Journal of the Acoustical Society of America最新文献

Road traffic noise represents a major source of environmental pollution, and its prediction remains a critical task. This challenge particularly emerges when traffic data are not available, such as during the design phases of new infrastructures, where it becomes necessary to predict the noise exposure affecting nearby residents, even in the absence of measurement data. To address this issue, this work augments a previously developed microscopic and stochastic-core traffic noise model, integrating it with forecasting time series models for traffic flows and average vehicle speeds. This integration produces a hybrid model that enables the estimation of hourly traffic noise levels based solely on historical traffic patterns, even in the absence of direct traffic observations for the period under investigation. The methodology has been evaluated through a statistical analysis of simulated noise levels, with a focus on error distribution and conventional error metrics. The mean error of 0.43 dBA and the mean absolute error of 1.30 dBA confirm the accuracy of the proposed approach for estimating road traffic noise in data-scarce scenarios. A comparison with the CNOSSOS-EU model's performance highlights the possibility of using such methodology in early-stage infrastructure design and planning.

The noise problem associated with the introduction of urban air mobility (UAM) is a critical challenge that must be addressed. Currently, noise evaluation methods and standards for UAM are lacking. The present study, as an initial step towards establishing UAM noise evaluation criteria, aims to analyze the noise impact range based on actual UAM noise data and propose appropriate UAM noise measurement locations comparing them with existing aircraft noise measurement locations. Using soundplan software, the noise impact ranges of noise hemisphere were predicted within the K-UAM Grand Challenge. The results showed that the noise hemisphere exerted noise influence up to a horizontal radius of ∼400-600 m. Furthermore, appropriate UAM noise measurement locations for each region were proposed comparing the UAM noise impact assessment with existing aircraft noise measurement locations. The findings of the present study can be validated through the actual noise measurements during future UAM demonstrations and contribute to the development of UAM noise evaluation standards.

Using phononic crystals (PnCs) to enhance the electrical performance of piezoelectric energy harvesting (PEH) devices is an effective strategy for enabling self-powered operation in low-power electronic systems. Building on prior studies of PnCs with incomplete line defects, this study proposes a PnC with decoupled double incomplete line defects. In the upper (y-direction) subsystem, the defect was extended stepwise from the second to the sixth supercell layer, while the other subsystem was kept fixed, yielding five supercells. Their dispersion relations, elastic wave localization, and energy harvesting characteristics were systematically examined. All supercells exhibited effective decoupling between the two subsystems. As the size of defects in the upper subsystem increased, the total system's electrical performance first increased and then decreased. Specifically, when the defect extended to the fourth layer, the total system reached its optimum, yielding 17.58 mW of output electric power and representing a 349-fold improvement compared with conventional materials. Furthermore, because incomplete line defects induce waveguide-localized coupling modes, an efficient, tunable, relatively broad energy harvesting bandwidth of elastic waves was achieved by adjusting the subsystem's defect size. Therefore, a practical route is provided to optimize PEH electrical output and tune the operating frequency range through multi-defect PnC designs.

Listeners vary in their sensitivity to acoustic-phonetic variation. In this study, we explored different ways of measuring such sensitivity. Study 1 used a visual analogue scale (VAS) task that elicited ratings for a set of four phonetic continua. Study 2 used a two-alternative forced choice task with eye tracking, which provided both binary response data and fine-grained fixation data for the same phonetic continua as study 1. In both studies, we asked how patterns of phonetic perception changed over the course of the adult lifespan by comparing a younger adult sample (ages 18 - 25) to an older adult sample (age 50+). In addition, we conducted several assessments to examine how language skill, hearing acuity, and speech-in-noise perception were associated with individual differences in phonetic categorization. We found that older adults displayed more categorical (as opposed to more gradient) patterns of perception than younger adults, particularly in the VAS task, where age-related differences persisted even after controlling for hearing loss and speech-in-noise perception. There was also evidence of more categorical patterns of perception among older adults in the eye tracking measures. Overall, these data suggest that VAS tasks may be particularly sensitive to both age-related factors and differences in language skill.

Matched field processing (MFP) requires prior knowledge of the frequency for the source, which is often unknown, and must be estimated from the received signals. Extending conventional MFP, incoherent frequency-unknown matched field processing (FU-MFP) is presented by incorporating the inversion of transmission frequency and radial velocity. Motion compensation of the Doppler frequency shift is achieved through the inversion of the radial velocity, thereby extending the Fourier transform window. Coherent FU-MFP is studied by combining passive synthetic aperture processing, which provides robust estimation of frequency and radial velocity at low signal-to-noise ratio (SNR). The joint processing gain from synthetic aperture processing and motion compensation enables coherent FU-MFP to achieve localization by weak line spectrum signals, which are indistinguishable in low-frequency analysis and recording spectra or power spectra. Simulations and experimental results confirm the ability of FU-MFP to estimate source frequency and location in low SNR, significantly outperforming conventional MFP.

This study investigated the effect of interlanguage vocalic distance on the perception of English alveolar (/n/) and velar (/ŋ/) nasal codas by Chinese learners. The aim is to explore the context effect on cross-language similarity at the syllabic level. Forty participants completed two tasks: (1) a perceptual assimilation task (PAT), mapping vowel-nasal syllables to native language (L1) categories, and (2) a perceptual discrimination test (PDT), assessing their ability to distinguish /n/-/ŋ/ codas across vowel contexts. PAT results revealed uncategorized-categorized assimilation patterns in native-distant vowel contexts (/æ/, /ɛ/) and single-category patterns in native-adjacent contexts (/ɔ/, /ʌ/). PDT results showed significantly higher discrimination accuracy in native-distant than in native-adjacent vowel contexts. These findings confirm the context effect of interlanguage vocalic distance on L2 nasal perception. The alignment between PAT and PDT patterns supports the Perceptual Assimilation Model, while the enhanced discrimination in phonetically dissimilar contexts provides empirical support for the Speech Learning Model's prediction that greater L1-L2 dissimilarity facilitates new category formation. The study further suggests that L1-L2 phonetic similarity extends beyond individual segments and interacts with coarticulatory influences at the syllabic level, offering new insights for similarity-related L2 phonetic theories.

Ultrasound (US) imaging is essential for monitoring thermotherapies, but accurate simulation of heating-induced artifacts remains challenging. Conventional single-sound-path (SSP) models approximate thermal effects as a channel-independent axial shift, failing to reproduce thermo-acoustic lens (TAL) artifacts observed in thermotherapy experiments. This study proposes a physically realistic multi-sound-path (MSP) simulation framework that captures TAL artifacts arising from temperature-induced speed-of-sound inhomogeneity in array-based US imaging. Transient temperature fields are computed using an alternating direction implicit solver, and US images are reconstructed via delay-and-sum beamforming. Compared to SSP, the MSP model successfully reproduces characteristic TAL artifacts, including lateral resolution degradation (up to 52.0% increase in full width at half maximum) and speckle brightness reduction (up to 49.1%). When applied to speckle tracking and thermal strain imaging, MSP also reveals substantial decorrelation and displacement errors consistent with experimental observations. By providing a computationally efficient imaging simulation framework that avoids the prohibitive cost of full-wave solvers, the proposed framework is well-suited for large-scale parametric studies and evaluation of US-based thermometry and other speckle-based functional imaging methods.

This study numerically solves inhomogeneous Helmholtz equations modeling acoustic wave propagation in homogeneous and lossless, absorbing and dispersive, and inhomogeneous and nonlinear media. The traditional Born series (TBS) method has been employed to solve such equations. Simulated pressure field patterns for a linear array of acoustic sources (a line source) estimated by the TBS procedure exhibit excellent agreement with that of a standard time domain approach (the k-wave toolbox). For instance, the maximum absolute error of normalized pressure amplitude made by the proposed technique for the homogeneous and lossless medium is ≈2% with respect to the latter method. The TBS scheme, though iterative, is a very fast method. For example, the graphics processing unit (GPU)-enabled cuda c code implementing the TBS procedure for calculating the pressure field for the homogeneous and lossless medium is 102× faster than the k-wave module and also 4× faster than the corresponding central processing unit C code for the computational domain considered in this study (4096×4096). The findings of this study demonstrate the effectiveness of the TBS method for solving inhomogeneous Helmholtz equation, while the GPU-based implementation significantly reduces the computation time. In this work, the capability and performance of the method have been tested in two dimensions only.

Sound field reproduction uses multiple loudspeakers to create a desired sound field within a target area. The placement of the secondary sources is a particularly critical factor influencing reproduction performance. Iterative optimization is a common class of placement optimization methods, but existing methods tend to either only select or only remove secondary sources unidirectionally. This characteristic often causes the search-algorithm to get stuck in a local optimum. This study proposes a secondary source placement optimization method based on bidirectional stepwise iteration. In each iteration, the proposed method first selects the two loudspeakers from the candidate set with the highest contribution to sound reproduction to become secondary sources. It then removes the secondary source with the lowest contribution from the entire set of selected sources and returns it to the candidate set. The proposed method was validated by simulations and a public experimental dataset. Results show that this method is less likely to get stuck in a local optimum compared to unidirectional iterative optimization methods, thus achieving better performance. This study also explores how factors like the number of secondary sources and room reverberation affect the performance and compares the computational complexity of our method with that of unidirectional optimization methods.

Near-linear arrays are widely used in the direction of arrival estimation. However, because if their cylindrical symmetry, port/starboard discrimination (PSD) remains a challenge. This paper introduces an adaptive loop gain CLEAN algorithm based on spatial source coherence (A-CLEAN-SC) to address the PSD problem and detect weak targets obscured by interference-induced mirror artifacts. The detection probability and the false alarm probability are formulated as functions of the loop gain, and the loop gain is adaptively determined by maximizing the difference between the detection probability and the false alarm probability. Simulations and experiments demonstrate that A-CLEAN-SC achieves a superior trade-off between mirror suppression and weak targets detectability compared to other methods (minimum variance distortionless response, blind source separation-port/starboard discrimination, CLEAN, and CLEAN based on spatial source coherence), particularly under steering vector mismatch conditions in near-linear arrays.