Journal of the Acoustical Society of America最新文献

The sound radiation of vibrating surfaces can be calculated using integral-based numerical methods. Due to the increasing discretization requirements, the computational effort increases significantly with increasing frequencies. Therefore, approximation methods with less computational effort are desirable. This paper introduces a method called the plane projection Rayleigh integral (PPRI), which combines low computational effort with high precision. The method approximates the sound radiation by applying the Rayleigh integral to a vibrating virtual plane representing the object in two dimensions. The method's performance is evaluated by comparing it to the visible element Rayleigh integral and the high frequency boundary element method (HFBEM), focusing on the accuracy and its dependence on radius of surface curvature, sound frequency, and distance from the surface. Analytical solutions for the breathing and oscillating sphere are used as benchmarks. The PPRI demonstrates the highest accuracy among the methods tested. Error values decrease significantly with larger radii and higher frequencies, falling below a 1% threshold at 4 times smaller Helmholtz numbers (radius-wavelength ratio) than the HFBEM. Additionally, the PPRI requires the least computational time in this consideration. Thus, the PPRI achieves both high precision and efficiency.

The distribution of perceptual attention across the myriad acoustic properties of speech undergoes developmental shifts through the first decade of life, changing from a focus on dynamic spectral structure to other kinds of temporal, amplitude, and static spectral properties. These developmental changes accompany a gradual enhancement in sensitivity to phonological structure. A central question concerning spoken language acquisition by children with hearing loss who use cochlear implants (CIs) concerns how they navigate these developmental changes and what effect signal degradation has on developing language abilities, especially sensitivity to phonological structure. To explore these questions, this report describes outcomes of data collected from adolescents with normal hearing and adolescents with CIs. Perceptual weighting factors were computed for static and dynamic spectral properties using a fricative-vowel labeling paradigm. Measures of speech recognition, language abilities, word reading, and phonological processing were also obtained. Results showed that the adolescents with CIs weighted dynamic spectral structure hardly at all. Weighting of static spectral structure was largely related to their abilities to manipulate and retain phonological structure in memory. Overall, these findings indicate that supporting developmental shifts in perceptual weighting strategies should remain a goal of intervention for children with hearing loss who use CIs.

Bone conduction (BC) transducers applied to skin-covered areas of the head differ in their positioning, contact area, and static force, all of which influence output characteristics. This study assesses the mechanical impedance of the skin-covered head under varying conditions. Measurements were conducted on 30 participants at 3 positions, earfront, forehead, and mastoid, using circular interfaces with diameters of 10, 15, and 25 mm, and 6 static forces ranging from 0.5 to 7 N. Results showed that mechanical impedance was stiffness-controlled below the resonance frequency and mass-controlled above it. Low-frequency impedance depended on position and static force, with the forehead producing the highest impedance magnitude and the earfront producing the lowest impedance magnitude. At high frequencies, impedance across positions was similar, except for the mastoid with 25 mm interface. Impedance magnitude increased with interface area below 350 Hz and above resonance frequency. These findings highlight an impedance mismatch between standard artificial mastoids and human mastoids, potentially leading to inaccurate force estimations in BC devices. Additionally, three-element and six-element lumped mechanical models for the earfront, forehead, and mastoid were developed, with parameter values as function of contact area and static force.

This paper proposes a single-carrier multiuser (MU) receiver for MU underwater acoustic communications with time-varying and strong multiple-access interference. The receiver integrates soft successive interference cancellation, successive weight update sparse Bayesian learning channel estimation based on approximate message passing (SWUSBL-AMP), and an improved channel update decision. After the first iteration, the improved channel update decision first estimates the channel of each subblock using the interference-cancelled signals from the previous iteration, avoiding the mismatch of time-varying channels. By running the factor graph serially, the SWUSBL-AMP channel estimation algorithm enables the factor graph of the current subblock to utilize the messages updated by the previous subblock, and update the correlation weighting factors, to accelerate the convergence speed and further improve the channel estimation accuracy. Using the experimental data collected in the South China Sea in 2023 for processing, the results demonstrate that the bit error rate performance of the proposed receiver is better than that of other receivers of the same type. Moreover, we also verify the complexity of the proposed SWUSBL-AMP algorithm can be nearly an order of magnitude lower than that of other algorithms.

This study introduces the concept of activity-based acoustic situations in primary schools, which describe the everyday sound environment in classrooms. During a series of noise measurements in seven German primary schools, differences in noise parameters and subjective listening effort, as assessed by questionnaires, were investigated across the activity-based acoustic situations. Classroom noise was analyzed for sound pressure level (SPL), A-weighted SPL, loudness, and sharpness. The results showed statistically significant differences in average loudness and A-weighted SPL between the activity-based acoustic situations, with silent work yielding 55.48 dB(A), student-teacher interaction 65.13 dB(A), group work 67.44 dB(A), and breakfast break in the classroom 69.34 dB(A). All loudness parameters, SPL, A-weighted SPL, and loudness, showed higher values for first grade than for fourth grade supporting that noise levels decrease with increasing age. Subjective listening effort, as assessed by questionnaires, did not differ significantly between activity-based acoustic situations. This suggests that the questionnaire may not have been suited to evaluate subjective listening effort for the age group investigated. The present study highlights the importance of activity-based assessment of classroom noise to better represent the classroom sound environment.

Social information such as a talker's ethnicity, gender, and age are found to affect accent perception and attitudes. While existing research primarily focuses on English-dominant communities, this study aims to fill the gap by examining the impacts of ethnic bias and face on three Cantonese accents in Hong Kong. Nine groups of 20 Hong Kong Cantonese listeners were exposed to three Cantonese accents (i.e., Hong Kong local Cantonese, Mandarin-accented, and English-accented Cantonese) in three conditions of visual cues (i.e., a silhouette, a South Asian face and a White face). For accent identification, seeing a South Asian face in a mismatch condition led to more errors compared to seeing a White face in the same condition. For intelligibility, an enhancement of intelligibility was found when the face and accent were misaligned (e.g., an English accent matched with a South Asian face), supporting the general adaptation mechanism instead of the expectation mechanism. We argue that listeners might perceive South Asian and White faces as the same broad social category "foreigners/outgroup members," resulting in a similar enhancement effect in the aligned and misaligned conditions. A dual-activation mechanism is proposed to account for the complementary effect of phonological and visual cues on accent perception.

The adult auditory system adapts to changes in spectral cues for sound localization. This plasticity was demonstrated by modifying the shape of the pinnae with molds. Previous studies investigating this adaptation process have focused on the effects of learning one additional set of spectral cues. However, adaptation to multiple pinna shapes could reveal limitations in the auditory system's ability to encode discrete spectral-to-spatial mappings without interference and thus help determine the mechanism underlying spectral cue relearning. In the present study, listeners learned to localize sounds with two different sets of earmolds within consecutive adaptation periods. To establish both representations in quick succession, participants underwent daily sessions of sensory-motor training. Both pinna modifications severely disrupted vertical sound localization, but participants recovered within each 5-day adaptation period. After the second adaptation, listeners were able to access three different sets of spectral cues for sound localization. Participants adapted to both sets of earmolds with equal success, and learning a second set of modified cues did not interfere with the previous adaptation. We found no indication of meta-adaptation as the rate of adaptation to the second molds was not increased.

This paper postulated and tested the possibility that the mouth rhythm functions as a "packaging mechanism" of information in speech. Cross-spectral analysis between two time series of mouth aperture size [parameterized as sample-by-sample interlip distances, i.e., o(t)] and information variations in speech [parameterized as frame-by-frame spectral entropy values, i.e., h(t)] was employed to reveal their underlying spectro-temporal relationship. Using a corpus containing more than 1000 utterances produced by a typical British English speaker, it was observed that both signals share slow recurring rates corresponding to the stress and syllable, with a slight phase lag of h(t) behind o(t) in the vicinity of 5 Hz.

Listeners can adapt to noise-vocoded speech under divided attention using a dual task design [Wang, Chen, Yan, McGettigan, Rosen, and Adank, Trends Hear. 27, 23312165231192297 (2023)]. Adaptation to noise-vocoded speech, an artificial degradation, was largely unaffected for domain-general (visuomotor) and domain-specific (semantic or phonological) dual tasks. The study by Wang et al. was replicated in an online between-subject experiment with 4 conditions (N = 192) using 40 dysarthric sentences, a natural, real-world variation of the speech signal listeners can adapt to, to provide a closer test of the role of attention in adaptation. Participants completed a speech-only task (control) or a dual task, aiming to recruit domain-specific (phonological or lexical) or domain-general (visual) attentional processes. The results showed initial suppression of adaptation in the phonological condition during the first ten trials in addition to poorer overall speech comprehension compared to the speech-only, lexical, and visuomotor conditions. Yet, as there was no difference in the rate of adaptation across the 40 trials for the 4 conditions, it was concluded that perceptual adaptation to dysarthric speech could occur under divided attention, and it seems likely that adaptation is an automatic cognitive process that can occur under load.

Breast cancer is a leading cause of death for women. Quantitative ultrasound (QUS) and ultrasound computed tomography (USCT) are quantitative imaging techniques that have been investigated for management of breast cancer. QUS and USCT can generate ultrasound attenuation images. In QUS, the spectral log difference (SLD) is a technique that can provide estimates of the attenuation coefficient slope. Full angular spatial compounding (FASC) can be used with SLD to generate attenuation maps with better spatial resolution and lower estimate variance. In USCT, high quality speed of sound (SOS) images can be generated using full wave inversion (FWI) method, but attenuation images created using FWI are often of inferior quality. With the QTI Breast Acoustic CTTM Scanner (QT Imaging, Inc., Novato, CA), raw in-phase and quadrature data were used to implement SLD combined with FASC. The capabilities of SLD were compared with FWI through simulations, phantom experiments, and in vivo breast experiments. Results show the SLD resulted in improved accuracy in estimating lesion sizes compared to FWI. Further, SLD images had lower variance and mean absolute error (MAE) compared to FWI of the same samples with respect to the attenuation values (reducing MAE by three times) in the tissue mimicking phantoms.