work presents an approach to calculating a discrete directivity pattern of a rotating sound source using inverse microphone array methods. The proposed method is divided into three consecutive steps. Firstly, a virtual rotating array method that compensates for motion of the source is employed in order to calculate the cross-spectral matrix. Secondly, the source locations are determined by a covariance matrix fitting approach. Finally, the sound source directivity is calculated using the inverse method SODIX on a reduced focus grid. Experimental validation and synthetic data from a simulation are used for the verification of the method. For this purpose, a rotating parametric loudspeaker array with a controllable steering pattern is designed. Five different directivity patterns of the rotating source are compared. The proposed method compensates for source motion and is able to reconstruct the location as well the directivity pattern of the rotating beam source.
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Koopmann, G. H., W. Neise, and W. Chen. "Active Noise Control to Reduce the Blade Tone Noise of Centrifugal Fans." Journal of Vibration and Acoustics 110, no. 3 (July 1, 1988): 377–83. http://dx.doi.org/10.1115/1.3269529.
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This paper describes an active noise control method to suppress the blade tones of centrifugal fans. Two secondary sound sources are mounted into the cutoff region of the fan casing. These sources are driven with electrical signals that are synchronized with the rotation of the impeller, and their amplitudes and phase are adjusted to give maximum reduction for the blade tone levels in the inlet and outlet duct of the fan. With this design, the sound emitted by the secondary sources is introduced into the interior of the casing near the source region where the blade tone is generated, i.e., the cutoff. The present experiments were concentrated on the reduction of the fundamental of the blade tone for centrifugal fan with impeller diameters between 280 mm (11 in.) and 710 mm (28 in.). Two different designs of secondary sources were investigated. In the first, two loudspeakers are contained within an enclosure which has an open end made of a curved perforated plate which replaces part of the original cutoff. The second design incorporates two vibrating plates which replace portions of the outlet duct side and the volute side of the cutoff. Reductions in tone sound pressure level of up to 23 dB have been observed for a variety of aerodynamic loading conditions and fan inlet geometries. To obtain a better understanding of the physical mechanism of this active noise control method, sound pressure measurements were also made on the inner surface of the fan casing along the volute. Both amplitude and phase of the blade passing frequency component were measured relative to a reference signal derived from the impeller rotation. The result of this experiment is that the sound field inside the casing is dominated by the pressure pattern rotating together with the impeller. Since the impeller tip Mach number is well below sonic speed, however, the radiation efficiency of the rotating pressures is very low. The blade tone noise measured in the far-field is generated by the unsteady pressures at the cutoff which in turn are produced by the flow leaving the impeller. This aerodynamic noise generating mechanism is modified by the active sources located in the cutoff.
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Kim, Hyun-Don, Kazunori Komatani, Tetsuya Ogata, and Hiroshi G. Okuno. "Binaural Active Audition for Humanoid Robots to Localise Speech over Entire Azimuth Range." Applied Bionics and Biomechanics 6, no. 3-4 (2009): 355–67. http://dx.doi.org/10.1155/2009/817874.
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We applied motion theory to robot audition to improve the inadequate performance. Motions are critical for overcoming the ambiguity and sparseness of information obtained by two microphones. To realise this, we first designed a sound source localisation system integrated with cross-power spectrum phase (CSP) analysis and an EM algorithm. The CSP of sound signals obtained with only two microphones was used to localise the sound source without having to measure impulse response data. The expectation-maximisation (EM) algorithm helped the system to cope with several moving sound sources and reduce localisation errors. We then proposed a way of constructing a database for moving sounds to evaluate binaural sound source localisation. We evaluated our sound localisation method using artificial moving sounds and confirmed that it could effectively localise moving sounds slower than 1.125 rad/s. Consequently, we solved the problem of distinguishing whether sounds were coming from the front or rear by rotating and/or tipping the robot's head that was equipped with only two microphones. Our system was applied to a humanoid robot called SIG2, and we confirmed its ability to localise sounds over the entire azimuth range as the success rates for sound localisation in the front and rear areas were 97.6% and 75.6% respectively.
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Chide, Baptiste, Ralph Lorenz, Naomi Murdoch, Alexander Stott, David Mimoun, Xavier Jacob, Tanguy Bertrand, Nina Lanza, Sylvestre Maurice, and Roger Wiens. "Mars soundscape: Review of the first sounds recorded by the Perseverance microphones." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A184. http://dx.doi.org/10.1121/10.0011042.
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On February 18, 2021, NASA’s Perseverance rover landed in Jezero Crater carrying the two first microphones operating on the surface of Mars: the SuperCam microphone, positioned on top of the rotating rover’s mast and the EDL microphone fixed on the body of the rover. Working flawlessly since then, they provide the first characterization of Mars’ acoustic environment in the audible range and beyond, from 20 Hz to 50 kHz. Recorded sounds originate from three main sources: the atmosphere (turbulence, wind), the shock-waves generated by the Supercam pulsed laser ablating rocks, and hardware-induced artificial sounds such as the signal generated by the high-speed rotating blades of the Ingenuity helicopter. After one year, the Perseverance playlist features more than 5 hours of martian sounds. In addition to providing an unprecedented short timescale characterization of the wind, temperature fluctuations, and the turbulence dissipative regime, this dataset highlights the unique sound propagation properties of the low-pressure CO2-dominated Mars atmosphere: acoustic impedance varying with the season, large intrinsic attenuation of the high frequencies, and the dispersion of the sound speed in the audible range. This presentation will review these results to date.
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Herold, Gert, and Ennes Sarradj. "Microphone array method for the characterization of rotating sound sources in axial fans." Noise Control Engineering Journal 63, no. 6 (November 1, 2015): 546–51. http://dx.doi.org/10.3397/1/376348.
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Nakamura, Hisahide, Keisuke Asano, Seiran Usuda, and Yukio Mizuno. "A Diagnosis Method of Bearing and Stator Fault in Motor Using Rotating Sound Based on Deep Learning." Energies 14, no. 5 (March 1, 2021): 1319. http://dx.doi.org/10.3390/en14051319.
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Various industrial fields use motors as key power sources, and their importance is increasing. In motor manufacturing, various tests are conducted for each motor before shipping. The no-load test is one such test, in which, for instance, the current flowing into the motor and temperature of the bearing is measured to confirm whether they are within specific values. Reducing labor, cost, and time in identifying an initially defective product requires a simple and reliable method. This study proposes a new diagnosis to identify the motor conditions based on the rotating sound of the motor in the no-load test. First, the rotating sounds of motors were measured using several healthy motors and motors with faults. Second, their sound characteristics were analyzed, and it was found that the characteristic signals appeared in a specific frequency range periodically. Then, considering these phenomena, a diagnostic method based on deep learning was proposed to judge the faults using long short-term memory (LSTM). Finally, the effectiveness of the proposed method was verified through experiments.
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Zhang, Xiao-Zheng, Chuan-Xing Bi, Yong-Bin Zhang, and Liang Xu. "A time-domain inverse technique for the localization and quantification of rotating sound sources." Mechanical Systems and Signal Processing 90 (June 2017): 15–29. http://dx.doi.org/10.1016/j.ymssp.2016.12.003.
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Herold, Gert, Florian Zenger, and Ennes Sarradj. "Influence of blade skew on axial fan component noise." International Journal of Aeroacoustics 16, no. 4-5 (July 2017): 418–30. http://dx.doi.org/10.1177/1475472x17718740.
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Microphone arrays can be used to detect sound sources on rotating machinery. For this study, experiments with three different axial fans, featuring backward-skewed, unskewed, and forward-skewed blades, were conducted in a standardized fan test chamber. The measured data are processed using the virtual rotating array method. Subsequent application of beamforming and deconvolution in the frequency domain allows the localization and quantification of separate sources, as appear at different regions on the blades. Evaluating broadband spectra of the leading and trailing edges of the blades, phenomena governing the acoustic characteristics of the fans at different operating points are identified. This enables a detailed discussion of the influence of the blade design on the radiated noise.
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Gombots, Stefan, Jonathan Nowak, and Manfred Kaltenbacher. "Sound source localization – state of the art and new inverse scheme." e & i Elektrotechnik und Informationstechnik 138, no. 3 (March 25, 2021): 229–43. http://dx.doi.org/10.1007/s00502-021-00881-6.
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AbstractAcoustic source localization techniques in combination with microphone array measurements have become an important tool for noise reduction tasks. A common technique for this purpose is acoustic beamforming, which can be used to determine the source locations and source distribution. Advantages are that common algorithms such as conventional beamforming, functional beamforming or deconvolution techniques (e.g., Clean-SC) are robust and fast. In most cases, however, a simple source model is applied and the Green’s function for free radiation is used as transfer function between source and microphone. Additionally, without any further signal processing, only stationary sound sources are covered. To overcome the limitation of stationary sound sources, two approaches of beamforming for rotating sound sources are presented, e.g., in an axial fan.Regarding the restrictions concerning source model and boundary conditions, an inverse method is proposed in which the wave equation in the frequency domain (Helmholtz equation) is solved with the corresponding boundary conditions using the finite element method. The inverse scheme is based on minimizing a Tikhonov functional matching measured microphone signals with simulated ones. This method identifies the amplitude and phase information of the acoustic sources so that the prevailing sound field can be with a high degree of accuracy.
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Genzel, Daria, Uwe Firzlaff, Lutz Wiegrebe, and Paul R. MacNeilage. "Dependence of auditory spatial updating on vestibular, proprioceptive, and efference copy signals." Journal of Neurophysiology 116, no. 2 (August 1, 2016): 765–75. http://dx.doi.org/10.1152/jn.00052.2016.
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Humans localize sounds by comparing inputs across the two ears, resulting in a head-centered representation of sound-source position. When the head moves, information about head movement must be combined with the head-centered estimate to correctly update the world-centered sound-source position. Spatial updating has been extensively studied in the visual system, but less is known about how head movement signals interact with binaural information during auditory spatial updating. In the current experiments, listeners compared the world-centered azimuthal position of two sound sources presented before and after a head rotation that depended on condition. In the active condition, subjects rotated their head by ∼35° to the left or right, following a pretrained trajectory. In the passive condition, subjects were rotated along the same trajectory in a rotating chair. In the cancellation condition, subjects rotated their head as in the active condition, but the chair was counter-rotated on the basis of head-tracking data such that the head effectively remained fixed in space while the body rotated beneath it. Subjects updated most accurately in the passive condition but erred in the active and cancellation conditions. Performance is interpreted as reflecting the accuracy of perceived head rotation across conditions, which is modeled as a linear combination of proprioceptive/efference copy signals and vestibular signals. Resulting weights suggest that auditory updating is dominated by vestibular signals but with significant contributions from proprioception/efference copy. Overall, results shed light on the interplay of sensory and motor signals that determine the accuracy of auditory spatial updating.
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Dreier, Christian, and Michael Vorländer. "Sound source modelling by nonnegative matrix factorization for virtual reality applications." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 5 (August 1, 2021): 1053–61. http://dx.doi.org/10.3397/in-2021-1742.
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Auralization is a suitable method for subjective noise evaluation of virtual prototypes. A basic requirement is the accurate modelling of the sound sources. This includes a dynamic and parametric description at multiple operating conditions. In the case of wave propagation including flow, such as aircraft or vehicle noise, aeroacoustics or fluid dynamics simulations are practically limited to the acoustic near field due to high computational costs. Especially challenging are simulations of rotating systems, such as fan noise radiation. For better applicability, the proposed method is based on in-situ recordings of flyovers. The processing chain compensates for source position and movement as well as atmospheric and soil damping effects on recorded data. The compensated source signal is decomposed into partial sources in spectro-temporal domain with nonnegative matrix factorization (NMF) and can optionally be enhanced by physically-based source information. The format of the source model obtained is ready to use for dynamic sound synthesis in real-time virtual reality applications.
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Ocker, Christof, and Wolfram Pannert. "Acoustic ray method derived with the concept of analogue gravity for the calculation of the sound field due to rotating sound sources." Applied Acoustics 168 (November 2020): 107422. http://dx.doi.org/10.1016/j.apacoust.2020.107422.
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Gaunaurd, G. C., and T. J. Eisler. "Classical Electrodynamics and Acoustics: Sound Radiation by Moving Multipoles." Journal of Vibration and Acoustics 119, no. 2 (April 1, 1997): 271–82. http://dx.doi.org/10.1115/1.2889714.
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In classical electrodynamics (CED) P. Dirac used the average of retarded and advanced fields to represent the bound field and their difference to represent the free field in his derivation of the (Lorentz-Dirac) equation of motion for an electron. The latter skew-symmetric combination filtered out the radiation part of the field. It can also be used to derive many properties of the power radiated by acoustic sources, such as angular and frequency distributions. As in CED there is radiation due to source acceleration and radiation patterns exhibit the “headlight effect.” Power radiation patterns are obtained by this approach for point multipoles undergoing various motions. Applications to sound radiation problems from rotating machinery are shown. Numerous computed plots illustrate all cases.
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Ardavan, H. "Asymptotic analysis of the radiation by volume sources in supersonic rotor acoustics." Journal of Fluid Mechanics 266 (May 10, 1994): 33–68. http://dx.doi.org/10.1017/s0022112094000923.
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The application of Lighthill's acoustic analogy to the generation of sound by rotating surfaces with supersonic speeds results in radiation integrals in which the stationary points of the phase function – that describes the sapce-time distance between each source point and a fixed observation point – have variable positions and coalesce at a caustic in the space of source points. Here, the leading term in the asymptotic expansion of the corresponding Green's function at this caustic is calculated, both in the time and the frequency domains, and it is shown that the radiation generated by volume sources, which are steady in the uniformly rotating blade-fixed frame, has an amplitude that does not obey the spherical spreading law, i.e. does not fall off like RP–1 with the radial distance RP away from the source. Within a finite solid angle, depending on the extent of the source distribution, the amplitude of this newly identified sound decays like RP–½, so that it is stronger in the far field than any previously studied element. That this is not incompatible with the conservation of energy is because the emission time intervals associated with the volume elements of the source distribution which contribute towards the non-spherically decaying component of the radiation are by a large (RP-dependent) factor greater than the time intervals during which the signals generated by these elements are received. The contributing source elements are those whose positions at the retarded time coincide witht the locus of singularities of the Green's function, i.e. with the one-dimensional locus of points, fixed in the rotating frame, which approach the observer with the wave speed and zero acceleration along the radiation direction. Because the signals received at two neighbouring instants in time arise from distinct, coherently radiating filamentary parts of the source which have both different extents and different strengths, the resulting overall waveform in the far zone consists of the superposition of a (continuous) set of narrow subpulses with uneven amplitudes. These subpulses are narrower the larger the distance from the source.The differences between the new results and those of the earlier works in the literature are shown to arise from the error terms in the far-field and high-frequency approximations, approximations that are inappropriate for volume sources moving supersonically.
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UMEDA, Yoshikuni, and Ryuji ISHII. "Mach cones rotating with the sound sources of the screech tone radiated from the circular supersonic jet." Proceedings of the JSME annual meeting 2003.7 (2003): 299–300. http://dx.doi.org/10.1299/jsmemecjo.2003.7.0_299.
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MAJUMDAR, S. J., and N. PEAKE. "Noise generation by the interaction between ingested turbulence and a rotating fan." Journal of Fluid Mechanics 359 (March 25, 1998): 181–216. http://dx.doi.org/10.1017/s0022112097008318.
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An important criterion in the development of modern aeroengines is the identification of the dominant noise sources under typical aircraft take-off and approach conditions, and also in ground-based tests in which the engine is stationary. In this paper, we develop a theoretical model for unsteady distortion noise, which results from the interaction of ingested atmospheric turbulence with the rotating fan, with a view to providing a better understanding of the important physical mechanisms in this particular aspect of sound generation. The theory, developed in the frequency domain, is applicable for any arbitrary spectral form of atmospheric turbulence upstream of the fan, and as a simple model we take the von Kármán spectra for isotropic turbulence. The key fluid dynamical process in unsteady distortion is the deformation of turbulent eddies into long, narrow filaments as they enter the engine, due to the strong streamtube contraction experienced by the steady, non-uniform mean flow generated by the fan. Simple models of the steady flow fields are provided for both open and ducted rotor geometries. The distorted turbulent field at the fan face can be obtained using rapid distortion theory, and considerable simplification is made here by noting that the number of blades in typical aeroengine fans is large, allowing the application of asymptotic analysis and the derivation of closed-form expressions for those parts of the turbulence spectrum at the fan face which dominate the radiation. The unsteady forces exerted on the rotating fan blades are then calculated via a strip-theory approach. The resulting sound scattered to the far field is then evaluated using asymptotic theory for open and ducted rotors. Results are presented in the form of frequency spectra for the turbulent field at the fan face, the blade forces and the radiated sound for typical testing and aircraft operating conditions. High tonal noise levels are obtained under static conditions, whereas the sound is generally broadband in flight. The dependence on turbulence parameters such as the integral lengthscale is highlighted.
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Zhang, Haitian, Bálint Kocsis, and Csaba Horváth. "Segmented ROSI method: Beamforming method for investigating turbomachinery noise sources along segmented trajectories." Noise Control Engineering Journal 70, no. 1 (January 1, 2022): 62–76. http://dx.doi.org/10.3397/1/37705.
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The rotating source identifier (ROSI) beamforming method is a method designed for localizing rotating noise sources in a uniform flow based on out-of-flow acoustic pressure field measurement data. It has been developed for sources moving along a circular trajectory, such as turbomachinery blades. The original ROSI method processes the measured acoustic signals over a long time segment to reconstruct the noise sources, providing time-averaged results for each noise source. By doing so, it does not take into consideration certain features of the noise sources, such as the directivity of the trailing edge and leading-edge noise sources. A further development of the ROSI method is presented herein, which separates the sound-pressure signal of one revolution into multiple segments. In this way, the beamforming maps can provide one with a better understanding of the differences between the noise sources as a function of angular position. This method will be referred to herein as the segmented ROSI method. The goal of this further development is to improve the capability of the method in identifying the position-dependent modulations of the various noise sources as they are moving along their trajectories, rotating around the axis. The investigation presents the theory behind the new segmented ROSI method along with simulation and measurement-based test cases which help in comparing the new method to the original ROSI method. The results show that the novel method provides a strong tool for investigating turbomachinery noise sources that vary along segments of their trajectories. It is therefore expected that the tool will be useful in cases that look at turbomachinery from an angle and cases where the loading of the blades changes as a function of angular position.
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Ardavan, H. "The breakdown of the linearized theory and the role of quadrupole sources in transonic rotor acoustics." Journal of Fluid Mechanics 226 (May 1991): 591–624. http://dx.doi.org/10.1017/s0022112091002537.
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The retarded Green's function for the linearized version of the equation of the mixed type governing the potential flow around a rotating helicopter blade or a propeller (with no forward motion) is derived and is shown to constitute the unifying feature of the various existing approaches to rotor acoustics. This Green's function is then used to pinpoint the singularity predicted by the linearized theory of rotor acoustics which signals its experimentally confirmed breakdown in the transonic regime: the gradient of the near-field sound amplitude, associated with a linear flow which is steady in the blade-fixed rotating frame, diverges on the sonic cylinder at the dividing boundary between the subsonic and supersonic regions of the flow. Prom the point of view of the equivalent Cauchy problem for the homogeneous wave equation, this singularity is caused by the imposition of entirely non-characteristic initial data on a space—time hypersurface which, at its points of intersection with the sonic cylinder, is locally characteristic. It also emerges from the analysis presented that the acoustic discontinuities detected in the far zone are generated by the quadrupole source term in the Ffowcs Williams-Hawkings equation and that the impulsive noise resulting from these discontinuities would be removed if the flow in the transonic region were to be rendered unsteady (as viewed from the blade-fixed rotating frame).
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McShane, John, Abe Lee, Parthiv Shah, and Peter Kerrian. "Partial field visualization using an advanced circular aperture, continuous-scan acoustic array." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A135. http://dx.doi.org/10.1121/10.0010898.
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ATA Engineering, Inc. designed, fabricated, and tested a novel circular aperture acoustic array for continuous-scan beamforming and acoustical holography applications. The array comprises an outer perimeter of stationary reference sensors coupled to a multi-arm inner rotating array that samples the entire aperture plane. The unique architecture allows the user to perform both fixed-receiver and continuous-scan beamforming with a single array with the latter method also enabling high-spatial-resolution partial field visualization. The presentation will show results from far- and near-field partial field visualizations over the rotating array circular aperture taken at different orientations. The presentation will also describe the use of the array to measure and model isolated sources, and experimentally verify their boundary element method-predicted sound fields in the presence of a scattering body.
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Liu, Zhen, Chen Bu, Xiangxu Kong, Dong Yang, and Bingfei Li. "Computational investigation of noise interaction for a nano counter-rotating rotor in a static condition." International Journal of Computational Materials Science and Engineering 07, no. 01n02 (June 2018): 1850004. http://dx.doi.org/10.1142/s2047684118500045.
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The interaction between the upper and lower rotors greatly influences the aeroacoustic characteristics of a counter-rotating nano-coaxial rotor. To study this influence, a numerical investigation was carried out. The unsteady flow field of a single upper rotor was first studied with a large-eddy simulation computational fluid dynamics method coupled with a sliding-mesh technique. The Ffowcs Williams–Hawking equation method was used to investigate the aeroacoustic characteristics of the upper rotor based on the flow field. An experimental setup was established to validate the computational approach. The experimental results matched well with the computational results. Additionally, results show that the peak value of the total sound pressure level appeared near the blade tip, which verified that the tip vortex was one of the most important sources of rotor noise. Then the aeroacoustic noise of the nano-coaxial rotor was studied numerically. It was found that the total sound pressure level of the nano-coaxial rotor was greater than that of the upper rotor. Flow field analysis showed that the shedding vortices of the upper rotor interacted with the lower rotor, resulting in a blade–vortex interaction. It was evident that the aeroacoustic noise was enhanced by the interference between the upper and lower rotors.
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Zarri, Alessandro, Julien Christophe, Stéphane Moreau, and Christophe Schram. "Influence of Swept Blades on Low-Order Acoustic Prediction for Axial Fans." Acoustics 2, no. 4 (November 28, 2020): 812–32. http://dx.doi.org/10.3390/acoustics2040046.
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The low-speed fans used for automotive engine cooling contribute to a significant part of the global noise emitted by the vehicle. A low-order sound-prediction methodology is developed considering the blade sweep-angle effect on the acoustic predictions of the turbulence-impingement and the trailing-edge noise-generating mechanisms. We modeled these through the application of a semianalytical method based on Amiet’s airfoil theory, appropriately adapted via a strip-theory approach accounting for rotation and modified to include the blades forward curvature. Sweep was already shown in the literature to reduce the noise emitted by isolated airfoils, but its effect on rotating machines was not yet well understood. In this study, we show that the effect of the sweep-angle is to globally reduce the emitted noise by the fan and to change the sound distribution of the sources along the blade span. Thus, the sweep-angle must be considered not only because it yields a better comparison with experimental results but also because wrong conclusions on the dominating noise-generating mechanisms can be drawn when this effect is not taken into account. The investigation is finally complemented by a sensitivity analysis focusing on some of the key parameters characterizing the acoustic prediction.
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Abe, Junya, and Masayoshi Yokosawa. "11.10. The propagation of fast magnetoacoustic waves near a rotating black hole." Symposium - International Astronomical Union 184 (1998): 475–76. http://dx.doi.org/10.1017/s0074180900085648.
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We belive that Active Galactic Nucleis(AGNs) have one or a few black holes in the center and get the activity from the binding energy of the matter falling into the black hole or(and) the rotational energy of the black hole. Since the sources of their energy exist near the black hole, the energy have to be carried from the vincity of black hole to a distance by some ways. As one of the way, we study the propagation of the waves (ex. The case of the light waves, Hanni 1977, and of sound wave, Takahashi et al. 1990). We investigated the propagation of fast magnetoacoustic wave. We belive the collimation of jet are caused by magnetic field. Further more, we think that the waves can extract the rotational energy of the black hole. This process is the version of wave of Penrose process(Penrose 1968), and is called the super radiant scattering.
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ZhiPing, Zhai, Li ZhuWei, Zhang Long, Yang Zhongyi, and Lan Yuezheng. "Numerical prediction of aerodynamic noise from impeller blowers of straw threshing machines." Noise & Vibration Worldwide 51, no. 1-2 (December 2, 2019): 21–32. http://dx.doi.org/10.1177/0957456519890262.
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An impeller blower is one of the major aerodynamic noise sources in straw threshing machines. To reduce its aerodynamic noise, it is essential to understand the mechanism of gas-material-coupled unsteady flow causing aerodynamic noise. However, it is difficult to clarify the mechanism through measurement. Therefore, the following topics are studied in this article. First, a full-field transient numerical simulation of the gas and solid particulates’ unsteady flow inside the impeller blower was carried out using a dense discrete phase model and a large eddy simulation turbulence model. Second, based on the Ffowcs Williams–Hawkins equation, the aerodynamic noise of the impeller blower of the straw threshing machines was numerically calculated. Finally, the numerical results were verified by aerodynamic noise test. The results indicate that (1) sound pressure level at the inlet of the impeller blower is the highest, mainly at 100 Hz, which is the fundamental frequency of the rotating impeller, while the sound pressure level at the fourth harmonic frequency of 400 Hz is the main source of the outlet. The total sound pressure level at the inlet is greater than that at the outlet. It is concluded that the dipole source of the rotating impeller is the main noise source, which was generated by the interaction of blade with the air and material as the impeller rotated. Also, acoustic attenuation, acoustic resonance, and impact noise of material and machinery play important roles in aerodynamic noise distribution. (2) The test and simulation results show good agreement, so the numerical model of aerodynamic noise is reliable. This study will provide a reference for the structural and acoustic optimization design of impeller blowers and their integration into threshing machines.
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Viqueira-Moreira, Manuel, and Esteban Ferrer. "Insights into the Aeroacoustic Noise Generation for Vertical Axis Turbines in Close Proximity." Energies 13, no. 16 (August 11, 2020): 4148. http://dx.doi.org/10.3390/en13164148.
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We present Large Eddy Simulations and aeroacoustic spectra for three configurations of increasing flow complexity: an isolated NACA0012 airfoil, an isolated rotating vertical axis wind turbine composed of three rotating airfoils and a farm of four vertical axis turbines (with identical characteristics as the isolated turbine), which are located in close proximity. The aeroacoustic signatures of the simulated airfoil and the isolated turbine are validated using published numerical and experimental data. We provide theoretical estimates to predict tonal frequencies, which are used to identify the main physical mechanisms responsible for the tonal signature and for each configuration and enable the categorisation of the main tonal aeroacoustic sources of vertical axis turbines operating in close proximity. Namely, we identify wake, vortex, blade passing and boundary layer phenomena and provide estimates for the associated tonal frequencies, which are validated with simulations. In the farm, we observe non-linear interactions and enhanced mixing that decreases tonal frequencies in favour of larger broadband amplitudes at low frequencies. Comparing the spectrum with that of the isolated turbine, only the blade passing frequency and the boundary layer tones can be clearly identified. Variations in acoustic amplitudes, tonal frequencies and sound directivities suggest that a linear combination of sources from isolated turbines is not enough to characterise the aeroacoustic footprint of vertical axiswind turbines located in close proximity, and that farms need to be considered and studied as different entities.
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Edelman, Rachel C., Brian E. Anderson, Samuel D. Bellows, and Timothy W. Leishman. "Measured high-resolution directivities of guitar amplifiers." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A157. http://dx.doi.org/10.1121/10.0010961.
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Guitar amplifiers comprise specialized powered loudspeakers with distinct configurations and directivity characteristics. Recently, the authors measured the directivities of six guitar amplifiers using a new measurement system. The system employs a rotating semicircular microphone array in an anechoic chamber, with 2522 unique microphone positions over a surrounding sphere (i.e., 5-deg resolution in both the polar and azimuthal angles). This presentation will describe the measurement and processing procedures and compare the measured results to those produced by theoretical directivity models. An online archival database provides easy access to the guitar amplifier data and other directivity data from the human voice, played musical instruments, and other sound sources. The data are available in several commonly used file formats and should provide valuable information for many applications, including spatial audio, architectural acoustics modeling, and microphone placement.
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Heydari, Morteza, Hamid Sadat, and Rajneesh Singh. "A Computational Study on the Aeroacoustics of a Multi-Rotor Unmanned Aerial System." Applied Sciences 11, no. 20 (October 18, 2021): 9732. http://dx.doi.org/10.3390/app11209732.
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The noise generated by a quadrotor biplane unmanned aerial system (UAS) is studied computationally for various conditions in terms of the UAS pitch angle, propellers rotating velocity (RPM), and the UAS speed to understand the physics involved in its aeroacoustics and structure-borne noise. The k-ω SST turbulence model and Ffowcs Williams-Hawkings equations are used to solve the flow and acoustics fields, respectively. The sound pressure level is measured using a circular array of microphones positioned around the UAS, as well as at specific locations on its structure. The local flow is studied to detect the noise sources and evaluate the pressure fluctuation on the UAS surface. This study found that the UAS noise increases with pitch angle and the propellers’ rotating velocity, but it shows an irregular trend with the vehicle speed. The major source of the UAS noise is from its propellers and their interactions with each other at small pitch angle. The propeller and CRC-3 structure interaction contributes to the noise at large pitch angle. The results also showed that the propellers and structure of the UAS impose unsteadiness on each other through a two-way mechanism, resulting in structure-born noises which depend on the propeller RPM, velocity and pitch angle.
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Adaileh, Wail M. "Engine Fault Diagnosis Using Acoustic Signals." Applied Mechanics and Materials 295-298 (February 2013): 2013–20. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.2013.
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This work presents an experimental study to detecting the faults of engine using its noise. The noises produced by the engine and its accessory systems are numerous: whines, squeals, knock, rattles, and many other sounds. Faults diagnosis for Mitsubishis car engine model 2006 has been conducted and this diagnosis includes normal operating conditions for the engine (without malfunction) and for malfunctions situations at variable engine speed 1000,2000, 3000 and 4000 rpm respectively The engine data is acquired from a four cylinder one- petrol engine test bed under consideration at different operating states, and then simulated. Most of the conventional fault diagnosis techniques using sound emission and vibration signals are based on analyzing the signal amplitude in the time or frequency domain. For engine under fired and misfires spark the all the domain parameters (RMS amplitude, peak amplitude and energy) was processed using MATLAB software.It was found that fault detection and diagnosis for internal combustion engines is complicated by the presence of engine noise during normal operation. The average of amplitude found to be 450 x10-3m for normal engine working without any malfunction and 458x10-3m for misfire of one spark plug and for misfire of two spark plugs 457.8 x10-3m. In this study, some of the engine malfunction such as failure spark plug has been recorded, but we can generalize it to include all engine breakdown. Generally, sound emission signal serves as a promising alternative to the condition monitoring and fault diagnosis in rotating machinery when the vibration signal is not available. This research paper explores that automobiles could be major sources of noise pollution. Condition monitoring and fault diagnosis of IC engine through acoustic signal analysis is an established technique for detecting early stages of component degradation.
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Zhong, Xuan, and William Yost. "Multiple sound source localization when sounds are stationary or rotating." Journal of the Acoustical Society of America 137, no. 4 (April 2015): 2228. http://dx.doi.org/10.1121/1.4920122.
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Hou, Lanlan, and Shuqian Cao. "Evaluation Method for Vibration Measurement on Casing in Aeroengine: Theoretical Analysis and Experimental Study." Shock and Vibration 2019 (March 14, 2019): 1–15. http://dx.doi.org/10.1155/2019/1648709.
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The vibration measurement location is the basis for effective monitoring of aeroengine vibration conditions. Measurement locations need to reflect the vibration of the rotor sufficiently, while complex structures of the aeroengine bring many excitation sources. This paper presents an evaluation methodology for vibration measurement on casing in the aeroengine. A number of indexes are defined to quantify and characterize the vibration measurement ability of main measurement locations on casing for rotor vibration. A dynamic model of a dual-rotor-casing system is established according to the support structure of a certain type of aeroengine. By means of the introduced evaluation method, the vibration relation between rotors and the main vibration measurement sections is analyzed. Response characteristics and performance orders of measurement sections are given. The rationality of theoretical results is sound verified by experiments on a designed pneumatic-driven double-rotor-casing test bench. The best measured vibration section is consistent with the actual on-board vibration section of the engine, which further demonstrates the effectiveness of the evaluation method. The research results can provide a basis for the selection and optimization of vibration measurement locations and fault diagnosis in the aeroengine. Furthermore, the application of this method is not limited to aeroengine vibration analysis and sensor measurement location optimization, but will be useful for vibration analysis of other rotating machinery.
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Li, Qiuzi, Harry W. Deckman, Deniz Ertaş, and Lang Feng. "The magneto-seismic method in geoscience." Leading Edge 40, no. 3 (March 2021): 194–201. http://dx.doi.org/10.1190/tle40030194.1.
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Key concepts and potential applications associated with a phenomenon hitherto unexplored by the geoscience community, which we have named the magneto-seismic effect, are introduced. The method is based on the simple principle that when an electric charge moves in the presence of an external magnetic field, the charge carrier experiences an instantaneous force, which is equal to the vector cross product of the current it carries and the magnetic field that is present. This “Lorentz force” can create both compressional and shear sound waves in electrical conductors by passing an alternating current through them via an electromagnetic source. In laboratory settings, this magneto-seismic effect can produce readily detectable rock frame displacements. This opens up the possibility of developing new experimental methods to interrogate elastic and poroelastic response of rocks in a broad frequency range from subhertz to megahertz, potentially closing the frequency gap between traditional ultrasonic characterization and properties of interest in the seismic frequency band. In exploration settings, electric current dipole/bipole sources, or novel rotating magnetic dipole sources, can be used to generate electric currents at depth. These currents produce seismic waves at interfaces (or boundaries) where conductivity abruptly changes. The amplitude and propagation directions of these generated seismic waves depend on the relative orientation of the interfaces (or boundaries) with respect to the earth's magnetic field. These seismic waves can then be recorded by receivers at the surface and, in principle, might be processed to yield a resistivity map with seismic resolution. It is shown that processing to obtain a signal from deep targets is significantly limited by seismic background noise. However, an acceptable signal-to-noise ratio might be achieved for shallower targets. The difference between the magneto-seismic response and the previously well-studied electro-seismic response will be discussed.
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Clark, Sierra N., Abosede S. Alli, Michael Brauer, Majid Ezzati, Jill Baumgartner, Mireille B. Toledano, Allison F. Hughes, et al. "High-resolution spatiotemporal measurement of air and environmental noise pollution in Sub-Saharan African cities: Pathways to Equitable Health Cities Study protocol for Accra, Ghana." BMJ Open 10, no. 8 (August 2020): e035798. http://dx.doi.org/10.1136/bmjopen-2019-035798.
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IntroductionAir and noise pollution are emerging environmental health hazards in African cities, with potentially complex spatial and temporal patterns. Limited local data are a barrier to the formulation and evaluation of policies to reduce air and noise pollution.Methods and analysisWe designed a year-long measurement campaign to characterise air and noise pollution and their sources at high-resolution within the Greater Accra Metropolitan Area (GAMA), Ghana. Our design uses a combination of fixed (year-long, n=10) and rotating (week-long, n =~130) sites, selected to represent a range of land uses and source influences (eg, background, road traffic, commercial, industrial and residential areas, and various neighbourhood socioeconomic classes). We will collect data on fine particulate matter (PM2.5), nitrogen oxides (NOx), weather variables, sound (noise level and audio) along with street-level time-lapse images. We deploy low-cost, low-power, lightweight monitoring devices that are robust, socially unobtrusive, and able to function in Sub-Saharan African (SSA) climate. We will use state-of-the-art methods, including spatial statistics, deep/machine learning, and processed-based emissions modelling, to capture highly resolved temporal and spatial variations in pollution levels across the GAMA and to identify their potential sources. This protocol can serve as a prototype for other SSA cities.Ethics and disseminationThis environmental study was deemed exempt from full ethics review at Imperial College London and the University of Massachusetts Amherst; it was approved by the University of Ghana Ethics Committee (ECH 149/18-19). This protocol is designed to be implementable in SSA cities to map environmental pollution to inform urban planning decisions to reduce health harming exposures to air and noise pollution. It will be disseminated through local stakeholder engagement (public and private sectors), peer-reviewed publications, contribution to policy documents, media, and conference presentations.
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Yost, William A., Xuan Zhong, and Anbar Najam. "Judging sound rotation when listeners and sounds rotate: Sound source localization is a multisystem process." Journal of the Acoustical Society of America 138, no. 5 (November 2015): 3293–310. http://dx.doi.org/10.1121/1.4935091.
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Ma, Wei, and Ce Zhang. "A frequency-domain beamforming for rotating sound source identification." Journal of the Acoustical Society of America 148, no. 3 (September 2020): 1602–13. http://dx.doi.org/10.1121/10.0001939.
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Ma, Wei, Huan Bao, Ce Zhang, and Xun Liu. "Beamforming of phased microphone array for rotating sound source localization." Journal of Sound and Vibration 467 (February 2020): 115064. http://dx.doi.org/10.1016/j.jsv.2019.115064.
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Macpherson, Ewan A., and Janet Kim. "Temporal integration in sound localization via head rotation." Seeing and Perceiving 25 (2012): 211. http://dx.doi.org/10.1163/187847612x648396.
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Information about a sound source’s location in the front/back dimension is present in the relation between head rotation and the resulting changes in interaural time- or level-difference cues. The use of such dynamic cues for localization requires the auditory system to have access to an accurate representation of the orientation and motion of the head in space. We measured, in active and passive rotation conditions, and as a function of head-rotation angle and velocity, normally hearing human listeners’ ability to localize front and rear sources of a low-frequency (0.5–1 kHz) noise band that was not accurately localizable in the absence of head motion. Targets were presented while the head was in motion at velocities of 50–400°/s (active neck rotation) or 25–100°/s (whole-body passive rotation), and were gated on and off as the head passed through a variable-width spatial window. Accuracy increased as window width was increased, which provided access to larger interaural cue changes, but decreased as head-turn velocity increased, which reduced the duration of the stimuli. For both active and passive rotation, these effects were almost exactly reciprocal, such that performance was related primarily to the duration of the stimulus, with ∼100 ms duration required for 75% correct front/back discrimination regardless of the cue-change magnitude or mode of rotation. The efficacy of the dynamic auditory cues in the passive rotation condition suggests that vestibular input is sufficient to inform the auditory system about head motion.
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Mao, Yijun, Chen Xu, Datong Qi, and Hongtao Tang. "Series Expansion Solution for Sound Radiation from Rotating Quadrupole Point Source." AIAA Journal 52, no. 5 (May 2014): 1086–95. http://dx.doi.org/10.2514/1.j052706.
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McQueney, Elizabeth, Maryam Landi, and Likun Zhang. "Measurements of the Doppler effect due to a rotating sound source." Journal of the Acoustical Society of America 142, no. 4 (October 2017): 2542. http://dx.doi.org/10.1121/1.5014291.
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Zhang, Ce, and Wei Ma. "Efficient computation of modal transfer function in mode composition beamforming for rotating broadband source localization." Journal of the Acoustical Society of America 152, no. 6 (December 2022): 3422–28. http://dx.doi.org/10.1121/10.0016511.
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For rotating sound source localization, there are mainly two types of frequency-domain beamforming methods, the virtual rotating array (VRA) method and mode composition beamforming (MCB). Compared with the VRA method, MCB overcomes the constraint of microphone array configuration and avoids error introduced by interpolation. In order to obtain the MCB result, modal transfer functions, which are the modal coefficients in the analytical solution of the sound field of rotating source, should be pre-calculated. However, the computation of modal transfer functions takes a long time, especially under a large number of considered frequencies. Therefore, the computational efficiency of MCB is limited by the computation of modal transfer functions. In this paper, an expression of modal transfer functions at multiple considered frequencies is derived first. According to this expression, intermediate variables independent of frequency are computed in a fast way, then modal transfer functions at each considered frequency are calculated through these intermediate variables. This expression is successfully applied to improve the computational efficiency of MCB for rotating broadband source localization.