Showing papers in "Applied Acoustics in 2015"

TL;DR: In this article, a mathematical analysis to select the most significant intrinsic mode functions (IMFs) is presented, and the chosen features are used to train an artificial neural network (ANN) to classify bearing defects.

TL;DR: In this article, a modular-based green wall was evaluated for noise attenuation and the main results were a weighted sound reduction index (Rw) of 15 dB and a weighted acoustic absorption coefficient (α) of 0.40.

TL;DR: In this paper, the authors present a review of ways of reducing surface transport noise by natural means, which can be easily (visually) incorporated in the landscape or help with greening the (sub)urban environment.

TL;DR: In this paper, the authors investigated the impact of soundscapes on physiological measures obtained after a stressor or a period of rest, and found that autonomic function during stress recovery and at rest can be influenced by subjective response to the acoustic environment.

TL;DR: In this article, a Bayesian solution is proposed that consists either in directly finding the most probable value of the regularization parameter or, indirectly, in estimating it as the ratio of the most likely values of the noise and source expected energies.

TL;DR: The accuracy of the developed algorithm is validated by conducting a traffic noise monitoring experiment in several districts of Guangzhou with different road types and the results show that the average error between the estimated and measured values is below 2.0 dB.

TL;DR: In this paper, the authors proposed an envelope analysis method for bearing incipient defect detection, which is able to identify localized defects in an incipient stage, in which the signal-to-noise ratio (SNR) is extremely low.

TL;DR: This work proposes a method for bird acoustic activity detection, based on morphological filtering of the spectrogram seen as an image, validated on the automated acoustic recognition of Southern Lapwing Vanellus chilensis, a common Neotropical bird species.

TL;DR: In this paper, the authors investigated the effect of multiple indentations of power-law profile on the radiated sound power of a rectangular plate and showed that the resulting reduction of vibration response over the plate is large enough to cause a substantial reduction in the resulting sound radiation from plates containing indentations.

TL;DR: In this paper, a micro-perforated panel with mechanical impedance plates (MIP) is proposed to enhance the performance of low-frequency sound absorption, where conventional MPP absorbers cannot provide sufficient absorption in the case that the backed cavity is limited.

TL;DR: In this article, a logistic regression model was considered to study the relationship between the objective acoustic indices mentioned above and the subjective descriptions of the urban soundscapes, and a significant correlation between the perception of a soundscape as very unpleasant and the four objective indices considered for its acoustic characterization is found.

TL;DR: In this article, an Acoustic Emission (AE) testing method was presented to monitor the process of the single-particle fragmentation. But the results showed that AE activity was relatively low at first, followed by an inactive period, and the AE signals tended to be significant active and exhibited a clustering of high frequency AEs before the impending fracture failure.

TL;DR: In this paper, the authors compared the acoustics of four different Kindergarten classrooms: an enclosed classroom with 25 students, a double classroom with 44 students and a linear fully open plan triple classroom with 91 students, and a semi-open plan K-6 classroom with 205 students.

TL;DR: In this paper, a robust system of filters has been proposed for both the class of signals captured from geared and bearing systems for a wide range of faults in a rotary system.

TL;DR: In this paper, the authors examined the effect of visual landscape factors on the acoustic comfort of 11 types of sounds, including music-related and melodic characteristics, in an ecological waterscape.

TL;DR: In this article, the authors evaluated the performance of the LEOPOLDO road surface in terms of spatial homogeneity, a good time stability and a significant reduction in noise emission.

TL;DR: In this paper, a proper intelligent approach for fault diagnosis of spark plug in an IC engine based on acoustic and vibration signals using sensor fusion and classifier combination was developed for removing the signal noises.

TL;DR: In this article, the impact of elastic parameter uncertainty on the natural frequency and the radiated acoustic power of laminated composite plates is investigated, and a non-intrusive collocation based method is conducted in order to calculate the deterministic polynomial chaos coefficients of the natural frequencies and the acoustic power density.

TL;DR: In this article, a topology-optimization-based muffler design method for a reactive muffler is proposed and experimentally validated, and a partition-volume-minimization problem achieving target transmission loss values is formulated by using acoustical topology optimization.

TL;DR: Both kNN and SVM classifiers achieved the highest accuracy rates by the proposed PR feature set in age + gender and age classifications, and low classification accuracies are observed for young male speakers.

TL;DR: In this article, the effect of adding man-made sounds to the soundscape was shown to seriously degrade perceived tranquillity though ratings of wildness were not nearly as affected.

TL;DR: In this paper, the authors used the change in phase between the incident and reflected acoustic signals caused by a blockage, as well as the difference in the amplitude of each pulse, to generate two independent equations from which the area ratio and the length of the blockage may be recovered.

TL;DR: In this paper, a sound metric based on the Wigner-Ville distribution (SMWVD) was developed to investigate the relationship between subjective evaluations and vehicle suspension shock absorber rattling noise, which substantially affects passengers' psychological and physiological perceptions.

TL;DR: There are differences in the resulted noise levels when the intersection is detailed and these differences may affect the measures that can be undertaken by the local authorities for noise abatement.

TL;DR: In this paper, a full-scale field measurement of the acoustical insertion loss of plenum windows was carried out in the present investigation, and two identical mock-up test rooms with dimensions the same as those commonly adopted for Hong Kong public housing were built side-by-side next to a busy trunk road.

TL;DR: Some results illustrated in this work indicate that the PSO is a very appealing method for situations where there are multiple solutions or when the number of design variables is large.

TL;DR: In this paper, a flexible micro-perforated panel absorber based on Polyvinylidene fluoride (PVDF) piezoelectric film is proposed, which is composed of a perforated aluminum-electrode PVDF and a small air cavity.

TL;DR: In this article, ensemble empirical mode decomposition (EEMD), robust independent component analysis (RobustICA), and continuous wavelet transform (CWT) are applied to study the blind source separation and noise source identification of gasoline engine after the signal is decomposed with EEMD into a set of intrinsic mode function (IMFs), RobustICA has been applied to extract independent sources.

TL;DR: In this paper, a vehicle/slab track interaction model is developed based on vehicle-track coupling dynamics theory, and composite track elements are used to rapidly model the finite element equations of the slab track based on the stationary value theory of total potential energy.

TL;DR: In this article, the authors used the Johnson-Champoux-Allard (JCA) model to predict sound velocities at high frequency using measured non-acoustical physical parameters (tortuosity, viscous characteristic length, thermal characteristic length and porosity and flow resistivity).