bluuebunny/crossref_metadata_2025 huggingface dataset:
Where do Egyptian fruit bats fly when auditory and visual spatial information conflicts?
Authors: Finger Nikita , Chitnis Shivam , Moss Cynthia F.
Published: November 2023

Egyptian fruit bats, Rousettus aegyptiacus, present a distinct opportunity to unravel the relative contributions of auditory and visual stimuli for navigation. This species has evolved lingual echolocation, but also uses rod vision to navigate. Echolocation and visual gaze are anchored to the head, but the bat's active control over sonar beam aim, ear, and eye position can influence sampling of sensory space. We investigated the relative weighting of echolocation and vision in free-flying Egyptian fruit bats. In this experiment, we used stereo IR video and microphone array recordings to quantify the bat’s trajectory, head direction and sonar beam as it flew to a landing perch. We introduced sensory conflict by equipping the bats with goggles fit with prisms that shifted visual images by 23 degrees to the left or right. In control trials, prisms were replaced with clear or light-blocking lenses. When bats were presented with conflicting visual and echolocation information, they flew in the direction of the prism shift and often missed the perch. Preliminary analyses of sonar beam aim suggests that their navigation is largely guided by vision. These findings underscore the dominant role of vision in bats that have also evolved auditory specializations to operate in darkness.
The extremes of mammalian hearing: The evolution of whale hearing
Authors: Rogers Tracey L. , Walker Benjamin J. , Martin Kobe
Published: November 2023

The hearing of mammals spans extremes unseen in any other taxa and this diversity is best exemplified by the cetaceans. Conflicting hypotheses explain the evolution of the cetaceans’ extreme acoustic biology. Both lower- and higher-frequency hearing limits have been suggested to be ancestral for cetaceans. We investigate this intriguing problem further, through a comparative analysis across 161 extinct and extant mammal species. We show that ancestral whales and mysticetes do not have ultra-low lower frequency hearing limits, and their lower hearing limit is more typical, even slightly higher than that of land mammals of their size (driven by isometric scaling). We show that odontocetes, unlike other mammalian taxa, have reversed the mammalian body-size-hearing relationship. In odontocetes, larger body size is correlated with increased low-frequency hearing limit. We show that aquatically adapted mammals typically have higher lower-frequency hearing limits. Our results suggest that the shift to high frequencies occurred progressively over time. We ask why mysticetes did not evolve higher low-frequency hearing, in line with all other aquatically adapted ears.
Propagation of ship noise in shallow water over a high shear-speed seabed
Authors: Tollefsen Cristina , Duncan Alec J. , Parnum Iain M.
Published: November 2023

Assessing the acoustic impact of shipping close to the coast and within ports and harbours requires an understanding of the propagation of underwater sound in these environments. In the Australian context, this often means propagation over seabeds with shear speeds approaching the in-water sound speed, a situation that results in very different propagation conditions to the low shear speed sediments more commonly encountered in other parts of the world. Acoustic propagation modelling approaches were explored using a dataset of continuous underwater recordings featuring a mix of shipping, industrial, and recreational activities, acquired from 23 Jul to 16 Sep 2022 in Cockburn Sound, off the west coast of Australia. Cockburn Sound is a sheltered marine embayment with a relatively uniform water depth of 17–20 m in the 5 km × 11 km central portion of the basin, with a thin, variable thickness (0.5 m–5 m) layer of silty sediments overlying a calcarenite basement. The results of modelling the calcarenite basement as an equivalent fluid were compared to those obtained by modelling it as an elastic solid, and with measurements. Subsequent implications of the choice of geoacoustic model will be discussed
Vibration response of a finite airfoil under turbulent boundary layer excitation
Authors: Williams Paul , Karimi Mahmoud , Dylejko Paul
Published: November 2023

Turbulent boundary layers excite elastic surfaces leading to material fatigue and noise that may be transmitted into the body of a vehicle or reradiated back into the environment. Three different numerical methods, namely the spatial method, the reciprocity method and the uncorrelated wall plane wave method are employed to predict the vibration response of an airfoil excited by a turbulent boundary layer. These methods will be coupled with semi-empirical models which are used to simulate the wall pressure field beneath the turbulent boundary layer. The first method is performed in the spatial domain while the latter two are performed in the wavenumber domain. In this investigation, the efficacy of each of these will be examined when applied to a finite airfoil. The use of the two calculations will be compared to show any advantages in computational time and memory use.
Acoustic radiation from a baffled finite shell in an underwater waveguide
Authors: Kha Jamie , Karimi Mahmoud , Maxit Laurent
Published: November 2023

Analytical modelling of vibroacoustic systems can help us to understand the physical phenomena involved in more complex problems, and it provides a benchmark solution and reference upon which more complex systems can be built. In the present work, the system of interest consists of a finite elastic cylindrical shell inserted in infinitely rigid cylindrical baffles and immersed in an underwater acoustic waveguide. The latter consists of a finite fluid layer bounded by an upper free surface and a lower rigid floor. In such a fluid domain, the acoustic waves radiated from the excited shell will exhibit reflections off the boundaries. This phenomenon is modelled by the image-source theory and embedded in the fluid loading term, which intervenes in the shell equations. Investigations into the influence on the finiteness of the elastic shell, types of supports (i.e., simply supported, clamped, free, and combinations of these), and depth of the waveguide on the shell’s acoustic radiation are presented.
Target echo strength of small structured or resonant objects in water
Authors: Stoltenberg Arne , Schäfer Ingo
Published: November 2023

The Target Echo Strength (TES) of an object in water is a quantity for its ability to reflect sound waves. The TES value depends strongly on the directions of the incoming and the observed reflected wave, the structure of the object and of the frequency. In addition, resonant effects can increase its value significantly. These different effects were investigated in several TES reflection experiments in a water tank with varying small test objects of different material, scale and purpose. Devices under test were: a scaled massive steel structure with a thin hull, resonant PMMA balls and others. The experimental results are compared with the results of the BEM/FEM numerical modelling of each body. Limits of the concurrence are shown. Combinations of the effects might occur and increase the TES value beyond expectation.
Nonreciprocal phase shifts in spatiotemporally varying materials
Authors: Wu Jiuda , Yousefzadeh Behrooz
Published: November 2023

Materials with spatiotemporally varying properties exhibit nonreciprocal wave propagation characteristics. Nonreciprocity is predominantly identified by a left-to-right (L-R) transmission amplitude that is different from the right-to-left (R-L) transmission amplitude; a significant difference in the transmitted amplitudes is often desirable in this context. We review nonreciprocal vibration transmission in discrete mechanical systems with spatiotemporally modulated elasticity. We discuss the importance of the transmitted phase in this context, specifically that the difference between the L-R and R-L transmitted phases can be the main contributor to breaking of reciprocity in short systems. We show that the formulation of the problem in terms of response envelopes provides a computationally efficient path for exploring the steady-state nonreciprocal transmission characteristics of spatiotemporally modulated materials. In particular, we use this technique to identify response regimes that are characterized by a nonreciprocal phase shift in transmitted vibrations while maintaining equal transmitted amplitudes or energies.
An acoustic design project for final year engineering students using resonant arrays
Authors: Hall Andrew , Sorokin Vladislav , Dodd George , Schmid Gian
Published: November 2023

This paper reviews the creation of a design course for mechanical engineering students at the University of Auckland. The primary objective of the course is to introduce students to the field of acoustics, teaching basic theoretical and experimental acoustics principles, together with product design and fabrication methods, in an engaging and educational manner. During the course, students were assigned the task of developing a noise reduction duct jacket that reduced sound propagation whilst allowing free airflow, all within specified dimensions. Students were required to create designs that attenuated a predefined sound spectrum, with both narrow-band and wide-band components. Over six weeks students developed their designs using mathematical modelling and fabricated their prototypes. The performance of their suppressors was assessed through sound pressure level and impedance tube transmission loss measurements. Students then modified their designs to maximise performance before final submission. Four-person teams produced a diverse range of implementations. The most successful designs achieved impressive performance with peak transmission loss up to 70dB, 2kHz bandwidths of 10 + dB transmission loss and a delta dBA reduction of 21.5 dB. Student feedback indicates a high level of satisfaction with the course, highlighting its effectiveness in imparting key knowledge and skills in acoustics engineering.
Review and comments on ANSI-ASA S12.9 part 7 measurement of low frequency and infrasound
Authors: Woolworth David S. , Waxler Roger
Published: November 2023

ANSI-ASA S12.9 Quantities and Procedures for Description of Environmental Sound, Part 7: Measurement of Low Frequency Noise and Infrasound Outdoors and in the presence of Wind and Indoors in Occupied Spaces is currently being evaluated for potential revisions. This presentation will cover proposed revisions to the standard and reasoning used to arrive at these suggested revisions.
Predicting low-frequency noise using its own bandwidth
Authors: Montano Walter , Gushiken Elena I.
Published: November 2023

Soon after A-weighing began, an article of 1938 mentioned that as a metric it didn't represent true low-frequency loudness. In 1952, a method for “guessing” low-frequency energy was proposed and later, Beranek in 1954 recommended that if the dBC level is greater than dBA, an analysis should be performed below 150 Hz. In 1969, Botsford introduced a criterion for predicting the low-frequency level by [(dBC-dBA) > 10 dB], using the entire audible spectrum, so that this condition applies only if the spectrum is “balanced.” The German Standard DIN 45680 of 1997 proposed a similar criterion, limiting this calculation to one-third octave band frequencies from 8 to 100 Hz. Since 1999, the WHO recommends using the Botsford criterion, but warns that it is not valid if the spectrum contains tones or if it is unbalanced. This paper will demonstrate that the correct way to analyze the low-frequency sound levels is to use its own bandwidth, that to have a traceable noise descriptor the ISO low-frequency definition must be used, it means to use the one-third octave band frequencies between 16 and 200 Hz, to calculate the difference (dBC-dBA) in this range to predict its actual low-frequency sound level.
Low frequency noise study of entertainment venues
Authors: Nolan Matthew
Published: November 2023

Noise impacts from entertainment venues have long been a challenge to communities, local government and venue operators. A study into the decay rate of low frequency music noise from venues was undertaken in the Entertainment Precinct of Northbridge, Western Australia, for the Department of Water and Environmental Regulation (DWER). A drone mounted measurement method was utilised to gain an understanding of venue noise emissions via roof elements, combined with on-ground measurements and software noise modelling. The aerial measurements proved effective at low frequency, allowing for a more comprehensive analysis of the ten venues assessed. While the study revealed several challenges and discoveries, the concept of aerial noise measurement was proven to be useful in this application. The findings will further contribute to the development of guidelines and recommendations for noise management in Northbridge, ensuring a better acoustic environment for residents and visitors while maintaining the viability of the venues in the area.
Rail noise across three states in Australia—Operational noise assessment on Inland Rail
Authors: Deivasigamani Arvind , McKenzie Aaron , Kay Susan
Published: November 2023

Inland Rail Project is a proposed 1700 km freight rail line connecting Melbourne and Brisbane via three States in Australia–Victoria, New South Wales, and Queensland. Operational rail noise assessment is undertaken differently across these States in Australia. The assessment generally considers the existing and future noise exposure across day and night, along with single pass-by maximum levels. However, the assessment durations and statistical means of assessing single events differ across the States. The key acoustic criteria relevant to operational noise assessments and how they differ across the project footprint are discussed in this paper. Specifically, the effect of application of various criteria in the project context are discussed, along with statistical analysis of train pass-by noise data sets. A Monte-Carlo based methodology is proposed for estimating Single Event Maximum, a criterion for assessing single rail-noise events in Queensland. The methodology is discussed in the context of field data and greenfield scenarios where the method may be beneficial for acoustic consultants. The effects of inclusion of noise sources such as train horns and crossing bells are also briefly discussed. Finally, a proposed methodology for a consistent assessment of rail noise on such nationally spread projects is discussed.
Acoustic roughness outcomes from rail maintenance processes
Authors: Croft Briony E. , Reimer Mark , Miller Aaron , Hanson David
Published: November 2023

Rail roughness is a key determinant of the rolling noise emissions of many railway systems, particularly those systems where wheel roughness is relatively low. Rail roughness can vary considerably. The noise emissions from trains operating on very smooth, quiet, worn in systems can be 25 dBA less than the noise from identical trains operating on the same trackform but with rough or corrugated rails. Rail roughness varies over time, with changes resulting from gradual wear during normal operations but also from maintenance interventions. Rail grinding, milling or acoustic polishing can cause immediate and sometimes dramatic changes in rail acoustic surface condition, and noticeable changes in noise character. This paper documents the acoustic roughness outcomes achieved by various rail maintenance processes, in comparison to acoustic roughness from worn in tracks. The data presented includes measurements of surface finish from conventional rail grinding, rail milling, and from newer specialist acoustic grinding technologies. The rail roughness results are used to demonstrate the differences in noise emissions following rail maintenance activities. The results confirm the importance of maintaining low rail roughness as a means of noise control at source.
Hypothetical assessment of light rail vehicles idling at a terminus in New South Wales
Authors: Miller Aaron , Croft Briony E. , McMahon Jordan , Sirianni Adam
Published: November 2023

The NSW Rail Infrastructure Noise Guideline (RING) delineates the assessment of airborne noise from light rail vehicles and from railway activities taking place at fixed locations (stationary noise sources). Airborne noise from light rail vehicles is assessed against the RING criteria, while airborne noise from stationary noise sources is assessed against the much more stringent Industrial Noise Policy (INP) which has since been superseded by the Noise Policy for Industry (NPfI). In real-life operations, light rail vehicles will often idle with their air conditioners running at terminus locations that are often located near sensitive receivers due to network constraints. This creates a pseudo-stationary noise source, which to a nearby sensitive receiver is indistinguishable from a stationary noise source. This paper hypothetically assesses the noise emissions from light rail vehicles idling at a terminus against both the RING and hypothetical NPfI criteria, and examines the likely mitigation that would be required for each assessment. Commentary is also provided regarding the suitability of the RING and the NPfI to this kind of noise source.
Acoustic labelling of tires, road vehicles and road pavements: A vision for substantially improved procedures
Authors: Sandberg Ulf
Published: November 2023

The EU requires vehicle tires to be tested for noise emission and labelled. Some other countries also have similar procedures. Preparations for labelling of acoustical properties of road pavements is also ongoing in EU. Road vehicles and their tires must be tested and meet noise limits worldwide. However, all cases involve problems with measurement methods and conditions, which create uncertainties higher than desirable to make fair decisions on which product to select. For tires and road vehicles the major obstacle is the test track surface, which cannot be sufficiently well defined and reproducible. Also, far from all products (tires) are measured, so commonly only the noisiest products are correctly labelled. Although attempts are made to go indoors to do the measurements, they are still for the foreseeable future going to be made outdoors, with all the influence of weather and seasons that this causes. The author has worked most of his long career with such issues and in this paper, the author outlines his vision of how most of the problems (uncertainties) can be reduced to acceptable levels, mainly by making measurements indoors, with reproducible and representative conditions for both the labelling and the actual noise emission in traffic.
Unifying low and high-frequency noise mitigation: A novel dual noise barrier approach
Authors: Pingle Pawan , Pignatta Gloria , Schiavoni Samuele
Published: November 2023

Road highways and urban areas often employ noise barriers to shield residential areas from excessive traffic noise. Despite continuous efforts, developing materials for noise barriers that can effectively mitigate noise across a wide frequency range is still a challenge. Specifically, creating a single material capable of attenuating both low and high-frequency noise has proven to be a daunting task. Current practices incorporate porous materials for absorbing low-frequency noise at specific locations. To address this limitation and offer a technique for traffic noise reduction, this research proposes a novel approach utilizing two hindrances: pores for low-frequency and bristles for high-frequency sound waves. An ANSYS Harmonic Acoustic module simulation was conducted to assess the proposed technique's effectiveness. The simulation encompassed geometry definition, material selection, boundary condition constraints, meshing, and analysis. The results indicate a significant reduction in noise at high frequencies (16 000 Hz) of approximately 30 dB, decreasing from 101.4 to 68.1 dB. This demonstration showcases the potential of a staggered arrangement of bristles and pores to handle a wide range of frequency content and effectively mitigate both low and high-frequency traffic noise. The novel dual noise barrier approach offers a promising solution to combat diverse traffic noise challenges, providing a more peaceful soundscape for urban residents.
Nonlinear resonant ultrasound spectroscopy using white-noise excitation
Authors: Geimer Paul R. , Beardslee Luke , Ulrich Timothy J.
Published: November 2023

Nonlinear resonant ultrasound spectroscopy (NRUS) is a technique for non-destructive sample evaluation by which a strain-dependent nonlinear parameter is quantified that exhibits heightened sensitivity to defects as compared to monitoring of linear resonance attributes. As NRUS measurements have traditionally used a controlled sweep of sinusoidal inputs, applications of the method have been largely limited to laboratory experiments. Here we present NRUS results which utilized a white noise signal as input, in order to better approximate ambient excitation and facilitate efficient validation using time-domain models. Studied samples were chosen to reflect a range of nonlinear responses and underlying mechanisms (acrylic, sandstone, fractured steel). We excited the studied samples using bonded piezoelectric transducers which delivered white-noise inputs at increasing amplitudes, with the nonlinear response measured with a laser doppler vibrometer. By comparing results against those obtained from traditional NRUS, we find comparable trends in the nonlinear parameter under white-noise excitation, including similar relative differences in magnitude across the samples and consistent values across similar mode shapes. While we note that white-noise strain estimation is complicated by simultaneous excitation of multiple resonant modes, NRUS results from white-noise excitation demonstrate promising viability of the technique for (1) in-situ inspection, and (2) a more-tractable approach to model the physics of various NRUS signals.
Enhanced noise propagation due to atmospheric effects: Practical considerations—Part 1
Authors: Hancock Travis , Kemp Liam , Adcock Justin
Published: November 2023

How far should an acoustical consultant go to investigate enhanced noise propagation due to atmospheric effects? This paper was inspired by recent updates to Victorian noise policy, which includes more stringent requirements for consideration of atmospheric effects. The authors have identified an opportunity for development of a consolidated practical method for acoustical consultants to apply in Australian conditions. Predictive calculations implementing various standards can estimate atmospheric effects based on either broad assumptions, subjective observations, or detailed weather data. Acoustical consultants are often reliant on incomplete and potentially irrelevant weather data. This includes data from sources such as public weather stations far away or local weather stations close to ground level. This paper is the first part of a two-part study designed to inform a best practice method for acoustical consultants assessing atmospheric effects with respect to enhanced noise propagation. Part one, this paper, will review the current state of knowledge including different policy approaches and predictive standards. Part two would be a field study with concurrent detailed measurements of atmospheric conditions and noise levels to inform appropriate weather data collection methods and predictive standards for Australian conditions.
What we can do with sounds
Authors: Rodger Matthew
Published: November 2023

Auditory perception can be dynamic when sound sources are in motion or changing, when the listener is moving relative to the source of sound, or both. Moreover, our engagement with the acoustic environment is often active rather than passive. That is, sounds can be brought into use to support and guide perceptual-motor behaviour. This presentation will review examples of recent empirical work on the role of auditory perception in the control of motor behaviour: what we can do with sounds. Data from experiments on intercepting moving objects without vision, acoustic navigation and orientation in people with visual impairments, exploration and learning of novel digital musical instruments, and rhythmic sounds in gait rehabilitation, all demonstrate different ways that sounds can convey action-relevant information for skilful listeners. Furthermore, they point to a need to consider the auditory system not merely as a passive antenna for inert distal stimuli, but as integrated within an active meaning-seeking organism interacting with a dynamic environment.
Studies of multisensory integration in sound localization and updating of auditory spatial attention during head motion
Authors: Macpherson Ewan A.
Published: November 2023

In daily life, our heads are in continual motion, but much of our knowledge of spatial hearing is based on experimental paradigms in which this behavior is discouraged or prevented. Head motion can benefit spatial hearing though the creation of dynamic acoustical cues, but also creates challenges such as the need to update head-centered spatial representations or the locus of spatial auditory attention. To utilize acoustic information generated by, or to compensate for, head movements, the auditory system must integrate self-motion information provided by other sensory systems. This presentation will review and contextualize a series of studies from the author's laboratory focused on the psychophysics of dynamic sound localization and the weighting of sensory information from vestibular, proprioceptive, and visual modalities in dynamic localization and maintenance of spatially selective auditory attention during head rotation. Notable findings include a velocity-independent ∼100-ms minimum stimulus duration for disambiguation of front/rear location in dynamic localization and the apparent dominance of vestibular information in the interpretation of dynamic localization cues and in attentional updating. The approach taken provides a step towards understanding the effects of naturalistic behavior on spatial hearing while maintaining significant experimental control and repeatability of stimuli and head movements.
Binaural fusion with ecologically valid stimuli
Authors: Aronoff Justin , BK Prajna , Soleimanifar Simin , Bernstein Leslie
Published: November 2023

Binaural fusion, or the perception of a single auditory “image” can arise from simultaneous inputs across ears. Fusion is fundamental to binaural abilities, including sound source localization. One potent determiner of degree of fusion is the interaural correlation of the binaurally presented waveforms. Noise waveforms can be used to manipulate the interaural correlation, but the normalized correlation of the envelopes of such noises is limited to between 1.0 and 0.785 (π/4). As a result of differing properties between noises and speech, pairs of speech sounds can be generated having normalized interaural envelope correlations well below 0.785. We measured cochlear implant users’ perceived degree of binaural fusion while varying the interaural correlation of speech-like signals from 0.4 to 1.0. Stimuli were generated using speech-based envelopes from multi-channel vocoders that modulated 1000 pulse-per-second pulse trains. Envelopes derived from different vocoder channels were extracted to yield interaural correlations that varied over a wider range than would be possible using noises. Preliminary results suggest that the speech-based stimuli, while differing qualitatively from noises and being more ecologically valid, yield similar effects of interaural correlation on binaural fusion, while allowing a larger range of interaural correlations to be employed.
Allocation of cognitive resources for older adults with normal or impaired hearing when listening to temporally degraded and masked speech
Authors: Fogerty Daniel , Dubno Judy R.
Published: November 2023

Hearing impairment may affect how older listeners allocate cognitive resources when communicating in challenging environments. Older adults with normal or impaired hearing completed three speech recognition studies. The studies consisted of 15-16 measures of temporally filtered speech with (1) degraded spectral cues, (2) competing speech-modulated noise, and (3) speech vocoding in speech-modulated noise. Generalization was assessed with measures of speech interruption, segregation, and multitalker masking. To account for audibility differences, all listeners received spectral shaping fit to their hearing thresholds. Measures in each study were reduced to a single principal component (PC) that represented speech recognition abilities. Participants also completed a cognitive test battery that yielded domain-specific PCs and a measure of speech glimpsing. For each study, hierarchical linear regression analysis was completed separately for subgroups of older adults with normal or impaired hearing using cognitive PCs as predictor variables, followed by speech glimpsing, age, and hearing thresholds. Vocabulary knowledge was the best predictor of speech recognition for older adults with normal hearing, whereas working memory consistently explained ∼30%-40% of the variance in recognition for older adults with hearing loss. Thus, even with sufficient audibility, hearing impairment may alter allocation of cognitive resources for older adults listening to degraded speech.
Acoustic correlates of oral and glottal stops in Tahitian
Authors: Fletcher Janet , Gregory Adele , Volchok Ben
Published: November 2023

The Eastern Polynesian language Tahitian spoken in French Polynesia, is described as having a simple phonological inventory with a single stop series: /p, t, ʔ/. Little is known about the acoustic properties of these consonants compared to well-resourced languages. Five female speakers of Tahitian produced multiple repetitions of tokens that varied in terms of stress location and prosodic phrase position. Acoustic analyses of stop duration and VOT, as well as voicing measures including voicing fraction and strength of excitation were conducted. As predicted, oral stops were significantly longer than glottal stops by 63 ms in word medial contexts with no effect of stress. VOT values were on average 21–26 ms (with /t/ marginally longer than /p/) confirming these are short lag stops (Cho and Ladefoged, 1999). Stress was marginally significant with shorter VOT values in stressed syllable onsets with no affect of prosodic position, unlike Hawaiian (Davidson and Parker Jones, 2022). Like Hawaiian, however, (Davidson, 2021), the glottal stop in Tahitian has gradient realizations although the majority are realised with full glottal closure with low voicing fraction and strength of excitation values. There are also clear effects of greater coarticulation in unstressed versus stressed syllables suggesting localised hyperarticulation in the latter context.
Northern Lisu vowels & tones, and their interactions
Authors: Stanley Rael , Tabain Marija , Bradley David , Yu Defen
Published: November 2023

Lisu is a Sino-Tibetan language of Central Ngwi branch. It has multiple tonal contrasts and a typologically unusual vowel inventory. In this talk, I present an acoustic phonetic study based on data collected from eleven speakers of Northern Lisu, spoken in Nujiang Autonomous Prefecture in Yunnan, Southwestern China. The study focuses on the vowels and tones of the language, and their interaction. Northern Lisu has six tones, including four modal and two creaky-voiced tones; it has ten vowels, including five front vowels, four back vowels, and a central “fricative” vowel. Tone and vowel interaction is analyzed using Esling’s Laryngeal Articulator Model. Results show all speakers produce a lower f0 in the retracted vowel context, but it is not the case that all tones are creakier in this same vowel context. Simultaneously, male and female speakers show differences in terms of voice quality. Examination of the vowel space shows a reduction in many vowel contrasts. It is suggested that the vowel space is becoming regularised, with perceptually difficult contrasts being neutralised. In addition, it is shown that the fricative vowel contains minimal frication compared to the fricative consonants, and as such is better described as a syllabic retroflex approximant.
An underwater sound event detection algorithm based on Temporal Graph Convolutional Network
Authors: Lee Chong Hyun , Lee Kibae , Ko Guhn Hyeok
Published: November 2023

Accurate underwater sound event detection (SED) and real-time underwater situation awareness plays an important role in intelligent sonar system. However, little research on underwater SED has been done because underwater acoustics have very complex and dynamic spectral and temporal characteristics which make underwater SED difficult to solve. The goal of SED is to recognize type and time of the input audio signal and most of SED research have been focused on airborne sound so far. To address underwater SED problem, we adopt temporal graph convolutional network (T-GCN), which is originally designed for traffic prediction and is composed of GCN and gated recurrent unit (GRU) To capture spectral and temporal information simultaneously, the GCN is used to learn topological structures to capture spectral correlation and the GRU is used to learn changes of input sound to capture temporal correlation. The proposed model utilizes sound spectrogram and its annotation with temporal information as input and then the GCN and GRU of the model is employed to solve underwater SED problem. Experiments using urban SED dataset and underwater sound dataset, demonstrate that our proposed model expresses connection of spectral and temporal information effectively and shows reliable underwater SED performance accordingly.
Research on vessel noise signal compression sensing algorithm based on Particle Swarm Optimization and Variational Mode Decomposition
Authors: Wei Danni , Huang Haocai
Published: November 2023

Due to the complexity of marine environmental factors and strong background noise, the collected vessel signal becomes intricate and challenging to transmit and reconstruct using conventional parameter estimation methods. Additionally, identifying vessel targets becomes difficult. In order to detect the vessel target and obtain the corresponding orientation information, it is necessary to eliminate the interference of noise as much as possible and reconstruct the original signal more accurately. In this work, we propose an optimized signal denoising method PSO-VMD (Particle Swarm Optimization–Variational Mode Decomposition). By conducting simulations using experimental data and evaluating the model, we demonstrate the superior denoising capabilities of this method. Then we apply this method to denoise the real vessel sound signal and then compress and reconstruct the signal using compressed sensing. The experimental results show that the signal processed by PSO + VMD method has the maximum SNR and the minimum RMSE and MAE. What’s more, the selected suitable denoising method can effectively suppress the environmental noise in the signal and improve the reconstruction efficiency of compressed sensing.
A novel audio-visual based beamformer using a 360° camera and planar microphone array system
Authors: Phan Hoang Phuc , Ibrahim Ronny , Buchholz Joerg M. , Kan Alan
Published: November 2023

Beamforming systems that rely only on microphone arrays may suffer from poor performance in complex acoustic environments with multiple sources and room reverberation. To overcome this limitation, we propose a novel method that combines a planar microphone array and a 360° camera to steer the beamformer. The camera provides visual information about the location and orientation of sound sources, which can be used to adjust the beamformer parameters. We will present results that compare the signal-to-noise ratio (SNR) of the proposed method with a conventional beamforming microphone-based method in a simulated room with different source positions, orientations, and noise levels to investigate the benefit of visual information for beamforming in different environments. The proposed method has the potential to improve the performance of beamforming systems in applications such as speech enhancement, speech recognition, and speaker localization.
Examining the voice verification system resistance developed for banking to attacks employing the voice cloning
Authors: Czyzewski Andrzej
Published: November 2023

The developed system for verifying the speaker identity in banking branches is based on voice biometrics employing DeepSpeaker neural network model. The testing of its resistance to a potential attack using voice cloning also employed neural networks, such as SV2TTS, Tacotron, WaveRNN, and GE2E. Subjective listening tests indicated that people might easily get confused and point out cloned recordings as an original sample. Nearly 50% of respondents pointed to the wrong answer, confusing the synthesized recording with the original one. Subjects in most cases declared that the quality of cloned and original recordings is similar (Good or Fair according to ITU-R BS.1534 recommendation) and, in some cases, even better than the original (graded as Good for synthesized sample, Fair for original one). Meanwhile, nearly all verification attempts with cloned samples failed (98.8% of samples were rejected). It proves that voice biometrics based on deep neural networks can identify cloned samples better than human listeners. Methods and results of testing the resistance of the developed voice biometrics system to voice cloning attacks are discussed in thepaper. This research was funded from the budget of project No.POIR.01.01.01-0092/19 subsidized by the Polish National Centre for Research and Development (NCBR).
Event-driven online-learning using the CAR-FAC cochlea model
Authors: Xu Ying , Bethi Yeshwanth , Afshar Saeed , André van Schaik
Published: November 2023

This work explores using a local spike-timing-dependent adaptation of thresholds and weights to learn to classify spectro-temporal representations of audio represented by neural spikes. We use the Cascade of Asymmetric Resonators with Fast Acting Compression (CAR-FAC) cochlea model and Leaky Integrated-and-Fire (LIF) neurons to generate the spikes from audio. This event stream is fed into the Optimised Deep Event-driven Spiking Architecture (ODESA) to learn spectro-temporal features in a hierarchical architecture. The cochlear events provide robust spectro-temporal representations of audio, and the ODESA performs online learning without needing error back-propagation or the calculation of gradients. Using simple local adaptive selection thresholds at each node, ODESA rapidly learns to appropriately allocate its neuronal resources at each layer in the hierarchy to learn features at different spatial and temporal scales. Information transmission throughout the system is event-based and all computing is performed asynchronously and online. We tested the approach on the TIDIGTIS benchmark and compare the performance with existing event-driven TIDIGTIS datasets and feature extraction and classification algorithms. With a three-layer ODESA, the proposed approach achieves 84.2% accuracy.
Performance evaluation on a convolutional neural network with adaptive interference cancellation for detecting a buried person's voice in a disaster situation
Authors: Choi Jungyu , Im Sungbin
Published: November 2023

In a disaster situation, rapid detection of victims is critical to prevent life-threatening accidents. However, it is not easy to detect the target's sound due to noise and interference which are difficult to predict. In addition, it is difficult to collect acoustic data in disaster situations. Therefore, this study proposes a target detection scheme in which untrained noise is added through a binary classification model trained only with a clean target signal and additive white Gaussian noise (AWGN). The feature uses the Mel spectrogram of the signal, and the model adopts a convolutional neural network (CNN). Two acoustic sensors are used in this study to adaptively remove environmental noise and a CNN to detect target signals. The first process trains a CNN using the target signal and AWGN data. In the next step, environmental noise is removed by compensating for the gain difference and delay characteristics between the two acoustic sensors through adaptive filtering. The input signal passes through preprocessing to eliminate noise through an adaptive filter. This signal is converted into a Mel spectrogram, which is then detected through a CNN model. The simulation results show that the model improves from 50% to 99% in detection rate at SNR 0 dB. In a catastrophe, there are many sounds that are difficult to discern. However, the model cannot learn from noise. Therefore, it shows that the target detection method using adaptive filter-based noise cancellation is effective in disaster situations.
Acoustic characteristics of the seismic airgun sound propagation in the East Siberian Sea
Authors: Han Dong-Gyun , Kim Sookwan , Landrø Martin , Son Wuju , Lee Dae Hyeok , Yoon Young Geul , Choi Jee Woong , Yang Eun Jin , Choi Yeonjin , Jin Young Keun , Hong Jong Kuk , Kang Sung-Ho , Rhee Tae Siek , Shin Hyoung Chul , La Hyoung Sul
Published: November 2023

A passive acoustic monitoring has been conducted by Korea Polar Research Institute (KOPRI) since 2017 in the East Siberian Sea using an autonomous passive acoustic recorder. Seismic airgun sounds, generated from the multichannel seismic survey system of the ice-breaking research vessel Araon, were measured from 18.6 km to 164.2 km in September 2019. During the survey, the R/V Araon maintained the ship’s trajectory at a constant heading and speed to obtain useful acoustic data for investigating the acoustic propagation properties with a distance between the source and receiver in shallow water. The decrease in sound pressure levels as a function of distance was compared with the least-square regression curves and numerical propagation modeling based on the parabolic equation. The broadband sounds in a low-frequency range were propagated over long distances with distinctive characteristics such as precursor arrivals, modal dispersion, and rapid decrease in spectrum level at low frequencies. Our results will be discussed in comparison with the sediment structure and geological history of the measurement region. [This research was supported by Korea Institute of Marine Science & Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries (20210605, Korea-Arctic Ocean Warming and Response of Ecosystem, KOPRI and 20210632, Survey of Geology and Seabed Environmental Change in the Arctic Seas, KOPRI).]
A simple formula for coherent specular reflection loss of underwater sound from rough ocean surfaces
Authors: Zhang Zhiyong
Published: November 2023

The interaction of underwater sound with rough sea surfaces affects its propagation. The interaction may involve several coupled mechanisms: (1) a rough air-sea interface scatters and spreads the incident sound energy over a range of angles, (2) entrapped sub-surface air bubbles absorb and scatter sound energy, and (3) medium of bubble clouds refract sound energy upwards. In this paper, we ignore the effect of bubbles and consider the effect of rough air-sea interface only. We further limit our consideration to the coherent component in the specular direction. Two simple closed-form formulas are often used to model the coherent reflection loss from rough ocean surfaces. One is derived from perturbation approximation and suitable for smaller grazing angles. The other is from Kirchhoff approximation and suitable for larger grazing angles. More accurate approximations over a wide-range of grazing angles require numerical evaluation of integrals or complex special functions. In this work, we simplify and adapt earlier results by other authors to obtain a simple expression that transits from the perturbation to the Kirchhoff formulas as grazing angle increases. The new simple analytical formula is easy to use and compares well with results from complex numerical methods.
Acoustic signature of strong deep-water currents in the vicinity of the New England Seamounts
Authors: Tan Tsu Wei , Joseph John , Godin OLEG A. , Walters Matthew
Published: November 2023

This paper presents some initial findings from the New England Seamount Acoustics (NESMA) Pilot experiment, focusing on the data obtained in April—June 2023 with three moored autonomous noise recorders (MANRs). Two MANRs were each equipped with a tilt current meter (TCM). Unexpectedly strong near-bottom currents were observed at depths of 2500m and 4443m, with the flow speeds reaching 110 cm/s and 80 cm/s, respectively. At 2500 m, recorded current speeds exceeded 20 cm/s approximately 5% of the time throughout the entire eight-week measurement period. Collocated ambient sound measurements revealed episodic large increases in the low-frequency noise intensity. A strong correlation is found between the noise intensity in the 2–20 Hz band and the measured current speed. As expected for flow noise, the intensity and the characteristic frequency of the power spectrum peaks increase with the increasing current speed. Observations of the flow noise by the MANR not equipped with a TCM indicate the presence and timing of strong current events and allow for an estimate of the current speeds at that location. The possible origins of the strong near-bottom currents and the flow noise effect on operation of deep-water acoustic systems will be discussed.
The acoustic propagation environment surrounding the New England seamounts
Authors: Taylor Robert
Published: November 2023

The New England Seamounts lie in a complex oceanographic environment that frequently sees both the colder Slope Sea waters and the warmer Sargasso Sea waters. The Gulf Stream, a meandering current that separates these two bodies of water, can be difficult to locate and frequently produces cold-core and warm-core eddies, complicating ocean modelling efforts. Regional temperature and salinity profile measurements gathered by the Argo program enable an investigation of the accuracy of the Hybrid Coordinate Ocean Model (HYCOM), a popular ocean circulation model. Simple range-independent calculations of acoustic propagation conditions provide a means of characterizing the acoustic environment by detailing common propagation paths associated with the New England Seamounts region. Contrasting the range-independent calculations for the Argo measurements with those of the oceanographic model indicates that persistent temperature features absent from the model impact predictions of the acoustic propagation environment.
Sensitivity of phase difference between short-range acoustic multipaths to changes in sound speed and source depth
Authors: DeFilippis Jacob P. , Cornuelle Bruce , Hodgkiss William S.
Published: November 2023

Ocean acoustic tomography often relies on precise clocks and knowledge of the range between acoustic instruments to estimate ocean-driven sound speed changes. In this study, we explore an alternative method utilizing the difference in the carrier phase between two broadband pulse arrivals to estimate small-scale changes in source depth and sound speed. By leveraging acoustic multipathing, this phase difference approach obviates the need to know the acoustic propagation's precise range and absolute travel time. Observations from a mid-frequency (1–10 kHz) acoustic experiment at short ranges (2–3 km) demonstrate the sensitivity of the difference in the 4 kHz carrier phase between two arrivals to changes in both source depth and sound speed. The difference in the arrival phase is modeled using measurements of the time-varying source depth and sound speed. The comparison between the modeled and observed arrival phase differences reveals a significant agreement, supporting the potential of using phase difference as a reliable estimator for perturbations in either source depth or sound speed for short-range acoustic propagation.