Acoustics Australia最新文献

{"title":"Comparison of Small Rotor Tonal and Random Noise Decomposition Methods","authors":"Justin Malkki,&nbsp;Yendrew Yauwenas,&nbsp;Con Doolan,&nbsp;Danielle Moreau","doi":"10.1007/s40857-024-00333-z","DOIUrl":"10.1007/s40857-024-00333-z","url":null,"abstract":"<div><p>This paper examines and compares methods of separating tonal and broadband components of the noise generated by small rotors as commonly found on small unmanned aerial systems (sUAS). Time synchronous analysis (TSA) methods with varying averaging algorithms, such as ensemble averaging (EA), exponential weighted moving averaging (EWMA) and Kalman filter averaging (KFA), are compared against themselves and against a cross-correlation-based method. The decomposition methods are used on noise measurements of a small isolated rotor under static operation and edgewise flight conditions at 10 m/s in the UNSW anechoic wind tunnel (UAT). The best method for isolating tones is TSA-EWMA and for isolating the broadband spectrum of noise is the cross-correlation method, based on the spectral reconstruction of the experimental data.\u0000</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 3","pages":"323 - 337"},"PeriodicalIF":1.7,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40857-024-00333-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Investigation on Aerodynamic Noise Source Identification and Far-Field Noise Characteristics of the High-Speed Train Bogie Region","authors":"Jiawei Shi,&nbsp;Jiye Zhang,&nbsp;Tian Li","doi":"10.1007/s40857-024-00332-0","DOIUrl":"10.1007/s40857-024-00332-0","url":null,"abstract":"<div><p>The bogie region is one of the most important aerodynamic noise sources of high-speed trains. A thorough understanding of the generation mechanism and characteristics of bogie aerodynamic noise is the prerequisite for effective implementation of noise control measures. In this study, a delayed detached eddy simulation (DDES) is performed to solve the unsteady flow field around the bogie region, and an aerodynamic noise source identification method based on the integral solution of the Ffowcs Williams-Hawkings (FW-H) equation is adopted to determine the dipole and quadrupole sources distribution in the bogie region. The identification results of the two types of sources provide different understandings of the noise generation mechanism of the bogie region but determine the same flow structures closely associated with the bogie aerodynamic noise, which are the shear vortex structures formed at the rear edge of the cowcatcher and the front side edges of the bogie cavity. The flow field data obtained by DDES simulation is also used as input for the FW-H solver to calculate far-field noise, and the source contribution, spectrum characteristics and directivity of the far-field noise are analyzed. The results show that at a speed of 350 km/h, the aerodynamic noise in the bogie region is still dominated by dipole sources, and the contributions of the bogie itself and the bogie cavity to far-field noise are equally important despite the significant differences in their radiation characteristics.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 3","pages":"375 - 391"},"PeriodicalIF":1.7,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Simulation and Experimental Study of Aerodynamic Noise Reduction of Elbow Based on Leading- and Trailing-Edge Serrated Guide Vanes","authors":"Lili Ye,&nbsp;Xianzhong Wang,&nbsp;Weiguo Wu,&nbsp;Haoran Ma,&nbsp;Weijia Feng","doi":"10.1007/s40857-024-00330-2","DOIUrl":"10.1007/s40857-024-00330-2","url":null,"abstract":"<div><p>The leading-edge and trailing-edge serrated guide vanes, inspired by the silent flight of owl wings, were designed to reduce the aerodynamic noise produced by elbows in cruise. Using the acoustic finite element approach in conjunction with the large eddy simulation model, the aerodynamic noise produced by the elbow is calculated. Using an air piping test platform, this hybrid simulation technique is validated. Further simulation results showed that these two bionic guide vanes contributed to the decrease in the aerodynamic noise by streamlining the airflow and lowering the formation of laminar flow separation bubbles. In particular, the leading-edge serrated guide vane reduced noise by 4.6 dB, whereas the trailing-edge serrated guide vane reduced noise by 3.4 dB.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 3","pages":"349 - 365"},"PeriodicalIF":1.7,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"News Item","authors":"","doi":"10.1007/s40857-024-00329-9","DOIUrl":"10.1007/s40857-024-00329-9","url":null,"abstract":"","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 2","pages":"113 - 130"},"PeriodicalIF":1.7,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141662768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing Noise from Light Rail Vehicles Idling at Termini in NSW, Australia","authors":"Aaron Miller,&nbsp;Briony Croft,&nbsp;Jordan McMahon","doi":"10.1007/s40857-024-00328-w","DOIUrl":"10.1007/s40857-024-00328-w","url":null,"abstract":"<div><p>Light rail vehicles will often idle with their air conditioners running at terminus locations that may be located near sensitive receivers due to network constraints. This creates a pseudo-stationary noise source with similar level and characteristics to industrial air conditioners that can result in disturbance and complaints from nearby sensitive receivers. However, in practice in the state of New South Wales (NSW), Australia, this pseudo-stationary noise source is commonly assessed against airborne noise criteria for transportation noise. This is due to the Conditions of Approval on the Sydney Inner West Light Rail Extension project explicitly delineating noise produced by light rail vehicles from other sources. This interpretation has been applied on all subsequent light rail projects in NSW, which have assessed this noise source at termini against the Rail Infrastructure Noise Guideline (RING) requirements. The Noise Policy for Industry (NPfI) has been applied to other noise sources on these projects, specifically fixed equipment at stops and all noise sources at stabling facilities (including light rail vehicle air conditioning noise and traffic movements within the boundary of the facility). This paper examines the policy overlap between the RING and the NPfI that makes both documents potentially applicable to noise from light rail air conditioners when idling at termini, depending on interpretation and specific project conditions of approval. It also presents a hypothetical assessment of typical light rail activities near termini against both the RING and NPfI, to demonstrate the potential differences in project outcomes between the applications of the two documents. An example of a compromise that acknowledges the pseudo-stationary nature of the noise source as well as the benefits that public infrastructure provides relative to industrial facilities is also suggested, in lieu of a separate threshold or policy for this very specific circumstance.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 3","pages":"401 - 410"},"PeriodicalIF":1.7,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141532323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Assessment of the Flow Recirculation Effect on the Noise Measurement of a Free-Flying Multi-rotor UAS in a Closed Anechoic Chamber","authors":"Zhida Ma,&nbsp;Peng Zhou,&nbsp;Xin Zhang,&nbsp;Siyang Zhong","doi":"10.1007/s40857-024-00327-x","DOIUrl":"10.1007/s40857-024-00327-x","url":null,"abstract":"<div><p>The flow recirculation effect on the noise measurement of a multi-rotor unmanned aircraft system (UAS) hovering in a closed anechoic chamber is experimentally characterized in this work. The measured acoustic spectrogram reveals that the recirculation forms around 30 s after the UAS’s take-off, manifested as prominent fluctuations in blade passage frequency and its harmonics. However, the instantaneous overall sound pressure level shows no obvious increase with the development of the recirculation. The result indicates that the recirculation effect does not significantly change the total acoustic energy but increases the uncertainties in the spectral distribution, which can be quantified by spectral entropy. The quantitative analysis of different noise components shows that the recirculation has a minimal effect on the tonal noise levels but slightly increases the broadband noise level out of the rotors’ plane. The results from parametric tests suggest that this broadband noise increment has a positive correlation with the UAS’s hover height but a negative correlation with the UAS’s gross mass. The comparison with existing studies highlights the difference in the recirculation effect on the noise of isolated rotor(s) and free-flying multi-rotor UAS in confined spaces.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 3","pages":"313 - 322"},"PeriodicalIF":1.7,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40857-024-00327-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141354165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards an Acoustically Accessible Campus: A Case Study of the Acoustic Conditions of an Australian University","authors":"Kiri Mealings,&nbsp;Kelly Miles,&nbsp;Nicole Matthews,&nbsp;Joerg M. Buchholz","doi":"10.1007/s40857-024-00323-1","DOIUrl":"10.1007/s40857-024-00323-1","url":null,"abstract":"<div><p>University is an important stage of learning for students, so it is vital that higher education spaces are acoustically accessible to all and are places that promote equity and inclusion. The aim of this study was to measure the unoccupied noise levels and reverberation times of all of the classrooms in a typical Australian university to assess acoustic accessibility with a view to planning for a more accessible campus. A total of 166 classrooms were measured and categorised into good, ok, and poor classrooms according to the Macquarie University (MQU) Design Guidelines Review Performance Standards. Regarding unoccupied noise levels, 52% of classrooms were within the recommended &lt; 35 dBA limit. Regarding reverberation times, 65% of classrooms were within the recommended 0.4–0.6 s limit. Finally, 40% of classrooms met both the noise level and reverberation time limit. The plans at the university to incorporate these findings to make the campus more acoustically accessible are discussed, as well as future research avenues so that all students and teachers can flourish.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 2","pages":"273 - 278"},"PeriodicalIF":1.7,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s40857-024-00323-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Virtual Augmentation of the Beamforming Array Based on a Sub-cross-spectral Matrix Computation for Localizing Stationary Signal Noise Sources","authors":"R. Singh,&nbsp;A. Mimani","doi":"10.1007/s40857-024-00322-2","DOIUrl":"10.1007/s40857-024-00322-2","url":null,"abstract":"<div><p>This paper presents a generalized algorithm called the sub-cross-spectral matrix (SCSM) beamforming technique for the virtual augmentation of an <i>N-</i>channel beamforming array based on sequential computation of the cross-spectral matrix (CSM) terms for localizing stationary signal sources. To this end, first, the diagonal sub-cross-spectral matrices (SCSMs) of the <i>N</i>-channel array pertaining to <i>M</i> different spatial locations were obtained. Next, the off-diagonal SCSMs were systematically computed by directly evaluating the cross-spectral terms between some microphones placed in the array at <span>(i{text{th}})</span> location <span>((1 le i le M))</span> and the remaining microphones placed in the array at <span>(j{text{th}})</span> location <span>((j ne i, , 1 le j le M))</span>. As a proof of concept, the SCSM beamforming was used to virtually construct a 32<i>-</i>channel planar Underbrink spiral array by sequentially measuring data using <span>(left( {begin{array}{*{20}c} {32} 2 end{array} } right))</span> microphone pairs. The resultant 2-D beamforming map of a loudspeaker source was found to be nearly identical to the counterpart result produced when data from 32<i>-</i>channel simultaneous measurements were used. The SCSM technique was then extended to increase the density and aperture of a planar array by constructing a virtual 64-channel planar array from 32-channel simultaneous measurements. For the former case, the source maps were found to be identical to the counterpart results obtained from the existing geometric mean and combined CSM algorithms. However, for the latter case, the SCSM beamforming delivered a noticeably improved focal-resolution along the direction in which there was a virtual increase in aperture. For localizing loudspeaker source(s) in a 3-D domain, the SCSM beamforming implemented using two orthogonal Underbrink arrays was shown to deliver a significantly improved resolution (focal lobe) and unambiguous localization because it considers the complete CSM unlike the multiplicative beamforming and combined CSM algorithms which do not account for the phase-information between the two orthogonal arrays.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 2","pages":"225 - 246"},"PeriodicalIF":1.7,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140881714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-channel ANC System with Online Secondary Path Modeling for Turboprop Aircraft Cabin","authors":"Hao Shen,&nbsp;Qing Xue,&nbsp;Ningjuan Dong,&nbsp;Yixiao Chen,&nbsp;Xing Shen","doi":"10.1007/s40857-024-00317-z","DOIUrl":"10.1007/s40857-024-00317-z","url":null,"abstract":"<div><p>The engineering implementation of the multi-channel active noise control (MCANC) system for turboprop aircraft cabin is seriously hampered by its enormous computational complexity. This paper proposes the variable-P-sequential-partial-update filtered-x least mean square (VP-SPUFxLMS) algorithm, which achieves noise reduction performance comparable to that of the multi-channel FxLMS (MCFxLMS) algorithm while significantly reducing the computational complexity. Additionally, considering the time-varying nature of the secondary paths in practical applications, the Eriksson online secondary path modeling (OSPM) method is extended from single-channel to multi-channel, the problems that may be faced when the method is applied to MCANC systems are analyzed, and an improved alternative online secondary path modeling (AOSPM) method is proposed to address the above problems, which exhibits great online modeling capabilities without introducing excessive computational load. Simulation and experiment results validate the noise control performance of the proposed method, and the ANC experiment has achieved an average reduction of more than 15 dB in the sound pressure level (SPL) of the four channels, which fully demonstrates its broad engineering application prospects.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 2","pages":"175 - 190"},"PeriodicalIF":1.7,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140668100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the Acoustic Noise in Intensive Care Units via Deep Learning Technique","authors":"Awwab Qasim Jumaah Althahab,&nbsp;Branislav Vuksanovic,&nbsp;Mohamed Al-Mosawi,&nbsp;Hongjie Ma","doi":"10.1007/s40857-024-00321-3","DOIUrl":"10.1007/s40857-024-00321-3","url":null,"abstract":"<div><p>Intensive care unit (ICU) noise is a critical and often overlooked issue, impacting patient recovery and healthcare staff well-being. Existing research primarily relies on costly sound level meters for monitoring noise levels, where the characteristics of noise sources cannot be determined and discriminated. This study employs deep neural networks to detect and classify ICU noise events, enhancing source identification. A cost-effective internet of things-based audio recording and monitoring system has been designed and deployed in three ICUs for data collection. The acoustic event classification system described in the paper integrates convolutional neural networks for event detection, followed by clustering to isolate noise sources. Results demonstrate precise classification, with speech identified as a major contributor in all ICUs. This model offers valuable insights for characterising acoustic sources in typical ICUs, which could be the first step towards tackling the problem of excessive noise in ICUs as well as a starting point for further research in this area.</p></div>","PeriodicalId":54355,"journal":{"name":"Acoustics Australia","volume":"52 2","pages":"209 - 224"},"PeriodicalIF":1.7,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140672967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}