Journal of the Acoustical Society of America最新文献

The study aimed to develop and validate remote hearing detection (audiogram) and discrimination (notched-noise) tests, which used Bayesian active-learning based Gaussian processes, as a binary discriminator between audible and inaudible sounds, and to choose the stimulus parameters. Forty-two participants (aged 48-75 years) performed the two tests remotely using their own equipment. The participants were recruited with pure-tone audiometry known a priori. The agreements between the true and estimated hearing thresholds were assessed using Bland-Altman plots and concordance correlation coefficients (CCC). The notched-noise test was used to derive auditory filter shape parameters, from which equivalent rectangular bandwidths (ERBs) were estimated. The ERBs were correlated with participants' hearing thresholds and compared to published data. The agreement between the true and estimated hearing thresholds ranged between poor and fair (CCC = 0.19 and 0.34), with an average bias (±limit of agreements) of 27.3 (±17.8) dB. This was attributed to the lack of calibration of the participants' equipment. The estimated ERBs followed the trend of published data and were significantly correlated with pure-tone audiometry at 1000 Hz (rs = 0.36). Our findings indicate that the remote detection and discrimination tests can collectively track the breakpoints, slopes of thresholds, and the width of auditory filters.

The measurement of sound absorption coefficients in a reverberation chamber often involves uncertainties owing to the insufficient diffusivity of the room sound field, which results from the low modal density at lower frequencies. This paper proposes a measurement method that uses damping density (DD) to address this problem. The DD treats the damping constants (DCs) at each frequency as a probability density function, and the DCs at each frequency are calculated from the room impulse response. A preliminary study showed that the proposed method yielded lower reverberation times (RTs) than conventional methods while maintaining measurement stability. Furthermore, the results confirmed that the proposed method successfully evaluated the initial decay characteristics. Measurements of 200 mm-thick urethane foam in an actual reverberation chamber demonstrated that the proposed method yielded intermediate RTs between early decay times and conventional RTs in the low-frequency range (below 315 Hz) under empty room conditions and achieved improved measurement stability across multiple measurement paths. The resulting sound absorption coefficients showed the smallest relative errors compared with the theoretical values in the 80-250 Hz range, except at 200 Hz.

Modulation statistics of "natural soundscapes" were estimated by calculating the modulation power spectrum (MPS) of a database of acoustic samples recorded in nine pristine terrestrial habitats for four moments of the day and two contrasting periods, differing in precipitation level. In particular, a set of statistics estimating low-pass quality, starriness, separability, asymmetry, modulation depth, and 1/ftα temporal-modulation power-law relationships were calculated from the MPS of the samples and related to geographical, meteorological factors and diel variations. MPS were found to be generally low-pass in shape in the modulation domain with most of their modulation power restricted to low temporal (<10-20 Hz) and spectral modulations (<0.5-1 cycle/kHz). Modulation statistics were distinguished between habitats irrespective of moment of the day and precipitation period with a greater role of modulation depth and starriness. Separability and starriness were found to be related to the global biodiversity decrease from tropical to polar regions, suggesting that the lack of joint high spectral and fast temporal modulations and MPS complexity are important features that may characterise "biophony," the collective sound produced by animals in a given habitat. These findings may help guide research on monitoring auditory behaviours and underlying mechanisms expected to exploit regularities of natural scenes.

Sound power is a fundamental characteristic of an acoustic source that is critical to developing radiation models. Current analytical methods for calculating sound power from a collection of monopoles either assume perfect coherence or incoherence. However, partially coherent sources are plentiful in structural acoustics and aeroacoustic applications. This paper expands the approach of Nelson, Curtis, Elliott, and Bullmore [(1987). J. Sound Vib. 116, 397-414], who calculated sound power due to mutual coupling between coherent sources, to allow for partially coherent interactions. This expression is used to find the sound power from quadrupole-like source configurations with varying degrees of coherence. When calculating the sound power, partially coherent interactions are limited by two factors: a coupling distance and the coherence length. A numerical example of a driven plate is used to demonstrate the regions where the partially coherent sound power is most applicable. It is shown that when the system coherence length is larger than about one wavelength, the sound power can be calculated assuming a fully coherent source. A final example is shown for the T-7A jet at MIL and AB engine conditions. Sound power spectra are created from an equivalent source model of partially coherent monopoles and compared to measured far-field spectra.

Beaked whales are elusive deep-diving odontocetes, and their distribution and foraging ecology remain poorly documented in Australian waters. This study presents a passive acoustic monitoring (PAM)-based assessment of beaked whale foraging activity along Australia's Northwest Shelf-a continental shelf region with features typically conducive to beaked whale sustenance. The area is also of economic significance due to ongoing offshore oil and gas production, commercial fishing, and commercial shipping, raising concerns about potential impacts on these deep-diving cetaceans. This study collected year-long underwater acoustic datasets from three deep-water sites in the region. Using a semi-automated workflow based on correlogram visualizations, the study identified beaked whale foraging buzzes-short, rapid echolocation click trains associated with prey capture attempts. Analyses revealed year-round foraging activity, with significantly higher levels at night, but no strong spatial or seasonal variations across the study area. These findings suggest persistent use of the region by beaked whales despite offshore industry presence, underscoring the ecological significance of these deep-water habitats. This study highlights the value of PAM, combined with efficient analytical approaches, for monitoring cryptic species in data-limited, industrialized marine environments.

This study investigates whether the visual color design of concert halls influences the room acoustic impression during musical performances. While previous research has failed to show effects on the perceived loudness and reverberance of music venues, the present audiovisual experiment explores the cross-modal impact of vision on a broader set of room acoustic properties, including timbre-related attributes such as brilliance, warmth, clarity, and roughness. For this purpose, 48 participants rated eight room acoustic attributes while listening to motion-tracked musical performances in virtual concert halls with systematically varied color schemes. Musical experience and expertise of the participants were assessed as moderating variables using the Goldsmiths Musical Sophistication Index. The results showed no significant effects of color on perceived loudness or reverberance, suggesting that these attributes remain predominantly unimodal. However, a significant visual influence was observed on the perceived acoustic "Warmth" and overall "Liking" of the performance. These effects were significantly moderated by the participants' musical experience. Thus, this study suggests that concert hall color design can affect auditory timbre perception through semantically mediated cross-modal interactions, highlighting the interplay between visual aesthetics and auditory experience during musical performances.

Research has acknowledged the substantial impact of short auditory training on performance enhancements, but the neural mechanisms involved are not fully understood. This study aimed to explore these mechanisms by examining the cortical effects of single-session speech-in-noise (SIN) training with spectrally degraded stimuli, using functional near-infrared spectroscopy (fNIRS). Twenty-four young adults with normal hearing participated in SIN training using noise-vocoded stimuli. Behavioral improvements were evaluated 1-3 days after training. fNIRS recordings were taken before training, 1-3 days after training, and again 1-3 days following the second evaluation, employing a pseudorandom block design with speech, noise, and SIN stimuli. Training led to significant improvements in SIN perception, accompanied by a non-significant trend toward reduced oxygenated blood beta values in the left middle temporal gyrus in response to the trained stimuli across training and testing sessions. This pattern is consistent with the possibility of cortical adaptation and increased neural efficiency during processing of degraded auditory input following brief training, with effects that appear to extend beyond the immediate training session. Further research is needed to determine whether similar short-term training approaches could benefit individuals with hearing or speech perception difficulties.

Thanks to recent advancements in distributed acoustic sensing (DAS) techniques, we can measure the time series of axial strains along an optical fiber at extremely dense spatial intervals. However, only a single component of a strain tensor is measured, and the partitioning of seismic energy into this component is unknown. In this study, we address this problem by formulating energy partitioning into different strain components for diffuse waves in a three-dimensional homogeneous isotropic half-space, building upon previous studies on energy partitioning into displacement components. We investigate how the contributions of both body and surface waves to the six independent components of a strain tensor change with depth. The results show that the horizontal normal strains, which surface DAS observation can measure, are primarily composed of shear horizontal-waves and Rayleigh waves at the free surface. The vertical normal strain, which borehole DAS observation can measure, is dominated by Rayleigh waves at the free surface. However, that contribution quickly decays within the depth of one shear wave-wavelength, and the shear vertical-wave contribution remains. This study serves as a reference for further extension to more realistic media, such as horizontally layered media, and opens a way to interpret the late coda of DAS strain seismograms quantitatively.

The Speech Intelligibility Index (SII) is a metric of the amount of information available in a degraded or masked speech signal. The SII is used to predict speech recognition outcomes and is part of hearing aid prescription formulae. A critical assumption in the calculation of the SII is that frequency bands contribute independently to speech recognition, i.e., the importance of a band does not change based on the context of speech cues in other bands. Prior work has challenged this assumption by demonstrating that pairs of bands can contain synergistic or redundant information. The present work extends these findings by directly measuring pairwise interactions between the 21 frequency bands defined by the Critical Band Procedure of the SII. Forty-one participants with normal hearing identified words filtered to contain pseudorandom combinations of four or five bands. Pairwise interactions indicated both synergy and redundancy and accounted for substantial variability in recognition accuracy. The importance of individual bands decreased when pairwise interactions were considered, with the largest decreases for frequency bands above 1 kHz. The spectral proximity and envelope correlation between pairs of bands predicted whether their combination was synergistic or redundant. Interactions between bands play a critical role in speech recognition.

Class III flextensional transducers have been widely used as low-frequency projectors, but their characteristics also make them promising candidates for broadband low-frequency hydrophone applications. In this study, we propose a design of Class III flextensional hydrophone featuring significant structural modifications to achieve wider receiving bandwidth and higher sensitivity in the low-frequency range. Traditional hydrophones often increase bandwidth by reducing size-a straightforward and effective approach. However, this comes at the cost of reduced receiving sensitivity, as sensitivity is generally proportional to the hydrophone's surface area. To overcome this limitation, we developed a wideband hydrophone design that maintains a similar physical size, thereby preserving high receiving sensitivity. We constructed finite element analysis models of the Class III flextensional hydrophone to investigate how various structural parameters influence its acoustic receiving characteristics. Based on the simulation results, we determined the optimal combination of the parameters to maximize bandwidth while keeping the first receiving-voltage-sensitivity peak within a specific frequency range. The designed hydrophone demonstrated a fractional bandwidth 2.51 times greater than that of the conventional model, while maintaining a comparable receiving voltage sensitivity level.