JASA express letters最新文献

Many fish species are suspected to produce sound, but the variety of sounds they produce is still largely undocumented. This study investigated the presence and diversity of fish sounds in the Channel Islands National Marine Sanctuary. Besides regular sounds from three known species-bocaccio (Sebastes paucispinis), plainfin midshipman (Porichthys notatus), and white seabass (Atractoscion nobilis)-two unusual sound types were observed that require further analyses and for which the species is still unknown: Unidentified Fish or UF200 and UF450. Sound types had distinct acoustic signatures and varied in diel presence. Monitoring fish sounds is a promising technique for non-invasive monitoring of fish presence with conservation applications.

This study introduces a convolutional neural network based method for rapid prediction of underwater acoustic propagation fields, addressing the high computational cost of traditional methods. By analyzing regional terrain features and constructing a training dataset, the model learns acoustic transmission loss patterns across various terrain conditions. Tests in the Western Pacific demonstrate a root mean square error of 3.48 dB for non-smoothed fields, with an average prediction time of 1.95 ms per batch (10 samples). This method highlights the potential for fast acoustic propagation predictions using simplified inputs, offering a promising direction for real-time applications.

Drones have become essential tools for applications ranging from aerial surveillance to last-mile delivery, raising concerns about noise pollution in populated environments. This paper presents a directional active noise control (ANC) framework that targets far-field noise reduction, rather than local suppression. A virtual microphone-based ANC algorithm is employed, using a near-drone microphone array to attenuate noise in a specific region. Experiments in a semi-anechoic chamber show an average reduction of 4.78 dB in the 1500-2400 Hz band and up to 10 dB at harmonic frequencies, highlighting the promise of directional ANC for quieter drone operations in sensitive settings.

Earthquakes excite sound waves along continental margins, T waves, that can propagate for thousands of kilometers in the ocean. The complex T waveforms are shaped by the extended region of seismic-to-acoustic conversion. Because the conversion has a width comparable to ocean eddies, T waveforms can be modified substantially by the subsequent propagation through eddies. Sound speed anomalies associated with eddies shift arrival times, so waves arriving from different azimuths can have experienced different phase shifts, making the recorded waveform an eddy-dependent interference pattern. Leveraging this multipath propagation can improve the spatial resolution of deep-ocean temperature change estimated with T waves.

To extend the assessment of listening effort beyond a sound booth, we validated mobile eye-tracking glasses (Pupil Labs Neon; Pupil Labs, Berlin, Germany) by comparing them to a stationary system (Eyelink DUO; SR Research Ltd., Ottawa, Canada) in a controlled environment. We recorded eye movements, pupil size, and head movements from 26 young adults during a speech-in-noise task. When listening conditions became challenging, we observed reduced gaze dispersion and increased pupil sizes of similar magnitude from both devices, in addition to reduced head movements recorded solely by the mobile device. These findings suggest that mobile eye-trackers reliably capture listening effort, paving the path towards assessments in daily settings.

Prompt management of ascites via image-guided paracentesis can provide therapy for patients with ascites and identify potentially fatal infections. However, not all medical facilities have trained providers readily available. The goal of this study was to develop an algorithm that can reliably identify and localize ascites on abdominal ultrasound images autonomously. The proposed algorithm was developed via OpenCV image processing library on Python software and analyzed 16 random abdominal ultrasound images with multiple views to validate the software. The algorithm identified 100% of targeted ascitic regions. This study suggests that the proposed algorithm is a reliable tool for ascites detection.

Speech exhibits robust temporal characteristics, including syllable duration and the speech modulation spectrum. In real-world scenarios, speech is often exchanged over long distances. This study investigates how the temporal characteristics of speech are influenced by talker-to-listener distance. When talker-to-listener distance increases from 1 to 100 m, we observe a 48 ± 29% (M ± SD) increase in mean syllable duration. The temporal amplitude modulation spectrum, however, remains similar, regardless of talker-to-listener distance, with its peak frequency slightly lowering by -13 ± 41%. Finally, distance-related elongation of syllables occurs in addition to distance-related increases in syllable intensity or pitch, and longer syllable duration predicts greater speech intelligibility.

Gaussian processes (GPs) can densify and denoise sparsely sampled signals and have been applied in matched-field processing (MFP) localization to improve localization accuracy and robustness. Given a known true field, the minimum mean squared error criterion is proposed to evaluate the performance of GP interpolation and its application in MFP localization. This approach allows for the performance comparison of different kernel functions and likelihood functions, assisting in identifying the optimal hyperparameters, interpolation results, and localization outcomes. It also highlights possible challenges faced by existing GP methods under limited data conditions while establishing a performance upper bound for GPs-MFP.

Quantifying acoustic masking due to noise sources is an important part of marine mammal conservation. This study examines the relative masking of bearded seal vocalizations by ice-generated sounds, using passive acoustic data collected from the western Canadian Arctic. Broadband ice sound events and bearded seal calls were extracted from acoustic recordings, and masking potential was estimated using the listening space reduction (LSR) metric, based on the bearded seal audiogram and propagation loss in an ice-covered environment. Results indicate that bearded seal vocal activity decreased with increasing LSR and ambient sound exposure levels, suggesting a potential behavioural adjustment to elevated ice sound levels that warrants further investigation.