Journal of the Acoustical Society of America最新文献

As occupational hearing loss (OHL) is a concern among women, a cross-sectional study was conducted. Individual noise exposure energy and temporal structure were quantified using the 8 h continuous equivalent A-weighted sound pressure level (LAeq,8h) and kurtosis (β). High-frequency noise-induced hearing loss (HFNIHL) and noise-induced hearing impairment (NIHI) were calculated. The HFNIHL and NIHI prevalences were 13.45% and 13.20%, respectively. Hearing loss was symmetrically distributed, with the most significant threshold shifts occurring at 4.0 kHz. The OHL prevalence was significantly higher in individuals exposed to non-steady rather than steady noise. A marked increase in OHL prevalence was observed among women exposed to non-steady noise for 3 to 10 years. The steady noise group exhibited an increase, followed by a plateau or decline. Key influencing factors for women's OHL were LAeq,8h, age, and kurtosis, with odds ratios (ORs) ranked as follows: ORLAeq,8h > ORAge > ORKurtosis. After adjusting for kurtosis in LAeq,8h, the model fit (Akaike Information Criterion) of the dose-response relationship improved significantly. These findings suggested that female manufacturing workers were at high risk of OHL with significant clinical characteristics. Noise kurtosis could accelerate and exacerbate women's OHL development. Kurtosis adjustment for noise level could effectively evaluate women's OHL.

Anthropogenic noise may pose a threat to Kemp's ridley sea turtles in nearshore and offshore waters of the western North Atlantic and Gulf of America, where shipping and energy industries are widespread. Understanding hearing sensitivity is necessary for the development of effective noise impact mitigation strategies. However, data gaps currently exist. Therefore, in this study, we measured auditory evoked potentials (AEP) to determine the underwater hearing sensitivities of 13 juvenile Kemp's ridley sea turtles using hearing test frequencies ranging from 50 to 1600 Hz. We detected AEPs for hearing test signals between 50 and 800 Hz. Peak hearing sensitivity occurred between 200 and 300 Hz, followed by a decline in sensitivity above 400 Hz. The lowest hearing threshold averaged across all test subjects was 100 dB re 1 μPa at 300 Hz. No responses were detected at 1200 Hz (max received level = 143 dB re 1 μPa) and 1600 Hz (max received level = 143-165 dB re 1 μPa). Our results averaged across multiple individuals at 100 Hz (n = 9), 200 Hz (n = 8), 300 Hz (n = 5), and 400 Hz (n = 8) reveal lower hearing thresholds (greater sensitivity) than those reported in a previous study of two Kemp's ridley sea turtles at these frequencies. The results presented here should be considered a conservative estimate of hearing sensitivity, as perceptual hearing thresholds are likely lower than what can be determined with AEPs.

To address the dual demands of high static load capacity and low resonance frequency in underwater electrodynamic transducers, this study introduces a nonlinear supporting mechanism based on a tension spring-roller-cam quasi-zero stiffness (QZS) structure. The mechanism effectively reduces the equivalent stiffness while maintaining high static load capacity, achieving lower resonance frequency and enhanced ultra-low-frequency vibration performance. A nonlinear dynamic model of the transducer is developed, and displacement and sound pressure level responses are analyzed using the harmonic balance method. Numerical simulations reveal the influence of mechanical damping and excitation amplitude on the system's vibration characteristics. Comparative analysis shows that the QZS-supported system exhibits a significantly lower resonance frequency and improved low-frequency vibration behavior than the conventional linear system. Experimental validation using impact hammer testing confirms a significant reduction in resonance frequency and enhanced acceleration response in the ultra-low-frequency range. These findings validate the capability of the proposed QZS suspension mechanism to achieve ultra-low resonance frequency, suggesting its potential for application in underwater ultra-low-frequency electrodynamic transducers.

A formulation to introduce acoustic waves from a control surface using volumetric source terms is proposed for numerical simulations. A general expression of the source terms is derived from the non-linear Euler equations. The method is validated through three academic configurations: the injection of oblique plane waves and the radiation of a monopole source in two and three dimensions, in uniform flow. The governing equations are solved in a Cartesian grid using a low-dispersion and low-dissipation high order finite-difference numerical scheme. However, the control surface has an arbitrary shape, as demonstrated here with the use of a cylindrical surface. Numerical results show good agreement with analytical solutions in both phase and amplitude. The method is then applied to an open-fan aircraft engine configuration. The source terms are computed from a cylindrical control surface enclosing the rotor, based on data extracted from a previous fluid mechanics simulation. The radiated acoustic field is compared with the one obtained using the Ffowcs Williams-Hawkings integral formulation. The two solutions are again found in good agreement for this more realistic configuration.

Clear speech, a speaking style used to communicate with individuals with hearing loss and other communication difficulties, has been shown to sound "angry" more often than conversational speech [Morgan and Ferguson (2017). J. Speech. Lang. Hear. Res. 60, 2271-2280]. In this study, acoustic analyses of emotionally neutral sentences from a database of 41 talkers spoken both clearly and conversationally were analyzed in tandem with judgments of emotions for the same sentences to assess potential acoustic correlates of judgments of anger in clear speech. Principal component analyses were conducted to guide the selection of acoustic measures for statistical models. Decreases in speaking rate and increases in temporal fluctuations in amplitude centered at 1 Hz, both of which are prominent features of clear speech, were both associated with increases in judgments of anger. Increases in fundamental frequency variability, another common feature of clear speech, were associated with increases in judgments of any amount of anger but only in conversational speech. Finally, after controlling for speaking style and fundamental frequency variability, women were judged to sound angry more often than men. The results suggest that speaking rate, amount of word or phrase-level amplitude modulation, and fundamental frequency variability could possibly be manipulated to decrease judgments of anger in clear speech.

In underwater mobile spread spectrum communications, time-varying Doppler effects cause severe carrier phase jumps, significantly degrading spreading gain. Addressing the limitations of conventional compensation techniques under high relative velocities, this study investigates the correlation cost factor (CCF) during de-spreading in M-ary spread spectrum systems. Theoretical analysis reveals that CCF serves as an effective loss function for frequency offset compensation. Leveraging this, a high-resolution Doppler estimation method (HCCF-MSS) is proposed. HCCF-MSS employs the adaptive learning rate of the Adam optimizer to update step sizes, enabling rapid, high-precision convergence of the CCF loss function to the accurate frequency offset. To mitigate convergence to local minima in highly dynamic environments, the Multi-starting Point Parallel Gradient Search (MPGS) algorithm is introduced. MPGS initiates concurrent gradient searches from diverse starting points and selects the optimal solution by comparing CCF values across convergent paths. Numerical simulations and sea trials demonstrate that HCCF-MSS-9 (9 iterations) achieves performance comparable to CCF-MSS-0.02 (±6 Hz range, 0.02 Hz precision) with superior computational efficiency. Under accelerations up to 3 m/s2, HCCF-MSS-9+MPGS-6 (6 starting points) attains a Doppler estimation mean squared error of approximately -3.3 dB, outperforming other algorithms by 0.5-1.5 dB, demonstrating its effectiveness for precise frequency offset estimation under complex variable-motion conditions.

The measurement of acoustic performance of underwater panels, such as their reflection and transmission coefficients, has always been a challenge. The finite size of the tank imposes a low frequency limit, while diffraction by the edges of the panel disturbs measurements. Despite these difficulties, it remains a valuable tool for comparison with numerical and analytical studies. In a previous paper [Roux, Pouille, Audoly, and Hladky, J. Acoust. Soc. Am 147(2), 1104-1112 (2020)], the three-point method has been proposed and tested on a homogeneous panel. The present paper proposes an extension of the method applicable to periodic metamaterials. First, the applicability and robustness of the three-point method are tested on a periodic panel. Then, since it behaves like a diffraction grating, above the grating cut-off frequency, the measurement method must separate the specular wave from the other propagative contributions. For that purpose, the five-point method is proposed as a solution to separate these contributions to retrieve the reflection and transmission coefficients. The three- and five-point methods are applied to a test panel made of steel bars. Limitations on these methods are discussed and a solution is proposed to reduce their impact. Finally, a correct measurement-simulation agreement is observed for the reflection and transmission coefficients for both the specular and the first-propagative diffraction order.

The Reflections series takes a look back on historical articles from The Journal of the Acoustical Society of America that have had a significant impact on the science and practice of acoustics.

Acoustic signals with a center frequency of 35 Hz and a full bandwidth of about 4 Hz were transmitted over various ranges along a path extending from north of Svalbard to north of Alaska during the 2019-2020 US-Norwegian Coordinated Arctic Acoustic Thermometry Experiment (CAATEX). Three moorings were installed in the Canada Basin and three in the Nansen Basin, with one mooring in each basin hosting a source. All moorings had vertical receiving arrays, enabling spatial separation of the low-order acoustic normal modes. The modal group delays varied significantly over the year but were roughly consistent with predictions for the decade 2015-2022 based on the World Ocean Atlas 2023. The CAATEX signals traversed nearly the same trans-Arctic acoustic path as the 19.6-Hz signals in the 1994 Transarctic Acoustic Propagation (TAP) experiment. The TAP and CAATEX group delays cannot be directly compared because of the differing carrier frequencies. Thus, an indirect method using the group delays computed using WOA 2023 as a convenient standard was employed, but the large TAP mode-2 travel-time uncertainty precluded definitive comparisons. Nonetheless, CAATEX demonstrated that long-range acoustic transmissions provide precise, year-round measurements of large-scale ocean sound-speed (temperature) variability under the ice.