bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of surface layer and Pacific summer water properties from acoustic transmissions in the Beaufort duct using a tomographic array during 2016–2017
Authors: Colosi John A. , Vazquez Heriberto J. , Cornuelle Bruce , Worcester Peter F. , Dzieciuch Matthew A.
Published: November 2023

The 2016–2017 Canada Basin Acoustic Propagation Experiment (CANAPE) was conducted to assess the effects of the changing Beaufort Gyre on low-frequency underwater acoustic propagation and ambient sound. A 150-km radius ocean acoustic tomography array was deployed with six transceivers and a distributed vertical line array (DVLA) measuring the impulse responses every four hours with broadband signals centered from 172.5 to 275 Hz. The nominal transceiver source depth was 175-m, placing them near the Beaufort duct axis, and the 60 hydrophone DVLA spanned 50 to 600 m. The Beaufort duct (approximately 90-m to 240-m depth) and the surface layer (approximately 0 to 90-m depth) form a coupled double-duct system. Observed arrivals in this system show reverse dispersion with the lowest Beaufort duct modes arriving first and higher double duct modes making up a transmission finale. In this talk, we investigate the oceanographic information content contained in the first and last arrivals which are the easiest to detect and track. The first arrival shows fluctuations from eddies, tides/inertial oscillations, and small seasonal heating/cooling. The last arrival shows a strong seasonal heating/cooling signal but is un-trackable during periods of significant ice cover due to enhanced transmission loss.
Recurrence rate spectrograms for impact localization in wood
Authors: Hertrampf Thore , Oberst Sebastian , Sepehrirahnama Shahrokh
Published: November 2023

Characteristics like cellular grain structure, inhomogeneous density, aging, and altering environmental conditions (moisture, temperature) give wood highly anisotropic viscoelastic properties and non-linear vibrational wave propagation properties. Nonlinearity limits the use of linear methods, such as modal analysis and parameter identification via transfer functions. Acoustic localization of natural damage to wood, like crack growth, is of general interest in structural health monitoring of timber structures. Time-difference of arrival or energy attenuation is commonly used for localization, which are prone to boundary reflections or require the frequency response function. Recent advancements in machine learning-based classification of non-linear signals can achieve a much higher accuracy when recurrence rate-based spectrograms are used compared relative to conventional short-time Fourier transforms, especially in the presence of noise. Hence, in this work, multi-sensor measurements of impulse induced vibration in wood beams are classified by their distance to the excitation, based on their time series, avoiding a priori knowledge of a transfer function for the localization. The machine learning model is trained across various widths and thicknesses of samples, giving a localization estimate independent of beam dimensions. This research will contribute to early detection of damage in the field of vibration-based structural health monitoring of wood.
Progress update on inclusion of atmospheric profiling for sonic boom propagation through turbulence
Authors: Kapcsos Joshua L. , Sparrow Victor W.
Published: November 2023

Research continues in the field of sonic boom propagation to aid international efforts in technical standards of civil supersonic aircraft, and simulation is necessary to validate the data produced by up-and-coming demonstration aircraft. Turbulence is important when considering how sonic booms propagate; their effects can be heard at the ground as demonstrated through the SonicBAT project. Current efforts are being made to improve the turbulent sonic boom propagation code KZKFourier to increase accuracy and robustness. This presentation will serve as progress update on including atmospheric profiling in KZKFourier. Previous versions did not have this feature. The inclusion of atmospheric profiling in KZKFourier will allow for quantities such as humidity, density, and temperature to vary within the atmospheric boundary layer. The presentation will discuss both the analytical inclusion of profiling on the Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation methodology and its implementation in the C + + code. [Work supported by the FAA through ASCENT Project 57 under the supervision of Sandy Liu. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA.]
Vibroacoustic response of a cylindrical shell with a multilayered locally resonant coating
Authors: Lin Cikai , Sharma Gyani Shankar , Skvortsov Alex , MacGillivray Ian , Kessissoglou Nicole
Published: November 2023

A multilayered viscoelastic material used as an external coating on a marine vessel for underwater noise control is presented. The multilayered coating is designed using regular distributions of vacuous cavities and hard steel scatterers that yield monopole and dipole scattering responses, respectively. The coating is modelled as an equivalent fluid in which the layers of inclusions are modelled as homogenized layers with some effective properties. The coating is externally applied to a submerged cylindrical shell. Fully coupled fluid–structure interaction between the coated shell and the surrounding water is taken into account. The material and geometric parameters of the inclusions are observed to have a significance influence on the radiated sound from the shell. Different combinations of the material distribution of the inclusions on the vibroacoustic response of the submerged shell are presented, showing that the local resonances of the inclusions can be tuned to reduce the radiated sound in a broad frequency range.
Acoustic cloning
Authors: van Manen Dirk-Jan , Müller Jonas , Becker Theodor , Li Xun , Aichele Johannes , Serra-Garcia Marc , Robertsson Johan
Published: November 2023

Cloning refers to producing copies of objects that cannot be distinguished from the original based on their behavior or response. Here, we present a general methodology to clone objects that scatter acoustic waves and demonstrate it experimentally. We acquire digital twins and bring them back to life—a simple two-step process. First, we place the scattering object in a circular receiver aperture and insonify it from the outside using simple speakers. From the recorded data, which may be reverberative, we retrieve the object's scattering Green's functions for radiation conditions using a technique called multi-dimensional deconvolution. This process recovers the temporal and spatial bandwidth and removes the scattering interactions with the boundaries of the experimentation domain, if present. In the second step, the acoustic scatterer is removed and reconstructed holographically using the acquired scattering Green's functions. The hologram scatters arbitrary incident wavefields in real-time exactly like the original object. Low-latency feedback enables reproducing all orders of wave interactions between physical scatterers and the numerical hologram. The two-step process is demonstrated by cloning several rigid scatterers in a two-dimensional acoustic waveguide. Applications range from fully realistic digital scattering models to efficient meta-material experimentation. [Work supported by SNSF grant 197182.]
Noise reduction in an open structure by tailoring complex impedances on acoustic metasurfaces
Authors: Yang Eunjin , Kim Jiwan , Jeon Wonju
Published: November 2023

In this study, we design acoustic metasurfaces to the inner surfaces of the open structure to mitigate noise emanating through the opening by manipulating complex impedances along unit cells called impedance tiles. The impedance tile is comprised of subwavelength Helmholtz resonators, which have a theoretical model that accurately predicts the effective impedance, considering visco-thermal losses in narrow orifices. By adjusting thegeometrical parameters of these resonators, the surface impedance of the impedance tiles can be finely tuned to minimize noise escaping from the open structure at any desired target frequency. To evaluate the noise reduction performance, the designed metasurfaces were fabricated via 3D printing, and the sound pressure levels (SPLs) were measured before and after applying the metasurfaces inside the open structure. The experimental results show that the λ/31-thick metasurfaces achieve SPL reduction exceeding 12.6 dB at the target frequency of 360 Hz.
The lexical representation of coda /t/ by 14-month-olds
Authors: Khlystova Ekaterina , Sundara Megha
Published: November 2023

We evaluated 14-month-olds’ lexical representation of coda /t/. Pronunciation variation of /t/, one of the most frequent segments in English, is well documented. Crucially, in American English infant-directed speech, /t/s are most often produced as glottal stops. This is particularly the case in word-final position, where words like cat and night are produced as [kæʔ] and [naiʔ] around 42% of the time, but produced with word-final canonical stop consonants (e.g., [kæt] or [nait]) only 25% of the time. In Experiment 1, we found that infants preferred to listen to familiar monosyllabic words ending in glottal stops (like [kæʔ]) when compared to nonce words ([kɪp]). This suggests that infants encode the most frequently occurring variant in their lexical entries. We are now testing whether the preference for familiar words produced with a glottal stop in Experiment 1 is the result of coda underspecification or encoding of glottal stop. If codas are underspecified in infant’s lexical representations, we expect no preference between lists of familiar words with glottal stops ([kæʔ]), compared to minimal pairs with coda mispronunciations ([kæk]). We will discuss implications of these findings for infants’ developing lexical representations and knowledge of allophony, focusing on the contribution of input frequency.
Is secondary stress phonetically real for second-language learners? Evidence from Japanese-accented English
Authors: Yoneyama Kiyoko , Tajima Keiichi , Kitahara Mafuyu
Published: November 2023

Speakers of a non-stress language such as Japanese often have difficulty producing lexical stress distinctions in languages such as English. Distinguishing primary-stressed versus unstressed syllables may be difficult, but distinctions involving secondary stress may be even more challenging. Some studies report that Japanese learners of English (JE) do not distinguish secondary-stressed and unstressed syllables in terms of vowel duration and quality whereas native American English speakers (AE) do. However, the data are limited and inconclusive. To resolve this issue, the present study asked AE and two groups of JE differing in English proficiency to produce 83 English words that exhibit stress shift, e.g., phótogràph-phòtográphic-photógraphy and conducted acoustic analysis of vowels in corresponding positions, which have the same consonantal context but differ in stress level. Preliminary results indicate that JE frequently produce devoiced vowels in unstressed syllables, particularly in phonetic environments similar to where devoicing occurs in Japanese. Devoicing, however, does not seem to occur in secondary-stressed syllables, suggesting that JE might distinguish secondary-stressed and unstressed syllables with respect to devoicing. Results from duration and formant analysis will also be reported and discussed in relation to theories of native-language influences on second-language speech learning. [Work supported by JSPS.]
Visual cues in sound change: A cross-modal perceptual account for the typological rarity of labial palatalization
Authors: Havenhill Jonathan , Du Baichen
Published: November 2023

Auditory perceptibility is widely recognized as a major contributing factor to listener-based sound change. Although speech perception is also known to be influenced by vision, the role of visual cues in facilitating or inhibiting sound change is not well understood. Palatalization of /tʲ/ and /kʲ/ to /tʃ/ is a typologically common change that is frequently attributed to misperception, while full palatalization of labial consonants is exceedingly rare. We test whether visual cues contribute to this asymmetry by way of the visual distinctiveness of labial closure. An audiovisual perception experiment was conducted in which 40 native Korean speakers were presented with synthetically altered tokens along 5-step continua from /pʰ/, /tʰ/, or /kʰ/ to /t?ɕ/ in audio-only, audiovisual-congruent, and audiovisual-incongruent conditions. Acoustic cues to place of articulation, F2 onset, and spectral frequency during aspiration, were manipulated. Results show that presence of the visual lip closure cue significantly inhibited perception of labials as palatals: the /pʰ/-/tɕʰ/ boundary was shifted toward /tɕʰ/ in the AV-congruent group, and labials were more likely to be perceived as palatals in the absence of lip closure. This finding suggests that visual speech cues may contribute to the typological asymmetry and that sound change can be modulated by visual cues.
Using L1 tone and intonation categories to investigate patterns in nonnative tone identification
Authors: Chin Jessica L. , Antoniou Mark
Published: November 2023

Many languages utilise lexical tone, a feature which assigns meaning to words through variations in pitch contours. In some (but not all) cases, prior tone language experience can facilitate the learning of a nonnative tone language. Regardless, multiple sessions of tone training can improve nonnative tone perception for both tone and nontone L1 listeners. However, the influence of L1 tone and intonation categories on nonnative tone learning is underexplored. Across five sessions of tone training, listeners of nontonal English (n = 25), tonal Mandarin (n = 23), and tonal Vietnamese (n = 25) learned tones from an artificial language. While all groups improved in tone identification and tone word learning by session five (p < .001), Mandarin listeners outperformed the other groups overall (identification, p < .001; word learning, p < .05). Tone experience was a main effect only in word learning (p < .05). Tone- and language-specific identification patterns were also observed. The low level tone was easier for all listeners to perceive, while the tonal groups also showed greater accuracy for the mid level tone. Contrastingly, Mandarin listeners were hindered by their single L1 falling tone category when attempting to identify two distinct nonnative falling tones.
Cross-linguistic variability in audiovisual enhancement of coronal consonants
Authors: Havenhill Jonathan , Liu Ming , Zheng Shuang
Published: November 2023

The role of auditory perceptibility in phonological contrast is uncontroversial. In clear speech, speakers increase acoustic distance between contrastive phones, thereby improving perception. Although visual cues are also known to improve perception, it is unclear whether speakers actively enhance their speech for visual perceptibility. 20 native English and 20 native Mandarin speakers participated in a two-part production experiment. Words containing /l d n s r/ (and English /θ/) were elicited, with vowels balanced for height, backness, and rounding. Speakers first recited each word while alone in a soundproof booth. Words were then spoken for a native listener (who attempted to guess the word) over Zoom with heavily degraded audio. Audio and high-speed video were recorded. English speakers showed a significant increase in visually exaggerated articulations for /l, θ/ (but not /n, d, s, r/), including interdental and linguolabial productions with external lingual protrusion. Mandarin speakers increased their use of interdental articulation for /n, l, t, s/ (but not /r/), although lingual protrusion was limited. These results demonstrate that speakers may enhance their speech for visual over auditory perceptibility but suggest that enhancement is mediated by language-specific factors including phonological contrast and the articulatory characteristics of sounds in normal speech.
Influence of background noise on spatial audio localization for helicopter pilot headsets
Authors: Ernst Florian , Sachau Delf
Published: November 2023

A helicopter pilot is subjected to high workloads. A high noise level in the cockpit further increases stress. This stress can be reduced through headsets for hearing protection including active noise control (ANC). An actual research topic is the improvement of the human-machine-interface by 3-D-audio systems. These systems can improve pilot’s situational awareness and, therefore, reduce stress. This paper presents a 3-D-audio system for headphones. This binaural system uses head-tracking to process spatial information about the location of the sound source. The spatial sensation is achieved by convolving the source signal with head-related transfer functions. This sensation is influenced by background noise, which can be reduced by ANC. A first listening test with physical sound sources provides information on the localizability of sound sources at different elevation angles. This is compared to a second listening test with virtual sound sources generated by the 3-D-audio system. In a third listening test, the virtual sound source is located at variable azimuth and elevation angles. The system is evaluated with respect to sound source localization and the influence of background noise and ANC. This study highlights the potential of the 3-D-audio system to improve the helicopter pilot’s situational awareness in spatial acoustic environments.
Correction factors for loss estimation of sound propagation over high shear speed seabeds
Authors: Koessler Matthew W. , McPherson Craig , Duncan Alec J.
Published: November 2023

Modelling range dependent sound propagation over layered elastic seafloors with high shear speeds has proved to be a difficult problem for many widely used under water acoustic sound propagation models. The geologic evolution of large portions of the Australian continental shelf result in it being a commonly occurring problem for sound propagation modelling. There has been success in developing numerical methods that have shown that it is possible to obtain accurate results for these types of range dependent environments; however, there may be issues with stability and efficiency. This article explores the appropriateness of correction factors to estimate the loss due to elastic seabeds with high shear speeds. The focus is on layered calcareous seafloors that are typical of the Otway shelf, located on the western flank of Bass Strait. Several methods for obtaining a dB correction that can be applied to a fluid only propagation model are presented and compared. The methods are validated against measurement data from an oil and gas campaigns in the Otway basin.
Shear and Scholte wave measurements on surficial intertidal mudflat sediments using medical sonoelastography techniques
Authors: Venegas Gabriel R. , Chao Yu-hsuan , Kim Kang , Cormack John M.
Published: November 2023

In low-energy environments, the water–sediment interface often contains a dynamic fluffy transition layer (FTL) of suspended organic and inorganic matter, which is transformed by complex physical, biological, and chemical processes. The FTL mechanical properties are important for understanding carbon cycle dynamics and for robust sediment acoustic characterization, but erodibility and size make it difficult to study non-invasively and at sufficient resolution. In medical ultrasound sonoelastography, shear waves are excited within the body either using the acoustic radiation force (ARF) or via external vibration at the skin surface. Sub-micrometer displacements are measured remotely by subsequent ultrasound imaging at up to 10 kHz frame rate with approximately 0.5 μm spatial resolution. In this study, sediment cores were extracted from the intertidal mudflats from the Great Bay Estuary, USA. Compressional wave speed and attenuation measurements were performed using a core logger. Shear and Scholte waves were excited in the FTL using ARF- and external-vibration-based techniques and the motion detected with clinical ultrasound imaging arrays. Upward refraction of the shear wave was observed, and shear and Scholte wave speed and attenuation were measured. Finally, scanning electron microscopy was used to image the microstructure. Comparison between wave properties and microstructure will be discussed.
Effect of a low sound speed sediment layer on seismo-acoustic propagation in the New England Mud Patch
Authors: Lopez Case Jade F. , Miller James H. , Potty Gopu R. , McNeese Andrew R. , Wilson Preston S. , Knobles David P.
Published: November 2023

The New England Mud Patch (NEMP), located off the coast of Massachusetts, comprises at least four distinguishable sediment layers. The upper-most is a relatively thin, fluid-like layer (1) of mud. Below that lies more rigid mud (2) that has varying physical properties with depth. Below the mud is a sand layer (3) with a thickness of approximately 10 m. Finally, there lies a half-space layer (4) with a significantly higher density and faster compressional and shear speeds. In this paper, we explore the effect of the varying rigidity within the mud layer (2) and the sharp transition at the mud–sand interface, on forward-scattering. In the 2022 Seabed Characterization Experiment (SBCEX22), two different types of broadband sources (SUS and Rupture Disk sources) were deployed. The received signals show evidence of acoustic scattering and the generation of interface waves, along the interface between (1) and (2) and the mud-sand interface between (2) and (3). Results from normal mode modeling using Kraken and seismo-acoustic modeling using OASES suggest that the scattering can be attributed to inhomogeneities in the sediment layers. [Work supported by the Office of Naval Research Code 322OA.]
High-frequency ultrasound imaging of left-ventricle vortex flow in a mouse model
Authors: Gross Daniel H. , Phoon Colin K. , Fishman Glenn I. , Ketterling Jeffrey A.
Published: November 2023

Vector flow (VF) ultrasound is available for human cardiac imaging to quantify advanced flow parameters such as vorticity, an important component of healthy cardiac function. Similar methods have yet to translate to murine models because of the need for fine temporal and spatial resolution. We evaluate the ability of a 30-MHz high-frequency probe to quantify vorticity in the murine left ventricle (LV) using a Verasonics Vantage 256. Acoustic beam properties were characterized with an 18-um wire. A 1-cm diameter rotation phantom and a flow channel were used to validate vector estimates. Transthoracic LV image data were acquired from wild-type mice. Flow parameters were obtained with custom software that implemented a multi-angle least-squares VF method. Data were processed to obtain VF estimates and local time histories of vorticity. Velocity and vorticity estimates had more bias as the axial velocity component decreased. Aliasing was observed and a basic dealiasing approach was implemented prior to final velocity estimates. Vorticity peaked during diastole at roughly 300 rad/s, consistent with past measurements at lower frequency. Results show VF can be implemented in murine models with HF probes, but that aliasing must be addressed to obtain reliable estimates. [Work supported by NIH EB032082.]
Weakly nonlinear ray tracing approximations for focused ultrasound propagation
Authors: Foster Matt , Betcke Marta , Cox Ben , E. Treeby Bradley
Published: November 2023

Focused ultrasound is used in a therapeutic treatment (HIFU) and uses ultrasound waves to non-invasively destroy malignant cells inside the human body. The technique works by sending a high-energy beam of ultrasound into the tissue using a focused transducer. Numerically modeling HIFU presents a problem due to nonlinear effects leading to the formation of harmonics of the source frequency. Each harmonic requires a finer grid to resolve, rapidly increasing computational complexity. This work will focus on the derivation and benefits of two ray tracing methods using weakly nonlinear ray theory formed by different asymptotic expansions of the governing acoustic equations. The first has the ray equations identical to those from linear ray theory while the amplitude equation is a nonlinear transformation of the Burgers’ equation. In the second method the Eikonal and transport equations are coupled which results in ray trajectories which depend on the amplitude.
Physics-informed neural network assisted spherical microphone array signal processing
Authors: ma fei , Zhao Sipei , Abhayapala Thushara
Published: November 2023

Thanks to their rotational symmetry that facilitates three-dimensional signal processing, spherical microphone arrays are the common array apertures used for spatial audio and acoustic applications. However, practical implementations of spherical microphone arrays suffer from two issues. First, at high frequency range, a large number of sensors are needed to accurately capture a sound field. Second, the accompanying signal processing algorithm, i.e., the spherical harmonic decomposition method, requires a variable radius array or a rigid surface array to circumvent the spherical Bessel function nulls. Such arrays are hard to design and introduce a scattering field. To address these issues, this paper proposes to assist a spherical microphone array with a physics-informed neural network (PINN) for three-dimensional signal processing. The PINN models the sound field around the array based on the sensor measurements and the acoustic wave equation, augmenting the sound field information captured by the array through prediction. This makes it possible to analyze a high frequency sound field with a reduced number of sensors and avoid the spherical Bessel function nulls with a simple single radius open-sphere microphone array.
Didjeridu acoustics: A review
Authors: Wolfe Joseph , Smith John
Published: November 2023

The didjeridu is the principal musical instrument of the world’s oldest continuous culture and its sound is an acoustic icon of Australia. This lip-valve instrument usually produces a single, sustained, low note. The musical interest comes from rhythmic changes in timbre, including those associated with ‘circular breathing’, wherein exhalation from lungs to instrument with raised velum is alternated with expulsion of air from the inflated cheeks while air is quickly inhaled through the nose, with the velum lowered. This paper reviews research from our lab. Measurements of the acoustic impedance spectrum in the mouth during playing show that impedance peaks produce antiformants or minima in the output sound spectral envelope. The instrument’s slight flare and irregular bore geometry produce resonances that do not fall in harmonic ratios. Instruments judged good by players have particularly weak resonances in the formant frequency region so that the vocal tract impedance peaks can dominate the sound spectrum more easily. In one technique, players phonate at frequencies above that of the instrument, producing complicated heterodyne components. Lips are low Q oscillators and, as in other lip-valve instruments, the energetics of lip oscillation depends on the phase difference between the lips’ longitudinal and lateral motion.
Control of natural resonance frequencies in warbling native American flutes
Authors: Beeghley Joshua , Prairie Michael
Published: November 2023

The natural resonances in Native American flutes are inharmonic, and in many instances the arrangement of these frequencies can support production of a traditional warble. The bore dimensions and the configuration of a chimney around the sound hole affect those resonance frequencies. In this work the passive frequencies of flutes configured with five bore lengths and 13 chimney depths were investigated to characterize how the parameters control the placement of those frequencies, with emphasis on conditions that enable the warble. Each configuration was excited by a pure tone from an external speaker in a simple anechoic chamber. A microphone capsule was positioned near pressure antinodes and the excitation frequency was adjusted to maximize peaks and measure the first five resonant frequencies. Open tubes were tested as well. End corrections for each resonant frequency were determined and plotted versus frequency and wavelength. Analysis revealed nonlinearly decreasing end corrections versus frequency at the mouth as well as at the open foot, with the relative placement of the inharmonic resonance frequencies relative to the fundamental note being a function of bore length and chimney depth. Finally, parameters that favored warbling were identified, informing the relationship between flute design for warble production.
On the sound of a large 3D-printed and assembled musical instrument: The case of the yi?aki
Authors: Parikesit Gea O. , McCormack Jon , Fu Jing , Kim Yeonuk , Skinner Anthea , Carty John , Robertson Will , Djangirrawuy Gumbula-Garawirrtja Brian , Corn Aaron
Published: November 2023

Nowadays 3D printing technology has allowed humanities scholars and cultural materials conservators to create replicas of indigenous musical instruments, with which they can perform various studies. However, the size of the 3D printed objects are limited by the size and the range of movements of the 3D printer. Hence, large musical instruments have to be fabricated in parts and then carefully assembled prior to playing. Here we investigate the yi?aki, a large pipe-like indigenous Australian wind instrument that is played by vibrating the lips while breathing circularly on the mouthpiece. Traditionally, a yi?aki is made from the trunk of hardwoods hollowed by termites. We scanned the internal and external shape of a traditionally-made yi?aki, built a digital model from the scanning data, printed the model in several parts, and assembled the parts into a replica yi?aki. This replica was printed using sintered nylon and assembled using a two-part epoxy. Both the original and the replica yi?akis have been played by musicians and the resulting sound data have been analysed. Our results show that, even though the replica generates yi?aki-like sounds as expected, there are subtle differences between the sound of the original and the replica.
Stable distributions for randomly positioned sound emitters in an urban environment
Authors: Wilson D. Keith , Kamrath Matthew J. , Pettit Chris L.
Published: November 2023

Previously [D. K. Wilson, M. J. Kamrath, C. E. Haedrich, D. J. Breton, and C. R. Hart, J. Acoust. Soc. Am. 150(2), 783–800 (2021)], it was suggested that the probability distribution for sound levels in an urban environment could be usefully modeled with N randomly placed, independent sources in a circular region, with the receiver at the center. The sound decays away from the sources by a geometrical spreading law. With these assumptions, the received sound power consists of the sum of N Pareto-distributedrandom variables. Although an analytical solution for this sum is unavailable, some positively skewed, heavy-tailed distributions, such as the exponentially modified Gaussian distribution, provide reasonable approximations. The present study is motivated by the observation that, in the limit of large N, the Pareto sum must converge to a stable distribution; in particular, for spherical spreading, the limiting distribution is a Landau distribution. We have furthermore found that when N is drawn from a Poisson distribution, the Landau distribution is nearly exact for as few as eight sources. Hence, the Landau distribution provides a suitable general model for urban noise and other situations involving multiple, randomly placed sources.
Inverse design of acoustic coatings using Bayesian inference
Authors: Modur Karthik , Koncherry Abhinav , Lin Cikai , Schmid Jonas M. , Gurbuz Caglar , Marburg Steffen , Sharma Gyani S. , Skvortsov Alex , MacGillivray Ian , Kessissoglou Nicole
Published: November 2023

A Bayesian approach for the inverse design of acoustic coatings for underwater noise control is presented. The coating model comprises a periodic arrangement of voids embedded in a soft viscoelastic material. The viscoelastic material is attached to a steel backing with water on its incidence side and air on its transmission side. The acoustic performance of the coating is strongly dependent on the geometric properties of the voided inclusions as well as the number of layers of voids in the direction of sound propagation. The geometric optimization process using Bayesian inference proceeds inversely from a target absorption coefficient spectrum to the required number of voided layers, the geometric design parameters in each layer, and the distance between each layer. The Bayesian design process demonstrates that broadband sound absorption can be achieved using a multilayered coating with a gradient change in both void diameter and distance between each layer. Optimized designs using the Bayesian approach are validated against results obtained numerically as well as experimental results from the literature.
Optimization of a structural Acoustic Black Hole embedded in a stringer-stiffened composite laminate panel
Authors: Moorhouse Anna , Brown Avery , Beck Benjamin , Shepherd Micah
Published: November 2023

Many modern airframes are made of composite laminate materials due to their low mass but strong loadbearing capability. Carbon fiber composite laminates allow for a strong and lightweight aircraft, but create unhealthy levels of disruptive and uncomfortable noise within the fuselage. This work looks at the possibility of a structural Acoustic Black Hole (ABH) as a passive vibration damping solution for a common stringer-stiffened airframe panel. A 1-D symmetrically damped ABH was integrated vertically into the cross section of a stringer stiffener of a composite laminate plate. A multi-objective evolutionary algorithm was employed to search for the optimal ABH dimensions in terms of the tradeoff between weight, axial linear buckling load, and integrated vibration response. Computational results predicted the ability for damped ABH-stiffeners of a certain dimension to have less vibrational response than others with comparable linear density and axial strength. Mass normalized, non-tapered and ABH-tapered preliminary panels were manufactured and tested. These results showed a capability of ABH stiffeners to decrease vibrational response in the attached skin, more prominently above their cut-on frequency. Stiffened panels were manufactured to optimized specifications and their experimental results validate the presence of an optimal ABH dimension to achieve passive vibration damping in a system with mass and structural constraints.
Individual variation in the use of non-F0 cues in the realization of accentual contrasts
Authors: Hu Na , Arvaniti Amalia
Published: November 2023

Previous analysis of Greek H*, L + H*, and H* + L used FPCA on the f0 contours of these accents (N = 844; 13 speakers), and showed that they are distinguished by their PC1 and PC2 scores: PC1 captures differences in pitch height (H* < L + H* < H* + L) and PC2 differences in accent shape. We extend this analysis by investigating the use of voice quality (H1-H2) and duration in distinguishing the accents, with a focus on individual variation in the use of these cues. Results obtained from Bayesian multivariate analysis demonstrate considerable variability in the use of voice quality and duration in distinguishing between L + H* and H*, as compared to H* + L and H*. Specifically, all speakers used F0 to distinguish H* + L and L + H* from H*. In addition, 7/13 speakers employed a breathier voice to distinguish H* + L from H*, while the use of duration as a cue was relatively infrequent. In contrast, 8/13 speakers employed voicing and 7/13 employed duration to distinguish L + H* from H*, with most speakers using at least one parameter in addition to F0 to make this accentual distinction. These results highlight the importance of investigating non-F0 cues used in encoding intonation categories, as well as individual variation in such use.
Neural network-based measure of Consonant Lenition in L2 speech
Authors: Wayland Ratree , Tang Kevin , Wang Fenqi , Vellozzi Sophia , Meyer Rachel , Sengupta Rahul
Published: November 2023

This study investigates the gradient phonetic variations in the lenition of Spanish voiced and voiceless stops among second language (L2) learners with different levels of proficiency (beginning, intermediate, and advanced). The degree of lenition is measured using posterior probabilities of the continuant and sonorant phonological features, estimated by the deep learning model Phonet. The findings reveal that the degree of lenition, as indicated by the sonorant posterior probability, increases with proficiency. However, no significant effects of proficiency were observed for the continuant posterior probability. Similar to native speakers of Spanish, L2 learners exhibit effects of stress, voicing, and place of articulation on lenition. These results suggest that all learners exhibit lenition of stops as a fricative, but more advanced learners also exhibit lenition as a sonorant. Additionally, lenition in L2 is found to be gradient and influenced by linguistic factors. Moreover, the posterior probabilities of the continuant and sonorant phonological features, estimated by the Phonet model, serve as reliable measures of lenition. Overall, this study reveals the role of proficiency and linguistic factors in shaping the degree of lenition and highlights the effectiveness of the posterior probabilities obtained from the Phonet model in quantifying lenition.
A cross-dialect study of vowel production in Parkinson’s disease
Authors: Thompson Austin , Kim Yunjung
Published: November 2023

The impact of dysarthria on vowel formant frequencies is well established. Additionally, it is understood that speaker dialects significantly influence formant frequencies. However, the specific interaction between dysarthria and speaker dialect remains a relatively unexplored area in research. This knowledge gap may hinder the generalizability of dysarthria findings from one regional dialect to speakers of other dialects. As an initial step in this research line, the current study investigates the interaction between regional dialects and dysarthria in Parkinson’s disease (PD) on vowel production. To do this, our study analyzes acoustic and kinematic data from speakers with and without dysarthria, representing Midwestern and Southern United States dialects. We examine both single-word repetitions and passage-reading contexts, recognizing that there may be a significant task effect. The study includes 50 speakers, with 24 speakers (10 PD, 14 control) from the Southern Dialect (collected in Louisiana and Florida) and 26 speakers (13 PD, 13 control) from the Upper Midwest dialect (collected in Wisconsin). The findings will shed light on the interaction between regional dialects and dysarthria, offering valuable insights for speech rehabilitation and understanding speech variations across different populations.
Modeling split-beam sonar to evaluate fish target strength accuracy
Authors: Belgarde Axel , Zedel Len , Razaz Mahdi
Published: November 2023

Split-beam echosounders enable estimation of fish size by directly measuring their target strength. This measurement is achieved using compound transducer array geometries with accurate knowledge of resulting beam patterns. The multiple transducer components and required accurate calibration can present challenges in predicting the exact sonar capabilities. We present a model of the split-beam sonar system that can be used to evaluate and optimize sonar performance of a given transducer before committing to a hardware design. The model has been used to generate beam patterns to match prototype instruments and to simulate acoustic signals based on the scattering of sound from particles in a three-dimensional domain. Different split-beam sonar algorithms have been compared to measure the position and target strength of particles in the generated signal. The model's prediction capabilities were evaluated through comparisons with field trials of a prototype system. The field trials were conducted by lowering a calibration target sphere to a range of 200 m in the acoustic beam. Both model prediction and prototype system performance show accuracy of σ = ±0.2 dB at 25m range. Potential future applications of the model include exploring methods of target separation and improving accuracy when presented with complicated target structures.
Spatial audio reproduction of floor impact-borne sounds for auditory demonstrations in living environment
Authors: Kwon Youngmin , Jung Daewook
Published: November 2023

Floor impact-borne sound in the multistory residential buildings has been a serious social issue in Korea for a long time. The housing and land authority in a ministry of Korea recently amended the floor impact-borne sound evaluation method and criteria in response to the acoustic characteristics of the actual impact sources perceived in our daily lives. However, many people have not yet been convinced by the effectiveness of those evaluation method and criteria. This study discusses spatial audito reproduction of the various floor impact-borne sounds for auditory demonstrations to increase the laypersons’ understanding of the acoustic features of impact sources. The impact-borne sounds generated both by the standard impact sources used in evaluation and by some actual ones were recorded at a test-bed built in a typical apartment type. Their sound levels and reverberation times were also obtained across 1/3rd octave bands for reference. A multi-channel audio playback system engaging front/rear/ceiling speakers with subwoofers was integrated in a test-bed with a typical setting of living environment to reproduce a realistic sound field. It was optimized to create the sounds close to those actually heard in the room. The impact-borne sounds of the different damping floor systems will also be presented.
Enabling long-term soundscape observation via Ocean Networks Canada’s acoustic Northeast-Pacific infrastructure
Authors: Muzi Lanfranco , Barclay David R. , Smith Brendan , Bauer Kohen , De Leo Fabio , Heesemann Martin , Mihály Steven , Scherwath Martin , Dorocicz John , Correa Paulo , Hutchinson Jesse , Kanes Jasper
Published: November 2023

Data time series covering extended periods of time in support of long-term environmental studies are particularly difficult and expensive to collect, especially at offshore locations. Ocean Networks Canada’s (ONC) undersea cabled observatories in the Northeast Pacific ocean have been collecting an extensive array of oceanographic, seismic, geophysical, biological and acoustical data over periods that, in some cases, extend beyond sixteen years. With regard to soundscape studies, ONC currently owns and operates 22 hydrophones (including four 4-element, three-dimensional arrays) between the VENUS coastal observatory in the Salish Sea and the NEPTUNE offshore deep-sea observatory in the Northeast Pacific Ocean. The data, streamed in quasi-real-time to ONC’s web data portal, offer a window on a number of different environments, from the busy, shallow waters of the Salish Sea to the 2200 m of depth of the Endeavour hydrothermal-vent field. This presentation gathers highlights from the latest research utilizing ONC’s acoustic infrastructure and data, ranging from ambient noise to hydrothermal-vent soundscapes, seismic events, bioacoustics, and signal processing applications such as source localization.
Sonic environment mapping in Tunjungan road Surabaya with soundwalk method
Authors: Asyraf Muhammad A. , Arifianto Dhany , Putri Bina Artika
Published: November 2023

The soundscape analysis, based on the soundwalk method, was carried out at Tunjungan Street, which is one of the historical areas and a place of traffic. A soundwalk is one method that is used to get the impression of a soundscape. The parameters used in the assessment are acoustic parameters and semantic parameters. Acoustic parameters consist of loudness level, dynamic, and IACC. Semantic parameters are subjective judgments using 16 question items that were given by the researcher to the respondent in the questionnaire. The collection of data was done by the respondent in Tunjungan Street, which was divided into five sections or five points, and each point was measured at three times: morning, daytime, and nighttime. From the results of the study, several conclusions were drawn, namely that the morning has the largest loudness level 81 dBA. The highest dynamic span about 15 dBA and the lowest IACC value is 0.51. When daytime, it has larger loudness level and dynamic value, while at the nighttime it has the largest loudness level and IACC values in particular area only. This finding suggests that there are some part that offers comfort acoustically.
Reconfigurable labyrinth structures as low frequency sound absorbers
Authors: Lim Kian-Meng , Chen Yuelin , Lee Heow Pueh
Published: November 2023

In this work, we designed a metamaterial labyrinth structure as sound absorber for low frequency. The labyrinth structure is made by stacking disks with holes or openings at its front and back surfaces, and these openings are linked by air channels within the disks. Five disks with different opening locations were designed and fabricated using 3D printing. The disks were stacked and rotated with respect to each other, connecting different inlets and outlets, to form various patterns of labyrinth. Using a two-microphone impedance tube, the absorption coefficient of these stacks, ranging from one to five disks, was measured. The results show that a stacked structure with more disks enhances the absorption at low frequencies. As each disk was designed with twelve possible rotational positions, a stack of three disks will give more than 8000 combinations. It is not practical to conduct experiments to measure the absorption coefficient of all possible combinations. Hence, a neural network was used to fit and predict the absorption. Using the fitted neural network model, we would be able to predict the combinations to give best absorption and target frequency band. [Work supported by Singapore MOE Tier 1 Grant A-0009119-00-00.]
A comparison of binaural cues transmitted by clinically available cochlear-implant stimulation strategies
Authors: Mayo Paul G. , Brown Andrew D. , Goupell Matthew J.
Published: November 2023

Cochlear implants (Cis) effectively restore speech understanding in quiet for many recipients. However, bilateral CI listeners continue to perform poorer than acoustic-hearing listeners on spatial-hearing tasks (e.g., speech understanding in noise and sound localization). One explanation is that current clinically available stimulation strategies and unsynchronized sound processors degrade the fidelity of binaural cues. However, no conclusive comparison of the binaural cues transmitted by different stimulation strategies has been made. Therefore, this study compared binaural cues transmitted by two clinically available cochlear implant stimulation strategies. Two unsynchronized Cochlear Ltd. Nucleus 6 sound processors were placed on a binaural mannequin centered in a horizontal ring of loudspeakers in an anechoic chamber. Acoustic stimuli were presented from the loudspeakers and the resulting electrical pulse trains were recorded for both a peak-picking stimulation strategy and constantly stimulating strategy. Envelope interaural time differences and interaural level differences were extracted from the recordings and compared between stimulation strategies. Compared to the constantly stimulating strategy, results show that the peak-picking strategy led to more variable and less monotonic binaural cues, which could constrain sound-localization abilities. These findings argue for the bilateral synchronization of CIs in multiple domains, including electrode selection in peak-picking stimulation strategies and pulse timing.