The Journal Of The Acoustical Society Of America[JOURNAL]
Sun
200 papers
A multi-array bearing-only fusion framework for passive underwater multi-target localization.
Ling S, Ni YY, Han Y … +1 more , Yang Y
J Acoust Soc Am · 2026 May · PMID 42153802 · Publisher ↗
In strong interference underwater environments, multi-array multi-target bearing-only localization faces two major challenges: ambiguous measurement association and ghost points from incorrect bearing-line intersections....
In strong interference underwater environments, multi-array multi-target bearing-only localization faces two major challenges: ambiguous measurement association and ghost points from incorrect bearing-line intersections. This paper proposes an effective fusion framework to address both issues. For the former, other than geometric distance, such as nearest neighbor, we propose to use Fisher information with statistical-theoretical guarantees as an optimal measurement association (OMA) metric. For the latter, we propose a multi-target maximum likelihood (MML) estimator by constructing the objective function with probability hypothesis density. Both simulation and sea trial experiments show that our MML-OMA framework suppresses ghost points and improves localization accuracy. Since tracking is usually required after localization in the detection processing chain to estimate the target kinematic state, we further introduce multiple hypothesis tracking as a downstream process in the sea trial experiments to evaluate localization performance. Compared with the traditional localization method, the proposed method significantly improves downstream tracking performance.
Low-frequency interaural time differences are resistant to across-frequency binaural interference across a range of overall levels.
Bilokon A, Choi A, Goupell MJ
J Acoust Soc Am · 2026 May · PMID 42153801 · Publisher ↗
Low-frequency interaural time differences (ITDs) are the primary human horizontal-plane localization cue. Across-frequency binaural interference tasks, which assess changes in ITD sensitivity in the presence of a remote...
Low-frequency interaural time differences (ITDs) are the primary human horizontal-plane localization cue. Across-frequency binaural interference tasks, which assess changes in ITD sensitivity in the presence of a remote interferer, reveal how listeners weigh binaural information across frequency regions. Low-frequency (0.5-kHz) targets experience less interference from high-frequency (4-kHz) interferers compared to the reverse, but the role of relative signal level across frequencies remains relatively underexplored. This study measured ITD discrimination thresholds in ten young normal-hearing listeners using target and interferer frequencies of 0.5, 4, and 8 kHz and levels of 35, 55, and 75 dB-A. Binaural interference magnitude depended on both stimulus level and frequency. For a 4-kHz target and 0.5-kHz interferer, interference significantly increased with increasing interferer and decreasing target levels. For a 0.5-kHz target and 4-kHz interferer, interference significantly increased with increasing interferer level when the target level was 35 dB-A, but was unchanged when the target level was 55 or 75 dB-A. The resistance to binaural interference for the low-frequency target at higher target levels confirms the robustness of low-frequency ITD processing and highlights the level-dependent vulnerability of high-frequency targets to interference. This helps advance understanding of spatial hearing for complex stimuli in more realistic auditory scenes.
Potential energy of air bubbles in glacier ice and its conversion into acoustic energy.
Johnson HA, Deane GB, Stokes MD … +5 more , Glowacki O, Moskalik M, Chitre M, Vishnu H, Powell C
J Acoust Soc Am · 2026 May · PMID 42153800 · Publisher ↗
Air bubbles in glacier ice are released into the water and may generate sound as the ice melts. A major missing link in the study of this sound is an estimate of the sound energy radiated per unit of ice that melts. We p...
Air bubbles in glacier ice are released into the water and may generate sound as the ice melts. A major missing link in the study of this sound is an estimate of the sound energy radiated per unit of ice that melts. We present a theoretical upper bound for the sound energy that can be produced by the bubbles by computing their acoustically available potential energy. A more stringent upper bound based on a simple model for the behavior of the bubble upon release from the ice is then developed. These theory and model-based estimates are then compared to the results of experiments conducted with glacial ice collected from Hornsund Fjord, Svalbard. We find that the acoustic energy radiated by the melting ice in these experiments is less than the potential energy and the modeled maximum energy. However, we also find that there is substantial variability in the sound generated by the ice that is not explained by differences in the potential energy of the bubbles. We present some evidence that suggests this is a result of variation in the way in which individual bubbles are released, with bubbles that escape rapidly generating more sound than those that escape gradually.
Spatiotemporal variation of pulse abundance, sound pressure level, and frequency in Mutsu Bay: Implications for snapping shrimp activity and distribution.
Mishima Y, Igarashi T, Morisaka T
J Acoust Soc Am · 2026 May · PMID 42148850 · Publisher ↗
Diel, seasonal, and spatial variations and regional differences in the pulse abundance of snapping shrimp have been studied. Pulse abundance and acoustic characteristics are affected by environmental changes and anthropo...
Diel, seasonal, and spatial variations and regional differences in the pulse abundance of snapping shrimp have been studied. Pulse abundance and acoustic characteristics are affected by environmental changes and anthropogenic noise; however, little is known about the spatiotemporal variability of the latter. This study examined the temporal pulse variation at a fixed point from spring to summer from 2022 to 2024, and the spatial variation across 44 sites (including scallop farm areas) in Mutsu Bay in August 2024, focusing on acoustic parameters. The pulse rate increased with water temperature and depth, and at night, and tended to be higher inside the scallop farms than outside. The peak-to-peak sound pressure level distribution for each pulse shifted toward higher values in warmer months and at night, and appeared to have minimal spatial differences. The peak frequency of each pulse was distributed mainly 6-10 kHz at night; 11-14 kHz became dominant or increased slightly along with 15-18 kHz during the day, depending on the year. The peak frequency tended to dominate 8-10 kHz at shallower sites, 11-13 kHz at deeper sites, and within both these ranges at intermediate depths (35-40 m). Further investigation is required to understand the underlying mechanisms.
Dynamic 3D MRI of vocal fold oscillations: In vivo assessment of vocal fold thickness, contact area, and glottal area waveform across phonation types in comparison with high-speed imaging.
Traser L, Stritt F, Jordan PL … +8 more , Köberlein M, Kirsch J, Rummel S, Zhang Z, Richter B, Bock M, Fischer J, Echternach M
J Acoust Soc Am · 2026 May · PMID 42148849 · Publisher ↗
Conventional endoscopic imaging of vocal fold (VF) vibration provides only a two-dimensional superior view, missing essential vertical dynamics such as VF thickness and vertical displacement. Simulation studies have assi...
Conventional endoscopic imaging of vocal fold (VF) vibration provides only a two-dimensional superior view, missing essential vertical dynamics such as VF thickness and vertical displacement. Simulation studies have assigned these parameters important regulatory functions, underscoring the need for in vivo methods capturing the three-dimensional (3D) VF geometry and vibratory motion. In this in vivo case study, dynamic 3D VF MRI was applied in a professionally trained singer, achieving sub-millimeter spatial and sub-millisecond temporal resolution. Six phonation types were produced according to Estill Voice Training® terminology, each intended to elicit different VF thicknesses and supraglottic configurations. For each type, ten phase-binned 3D datasets of the larynx were reconstructed per oscillatory cycle. Segmentation yielded VF thickness, vertical and horizontal displacement, contact-area dynamics, glottal area waveforms, open quotient (OQ), and supraglottic/subglottic dimensions. These MRI-derived measures showed strong correspondence with those from high-speed imaging and electroglottography acquired from the same subject, indicating that dynamic VF MRI enables reliable in vivo quantification of vibratory and structural parameters. Each phonation type was characterized by distinct VF geometry, supraglottic shaping, and oscillatory behavior. Across types, OQ correlated closely with VF thickness, which systematically covaried with supraglottic adjustments. This suggests supraglottic posturing represents an additional dimension of control.
Radial quadrature method for evaluating the beam shape coefficients of the axisymmetric acoustical beams.
Yu B, Xu X, Jiang H … +2 more , Tang S, Shen J
J Acoust Soc Am · 2026 May · PMID 42148848 · Publisher ↗
The radial quadrature (RQ) method proposed recently for evaluating the beam shape coefficients (BSCs) of structured light (more exactly, electromagnetic) beams is applied to acoustical beams, based on the strong analogy...
The radial quadrature (RQ) method proposed recently for evaluating the beam shape coefficients (BSCs) of structured light (more exactly, electromagnetic) beams is applied to acoustical beams, based on the strong analogy between the acoustical scattering and light scattering. The BSCs of the scalar field of the acoustical beam are formulated in double integrals. For the on-axis located acoustical beams, which have axisymmetric structures, the integral expressions of the BSCs can be simplified to the closed-forms, thus, allowing efficient calculation. The Gaussian beam and high-order Bessel beam are studied with numerical calculations. The RQ method may serve as an alternative tool in studying the acoustical scattering and relevant applications.
Sensor beampattern and equivalent aperture in a distributed acoustic sensing system.
Xenaki A, Gerstoft P
J Acoust Soc Am · 2026 May · PMID 42139012 · Publisher ↗
Distributed acoustic sensing (DAS) turns a fiber-optic cable into a long, dense array of sensors for passive acoustic monitoring, which is well-suited for ocean acoustic measurements. DAS measures phase differences of th...
Distributed acoustic sensing (DAS) turns a fiber-optic cable into a long, dense array of sensors for passive acoustic monitoring, which is well-suited for ocean acoustic measurements. DAS measures phase differences of the backscattered light from a laser pulse in an optical fiber to provide localized strain estimates. These strain estimates enable distributed sensing of external acoustic vibrations. The transfer function between the measured optical signal and the external acoustic quantities is factorized into four terms, describing the filtering effect of the acquisition gauge window and spatial averaging window and the acoustic wavenumber and direction of arrival. The resulting beampattern, i.e., the sensitivity as a function of frequency and angular direction, of individual DAS sensors is derived, and it is related to the sensor's equivalent spatial aperture. The shape of the spatial aperture determines the spatial coherence of DAS measurements in a diffuse acoustic wavefield, as demonstrated on publicly available data. The corresponding spatial coherence predicts the statistical characteristics of the speckle pattern in DAS.
Time-domain simulation of harmonica pitch bending and overblowing.
Adachi S, Okada H, Samejima T … +1 more , Nishimiya K
J Acoust Soc Am · 2026 May · PMID 42138536 · Publisher ↗
A physical model for sound production in the harmonica is proposed that is capable of pitch bending, and tested against experimental measurements on a real instrument. The model couples reed vibrations, airflow through t...
A physical model for sound production in the harmonica is proposed that is capable of pitch bending, and tested against experimental measurements on a real instrument. The model couples reed vibrations, airflow through the reed openings, and the acoustic resonance on the mouth side of a harmonica hole. By using one of three cylindrical tubes with different diameters as a resonator, time-domain simulations are conducted while the tube length is varied. The simulations successfully reproduce blow bending at hole 7 of a 10-hole diatonic harmonica, draw bending at hole 4, and overblowing at hole 6. The blow-bending simulation closely matches the experimental results obtained under the same conditions. Using a small-amplitude approximation, the conditions for self-excitation are derived, and the frequencies satisfying these conditions are calculated. The frequencies obtained experimentally, those from simulation, and those predicted by the theoretical analysis-each depending on tube diameter and length-show good agreement. A detailed examination of the sounding conditions further explains that, in the bending simulation, the sound frequency changes continuously with tube length, whereas in the overblow simulation, normal blowing is suddenly transformed into overblowing after a brief silent interval.
Characteristics of flow-induced noise of finite hydrophone array in cavity.
Wu D, Yu M, Shen Q … +3 more , Hu D, Shi K, Bai Z
J Acoust Soc Am · 2026 May · PMID 42138535 · Publisher ↗
In this study, based on the prediction of the noise-field response of a ship sonar array, a computational model for the power-spectral-density function of a finite hydrophone array response under sonar-cavity noise field...
In this study, based on the prediction of the noise-field response of a ship sonar array, a computational model for the power-spectral-density function of a finite hydrophone array response under sonar-cavity noise field is established, targeting a sonar cavity formed by combining a rectangular cavity and an elastic plate. The calculation results indicate that when the finite hydrophone size is larger than the half-wavelength of the acoustic wave, the corresponding high-frequency-response spectrum level of the hydrophone decreases. Furthermore, as the hydrophone size and frequency increase, the hydrophone response spectrum level decreases. When the sensing area of the hydrophone array remains constant, an increase in the number of hydrophone array elements decreases the hydrophone array response spectrum level. A full-scale model test is conducted in a large cavitation channel for a rectangular hydrophone array model within a rectangular cavity. The calculated and tested noise-field response spectrum levels of the finite hydrophone array under medium to high ship speeds are found to be well-correlated.
End-to-end prediction of underwater sound field based on Fourier neural operator in variable sound speed profile environmenta).
Zhang Y, Wang Y, Tu H … +1 more , Wang Z
J Acoust Soc Am · 2026 May · PMID 42138534 · Publisher ↗
Underwater sound field prediction conventionally relies on numerically solving the Helmholtz equation, which is computationally expensive and struggles to meet real-time requirements. This study presents the shallow wate...
Underwater sound field prediction conventionally relies on numerically solving the Helmholtz equation, which is computationally expensive and struggles to meet real-time requirements. This study presents the shallow water Fourier neural operator (SWFNO), an end-to-end model based on the Fourier neural operator, for the rapid and accurate prediction of the amplitude and phase of two-dimensional underwater sound fields in shallow water environments with variable sound speed profiles (SSPs). To enhance the model's generalization capability, we design a hybrid sample generation scheme combining Gaussian random fields with simulated shallow water SSPs, constructing a training dataset that balances randomness and physical plausibility. Simulation results demonstrate that SWFNO achieves high sound field prediction accuracy on both test sets and generalization datasets containing actual ocean SSPs, demonstrating its robustness to out-of-distribution samples. Furthermore, the model exhibits super-resolution prediction capability, enabling high-resolution sound field prediction without retraining, and achieves a speedup of over an order of magnitude compared to the traditional spectral method for large-scale samples. These results indicate that SWFNO is an efficient and accurate surrogate model for underwater acoustic propagation, offering a promising route toward real-time, high-fidelity, and intelligent sound field prediction in complex marine environments.
A deep-sea passive ranging method for vertical double hydrophones based on equivalent bottom-reflection depth.
Qin Y, Mei J, Shen L … +1 more , Sun D
J Acoust Soc Am · 2026 May · PMID 42138533 · Publisher ↗
Passive ranging of sound sources in deep water has attracted considerable attention. This paper presents a passive ranging method using vertical double hydrophones, which estimates the range of near-surface sources based...
Passive ranging of sound sources in deep water has attracted considerable attention. This paper presents a passive ranging method using vertical double hydrophones, which estimates the range of near-surface sources based on the time delay between direct and bottom-reflection paths. Traditional methods commonly assume a stable seafloor reflection structure and use the visible seafloor depth directly. However, low-frequency sound penetration into the seabed and sub-bottom sound speed variations lead to an uncertain effective reflection interface and degraded ranging accuracy. To overcome this problem, we introduce and estimate an equivalent reflection depth to replace the actual seafloor depth in the ranging model. The proposed method is verified by numerical simulations and a sea experiment in the South China Sea, and parametric analyses are also conducted. Experimental results show that the estimated source ranges agree well with the ground truth, demonstrating the effectiveness of the method.
A model for a lipid-coated microbubble based on transient network theory.
Alnajar BM, Sridhar SL, Borden MA … +2 more , Vernerey FJ, Calvisi ML
J Acoust Soc Am · 2026 May · PMID 42138532 · Publisher ↗
Encapsulated microbubbles (EMBs) are widely used to enhance contrast in ultrasound sonography and are increasingly applied in biomedical therapies, such as drug/gene delivery and tissue ablation. EMBs consist of a gas co...
Encapsulated microbubbles (EMBs) are widely used to enhance contrast in ultrasound sonography and are increasingly applied in biomedical therapies, such as drug/gene delivery and tissue ablation. EMBs consist of a gas core enclosed by a stabilizing shell made of various materials, including polymers, lipids, and proteins. Lipid-coated EMBs are challenging to model due to their large oscillations and nonlinear, viscoelastic properties. We propose a lipid-coated, spherical EMB model that simulates the encapsulating material using a statistically based continuum theory based on transient networks. The use of transient network theory enables local calculation of the viscoelastic properties of the encapsulation, including stress, elastic energy, and entropy, based on lipid-molecular configurations. The model depends on five physically grounded parameters: optimum lipid area, maximum bonds per lipid, buckling radius, and lipid association and dissociation rates. The model accurately replicates the experimentally measured natural frequency and radial response of ultrasonically driven, lipid-coated microbubbles. It also captures experimentally observed nonlinear responses, such as "compression-dominated" and "expansion-dominated " behavior, and provides a mechanistic explanation in terms of lipid bond kinetics. Furthermore, the model can be readily extended to nonspherical EMB deformations, which are essential in many biomedical applications.
Assessment of time reversal acoustic focusing in a water pipe with relevance to biofouling control.
Stone AK, Waters TP
J Acoust Soc Am · 2026 May · PMID 42138531 · Publisher ↗
The proliferation of invasive mussel species in water-intake pipelines presents a major challenge for many industries, typically addressed through chemical or mechanical methods. In this work, an alternative acoustic del...
The proliferation of invasive mussel species in water-intake pipelines presents a major challenge for many industries, typically addressed through chemical or mechanical methods. In this work, an alternative acoustic delivery approach is assessed, based on time-reversal focusing in a rigid-walled, water-filled duct. Higher-order modes above cut-on are dispersive, causing broadband pulses to lose peak amplitude over distance through temporal spreading. Numerical simulations using a modal expansion model show that time reversal can instead exploit this dispersive behavior to refocus energy at a chosen location on the pipe wall. Under lightly damped conditions, time-reversal excitation yields impulsive acoustic pressure peaks exceeding 40 times those achieved by single-frequency excitation, with elevated pressures extending over a sizeable region around the focal point. Peak pressure is used here as a representative acoustic metric while acknowledging that the dominant biological mechanism for antifouling remains uncertain. By adjusting the focal waveform duration, a trade-off is demonstrated between peak pressure and pulse repetition frequency, indicating flexibility in how acoustic exposure may be delivered. Although real pipelines exhibit fluid-structure coupling and higher damping, these results help assess the potential of dispersive focusing for acoustic antifouling applications.
Acoustic bianisotropy in a subdivided meta-layer.
Hart CR, Muhlestein MB, Best CM … +2 more , Blevins MG, Wilson DK
J Acoust Soc Am · 2026 May · PMID 42138530 · Publisher ↗
Willis materials are a class of metamaterials exhibiting momentum-strain coupling. Asymmetry at the microscopic level and nonlocal effects at the mesoscale level give rise to Willis coupling, which is a form of acoustic...
Willis materials are a class of metamaterials exhibiting momentum-strain coupling. Asymmetry at the microscopic level and nonlocal effects at the mesoscale level give rise to Willis coupling, which is a form of acoustic bianisotropy. Resonant Willis meta-layers incorporate resonators into an isolated element to effectively obtain Willis coupling over a narrow frequency band. By subdividing a meta-layer into multiple resonator shapes, Willis coupling can be obtained over multiple frequency bands. A finite subdivision rule yields self-similar resonator shapes, which translates into resonance frequencies exhibiting a power-law dependence. Furthermore, manipulation of the internal asymmetry allows for tuning of the Willis coupling. This article reports on the measurement and modeling of resonant Willis meta-layers having parallel resonators. Measurements are obtained with a transmission impedance tube, and predictions are based on a lumped-element analysis. With resonator shapes based on subdivisions of the equilateral triangle, Willis coupling is obtained over several frequency bands in the range of 500-1500 Hz. For a subset of the resonators, Willis coupling is tuned by mirroring the asymmetric location of some resonator necks across the element's midplane. Directionally dependent acoustic absorption is observed, along with tuning of the absorption curves by introducing non-uniformity to the internal sample asymmetry.
Wave equation-informed generative networks for the design of speech recognition acoustic materials.
Wu H, Liu Y, Zhang H
J Acoust Soc Am · 2026 May · PMID 42138529 · Publisher ↗
The inverse problem of designing materials to achieve desired acoustic functionality while strictly adhering to acoustic principles remains an unresolved scientific challenge. This work introduces a generative adversaria...
The inverse problem of designing materials to achieve desired acoustic functionality while strictly adhering to acoustic principles remains an unresolved scientific challenge. This work introduces a generative adversarial network based on the wave equation (Wave-GAN), in which the governing equation is directly embedded into the training process to iteratively optimize the material density distribution. The physics-guided framework enables the model to learn acoustic patterns directly from sound and generate material distributions with specified functionalities. As a verification example, a speaker recognition task was conducted. The results demonstrate that Wave-GAN produces physically consistent materials, achieving a recognition accuracy of 95.6%. This opens a promising direction for fully physics-driven material design at the interface of acoustics and machine learning.
Continuous forecasting of range-dependent ocean sound speed field: Diffusion model meets multi-output Gaussian process.
Gao C, Li S, Cheng L … +3 more , Zhang T, Li J, Gerstoft P
J Acoust Soc Am · 2026 May · PMID 42138528 · Publisher ↗
Environment-aware underwater acoustic detection and communication require precise forecasting of the range-dependent sound speed field (SSF) at any given time. Recently, methods such as Gaussian process regression (GPR)...
Environment-aware underwater acoustic detection and communication require precise forecasting of the range-dependent sound speed field (SSF) at any given time. Recently, methods such as Gaussian process regression (GPR) and conditional diffusion models have shown advanced performance in SSF forecasting. However, limitations remain: standard GPR fails to capture the range-depth spatial correlations, and conditional diffusion models struggle with continuous forecasting. To address these issues, we integrate multi-output GPR and conditional diffusion models to enable continuous forecasting of range-dependent SSFs, employing careful designs for diffusion noise, neural architecture, and training strategies. Our experiments, conducted on HYCOM hindcast datasets from the South China Sea, demonstrate that our proposed model outperforms state-of-the-art baselines in forecasting range-dependent SSFs at any given time and the associated underwater transmission losses.
Listening with: Minds, machines, milieux, and music (L)a).
Thoret E, Lostanlen V
J Acoust Soc Am · 2026 May · PMID 42133803 · Publisher ↗
Human auditory ecology extends psychoacoustics beyond controlled stimuli to the complex realities of soundscapes, ecoacoustics, and musical practices. From Schafer's soundscape studies to ecoacoustic monitoring, research...
Human auditory ecology extends psychoacoustics beyond controlled stimuli to the complex realities of soundscapes, ecoacoustics, and musical practices. From Schafer's soundscape studies to ecoacoustic monitoring, researchers have shown how sonic environments reveal ecological processes and shape human perception and culture. Listening has been richly theorized across sound studies, music studies, and ecological approaches to perception, yet these perspectives remain unevenly integrated into hearing science, ecoacoustics, and computational and creative practices. In this Letter, we focus on human listening and argue that understanding it requires jointly considering four interdependent dimensions: minds (embodied perceptual and cognitive grounding), machines (technologies of capture, analysis, and transformation), milieux (ecological, cultural, and political embedding), and music (culturally organized forms of sound).
Wind-dependent and traffic-generated noise in marine mammal habitat: Assessment across three frequency bands in the St. Lawrence estuary.
Mérindol J, Gervaise C, Mercure-Boissonnault P … +2 more , St-Onge G, Cauchy P
J Acoust Soc Am · 2026 May · PMID 42133802 · Publisher ↗
Underwater sound is crucial for cetaceans, aiding behaviors such as foraging, communication, navigation, and reproduction. The St. Lawrence Estuary (eastern Canada), a key habitat for several cetacean species, also serve...
Underwater sound is crucial for cetaceans, aiding behaviors such as foraging, communication, navigation, and reproduction. The St. Lawrence Estuary (eastern Canada), a key habitat for several cetacean species, also serves as a major shipping corridor connecting the Great Lakes to the Atlantic Ocean, which exposes marine mammals to elevated levels of anthropogenic noise. Given the threatened status of species such as the blue whale (Balaenoptera musculus) and the beluga whale (Delphinapterus leucas), quantifying underwater noise and identifying its sources is essential for effective conservation. This study, conducted within the framework of the MARS (Marine Acoustic Research Station) project, analyzes acoustic data recorded from August to October 2021 in the Laurentian Channel. A model was developed to classify and quantify wind- and shipping traffic-generated noise across three biologically relevant frequency bands: 50, 300, and 6300 Hz. Results show that at 50 Hz, used by blue whales, traffic noise dominates nearly 100% of the time. At 6300 Hz, used by belugas, traffic noise accounts for 24.4% of the measured levels. These findings emphasize the importance of frequency- and species-specific assessments to inform mitigation strategies and support the development of sustainable marine traffic policies.
Needle and capsule hydrophone directivity, effective element size, and signal distortions in sub-megahertz ultrasound fields.
Xu R, Martin E
J Acoust Soc Am · 2026 May · PMID 42133460 · Publisher ↗
There is substantial interest in sub-megahertz ultrasound fields for therapeutic applications. Hydrophones with sensor apertures that are small compared to the wavelength are used to minimise spatial averaging in field c...
There is substantial interest in sub-megahertz ultrasound fields for therapeutic applications. Hydrophones with sensor apertures that are small compared to the wavelength are used to minimise spatial averaging in field characterisation, but data on effective aperture size are limited at these frequencies. This study presents measured directivity and effective element size of capsule and needle hydrophones at 200-500 kHz. Directivity depends on hydrophone structure, and effective element sizes can be many times larger than the nominal size. Internal reflections cause interference in some cases, creating directional sensitivity fluctuations at non-normal incident angles. These findings will help increase accuracy of sub-megahertz field characterisation.
Increasing ultrasound field-of-view with reduced element count arrays containing large elements.
Gardner M, Miller RJ, Oelze ML
J Acoust Soc Am · 2026 May · PMID 42133459 · Publisher ↗
Several applications of medical ultrasound can benefit from a larger field of view (FOV). This study is aimed at increasing the FOV of linear array probes by increasing the element width. Coupled elements were used to im...
Several applications of medical ultrasound can benefit from a larger field of view (FOV). This study is aimed at increasing the FOV of linear array probes by increasing the element width. Coupled elements were used to imitate a larger element width. Through Fourier analysis, theoretical pressure amplitudes, and bandwidth estimates, coupled elements are shown to be close approximations of large elements. The effects of coupling on resolution, contrast, and speckle signal-to-noise ratio are investigated through phantom images and in vivo images of a rabbit tumor reconstructed with plane wave compounding. Furthermore, a positioning system was used to acquire data from a virtual large aperture with 120 mm FOV and 128 elements, collected in sections with a single probe. The null subtraction imaging (NSI), sign coherence factor, and minimum variance (MV) beamformers are compared for regaining resolution lost by an increased F-number. The NSI beamformer decreased full-width at half-max estimates of wire targets by 79% with coupling by 2 compared to uncoupled DAS. The MV beamformer was best for maintaining speckle statistics while improving resolution. Our results demonstrate how increased element width can increase FOV with no increase to element count.
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