Journal of the Acoustical Society of America最新文献

Accurately characterizing bone properties using quantitative ultrasound remains a significant challenge due to the dispersive nature of guided waves, limited observations, irregularity of bone structure, and heterogeneity of bone tissues. In this paper, an inversion technique is proposed that combines weighted mean absolute criteria and the simulated annealing algorithm to extract the thicknesses and elastic properties of a bilayer bone model. By utilizing the L1 norm with an appropriate weighting parameter, this method effectively reduces the influence of outliers and noises commonly encountered in ultrasonic data, leading to more accurate estimation. This paper also introduces an asymptotic scheme to significantly reduce the search domain, improving the speed and precision of the inversion process. This approach employs a spectral collocation method as a forward modeling technique to simulate guided waves in a bone plate coated by a soft tissue layer. This paper validates the inversion using simulated and ex vivo data and demonstrates its ability to estimate features of cortical bone and soft tissue with high accuracy. Results are presented for the isotropic model. These findings hold great promise for the accurate characterization of bone properties using quantitative ultrasound, with potential applications in clinical diagnosis and treatment of bone-related diseases and injuries.

Although air sinuses are prevalent in odontocetes and are an integral component of their sound reception system, the acoustic function of these air-filled structures remains largely unknown. To address this, we developed a numerical model using computed tomography data from a Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) to investigate the role of the air sinuses in sound reception. By comparing sound reception characteristics between model cases with and without the air sinuses, we found that the air sinuses improved sound reception directivity. Across frequencies from 1 to 100 kHz, the directivity indexes for cases with and without the air sinuses ranged from 0.35 to 5.64 dB and 0.23 to 4.12 dB, respectively. Additionally, the air sinuses increased amplitude differences in received sounds, with maximum values of 2.05, 2.78, and -2.38 dB for the front-to-behind, ipsilateral-to-contralateral, and top-to-bottom aspects, respectively. These results indicate that the air sinuses effectively provided acoustic isolation for the bony ear complexes from the behind, contralateral, and top aspects, thereby enhancing asymmetric sound reception dominated by the front, ipsilateral, and bottom aspects. This study contributes to a deeper understanding of odontocete sound reception and sheds light on the significant role of the air sinuses in this context.

Profile-analysis experiments measure the ability to discriminate complex sounds based on patterns, or profiles, in their amplitude spectra. Studies of profile analysis have focused on normal-hearing listeners and target frequencies near 1 kHz. To provide more insight into underlying mechanisms, we studied profile analysis over a large target frequency range (0.5-4 kHz) and in listeners with both normal and elevated audiometric thresholds. We found that profile analysis degrades at high frequencies and that the effect of spacing between nearby frequency components differs with frequency. Consistent with prior reports, elevated audiometric thresholds were not associated with impaired performance when stimuli consisted of few distantly spaced frequency components. However, elevated audiometric thresholds were associated with elevated profile-analysis thresholds for stimuli composed of many closely spaced frequency components. Behavioral thresholds from listeners with and without hearing loss were predicted by decoding firing rates from simulated auditory-nerve fibers or simulated modulation-sensitive inferior-colliculus neurons. Although responses from both model stages informed some aspects of the behavioral data, only population decoding of inferior-colliculus responses accounted for the worsening of profile-analysis thresholds at high target frequencies. Collectively, these results suggest that profile analysis involves multiple non-peripheral factors, including multichannel comparisons and midbrain tuning to amplitude modulation.

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.