Acoustic Mapping Research Articles

An Inverse Method Using Cross-Spectral Matrix Fitting for Passive Cavitation Imaging.

High-intensity focused ultrasound (HIFU) can produce cavitation, which requires monitoring for specific applications such as sonoporation, targeted drug delivery, or histotripsy. Passive acoustic mapping has been proposed in the literature as a method for monitoring cavitation, but it lacks spatial resolution, primarily in the axial direction, due to the absence of a time reference. This is a common issue with passive imaging compared to standard pulse-echo ultrasound. In order to improve the axial resolution, we propose an adaptation of the cross spectral matrix fitting (CMF) method for passive cavitation imaging, which is based on the resolution of an inverse problem with different regularizations that promote sparsity in the reconstructed cavitation maps: Elastic Net (CMF-ElNet) and sparse Total Variation (CMF-spTV). The results from both simulated and experimental data are presented and compared to state-of-the-art approaches, such as the frequential delay-and-sum (DAS) and the frequential robust capon beamformer (RCB). We show the interest of the method for improving the axial resolution, with an axial full width half maximum (FWHM) divided by 3 and 5 compared to RCB and DAS, respectively. Moreover, CMF-based methods improve contrast-to-noise ratio (CNR) by more than 15 dB in experimental conditions compared to RCB. We also show the advantage of the sparse Total Variation (spTV) prior over Elastic Net (ElNet) when dealing with cloud-shaped cavitation sources, that can be assumed as sparse grouped sources.

Component-wise regression sound source models for the aircraft noise prediction framework J-FRAIN

In this study, we created sound source models for a newly developed simulation framework named 'J-FRAIN' that can accurately predict the time histories of noises from each major aircraft noise-generating component at ground observation points during the landing approach phase. Sound source distributions of more than twenty types of jet transport aircraft have been measured in flight using a microphone array deployed under the final approach path to an airport. In this paper, the Boeing 787-8 is presented as an example for modeling. The sound powers of each aircraft component - engines, landing gear, and high-lift devices - were calculated quantitatively from the domain integration of the measured acoustic maps. Then, component-wise regression sound source models were created based on the relationship between engine rotational speed, airspeed, and deployment angle of high-lift devices. The models were implemented in the 'J-FRAIN' simulation framework that integrates a sound propagation model. The predicted time histories of ground noise were compared with measurement results from a single microphone placed at the center of the microphone array, and were found to be in good agreement.

High-resolution acoustic field mapping of gigahertz phononic crystals with atomic force microscopy

High-resolution acoustic field mapping of gigahertz phononic crystals with atomic force microscopy

Acoustic corner state transfer mapping to synthetic higher-order topological semimetal

Acoustic corner state transfer mapping to synthetic higher-order topological semimetal

Weighted block ℓ1 norm induced 2D off-grid compressive beamforming for acoustic source localization: Methodology and applications

Identifying acoustic sources with high spatial resolution and precision is significant for machinery noise control. Off-grid compressive beamforming is an effective method for creating acoustic maps with a high spatial resolution. In this study, a two-dimensional off-grid compressive beamforming method via weighted block ℓ1 norm regularization (WBS-OCSBF) is proposed. The weighted ℓ1 norm offers a more uniform sparsity penalty compared to the ℓ1 norm. This method can enhance the performance of off-grid compressive beamforming. Additionally, it is easily implemented on mature linear programming solvers and converges with only a few iterations. Numerical simulations are conducted to analyze the effects of several major parameters on the performance of the proposed method. The simulation results demonstrate the superiority of the proposed method over some traditional methods. The proposed method is then validated using a loudspeaker noises localization experiment. A gearbox transmission system and a transformer are used as two specific objects to explore the industrial application value. The proposed method can effectively localize the gear meshing noise and transformer discharge faults with a high spatial resolution.

A Feasibility Study for a Hand-Held Acoustic Imaging Camera

Acoustic imaging systems construct spatial maps of sound sources and have potential in various applications, but large, cumbersome form factors limit their adoption. This paper investigates methodologies to miniaturize acoustic camera systems for improved mobility. Our approach optimizes planar microphone array design to achieve directional sensing capabilities on significantly reduced footprints compared to benchmarks. The current prototype utilizes a 128−microphone, 50 × 50 cm2 array with beamforming algorithms to visualize acoustic fields in real time but its stationary bulk hampers portability. We propose minimizing the physical aperture by carefully selecting microphone positions and quantities with tailored spatial filter synthesis. This irregular array geometry concentrates sensitivity toward target directions while avoiding aliasing artefacts. Simulations demonstrate a 32−element, ≈20 × 20 cm2 array optimized this way can outperform the previous array in directivity and noise suppression in a sub-range of frequencies below 4 kHz, supporting a 4× surface factor reduction with acceptable trade-offs. Ongoing work involves building and testing miniature arrays to validate performance predictions and address hardware challenges. The improved mobility of compact acoustic cameras could expand applications in car monitoring, urban noise mapping and other industrial fields limited by current large systems.

Acoustic Characteristics Analysis of Double-Layer Liquid-Filled Pipes Based on Acoustic–Solid Coupling Theory

Based on the theory of acoustic–solid coupling, the phase velocity-thickness product of a double-layer liquid-filled pipeline is analyzed, and the dispersion relationship between angular frequency and wavenumber–thickness product is analyzed, providing a theoretical basis for ultrasonic guided wave detection. The wave number analytical expression of the double-layer liquid-filled pipeline is constructed, and the dispersion relationship of the double-layer liquid-filled pipeline under different frequency–thickness products and wavenumber–thickness products is calculated through parameter scanning. The dispersion curves of the double-layer liquid-filled pipeline are numerically analyzed in the domains of pressure acoustics, solid mechanics, and acoustic–solid coupling. The numerically simulated dispersion curves show high consistency with the analytically calculated dispersion curves. The analysis of the phase velocity frequency–thickness product indicates that the axial mode dispersion curves of the pipe wall decrease with the increase in frequency–thickness product in the coupling domain, and then tend to be flat and intersect with the radial mode dispersion curves in the coupling domain; these intersection points cannot be used for ultrasonic guided wave detection. The T(0,1) mode dispersion curve in the coupling domain of the pressure acoustics domain remains smooth from low frequency to high frequency. It is found that the dispersion curves of the phase velocity frequency–thickness product, angular frequency wavenumber–thickness product, and the acoustic pressure distribution map of the double-layer liquid-filled pipeline based on acoustic–solid coupling can provide theoretical support for ultrasonic guided wave detection of pipelines.

Bottom-trawling signals lost in sediment: A combined biogeochemical and modeling approach to early diagenesis in a perturbed coastal area of the southern Baltic Sea

Trawl-fishing is broadly considered to be one of the most destructive anthropogenic activities toward benthic ecosystems. In this study, we examine the effects of bottom-contact fishing by otter trawls on the geochemistry and macrofauna in sandy silt sediment in an area of the Baltic Sea where clear spatial patterns in trawling activity were previously identified by acoustic mapping. We calibrated an early diagenetic model to biogeochemical data from various coring locations. Fitting measured mercury profiles allowed for the determination of the sediment mixing and burial velocity. For all sites, independent of the trawl mark density, good fits were obtained by applying the model with the same organic matter loading and parameter values, while iron fluxes scaled linearly with the burial velocity. A sensitivity analysis revealed that the fitted sulfate reduction rate, solid sulfur contents, ammonium concentration, and both the isotopic composition and concentration of dissolved inorganic carbon provided reliable constraints for the total mineralization rate, which exhibited a narrow range of variability (around ±20 % from the mean) across the sites. Also, the trawling intensity did not significantly correlate with total organic carbon contents in surficial sediment, indicating limited loss of organic matter due to trawling. The fits to the reactive iron, acid volatile sulfur, chromium(II) reducible sulfur contents, and porewater composition demonstrate that sediment burial and mixing primarily determine the redox stratification. The mixing depth did not correlate with trawling intensity and is more likely the result of bioturbation, as the analyzed macrofaunal taxonomy and density showed a high potential for sediment reworking. The extraordinarily long-lived Arctica islandica bivalve dominated the infaunal biomass, despite the expectation that trawling leads to the succession from longer-lived to shorter-lived and bigger to smaller macrofauna. Our results further suggest that a clear geochemical footprint of bottom-trawling may not develop in sediments actively reworked by tenacious macrofauna.

On the acoustics of “Argentina” and “Costanzi” Opera Houses in Rome by means of 3-D maps representation

The acoustics of Italian-style Opera Houses has been widely studied in the last 30 years, especially after the burning of the Teatro La Fenice in Venice in 1996. Starting from that disaster, the acoustics of these important buildings became a priority, especially for storing as much information about their acoustics as possible. The recent war events in Ukraine have underlined the importance of these acoustics for a proper reconstruction of theaters, and especially Oper Houses. This paper analyzes the acoustics of the two most important opera houses located in Rome, i.e., the “Teatro Argentina” and the “Teatro Costanzi” (also called “Teatro dell'Opera"). Both the theaters are located in the very city center of Rome and have a strong artistic activities. In both the cases, no info about their acoustics are available among the scientific community. This paper describes the most important results obtained measuring their acoustics using monoaural, binaural b-format microphones. Moreover, in order to determine 3-D acoustic maps, an EM32 Microphone from MHAcoustics was used for capturing sparial RIRs and mapping early reflection in a 360 pictures.

Optimizing transducer aperture subdivision for aberration correction during transabdominal histotripsy

This study investigated the effect of transducer aperture subdivision on aberration correction performance for transabdominal histotripsy. A transducer aperture and geometric curvature similar to clinical histotripsy devices (750 kHz, 20 × 16 cm width, 14 cm radius of curvature) was subdivided into 64, 256, and 1024 elements (10.7λ, 5.3λ, 2.6λ). For each of the three designs, optimal space filling (100%) equal area polygons with a pseudo-random arrangement of elements was used following the technique described by Rosnitskiy. 3D acoustic path maps were constructed from abdominal CTs of 3 de-identified human subjects and assigned acoustic properties from literature. For each transducer, acoustic transmission was simulated using k-Wave at 3 target locations in the liver of each subject with and without implementing ideal aberration correction. Across all subjects and targets (n = 9), AC increased the maximum focal pressure amplitude by 26% (0%-59%) on average for 64 elements, 38% (5%-84%) for 256 elements, and 42% (7%–92%) for 1024 elements. These results suggest 5.3λ elements may near an optimal subdivision for transabdominal histotripsy aberration correction when taking into account the cost of transducer and driving system fabrication. Acoustic simulations can save fabrication time and costs when optimizing device design.

Real-Time Passive Acoustic Mapping With Enhanced Spatial Resolution in Neuronavigation-Guided Focused Ultrasound for Blood-Brain Barrier Opening.

Passive acoustic mapping (PAM) provides the spatial information of acoustic energy emitted from microbubbles during focused ultrasound (FUS), which can be used for safety and efficacy monitoring of blood-brain barrier (BBB) opening. In our previous work with a neuronavigation-guided FUS system, only part of the cavitation signal could be monitored in real time due to the computational burden although full-burst analysis is required to detect transient and stochastic cavitation activity. In addition, the spatial resolution of PAM can be limited for a small-aperture receiving array transducer. For full-burst real-time PAM with enhanced resolution, we developed a parallel processing scheme for coherence-factor-based PAM (CF-PAM) and implemented it onto the neuronavigation-guided FUS system using a co-axial phased-array imaging transducer. Simulation and in-vitro human skull studies were conducted for the performance evaluation of the proposed method in terms of spatial resolution and processing speed. We also carried out real-time cavitation mapping during BBB opening in non-human primates (NHPs). CF-PAM with the proposed processing scheme provided better resolution than that of traditional time-exposure-acoustics PAM with a higher processing speed than that of eigenspace-based robust Capon beamformer, which facilitated the full-burst PAM with the integration time of 10 ms at a rate of 2 Hz. In vivo feasibility of PAM with the co-axial imaging transducer was also demonstrated in two NHPs, showing the advantages of using real-time B-mode and full-burst PAM for accurate targeting and safe treatment monitoring. This full-burst PAM with enhanced resolution will facilitate the clinical translation of online cavitation monitoring for safe and efficient BBB opening.

Ultrasound imaging of lung disease and its relationship to histopathology: An experimentally validated simulation approach.

Lung ultrasound (LUS) is a widely used technique in clinical lung assessment, yet the relationship between LUS images and the underlying disease remains poorly understood due in part to the complexity of the wave propagation physics in complex tissue/air structures. Establishing a clear link between visual patterns in ultrasound images and underlying lung anatomy could improve the diagnostic accuracy and clinical deployment of LUS. Reverberation that occurs at the lung interface is complex, resulting in images that require interpretation of the artifacts deep in the lungs. These images are not accurate spatial representations of the anatomy due to the almost total reflectivity and high impedance mismatch between aerated lung and chest wall. Here, we develop an approach based on the first principles of wave propagation physics in highly realistic maps of the human chest wall and lung to unveil a relationship between lung disease, tissue structure, and its resulting effects on ultrasound images. It is shown that Fullwave numerical simulations of ultrasound propagation and histology-derived acoustical maps model the multiple scattering physics at the lung interface and reproduce LUS B-mode images that are comparable to clinical images. However, unlike clinical imaging, the underlying tissue structure model is known and controllable. The amount of fluid and connective tissue components in the lung were gradually modified to model disease progression, and the resulting changes in B-mode images and non-imaging reverberation measures were analyzed to explain the relationship between pathological modifications of lung tissue and observed LUS.

Shift-variant deconvolution beamforming using Implicit Neural Representation for near-field acoustic image measurement

The conventional beamforming (CBF) output can be expressed as a convolution of the source distribution and the array dependent point spread function (PSF), which is defined as the response of the beamformer to a point source. The resolution and accuracy of sound source localization can be improved by deconvolution of CBF. The shift-invariant PSF assumption is only a good approximation when the source region is small compared to the distance between the array and the source. However, the PSF of the near-field underwater acoustic map measurement is shift-variant, whose mismatch with the beam could lead to performance degradation. In this paper, we proposed an optimized deconvolution method by using the neural network called implicit neural representation (INR) to solve the beam mismatch problem, due to its strong performance in learning and reconstructing spatial scenes. Rather than recompute the PSF for each pixel in the scene, INR predicts the complex-valued weight matrix in two-dimensional space that encapsulates both the spatially varying properties of the PSF and the scatter distribution of the scene. Numerical simulations and experimental results verify the effectiveness of our method. And this work can be broadly applied to arrays with shift-variant PSFs.

Investigation of spatio-temporal inertial cavitation activity for optimization of needle-free ultrasound-enhanced vaccine delivery

Ultrasound-induced cavitation is a promising mechanism for pain-free delivery of vaccines without needles. However, the relationships between cavitation energy and the various bioeffects involved in transdermal vaccination, including skin permeabilization, convective drug transport, reversible and irreversible sonoporation, and immune-stimulation, are not well understood. Previous transdermal ultrasound experiments have demonstrated inhomogeneous delivery across the exposed surface, which remains poorly understood. In this work, we first seek to fully characterize and quantify spatio-temporal cavitation activity across the skin surface, to identify a local cavitation dose that is optimal for all four key bioeffects. We have designed a new in vitro experimental setup that exposes several potential skin models to 265 kHz focused ultrasound, a new generation of protein-based cavitation nuclei (pCaNs), and a fluorescently labelled vaccine analogue, while simultaneously imaging cavitation activity parallel to the skin surface by Passive Acoustic Mapping (PAM). Subsequent staining and multi-photon microscopy of the skin models allows a direct comparison between the PAM-derived spatiotemporal inertial cavitation dose and locations where particular bioeffects were maximized. We will discuss the results of this investigation, how they relate to our recent in vivo study, and whether these findings enable enhancements of the spatial homogeneity and reproducibility of needle-free ultrasound vaccination.

Comparison of simultaneous auscultation and ultrasound for clinical assessment of bowel peristalsis in neonates.

Assessment of bowel health in ill preterm infants is essential to prevent and diagnose early potentially life-threatening intestinal conditions such as necrotizing enterocolitis. Auscultation of bowel sounds helps assess peristalsis and is an essential component of this assessment. We aim to compare conventional bowel sound auscultation using acoustic recordings from an electronic stethoscope to real-time bowel motility visualized on point-of-care bowel ultrasound (US) in neonates with no known bowel disease. This is a prospective observational cohort study in neonates on full enteral feeds with no known bowel disease. A 3M™ Littmann® Model 3200 electronic stethoscope was used to obtain a continuous 60-s recording of bowel sounds at a set region over the abdomen, with a concurrent recording of US using a 12l high-frequency Linear probe. The bowel sounds heard by the first investigator using the stethoscope were contemporaneously transferred for a computerized assessment of their electronic waveforms. The second investigator, blinded to the auscultation findings, obtained bowel US images using a 12l Linear US probe. All recordings were analyzed for bowel peristalsis (duration in seconds) by each of the two methods. We recruited 30 neonates (gestational age range 27-43 weeks) on full enteral feeds with no known bowel disease. The detection of bowel peristalsis (duration in seconds) by both methods (acoustic and US) was reported as a percentage of the total recording time for each participant. Comparing the time segments of bowel sound detection by digital stethoscope recording to that of the visual detection of bowel movements in US revealed a median time of peristalsis with US of 58%, compared to 88.3% with acoustic assessment (p < 0.002). The median regression difference was 26.7% [95% confidence interval (CI) 5%-48%], demonstrating no correlation between the two methods. Our study demonstrates disconcordance between the detection of bowel sounds by auscultation and the detection of bowel motility in real time using US in neonates on full enteral feeds and with no known bowel disease. Better innovative methods using artificial intelligence to characterize bowel sounds, integrating acoustic mapping with sonographic detection of bowel peristalsis, will allow us to develop continuous neonatal bowel sound monitoring devices.

Three-dimensional super resolution ultrasound imaging with a multi-frequency hemispherical phased array.

High resolution imaging of the microvasculature plays an important role in both diagnostic and therapeutic applications in the brain. However, ultrasound pulse-echo sonography imaging the brain vasculatures has been limited to narrow acoustic windows and low frequencies due to the distortion of the skull bone, which sacrifices axial resolution since it is pulse length dependent. To overcome the detect limit, a large aperture 256-module sparse hemispherical transmit/receive array was used to visualize the acoustic emissions of ultrasound-vaporized lipid-coated decafluorobutane nanodroplets flowing through tube phantoms and within rabbit cerebral vasculature in vivo via passive acoustic mapping and super resolution techniques. Nanodroplets were vaporized with 55kHz burst-mode ultrasound (burst length=145μs, burst repetition frequency=9-45Hz, peak negative acoustic pressure=0.10-0.22MPa), which propagates through overlying tissues well without suffering from severe distortions. The resulting emissions were received at a higher frequency (612 or 1224kHz subarray) to improve the resulting spatial resolution during passive beamforming. Normal resolution three-dimensional images were formed using a delay, sum, and integrate beamforming algorithm, and super-resolved images were extracted via Gaussian fitting of the estimated point-spread-function to the normal resolution data. With super resolution techniques, the mean lateral (axial) full-width-at-half-maximum image intensity was 16±3 (32±6)μm, and 7±1 (15±2)μm corresponding to ∼1/67 of the normal resolution at 612 and 1224kHz, respectively. The mean positional uncertainties were ∼1/350 (lateral) and ∼1/180 (axial) of the receive wavelength in water. In addition, a temporal correlation between nanodroplet vaporization and the transmit waveform shape was observed, which may provide the opportunity to enhance the signal-to-noise ratio in future studies. Here, we demonstrate the feasibility of vaporizing nanodroplets via low frequency ultrasound and simultaneously performing spatial mapping via passive beamforming at higher frequencies to improve the resulting spatial resolution of super resolution imaging techniques. This method may enable complete four-dimensional vascular mapping in organs where a hemispherical array could be positioned to surround the target, such as the brain, breast, or testicles.

Localization of cyclostationary acoustic sources via cyclostationary beamforming and its high spatial resolution implementation

The localization of cyclostationary sound sources is important for rotating machinery noise source identification and fault diagnosis. Cyclostationary sound sources are a special class of nonstationary sound sources, which exhibit periodic changes in statistics. Most of the conventional sound source identification methods are based on the stationary sound source assumption, which do not consider the cyclostationarity of the radiated sound field by rotating machinery. Thus, they are hard to localize the acoustic sources with different cyclic frequencies. In this paper, a novel technique of localizing the cyclostationary acoustic sources with different cyclic frequencies is proposed. First, the cyclostationary conventional beamforming (CSCBF) method is deviated. In CSCBF, the cyclic-cross-spectral matrix (CCSM) is defined considering all the cross cyclic spectral correlation (CSC) between different microphones in the array. The left steering vector and right steering vector are constructed to focus the CCSM on each scanning grid point at a given combination of cyclic frequency and spectral frequency. Then, the high resolution cyclostationary beamforming (HR-CSBF) is further developed to improve the spatial resolution of CSCBF. In HR-CSBF, two linear equations according to the property of CSC is established as the acoustic inverse problems. With the sparse distribution of the cyclostationary sources in the space as the prior knowledge, the iterated Bayesian focusing (IBF) is utilized to obtain a robust and sparse solution in HR-CSBF. Numerical simulations and experiments are conducted to validate the proposed methods. To explore the potential applications of the proposed methods, the localization of high pressure pump (HPP) and rolling bearing with outer-race failure are also used to evaluate the effectiveness of the proposed methods. It turns out that both CSCBF and HR-CSBF can localize the cyclostationary sources with different cyclic frequencies. Compared with CSCBF, HR-CSBF can achieve a higher spatial resolution in the obtained acoustic map.

Experimental Investigation of Helicopter Noise While Approaching an Elevated Helipad

The present paper describes a test campaign performed to investigate the noise footprint emitted by a helicopter in an idealised urban context, reproducing the approach to an elevated helipad. The test campaign was performed in Politecnico di Milano’s anechoic chamber and was finalised to investigate the effects produced only by helicopter noise. The set up consisted of a two-blade main rotor helicopter model and an aluminium rectangular prism model reproducing the landing building. Ground observer perceptions were recorded by means of a surface microphone and a realistic landing trajectory was approximated as a succession of fixed point measurements. Collected data were analysed through acoustic spectra and sound maps. Spectra were used to comprehend physical phenomena, such as reflection, diffraction and shielding, and to analyse the different contributions of helicopter noise. A sound map analysis enabled us to obtain a global perspective of the involved phenomena and to understand th extent to which people close to a building are stressed by a helicopter approaching an elevated urban helipad. Moreover, the experimental database, obtained over a free geometry, can be considered a useful tool for the validation of aeroacoustic solvers with different levels of fidelity.

Improved source localization in passive acoustic mapping using delay-multiply-and-sum beamforming with virtually augmented aperture

High-intensity focused ultrasound (HIFU) is a promising non-invasive treatment method whose applications include tissue ablation, hemostasis, thrombolysis and blood–brain barrier opening etc. Its therapeutic effects come from the thermal necrosis and the mechanical destruction associated with acoustic cavitation. Passive acoustic mapping (PAM) is capable of simultaneous monitoring of HIFU-induced cavitation events using only receive beamforming. Nonetheless, conventional time exposure acoustics (TEA) algorithm has poor spatial resolution and suffers from the X-shaped artifacts. These factors lead to difficulties in precise localization of cavitation source. In this study, we proposed a novel adaptive PAM method which combines Delay-Multiply-and-Sum (DMAS) beamforming with virtual augmented aperture (VA) to overcome the problem. In DMAS-VA beamforming, the magnitude of each channel waveform is scaled by p-th root while the phase is multiplied by L. The p and L correspond respectively to the degree of signal coherence in DMAS beamforming and the augmentation factor of aperture size. After channel sum, p-th power is applied to restore the dimensionality of source strength and then the PAM image is reconstructed by accumulating the signal power over the observation time. Based on simulation and experimental results, the proposed DMAS-VA has better image resolution and image contrast compared with the conventional TEA. Moreover, since the VA method may introduce grating lobes into PAM because of the virtually augmented pitch size, DMAS coherent factor (DCF) is further developed to alleviate these image artifacts. Results indicate that, with DCF weighting, the PAM image of DMAS-VA beamforming could be constructed without detectable image artifacts from grating lobes and false main lobes.

Soundscapes of Urban Parks in Cities with Populations of Over 100,000 in the Silesian Voivodeship

The article presents the results of soundscape assessments conducted in urban parks in the Silesian Voivodeship. The Silesian Voivodeship is characterised by a high degree of industrialisation and the greatest population density in Poland. The studies were conducted in the urban parks of all the cities in the voivodeship with populations of over 100,000 citizens. This selection was determined based on acoustic maps that are prepared for cities with populations of over 100,000 citizens as required by law, and on the fact that the role of urban parks is frequently marginalised in the context of city life. The goal of the studies was to define an objective acoustic appeal assessment method for urban parks in city centres. Measurements were carried out in 34 parks located in the centres of 12 cities. A-weighted sound levels LAeq were determined for 107 measuring points in urban parks and the streets adjacent to them. Differences in the A-weighted sound levels LAeq were presented for each studied park and the adjacent streets. Minimum and maximum sound values were subsequently determined for each measuring point. Significant differences in the minimum and maximum sound values in given locations were found despite minor differences in LAeq values. It was also discovered that though parks may often exhibit high A-weighted sound levels LAeq, there are other factors that influence the appeal of park soundscapes.