An experimental method in a real-working condition was conducted to collect acoustic emission (AE) signals emitted from cylinders of a large two-stroke low-speed marine diesel engine. Measurements were performed in an axial direction of the cylinder in medium-frequency (20–80 kHz) and high-frequency (100–900 kHz) ranges and in a vertical direction only in the medium-frequency range under two engine

The paper presents a retrospective and prospective view of noise mapping strategy followed across the globe as a diagnostic tool for controlling the noise pollution in urban cities. The concept of noise mapping is primitive in India and thus developing the noise maps is really a great challenge for big metropolitan cities of India. The paper discusses the benefits associated, input parameters required

The supra-aural headphone concentrates the sound in the listener’s ears, so the loudspeaker sound is confined to the cavity between the pinna and the headphone casing. It is then directed toward the tympanic membrane through the ear-canal. The high-quality sound requirement of supra-aural headphone on one side and space limitation on the other prompted this research. Similarly, inherent sound leakages

Despite intensive management, the increasing conflict between humans and saltwater crocodiles in places such as Queensland, Australia, has led to the investigation of alternative techniques to improve public safety. The reliability of digital video surveillance systems (DV) placed above water and multi-beam sonar (sonar) placed under water to detect and monitor saltwater crocodiles was tested in a

Traditional acoustic liners used in nacelles and fan ducts include a perforated face sheet bonded to a honeycomb core. A tunable acoustic liner with a piezoelectric substrate is developed to overcome the shortages of current liner such as unchangeable structure and uncontrollable bandwidth. After the piezoelectric panel deformed under the driving voltage, the resonant chamber changed, and the resonant

This study addresses the problem of source depth discrimination in the context of shallow-water acoustics. From the perspective of beam pattern correlations, a discriminating characteristic quantity, which implies the information of source depth, is presented and defined as the difference factor of the vertical beam pattern. In applying the proposed difference factor for source depth discrimination

Acoustic emission (AE) technique has been merged to a promising method for structural health monitoring in non-destructive technique. So an analysis of the AE signal is becoming a very important research component. In this paper, an algorithm is developed for detection of the crack signal among different noise signals since the AE signal is also generated by several means like any impact or rubbing

Effective low-frequency and large-scale noise reduction are crucial in industrial applications. Conventional passive methods lack the effective low-frequency performance, and existing hybrid methods are costly to realize large-scale absorption. Hence, an effective and simply actuated solution for low-frequency and large-scale absorption is urgently needed. In this study, the low-frequency (100–500 Hz)

An accurate head-related transfer function can improve the subjective auditory localization performance of a particular subject. This paper proposes a deep neural network model for reconstructing the head-related transfer function (HRTF) based on anthropometric parameters and the orientation of the sound source. The proposed model consists of three subnetworks, including a one-dimensional convolutional

Freshwater hydroacoustic surveys are frequently performed with small research boats. Thus, the transducer, usually fixed on a pole on the side of the boat, could be misaligned with the horizontal axis (i.e., the lake surface). Given that fish acoustic responses are strongly directional, the transducer angle could induce attenuation of their backscattering strengths. To test the influence of a small

Nowadays, the sound source localization is widely applied in various fields, with a focus on arrays or algorithms. Meanwhile, acoustic metasurfaces have recently attracted enormous interest in material science. This paper proposed a kind of piezoelectric acoustic metasurface, whose structure is theoretically proved to be useful in sound field orientation or sound source localization. The metasurfaces

In the context of eatery places, it is important that people concentrate and focus on the smells and tastes of their food and drinks to ensure that they are satisfied with their meals, as this influences the positive behavior of the intent to return and can prompt them to recommend an eatery place to others later. A higher level of noise may distract people from having a fine dining experience and

A new method of head-related transfer function (HRTF) personalization was built to optimize new user matching in the HRTF database to enhance 3D virtual hearing. The method of modified sparse representation (MSR) treated the HRTF personalization for an incomer as the task of finding similar subjects in the HRTF database with sparse representation (SR) of the incomer’s anthropometric features under

Restoration of historical buildings should be carried out without giving damage to the existing historical building, and material selections should be determined in accordance with the historical building structure. In addition to the selection of materials compatible with the historical structure, the selection of materials that can improve the interior acoustic quality of the space is one of the

The article A Review of the Potential Impacts of Wind Turbine Noise in the Australian Context, written by John Laurence Davy, Kym Burgemeister, David Hillman & Simon Carlile, was originally published electronically on the publisher’s internet portal on 27 June 2020 without open access.

Aiming at the problem that it is difficult to accurately predict the aerodynamic noise in the safety valve exhaust process, a new numerical simulation method that comprehensively considers the dipole sources and the quadrupole sources is proposed. The RNG k–ε model is used to simulate the steady-state flow fields, LES numerical method is used to simulate the transient flow, and then the unsteady disturbances

The engine compartment is the main source of automobile noise. In this paper, based on the study of the noise characteristics of the engine compartment, the relationship model is established between engine speed and noise frequency, and an active noise reduction method is proposed based on the adaptive least mean square (LMS) algorithm. Because the adaptive change of the convergence factor is controlled

With the rapid advancement of technology of unmanned aerial vehicles (UAVs), security and safety of military and civil infrastructure have been jeopardized. By exploiting the unreliable capabilities of radar to detect low-flying UAVs with small radar cross section, they can be utilized for malicious purposes, e.g., unauthorized surveillance. To detect UAVs, therefore, various other techniques including

To research the effect of blade outlet angle on acoustics of marine centrifugal pump, the unsteady numerical simulation analysis of the four models is carried out and the dipole source of pump shell is extracted. The constraint modal of pump, interior sound pressure level (SPL), exterior acoustic directivity and sound power level are obtained. The results show that five and six SPL peaks appear at

The acoustic performance of multilayered structures (MLSs) can be identified by experiments and calculation models that use commercially available software. This paper presents both an experimental method and data processing techniques that can be used for obtaining the acoustic characteristics of MLSs. During the described experiments, three types of MLSs with different structures are designed and

Continuum topology optimization is an effective way to reduce vibration and noise of vibro-acoustic coupling system. However, the high computation time required for calculating the vibro-acoustic responses during topology optimization is a major obstacle for practical applications. In this paper, a novel symmetric method of vibro-acoustic system matrix is proposed, and a new model reduction method

Fitness culture has significantly grown since the nineteenth century. In the recent decade, the gym and fitness industry have thrived in many countries. The construction of gymnasiums has increased dramatically, and fitness centres have become one of the most common spaces in mix-used buildings around the world. There are a significant number of gyms located relatively close to residential areas, some

This manuscript describes a range of technical deliberations undertaken by the authors during their work as members of the Australian Government’s Independent Scientific Committee on Wind Turbines. Central to these deliberations was the requirement upon the committee to improve understanding and monitoring of the potential impacts of sound from wind turbines (including low frequency and infrasound)

One of the applications of the acoustic reflectometry technique is to study the layered media structures such as soil, snow. The issues of acoustic reflectometry system to study the layered media structures related with using non-ideal components are given in this paper. It has been demonstrated that there are several artifacts present in the acoustic reflectometry analysis in practice. The paper presents

The classical transfer path analysis (TPA) method has become a standard measurement method. It has high accuracy but remains a time-consuming and complex measurement, which limits its application in industry. The operational transfer path analysis (OTPA) method is known for its high efficiency; however, the accuracy of this method for industrial application is controversial. To separate the intake

A statistical energy analysis (SEA) model of a 510 l capacity refrigerator is used to calculate the sound pressure level generated in a reverberation room. This is a reliable indicator of the vibroacoustic performance of the refrigerator, and it is in some countries as a pre-commercialization test. The main contributions of the SEA model are the characterization of the refrigerator structure (three-layer:

To solve the beamforming performance degradation problem of the towed linear array caused by the shape distortion, we propose a robust beamforming way for distorted towed linear array. The proposed method basically uses the segmented processing, which can be divided into 3 steps. Firstly, towed linear array is divided into sub-arrays. Then, the weights of sub-arrays are obtained and outputs of beamforming

This work examines experimentally the absorption characteristics of empty plastic water bottles. It focuses on the three common sizes of bottles widely available in the Saudi market (1500, 600 and 330 ml). Measurements were performed according to ISO 354 and ISO 9613-1 standards in the reverberation chamber. Three systematic groups of measurements were performed, each of which examined only one of

Structural finite element coupled with the conjugated infinite element method is an efficient numerical technique for solving the acoustic radiation problem due to the vibration of underwater objects. However, for large complex structures, the total acoustic mesh would become very large if the artificial boundary is too far away from the structural wetted surface. Thus, the calculation time can become

Discrete singular convolution (DSC) algorithm is an accurate dynamic analysis method for single structures. However, vibration analysis of connected structures via the DSC method is limited to step beams and plates. This paper extends the applicability of the DSC method in handling acoustic transmission lines composed of several duct elements with different diameter ratios. Connections of elements

Noise may cause hearing damage and delayed growth and development in newborns in neonatal intensive care units. Hence, it is necessary to reduce noise in these environments. Training and use of visual signs have been investigated as the interventional strategies with the aim of reducing noise level and exposure in neonatal intensive care units. This quasi-experimental study (before and after design)

The source parameters of Irrawaddy dolphins’ echolocation click in the Bay of Brunei were estimated. Analysis of eight parameters shows that the Irrawaddy dolphins produce broadband echolocation clicks with mean click duration of 21.1 ± 7.2 μs. The clicks had a mean peak-to-peak apparent source level (ASLpp) of 201.2 ± 7.3 dB re 1 μPa (N = 350), a mean peak frequency of 116.5 ± 15.2 kHz, a mean centroid

Manual bone drilling in orthopedic surgical operations may cause injury to patient tissues if the drill bit continues to progress after exiting the bone. In this study, a new bone breakthrough detection algorithm based on acoustic emission (AE) signal analysis has been developed to minimize temporary and permanent injuries that can be caused by surgeon-controlled surgical drills. Three parametric estimation

In this work, we develop an optimization approach to optimize the distribution of porous material layer inside cavity. The optimization seeks to improve the absorbing effects of the porous material, decreasing the noise level at regions of interest or increasing the sound energy dissipated by the porous material. To achieve the preset optimization aim, two different objective functions are accordingly

Chatter-free turning has been a matter of concern for engineers. Improper selection of cutting parameters leads to regenerative chatter and loss of productivity. In the present work, a methodology has been proposed to select an appropriate combination of input cutting parameters for stable turning with improved metal removal rate (MRR). Chatter signals generated during the turning of Al 6061 are acquired

Due to their disproportionate geometries and uneven distribution of sound, the interior sound field analysis of subway stations has always been challenging. The field necessitates reliable tools for real-case design applications, while the research and discussions on the topic are still ongoing. This study compares two major room acoustics simulation approaches, namely ray tracing and diffusion equation

The Swan–Canning River System is home to an Indo-Pacific bottlenose dolphin (Tursiops aduncus) community of currently 17 adult and juvenile individuals. While a complete photo-identification catalogue exists, visual monitoring requires repeated boat-based surveys and is thus laborious and expensive. Bottlenose dolphins are known to emit individually distinctive signature whistles, and therefore, passive

The purpose of this paper is to calculate an accurate sound absorption coefficient for a micro-perforated panel absorber (MPPA). When the sound absorption coefficient is calculated, there is a difference between the measurement and the calculation. In the calculation, a resistive end correction coefficient (β) of 2 or 4 and a reactive end correction coefficient (δ) of 0.85 are generally applied. However

Double-layer micro-perforated panels (MPPs) have been studied extensively as sound absorption systems to increase the absorption performance of single-layer MPPs. However, existing proposed models indicate that there is still room for improvement regarding the frequency bands of absorption for the double-layer MPP. This study presents a double-layer MPP formed with two single MPPs with inhomogeneous

The interior noise in train carriages has become an important design parameter for passenger comfort with the proliferation of high-speed rail systems around the world, because passengers spend a few hours on these trains for traveling between cities spanning more than 1000 km apart. However, there are limited reported studies on comparing the carriage noise for different high-speed rail systems. In

The present research focuses on the soundscapes of two localities representative of the oasis cities of southeast Algeria, Sidi Okba and El Kantara, in order to define the nature of the soundscapes and the impact that road traffic can have on them. In this paper, the method of sound walks has been used in order to record the sound experience of city dwellers in pre-selected routes. The processing of

A model of a novel metamaterial beam with periodically attached spring–mass combinations is presented. Dispersion relation, reaction forces and power flow are calculated and aided by the finite element method, to help understand the actual band gap generation and wave attenuation mechanism. Results show that multiple large low-frequency band gaps are generated and can be overlapped to form a broad

Personalization of head-related transfer functions (HRTFs) is an essential task in the research on virtual hearing. In this paper, a method based on sparse principal component analysis (SPCA) and sparse representation (SR) was proposed to personalize HRTFs. The fundamental assumption is that an equivalent sparse combination can express the same anthropometric parameters. SPCA was first used to reduce

The acoustic stealth shape design of the underwater vehicle has become a topic of considerable current interest to the experts engaging underwater acoustic countermeasure technology in recent years. During tracking the target, the echo strength of head shape is easily exposed and detected for the underwater vehicle, which directly affects its acoustic stealth performance. This paper proposes an optimal

This work examines the absorption characteristics of two well-known porous materials—polyurethane foam (PUF) and polystyrene foam (PSF)—both of which are locally produced and readily available in Saudi Arabia. Nine samples were selected after a careful investigation of the local markets. The chosen samples were systematically tested in conformance with the ISO 354 and ISO 9613-1 standards in the reverberation

In order to evaluate the adverse effects of combined traffic noise, a face-to-face survey was carried out among 1433 local residents aging from 15 to 75 years. The relationships between the percentage of highly annoyed (%HA), sleep disturbance and acoustical/non-acoustical factors (Ldn, age, gender, residence time, time at home, etc.) were analyzed, respectively. Results showed that %HA caused by road–rail

Speaking and listening are the primary modes of communication in the classroom. Therefore, optimal acoustic conditions are vital for children’s learning. The aim of this study was to assess the accuracy of the SoundOut Room Acoustics Analyzer iPad app developed by the National Acoustic Laboratories against a sound level meter. Forty-eight noise level measurements were compared in laboratory settings

All industrial equipment in operation generates vibrations and noise and we perceive and interpret them. Noise is therefore associated psychologically with the objects that emit them. The techniques of vibratory signal processing and generated sounds have allowed refining their perceptive impact and relating it to the structures characteristics. Our work essentially consists in establishing a relationship

Reverberation is an important ocean phenomenon that involves bottom properties. This paper proposes a method of geoacoustic inversion using bottom reverberation in the deep ocean. Models for the probability density function, including Rayleigh, Lognormal normal, K, and Weibull distributions, are commonly used to describe the envelope of bottom reverberation. Based on the measured data in South China

This research is focused on identifying the porosity in concrete manufactured with air-cooled blast furnace slag as coarse aggregate and analyzing its potential use as sound absorption material. Six concrete mixes were manufactured by using three types of aggregate with different particle size distributions and consequently, diverse porosity in the matrix. Acoustic characteristics and mechanical properties

Hybrid accelerometers comprise sensor elements from different technologies, capable of combining two output signals into a highly linear response. Typically, a piezoaccelerometer would be combined with a MEMS accelerometer to extend an otherwise AC coupled response down to DC. The complementary filter function is an effective and distortion-free method for combining a DC capacitive sensing element

Medium noise levels are very common in work environments, and few studies have addressed their effects. This study aims to investigate the effects of real noise levels from four types of workplaces on psychophysiological responses. Thirty-one normal hearing male subjects were recruited. They were asked to judge the noise annoyance (NA) and noise-induced subjective load (NISL) of four occupational environments

A cold eddy was detected east of Taiwan. The two-dimensional (2-D) eddy structure for the cold eddy was constructed with Argo data. Results show that the eddy structure follows that of an ellipsoid, where the largest anomaly occurs near the center at almost 400 m depth. The horizontal diameter was 200 km, and the vertical diameter was 500 m. The 2-D sound speed profile feature model for the cold eddy

The boundary element method was used to calculate the sound pressure levels at the two ears of an artificial head when a sound source was located in different directions and distances in the near field (within 1 m). Total loudness was then calculated by using a binaural loudness model. Results showed that, in the near field, total loudness does not always increase monotonically as the source distance

Linear towed arrays are one of the principal methods of underwater target detection, especially at low frequencies. A typical towed array contains many hydrophones in a flexible tube towed several hundred meters behind the ship. A practical problem in towed arrays is hydrophone or channel failures. Failed channels impact the side lobe levels and increase the leakage from tow-ship noise. This significantly

A theoretical modelling approach is proposed for the vibroacoustic problem of sound transmission across a rectangular double-wall panel clamp mounted on an infinite rigid baffle with magnetically connected stiffness. The magnetic stiffness is derived based on interaction energy between the two rectangular magnets attached to the clamped plates. The exact solution for the vibration of the clamped double

In recent years, high-speed train operations have been increasing, yet their environmental impact is still not well researched and understood. Evaluation of the impacts of Turkey’s new high-speed train lines from the perspectives of noise, vibration and socio-economic issues is important to secure sustainable development in the sector. National and international regulations are important to enable

Vibration and acoustic emission have received great attention of the research community for condition-based maintenance in rotating machinery. Several signal processing algorithms were either developed or used efficiently to detect and classify faults in bearings and gears. These signals are recorded, using sensors like tachometer or accelerometer, connected directly or mounted very close to the system

The remarkable properties of natural lignocellulosic fibers such as biodegradability, light weight, low density, low cost and non-toxicity as well as being an alternative to sound absorbers made of synthetic fibers have attracted many researchers in the field of acoustics. The purpose of the present study was to compare the estimated sound absorption coefficient of composite samples made of natural