Journal of the Acoustical Society of America最新文献

The role of medial olivocochlear (MOC) efferent gain control in auditory enhancement (AE) was investigated using a subcortical auditory model. AE refers to the influence of a precursor on detectability of targets. The absence (or presence) of a precursor component at the target frequency enhances (or suppresses) detection under simultaneous masking conditions. Furthermore, the enhanced target under simultaneous masking acts as a stronger forward masker for a delayed probe tone, known as AE under forward masking. Psychoacoustic studies of AE report findings that challenge conventional expectations, and the underlying mechanisms remain unclear. For instance, listeners with hearing impairment have AE under simultaneous masking but not forward masking [Kreft, Wojtczak, and Oxenham (2018). J. Acoust. Soc. Am. 143(2), 901-910; Kreft and Oxenham (2019). J. Acoust. Soc. Am. 146(5), 3448-3456], whereas listeners with normal hearing have level-dependent AE under forward masking [Kreft and Oxenham (2019). J. Acoust. Soc. Am. 146(5), 3448-3456]. Our model with MOC efferent gain control successfully replicated these findings. In contrast, a model without efferent gain control failed to capture these effects, supporting the hypothesis that MOC-mediated cochlear gain modulation may play a role in AE and its alteration by hearing loss.

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.

Momentum bias within one-dimensional elastic media introduces non-reciprocal phenomena in the propagation of elastic waves, manifesting as Willis coupling in the governing wave equation. To the best of our knowledge, the implications of Willis coupling being the sole coupling mechanism within elastic media and the understanding of non-reciprocity through finite structure analysis remain unexplored. In this paper, a non-reciprocal wave phenomenon with pure Willis coupling is synthesized using feedback control in mechanical lattices consisting of masses, grounded springs, and linear actuators. The proposed system presents a unique lack of physical connections between masses, allowing for pure Willis coupling through feedback forces exerted by the linear actuators. The dynamical behavior of a unit cell segment from an infinite lattice chain is considered, and the emergent non-reciprocal dispersion relation is detailed, including an analytical quantification of the Brillouin-zone translation resulting from pure Willis non-reciprocity. Analytical derivations of the eigenpairs of a finite lattice configuration are established, and the theoretical analyses reveal the mechanism of non-reciprocity through the lens of the lattice's natural frequencies and corresponding mode shapes.

This study introduces directional coherence loss coefficients (DCLCs) to quantify the angular distribution of sound field coherence loss, which arise from localized scattering distributions within an enclosure, from a receiver's perspective. Sound fields in the room are sampled by a spherical receiver and decomposed into plane waves using spherical harmonics expansion, yielding directional impulse responses (IRs). The time-dependent coherence coefficients between directional IRs in furnished rooms and their empty counterparts are analyzed for each direction. DCLCs are derived from these coherence coefficients and decide the transition between the coherent component-mainly representing specular reflections-and the incoherent component, accounting for scattering contributions from interior elements. This research extracts DCLCs from rooms with varying transducer positions founded on wave-based simulations and measurements from rooms with different element distributions. A hybrid model is proposed to reconstruct the sound field in a room with a single diffusive wall, where the coherent component is computed from the empty room case, and the incoherent component is simulated stochastically, with their relative weighting decided by DCLCs. Directional IRs from the hybrid model exhibit agreement with ground truth in terms of reverberation time, clarity, kurtosis, and spatial cross correlation coefficients, verifying the ability of DCLCs to characterize localized scattering distributions in enclosures.

Time histories of broadband ship noise measured at the Lofoten-Vesterålen cabled observatory (on the seafloor at 255 m depth in the Norwegian Sea) are compared to model-based predictions. Fifty-four tracks of 26 different vessels are included in our analysis; all 54 ship tracks pass within 520 m horizontally of the hydrophone. Ships were tracked using the Automated Identification System. A striking feature of the ship noise measurements is azimuthal anisotropy of the sound radiated by the passing ships; sound intensity aft of the vessels is higher than sound intensity fore of the vessels. Anisotropy of the radiated ship noise is accounted for in the ship noise propagation model used. Agreement between measurements and model predictions is good. Estimates of ship-radiated acoustic power and an azimuthal anisotropy strength parameter are obtained for each ship track. Estimates of the azimuthal anisotropy strength parameter depend on vessel type. Estimates of the azimuthal anisotropy strength parameter among different tracks of the same vessel show considerable variability, and estimates of radiated acoustic power show no clear increase with increasing ship speed; these unexpected results suggest that factors not accounted for in our analysis, including ship displacement, play a role in controlling the radiated ship noise.

Edema of the vocal folds (VFs) is the result of an inflammatory response to injury (phonotrauma), or other deleterious stimuli, causing fluid build-up in the VF tissue. Although a mild level of edema has been postulated to be prophylactic, excessive edema has been identified as a pathway in the development of vocal hyperfunction. Herein we present a multi-time scale finite element model to examine the progression of VF edema in response to phonotrauma. Phonotraumatic damage was assessed by two measures: viscous dissipation and positive strain energy rate. Time-averaged phonotrauma over short time scales was assumed to drive swelling over longer time scales in proportion to the damage measure via a damage sensitivity gain. Healing was assumed to continuously act to reduce swelling. Growth rate analysis indicated that edema depends on a balance between healing, compensatory adjustments to maintain desired voice output measures, and altered VF vibration due to edema. For high damage sensitivity relative to healing, peak edema resulted in roughly 25% local peak swelling at 0.15 h, whereas low damage sensitivity led to swelling trending toward a steady condition requiring little compensation to maintain voice outputs. In general, fluid accumulation was distributed non-uniformly across the VFs with concentrations near the VF medial surface and the superior end of the body. Results from this first-ever model connecting phonotrauma at the short time scale and swelling at the longer time scale exhibited rapid edema progression under certain conditions, aligned with the "vicious cycle" hypothesis of hyperfunction, wherein localized edema initiated a positive feedback loop that led to even greater localized swelling.

The dolphin's ability to detect changes in the phase of complex echo highlights was investigated by training two bottlenose dolphins to detect a phase "jitter" applied to the second highlight of a two-highlight "phantom" echo. One dolphin had normal hearing and the other had high-frequency hearing loss. The phase jitter changed the complex echo temporal and spectral fine structure without altering the echo energy, temporal and spectral envelopes, or spectral notch spacing. Over the course of testing, the inter-highlight interval (IHI) and frequency content of the echoes were varied. When echo IHIs were less than 300 μs, phase jitter thresholds for the two dolphins were equal, despite large differences in high-frequency hearing ability. At larger time separations, the perceptual cue appeared to change, presumably from spectral to temporal. High-pass filtering of echoes suggested that the lower range of echolocation frequencies are most useful for detecting echo highlight phase shifts. Simple models for across-channel spectral profile differences and differences in repetition pitch provided mixed results: both models matched the experimental data well for some conditions but poorly for other conditions, especially as the IHI and high-pass cutoff frequencies increased.

A weighted masking method based on the coherent-to-diffuse ratio is presented for robust binaural speech enhancement in real-time hearable devices. The method applies manually tuned weights across custom-defined critical frequency bands to improve the quality and intelligibility of frontal target speech in multi-talker reverberant environments. The algorithm was implemented in real time on a functional hearable prototype and evaluated in a perceptual listening study under realistic binaural hearing conditions. Subjective assessments with normal-hearing participants, including evaluations of audio quality, speech intelligibility, and spatial localization, demonstrated consistent improvements compared to baseline coherence-based filtering methods. Results indicate that the method suppresses diffuse background noise while preserving interaural spatial cues important for listening comfort and spatial awareness in complex acoustic scenes. These findings support the applicability of coherence-weighted masking in real-time binaural enhancement tasks under reverberant, multi-talker conditions, including potential use in hearable and hearing aid technologies. In addition to perceptual listening tests, objective evaluations across multiple reverberant environments demonstrate consistent performance improvements over baseline methods.

Accurate acoustic simulations of enclosed spaces require precise boundary conditions, typically expressed through surface impedances for wave-based methods. Conventional measurement techniques rely on simplifying assumptions about the sound field and mounting conditions, limiting their validity for real-world scenarios. To overcome these limitations, this study introduces a Bayesian framework for the in situ estimation of frequency-dependent surface impedances from sparse interior sound pressure measurements. The approach employs simulation-based inference, which leverages the expressiveness of neural network architectures to directly map simulated data to posterior distributions of model parameters, bypassing conventional sampling-based Bayesian approaches and offering advantages for high-dimensional inference problems. Impedance behavior is modeled using a damped oscillator model extended with a fractional calculus term. The framework is verified on a finite element model of a cuboid room with a volume of 1.95  m3 and further tested with impedance tube measurements used as reference, achieving robust and accurate estimation of all six individual impedances from 63 to 500 Hz. Application to a numerical car cabin model further demonstrates reliable uncertainty quantification and high predictive accuracy for complex-shaped geometries. Posterior predictive checks and coverage diagnostics confirm well-calibrated inference, highlighting the method's potential for generalizable and physically consistent characterization of acoustic boundary conditions in real-world interior environments.

Intracochlear recorded growth functions of cochlear potentials evoked by acoustic tones were analyzed by their phase coherence, variance, and density distribution. Potentials obtained from electrocochleography recorded in cochlear implant users with ipsilateral residual hearing were analyzed in the complex domain. The study shows that (1) the phase of the cochlear microphonic (CM) is coherent across stimulation levels, (2) CM potentials are circularly symmetric normally distributed in the complex domain, regardless of stimulation level or response amplitude, and (3) the variance of CM potentials remains consistent, irrespective of stimulation level. Based on these findings, we introduce a method that utilizes the phase coherence across stimulation levels to improve the accuracy of CM amplitude estimates, particularly when amplitudes are close to the noise floor. A key aspect of this method is addressing the bias introduced by the circularly symmetric normal distribution of additive Gaussian noise in the complex domain, which can lead to overestimation of signal magnitude. The results show that phase coherence can be used to enhance the accuracy of amplitude estimates of cochlear potentials, thereby making the recording process more efficient. Furthermore, the consistent variance of cochlear potentials enables noise estimations from recordings containing receptor potentials, independent of the stimulation level.