The cross-sectional shape of the metal studs in a double-leaf wall has a significant influence on its sound insulation. In a recent study, a numerical optimization of the stud shape resulted in designs that offer a significant increase in broadband airborne sound insulation, both when compared to conventional C-shaped studs and commercially available acoustic studs, but at the expense of a much higher

This paper reports results of full field vibration measurements conducted on a laboratory test case, a cantilever beam, submitted to a transient excitation using an impact hammer. The deflectometry technique in the visible and in the infrared spectra are employed to measure the beam’s vibration field using high-speed cameras. The respective performances and implementations of both techniques, as well

Acoustic lining treatments are widely used in modern aircraft engines for noise reduction. The key to the successful application of this technique is to establish a link between the geometry parameters (thickness, hole diameters, etc.) and the acoustic impedance. To achieve this goal, the impedance eduction technique is widely used by the aircraft engine noise research community. The technique iteratively

Active noise equalization or active sound profiling techniques for sound quality enhancement tend to balance the sound pressure levels (SPLs) of certain frequency points or frequency bands of target noise to meet human perception requirements rather than simply minimizing the SPLs like active noise control (ANC) technique. Therefore, when the secondary path is time-varying, online secondary path modeling

An acoustic metasurface (AMS) is proposed comprising a panel containing a micro slit of variable depth coupled to a thin cavity of symmetrical coiled spaces. Theoretical and numerical analyses are used to demonstrate that this metasurface has an effective low frequency sound absorption capability (i.e., between 100 Hz and 600 Hz) with a deep-subwavelength thickness. The mechanism underlying the sound

Passive target detection under low signal-to-noise ratio is essential in various underwater circumstances, but difficult as lacking of targets’ prior information, special propagation characteristics and effect of background noise. Based on the time–frequency representation, we develop a narrow band time–frequency space matched method. The time–frequency matrix is derived based on the ray theory, the

Long-time exposure to low-frequency vibration will negatively impact human health. A rapid biodynamic system modeling method has been proposed to study the human body’s response to the low-frequency vibration excitation in the whole vehicle environment. The sensitivity of design parameters of the seating suspension system to the vibration isolation performance will be studied. The dynamic model consists

A two-dimensional (2D) deconvolution beam imaging method based on distance and azimuth in active imaging sonar is proposed. First, the circular array is used to perform conventional beamforming for echo signal of each distance bin to obtain the distance and azimuth 2D acoustic image in active imaging sonar. Then, high-resolution azimuth information is obtained by using azimuth dimension deconvolved

The motors of the Unmanned Aerial Vehicle are critical parts, especially when used in applications such as military and defense systems. The fact that the brushless DC (BLDC) motors used in UAVs operate at high speed causes malfunctions. In this study, propeller, eccentric and bearing failures, which are frequently seen in UAV motors, were created. Then the fault diagnosis was made by applying the

Acoustic liners play a vital role in the reduction of aero-engine noise and combustion instabilities. In the present work, acoustic damping behavior of perforated cylindrical liners of mixed porosities is investigated both analytically and experimentally. The aim of the paper is to propose a generalized analytical model for the compliance of mixed porosity liners. The analytical results are obtained

Speaker extraction aims to extract the speech signal of the speaker of interest from a mixture of two or more speakers. We propose a set of novel psychoacoustic-based loss functions that each can be used to optimize a stacked network of Bidirectional Long Short Term Memories (BLSTM) to imitate the human hearing system, which has an extraordinary ability to perceive and separate speech signals. To do

As an important node in urban city, power substation provides the clean energy to thousands of households, ensuring a stable and high quality of urban life. However, the influence of noise emission from substation is always underestimated. With the improvement of environmental consciousness, making the substations quietly hidden in urban cities becomes an urgent issue which should be thoroughly considered

The inherent speckle noise in medical ultrasound image degrades valuable clinical information and affects the diagnosis quality. Therefore, commercial ultrasound systems always face a big challenge to improve the visual quality of ultrasound images by reducing the speckle noise. A new hybrid algorithm is proposed in the present paper for speckle reduction by combining nonlinear coherence diffusion

Although most modern communication devices use of multiple MEMS-based microphones, their application in continuous-outdoor applications has so far been very limited. Specifically, for constant operation in humid, rainy environments, additional weather protection of the MEMS element is required. Thus, a protective 3D-printed membrane has been developed for a multichannel outdoor application to monitor

Condition monitoring for water and sewerage pipes is essential for the safety of the environment, energy conservation and human health. This paper focuses on the application of acoustic and ultrasonic techniques for the detection and assessment of leaks, blockages and defect in buried pipes. The review includes acoustic methods (below 20 kHz) based on vibration sensing using accelerometers, hydrophones

Since the outbreak of the COVID-19 pandemic, as a result of the adoption of worldwide lockdown measures, the home environment has become the place where all the daily activities are taking place for many people. In these changed social and acoustical contexts, we wanted to evaluate the perception of the indoor acoustic environment in relation to traditional and new activities performed at home, i.e

Amplitude modulation (AM) is a characteristic feature of wind farm noise and has the potential to contribute to annoyance and sleep disturbance. Detection, quantification and characterisation of AM is relevant for regulatory bodies that seek to reduce adverse impacts of wind farm noise and for researchers and wind farm developers that aim to understand and account for this phenomenon. We here present

Microperforated panel (MPP) absorber progress has continued with various configurations for a relatively narrow bandwidth. Serial, parallel, and a combination of serial and parallel (hybrid) configurations of MPPs have been proposed to address the bandwidth problem, and experimental results agree well with theoretical ones. However, considerable space is still required, particularly at low frequencies

This paper presents a double-differential coded M-ary direct sequence spread spectrum (DD-MSS) underwater acoustic communication system to overcome problems of both low signal-to-noise ratio and severe Doppler effect. The system is very efficient in the challenging band-limited underwater acoustic channel and has many applications, particularly in which the transmitter and the receiver are mobile.

The slamming acoustic of a vehicle door is objectively not associated to the inherent character of the automobile however it is associated to the inherent structure of the vehicle door, which is an vital subjective performance to evaluate the vehicle. Vehicle exterior noise is the air borne noise created by this structural vibration in the slamming event. This paper investigates the effect of discretized

This paper describes a duct mounted with multiple hybrid Helmholtz resonators (HHRs) for low-frequency noise control in a piping system. The newly designed HHR is composed of a cavity and a connective neck with a coupling membrane and a perforated plate. Based on the transfer matrix method and equivalent mass-spring model of the membrane, the acoustic impedance of the HHR can be obtained. Sound radiation

Development of methodologies for the auralization of moving cars can be of great value for a virtual acoustic experience of urban areas. In this paper1 a methodology for the auralization of car pass-by based on measured binaural impulse responses (BIRs) is presented. Measured BIRs for different locations in a street canyon were convolved with dry synthesized car signals in which cross-fade windows

Voice-controlled systems (VCSs), a new class of cyber-physical systems (CPS), and Internet of Things (IoT) devices are increasingly employing smart speakers such as Google Home and Amazon Alexa, and other voice assistants to enable management of various remote operations at home and offices. However, these smart speakers and hence VCSs are susceptible to various voice spoofing attacks i.e. replay,

Acoustic signals passing through a material gather a great deal of analytical information. Such information act as a signature for classification of the materials. Therefore, the paper proposes a novel method for classification of oils by extracting spectral features from acoustic signals. A developed acoustic resonance spectrometry system has been used for the acquisition of acoustic signals from

Water hydraulic axial piston pump (WHAPP) is widely used in underwater vehicles. The noise and vibration of WHAPP are important for the concealment of underwater vehicles. In some hydraulic system, the oil and water inevitably permeate each other, resulting in changes of working medium characteristics and the vibration and noise of the WHAPP. In this study, the effect of working medium on the noise

Bionic camouflage covert underwater acoustic communication technology is playing an increasingly important role in the covert transmission of underwater information. Most cetaceans are group-living animals, and multiple cetaceans often appear in a specific ocean area at the same time. As a result, different cetacean individuals may generate whistles and clicks simultaneously, and the overlapping of

The average sound absorption coefficient of a composite absorber from 0 to 1.6 kHz was maximized using a teaching–learning-based optimization algorithm, where the geometric parameters were used as optimization variables. The effective-medium model and transfer-matrix method were used to calculate the sound absorption coefficient, and optimized sound absorption coefficient was maximized at 0.938. The

This paper describes the designing and optimization of tonpilz type transducers based on number of layers, width and thicknesses and type of active materials, dimensions of head and tail mass by exploiting finite element models for their effective and optimized usage in underwater SONAR applications. Geometry parameters of tonpilz transducers have been studied in terms of active piezoelectric stack

Railway acoustic problems commonly have a constant cross-section and uniform properties in the longitudinal direction. To solve such 3D acoustic problems with reduced effort, a wavenumber domain acoustic finite element (2.5D acoustic FE) method is introduced in which the cross-section of the domain is meshed and the third dimension is represented by a wavenumber transform. The acoustic wavenumber is

The last decades have seen the rapid development of laser ultrasonic (LU) techniques for remote inspection for composite structures. However, it is still challenging for current LU approaches to characterize the sub-mm layers in a multilayer structure. This study aims to apply the all-optical (AO) LU technique for the characterization of the sub-mm layers in a multilayer structure. A specific AOLU

High-resolution CLEAN-SC (HR-CLEAN-SC) with spherical microphone arrays is a promising technology for panoramic sound source identification. To further enhance the ability to resolve multiple closely spaced sources at low frequencies, filter-and-sum based HR-CLEAN-SC is proposed in this paper. Simulations and experiments demonstrate that the proposed approach is superior to the existing spherical harmonics

The detection of cavitation formation in hydraulic turbomachinery has been widely investigated due to its significant impact on their steady and dynamic operation. The aim of this study is the application of Spectral Kurtosis tool in order to effectively detect the impulsive shock waves generated during the implosion of vapour bubbles. The methodology is applied and evaluated on the vibration signals

Temporomandibular Joint sounds are a very common disorder in the general population. Temporomandibular Disorder (TMD) is any discomfort related to Temporomandibular Joint (TMJ). In this paper, a novel decision support system based on deep learning and neural network algorithms for diagnosis of Temporomandibular Joint disorder is introduced. A non-invasive device is designed for the recording of TMJ

Automatic language identification (LID) is the practice of detecting the language through linguistic content of speech spoken by certain anonymous speaker. In multi-lingual based Indian society, the capability to identify and classify a spoken language is an imperative task. In this work, convolutional neural network (CNN) based bidirectional long short-term memory (BiLSTM) model has been proposed

For an imaging sonar mounted onto a small sonar carrier (e.g., unmanned underwater vehicles), the angular resolution is strictly restricted by the limited physical size. To solve the problem, we propose a high-resolution imaging approach utilizing a multiple-input multiple-output (MIMO) sonar. The MIMO sonar is composed of two transmitting transducers and a receiving uniform linear array (ULA). The

Assessing the emotional impact that sounds have on individuals is of fundamental importance. In fact, individuals might choose a particular environment, such as a square or a green urban park, by also considering how positively or negatively the acoustic characteristics of that environment make them feel. However, at the moment, no questionnaire allows to reliably and clearly assess the emotional salience

It is generally alleged that the design choices of acoustic guitar bracing patterns lead to a specific sound of the instrument. However, in the presence of strong uncertainties due to variability of material properties and climatic conditions, the robustness of the soundboard dynamics has yet to be investigated. In this study, three types of bracing patterns are studied using physics-based models and

Ultrasonic array modelling is widely used to understand the performance of new transducer materials or geometries in a range of application scenarios. However, array modelling from first principles is both time-consuming and challenging due to the required knowledge of accurate acoustic and piezoelectric properties. This paper presents an alternative approach in which two elements are manufactured

In this paper, a novel approach, which is based on attention guided 3D convolutional neural networks (CNN)-long short-term memory (LSTM) model, is proposed for speech based emotion recognition. The proposed attention guided 3D CNN-LSTM model is trained in end-to-end fashion. The input speech signals are initially resampled and pre-processed for noise removing and emphasizing the high frequencies. Then

With a view to completing the fault diagnosis of rotating machinery efficiently and accurately, this paper presents a novel fault diagnosis model that combines multivariate hierarchical multiscale fluctuation dispersion entropy (MHMFDE), multi-cluster feature selection (MCFS) and gray wolf optimization-based kernel extreme learning machine(GWO-KELM). Firstly, MHMFDE is presented to capture the high-dimensional

The acoustic modelling of fibrous materials is fundamental for the design of a sound-absorbing acoustic treatment. Several analytical formulas have been proposed to calculate the acoustic performance of materials made of fibres with a homogeneous diameter and a mono, bi, or three-dimensional distribution, while only a few studies have been carried out on materials made up of a mixture of fibres with

An omnidirectional parametric loudspeaker (OPL) is a sound source that is made of hundreds of ultrasonic piezoelectric transducers set on a sphere. Relying on the parametric acoustic array (PAA) phenomenon, each transducer emits an ultrasonic carrier beam modulated by an audible signal. Thanks to non-linear propagation in air, natural demodulation takes place and focused audible beams are obtained

Heat exchangers can be found in a large number of technical systems and installations. They are usually operated in combination with other machines, such as axial fans, in order to remove or supply heat to a system. The heat exchanger can influence the existing flow field and thus lead to increased noise emission from fans located downstream of the heat exchanger. This can be observed, for example

In this study, an acoustic structure consisting of cellular and perforated panel absorbers has been designed to noise control. Then, the sound absorption behaviour of designed acoustic structure has been investigated experimentally by reinforcing with STFs having different rheological properties. In addition, the sound absorption performance of the designed acoustic structure has been compared with

The ISO 3382-3 standard (2012) defines single number quantities (SNQs) which evaluate the acoustic quality of open-plan offices, but does not address the issue of measurement uncertainties. This study focusses on the SNQs present in this standard related to spatial decay of speech, i.e. D2S, LpAS4m and rc. The aim is to provide additional information to the limited literature on the measurement uncertainties

The transfer matrix method (TMM) is a common method for the modelling of acoustical systems. Traditionally, this method requires each unique layer within a system to be defined by a transfer matrix and then for each matrix to be multiplied together in the sequential order of the system. Whilst the resulting matrix can be used to find the effective material properties of the modelled system, the resulting

This work aimed to develop an aeroacoustics analysis of a nose landing gear through rational and low-cost wind tunnel tests to develop potential noise mitigation technologies of aircraft components. This approach led to using a nose landing gear model of the Boeing 777 aircraft, whose more complex parts were 3D-printed. The aeroacoustics and aerodynamics tests were performed in a hard-wall wind tunnel

The scope of this paper is to investigate the sound transmission loss of a typical fuselage panel section, as well as to propose solutions based on the inclusion of a periodic pattern inside its foam core, which aim at passively improving the acoustic performance in a mid-high range of frequencies. In detail, a new fuselage panel configuration is numerically studied, starting from the state of the

Currently, traditional feature extraction algorithms have poor data expression and noise robustness. Moreover, traditional recognition methods are gradually falling behind the demand for increasing data, and struggle to extract deep features in targets. By considering the preceding issues, an integrated neural network has been created in this paper for underwater acoustic target recognition via feature

We hereby report on the incorporation of negative stiffness oscillators realized through Euler buckled beams within vibrating multilayered sandwich structures. Such devices have been extensively investigated as single degree of freedom isolation mechanisms when mechanical grounding is available. It is worth exploring the influences of implementing such mechanisms within continuous multilayered vibrating

An iterative approach is presented that couples the inhomogeneous Helmholtz equation with transform domain active noise control algorithms. The Boundary Element Method is utilized to provide solutions of the inhomogeneous Helmholtz equations for three dimensional pressure wave fields. The source terms in the inhomogeneous Helmholtz equations are adapted iteratively by the algorithm to achieve convergence

Based on the cellular automata (CA) method and the principle of wave superposition, this study examines a computational technique to analyze the sound radiation characteristics of arbitrary shape structures. The local evolution rule of the one-dimensional (1D) CA model of Y-function was derived from the acoustic wave equation in spherical coordinate, and the relationship between Y-function and sound

Recently, excellent performance has been achieved in Acoustic Scene Classification (ASC) by using Convolutional Neural Networks (CNNs) and Mel spectrogram feature representations. The utilization of Mel spectrogram feature is attracting increasing attention for its effectiveness in improving the performance. In this paper, Gradient-weighted Class Activation Mapping (Grad-CAM), a CNN visualization technique

Based on wave theory, the propagation equations of sound waves in single layer and multilayer media are established. In the traditional multi-layered structure and the microfiber multi-layered structure, the sound transmission characteristics of air in the middle and the back are analyzed by numerical simulation and acoustic parameter experiment. The effects of bending, viscous characteristic length

Construction site noise is the most significant cause of noise disputes in South Korea. We conducted an annoyance evaluation to produce annoyance prediction models for four kinds of construction noise that cause the most complaints, namely construction machinery noise from pile drivers, excavators, and concrete pumping vehicles and noise from concrete mold removal working. We adjusted these four noises

This paper presents a multiple sub-filter-based improved nonlinear acoustic echo cancellation (NAEC) framework to enhance the echo cancellation performance of the NAEC in the presence of nonlinear distortion. The proposed algorithm uses a novel combination of adaptive multiple sub-filter approach and proportionate filtering to enhance the convergence rate of the existing proportionate functional link-based

This paper explores the advantages of combining asynchronous microphone array measurements for acoustic source mapping in two and three–dimensional applications. Four different approaches are considered, three consisting of the combination of the source maps (arithmetic mean, geometric mean, and minimum value), and a fourth one obtained by combining the cross–spectral matrices of all the asynchronous