JASA express letters最新文献

In this Letter, a simplified expression of the vertical dimension narrowband interference pattern in deep water direct arrival zone is theoretically derived. The correlation between the vertical dimension interference pattern and source depth is analyzed, and the depth span corresponding to a complete interference cycle (interference period) is derived theoretically. A source depth estimation method is proposed based on matching the vertical interference pattern calculated from the data with theoretical predictions. The effectiveness of the theoretical approach in predicting the vertical interference pattern and effectiveness of the proposed depth estimation method are verified by experimental data.

Spatiotemporal modulation (STM) has recently been used to improve diffusion from finite apertures of conventional acoustic diffuser profiles by introducing STM of the termination impedance of the diffuser wells and to scatter acoustic energy at frequencies that are up- and down-shifted from the incident wave frequency by integer multiples of the modulation frequencies. The present work employs a semi-analytical model of acoustic scattering from an STM acoustic metasurface to investigate the tunability of scattering from a flat metasurface with STM admittance by demonstrating nonreciprocal and diffuse scattering of sound via a parametric study on the modulation frequency and admittance amplitude. The results provide insight into the use of STM of input admittance to control acoustic scattering from acoustic metasurfaces.

This paper examines voiceless aspiration duration in Tarifit, a Moroccan Amazigh language that allows vowelless productions of some words. Thirty-seven speakers produced words with a /CCəC/ structure containing a voiceless stop in the underlyingly pre-vocalic position (e.g., /skəf/) across speaking styles. Vowelless forms of these words occur for about 11% of productions. When these words surface as vowelless, they are produced with a longer aspiration than when they are produced with a vowel. Thus, vowellessness in Tarifit consists of articulatory restructuring of words involving aspiration lengthening, possibly in addition to either vowel deletion or devoicing. Results are discussed for models of sound change and phonological typology.

The generalized rainbow caustics in the scattering of laser light by acoustically levitated oblate water drops in air [Marston and Trinh, Nature 312, 529-531 (1984)] display relationships between optical wavefields and the shape of wavefronts. The shape of the scattered optical wavefront depends on the drop shape controlled by the levitator. The present investigation demonstrates that an alternative array-based ultrasonic levitator design known as "TinyLev" can be used to trap drops for the purpose of recording generalized rainbows. The hyperbolic umbilic focal section was viewed. The TinyLev combined with CCD-based imaging may make investigations of generalized rainbows more accessible.

Shadle [(2023). J. Acoust. Soc. Am. 153, 1412-1426] proposed that the spectral peak in mid-frequency (FM) is a superior measure of place of articulation of sibilant fricatives to the most commonly used measure, the first spectral moment (M1). It is examined as to whether FM predicts adult listener's ratings of the place of articulation of 2.5-3.5-year-old children's word-initial /s/ and /ʃ/ when compared to M1. Regression models reveal that FM in 3-9 kHz range best predicts listener's ratings of children's fricatives. These results provide additional validation for FM as a measure of fricatives' place of articulation, including in children's speech.

This Letter presents an analysis of near-field acoustic data collected on Space Launch System's Mobile Launcher tower during the Artemis I mission. Twelve pressure sensors located two and four effective nozzle diameters (De) from the vehicle centerline recorded maximum overall sound pressure levels ranging from ∼ 162 dB to more than 170 dB, originating ∼ 10 De downstream of the nozzle exit plane. Frequency-dependent characteristics are also discussed. The peak noise is radiated over a broader frequency range than in the far field. Low-frequency noise locations match other rockets, but high-frequency locations diverge, falling between prior measurements of undeflected and deflected plumes.

Spatial release from masking for an individual is dependent on the spatial separation between the target and the maskers, age, auditory capabilities, and working memory capacity. In this paper, a task is presented that estimates an individual's working memory capacity using a divided-attention version of the classic spatial release from masking task. Speech identification thresholds, temporal overlap thresholds, and working memory were measured for younger and older adults. The results showed younger listeners had better thresholds than older listeners across all the tests. Overall, this test can simultaneously estimate an individual's working memory and spatial processing capabilities.

Population-specific acoustic features are vital for using passive acoustic monitoring to study marine mammal populations in remote regions. Southern Hemisphere fin whale (Balaenoptera physalus) songs include region-specific high-frequency components, with the 86- and 99-Hz high-frequency components present in the Atlantic Sector of the Southern Ocean. Using long-term passive acoustic monitoring data, we show that, despite gradual interannual and intra-annual variabilities, these features remain distinct and recognizable across regions and years. Our findings support their use as reliable acoustic markers for monitoring fin whale populations, providing valuable insights into distribution and population structure.

Transfer learning (TL) is used to predict source-receiver range in a laboratory tank with varying water temperature. The input data are single-hydrophone spectral levels from linear chirps over the 50-100 kHz band recorded at different ranges. Data measured in room temperature water are used to train one-dimensional convolutional neural networks. When the trained models are applied to data measured in warmer water, a bias is introduced. TL with a small dataset improves the generalization results at the new temperature, demonstrating the potential of TL to improve performance under variable environmental conditions.

Psychophysical work suggested that humans discriminate diel changes in natural soundscapes based on spectral cues. The present study extended this investigation by assessing human discrimination for diel variations in natural soundscapes using a database of scenes recorded in three distinct habitats (two temperate forests and a tropical forest) marginally affected by human activity and processed by a multi-band noise vocoder to degrade selectively spectral and temporal cues. The results confirm that auditory sensitivity to diel variations is high and is only affected by degradations to spectral cues. They also indicate that the resolution of these spectral cues depends on habitat.