Journal of the Acoustical Society of America最新文献

The new generation of non-hydrostatic and compressible numerical models of the ocean can explicitly simulate acoustic waves when and where space and time resolution is adapted. We show that these models can consequently propagate accurately acoustic waves and modes through a free-surface, stratified ocean evolving simultaneously both in space and time, bringing them to the state of the art of acoustic propagation modelling. To some extent, both numerical cost and memory footprint may temper their range of applications but they are an unprecedented tool to evaluate deterministically the effects of ocean variability on low-frequency acoustic propagation in a realistically-evolving ocean. This potential is illustrated by two examples of three-dimensional propagation: the wedge benchmark and Kelvin-Helmholtz instabilities.

During its propagation, a shock wave may come across and interact with different perturbations, including acoustical waves. While this issue has been the subject of many studies, the particular acoustic-acoustic interaction between a weak shock and a sound wave has been very scarcely investigated. Here, a theory describing the encounter of those two waves is developed, up to second- and third-order. According to the incidence angle and shock strength, several regimes of acoustic transmission through the shock are identified. The generation of entropy as well as vorticity modes are determined, while the perturbation of the shock front by the acoustic wave is quantified. The theory predicts strongly different behaviors between air and water, and preliminary results are coherent with recent experimental observations in solids. It paves the way to both an acoustic monitoring of shock wave as well as a method to determine the quadratic and cubic nonlinear parameters of material.

Subjective factors of music have been proven to significantly influence the effect of music masking, while the neural mechanism of music masking is unknown. This study aims to explore the neural mechanism by which music masking improves subjective perception of noise in the population. A total of 40 healthy subjects were recruited for both the subjective evaluation and functional near-infrared spectroscopy scanning during music masking of hospital noise. Annoyance reduction percentage (ARP), likability, familiarity, and brain response data were collected and analyzed. The results showed that the increasing of ARP and likability was significantly correlated with the activation of the bilateral dorsal-lateral superior frontal gyrus (DLPFC) and the orbital middle frontal gyrus (OFC), while the improvement of familiarity significantly activated the triangular inferior frontal gyrus, supramarginal gyrus, and middle temporal gyrus. The repeatedly activated channels located in DLPFC and OFC indicate that likability may play a key role in reducing annoyance through music masking. This study provides a scientific basis for the selection of masking music future noise management in hospitals.

The fundamental frequency (fo) is pivotal for quantifying vocal-fold characteristics. However, the accuracy of fo estimation in hoarse voices is notably low, and no definitive algorithm for fo estimation has been previously established. In this study, we introduce an algorithm named, "Spectral-based fo Estimator Emphasized by Domination and Sequence (SFEEDS)," which enhances the spectrum method and conducted comparative analyses with conventional estimation methods. We analyzed 454 voice samples and used conventional methods and SFEEDS to calculate fo. The ground truth of fo was determined as the lowest frequency within the most dominant harmonic complex observed on the spectrogram. Subsequently, we assessed the concordance between each fo-estimation method and the fo ground truth. We also examined the variations in the accuracy of these methods when analyzing speech with hoarseness. Regardless of hoarseness, the fo-estimation accuracy was significantly greater by SFEEDS than by conventional methods. Moreover, whereas the conventional methods impaired fo-estimation accuracy in samples with roughness, the SFEEDS algorithm was robust and significantly reduced subharmonic errors. The SFEEDS fo-estimation algorithm accurately estimated the fo of both normal and hoarse voices.

Acoustic microscopy uses ultra-high frequency (UHF) ultrasound transducers over 80 MHz to perform high-resolution imaging. The pressure output of these transducers is unknown, as commercial calibrated hydrophones can measure pressure for transducers with frequencies only up to 80 MHz. This study used gas vesicle nanostructures (GVs) that collapse at 571 kPa to estimate the pressure of UHF transducers at 40, 80, 200, and 375 MHz. Agarose phantoms containing GVs were made, and a baseline ultrasound image was performed at low pressure to prevent GV collapse. Sections within the phantom were scanned at varying voltage to determine the GV collapse threshold. The pressure at full driving voltage was then calculated, assuming a linear relation between transducer voltage and pressure. The pressure calculated for the 40 MHz transducer was 2.2 ± 0.1 MPa at 21 °C. Using a hydrophone, the measured pressure was 2.1 ± 0.3 MPa, a difference of <2%, validating the method at this frequency. The pressure calculated for the other transducers was 2.0 ± 0.1 MPa (80 MHz), 1.2 ± 0.1 (200 MHz), and 1.05 ± 0.17 (375 MHz at 37 °C). This study addresses the challenge of estimating pressure output from UHF ultrasound transducers, demonstrating that the pressure output in the 40-400 MHz frequency range can be quantified.

Given the substantial time and complexity involved in the perceptual evaluation of head-related transfer function (HRTF) processing, there is considerable value in adopting numerical assessment. Although many numerical methods have been introduced in recent years, monaural spectral distance metrics such as log-spectral distortion (LSD) remain widely used despite their significant limitations. In this study, listening tests were conducted to investigate the correlation between LSD and the auditory perception of HRTFs. By distorting the magnitude spectra of HRTFs across 32 spatial directions at six levels of LSD, the perceived spatial and timbral attributes of these distorted HRTFs were measured. The results revealed the limitations of LSD in adequately assessing HRTFs' perception performance. Based on the experimental results, a perceptually enhanced spectral distance metric for predicting HRTF quality has been developed, which processes HRTF data through spectral analysis, threshold discrimination, feature combination, binaural weighting, and perceptual outcome estimation. Compared to the currently available methods for assessing spectral differences of HRTFs, the proposed method exhibited superior performance in prediction error and correlation with actual perceptual results. The method holds potential for assessing the effectiveness of HRTF-related research, such as modeling and individualization.

The high electrical output performance of the phononic crystal (PnC)-based piezoelectric energy harvesting (PEH) system is of great research value in self-powered applications. This work presents the effect of incomplete line defect size on elastic wave energy localization and harvesting. The results show that for a given 7 × 5 supercell when the incomplete line defect reaches the second to sixth layer, the energy localization and harvesting performance show a changing trend of first increasing and then decreasing; when the incomplete line defect reaches the 4th, 5th, 3rd, 2nd, and 6th layers of the supercell, respectively, the performance of PEH systems shows a trend from large to small. Among them, when the incomplete line defect reaches the fourth layer of the supercell, the performance of the PEH system is optimal, and the maximum output voltage and the maximum output electric power are 22.54 V and 12.78 mW, respectively. This work provides valuable insights for improving the performance of PEH devices by using the PnC with incomplete line defects.

Zero-directional refraction phenomenon refers to the capability where waves do not undergo refraction at a material interface under specific conditions, which has broad potential applications, particularly in the fields of optics, acoustics, and phononics. Previous research of zero-directional refraction rely on the zero or equivalent-zero index of the material parameters, which is quite challenging to manipulate the zero-directional transport of waves. In this paper, based on the topological theory, we have constructed a pillared phononic crystal (PnC) plate structure with pseudospin topologically protected transport, enabling zero-directional refraction of elastic waves without using zero or equivalent-zero index of the material parameters. By initially adjusting the contraction and expansion of the pillared unit cell, a band inversion effect between pseudospin dipoles and quadrupoles is induced, thus leading to a topological phase transition of elastic wave. Combining the phase matching between topological interface and terminal medias, the elastic waves in pillared PnC plate can exhibit zero-directional refraction behavior. Finally, it was demonstrated that the phenomenon of zero-directional refraction exhibits robustness in the presence of cavities and bends, and different incident angles. This research result provides new insights for designing and manipulating the emission and directional antennas of elastic waves.

Deploying acoustic sensors on free-flying, long-living balloons helps to reach the areas not accessible with the traditional ground-based sensors, reduce flow noise, and improve characterization of various infrasound sources. Instrumented balloons can potentially increase the infrasonic detection range and early warning lead time for natural hazards. Balloons are also considered as platforms for planetary exploration. When assessing the capabilities of balloon-borne infrasonic sensors and interpreting the measurements, it is imperative to recognize that the balloon inevitably distorts the signals and background infrasound field by scattering the incoming sound. This paper quantifies the effects of hot-air and helium balloons on acoustic pressure and particle acceleration and the role of balloon skin in infrasound diffraction. It is found that balloon-borne vector sensors are more susceptible to distortions than pressure sensors, leading to major differences between the apparent and true source bearing and directionality.