bluuebunny/crossref_metadata_2025 huggingface dataset:
Psychoacoustic analyses of urban noise from long-term monitoring—Findings and outlook
Authors: Fiebig Andre , Schuck Moritz , Haselhoff Timo , Moebus Susanne
Published: July 2024

Urban noise is usually assessed using sound pressure level indicators to assess harmful noise effects. However, studies have shown that human responses to environmental noise are driven by psychoacoustic properties even beyond sound pressure level indicators. Although the value of psychoacoustic parameters for an improved characterization of environmental noise appears plausible and has often been shown in laboratory studies, a systematic examination of psychoacoustic parameters over long measurement intervals is lacking. In the research project SALVE+, long-term acoustic measurements at several locations in a German city were subject to psychoacoustic analyses and the location-dependent behavior of psychoacoustic parameters over time was examined. The measurements were analyzed to determine the acoustic quality of urban sound beyond sound pressure level and noise annoyance. Based on statistical analyses, the psychoacoustic properties of urban locations considering their land use are discussed regarding an improved characterization of acoustic environments. Based on this approach, the suitability of psychoacoustic parameters for mapping of spatial and temporal patterns is investigated. The presentation aims to highlight the value of noise monitoring in cities and analyze opportunities for improved urban noise management that additionally considers issues such as restoration quality and health promotion.
Energy absorption from an oscillating fluid using an engineered acoustic diode
Authors: Schmidt Rico , Roy Indradip , Yousef Hosam , Aboueria Alex , Scalo Carlo , Nouh Mostafa
Published: July 2024

Over the past decade, engineered subsurface structures inspired by acoustic metamaterial configurations have shown promising results in boundary layer control through different energy stabilization mechanisms. Despite the potential shown via numerical simulations, the underlying interfacial dynamics between a fluid column and a compliant metamaterial remain largely unexplored. Our preliminary studies have shown that conventional phononic band gaps are insufficient for effective control since the bulk of the absorbed energy remains confined to the fluid-structural interface, a direct consequence of localized modes associated with band gap truncation resonances. In this talk, we will discuss the mathematical intricacies of impedance boundary conditions (IBCs) at the interface of a one-dimensional fluid and an engineered structure, shedding light on both linear and non-linear subsurface behaviors. Through which, we will present a new pathway to effectively transmit a pressure wave from an oscillating fluid away from the interface, and into a structural medium.
Variational study of a model for near-perfect transmission through lossy media with acoustic sources
Authors: Geib Nathan P. , Wallen Samuel P. , Haberman Michael R. , Naify Christina
Published: July 2024

Complementary acoustic metamaterials have been proposed as a means of compensating for the high impedance mismatches of aberrating layers that disrupt the acoustic field and hence distort acoustic images. Recently, a complementary acoustic metamaterial featuring active components was shown in principle to compensate for both the impedance mismatch and energy attenuation of lossy materials, but a physical realization of the concept has not yet been implemented. Here, we present results from a one-dimensional acoustic model showing how a plane wave incident on a lossy material can be augmented by point monopole and dipole sources to allow for near-perfect transmission, thus rendering the lossy medium acoustically transparent. We present general expressions for source magnitudes that are dimensionless with respect to frequency, material thickness, and the background medium. We explore the sensitivity of the performance to variations in each of the model parameters, considering both theoretical and practical limitations to the proposed method. We show that these findings are consistent with three-dimensional finite element simulations.
Localization-antilocalization of soundwaves in a disordered phononic crystal with mirror symmetry
Authors: McKinstry Michael , Shymkiv Dmitrii , Krokhin Arkadii
Published: July 2024

Anderson localization in a disordered potential leads to exponential decay of an incoming wave. However, if a 1D disordered potential possesses mirror symmetry, V(-x) = V(x), then the eigenstates are either even or odd functions of x. As such, a wave localized on one side of such a symmetric disordered potential should elicit a corresponding antilocalized peak at the symmetric position on the other side. The distribution of pressure in a symmetric disordered potential is similar to the wave function profile in a symmetrical double-well potential. This similarity opens a way to demonstrate quantum tunneling using acoustic waves. This effect has an important application to secure communications, as the transmitted signal is reduced by disorder to the level of noise, thus excluding the possibility of signal interception, then enhanced by the symmetric part of the potential at the receiver. This is a secure method of information transmission without the need for encryption and decryption. We developed a methodology for identifying the frequency spectrum consisting of narrow doublets that correspond to eigenstates of different parities. A 2 × 30 phononic crystal with orientational disorder was fabricated for experimental observation of antilocalization. [This work is supported by the NSF under EFRI Grant No. 1741677.]
Vowel perception research from formant thresholds to sentence intelligibility
Authors: Kewley-Port Diane
Published: July 2024

Historically, research on the contribution of vowels to speech understanding lagged that of consonants. Speech synthesis techniques were then developed that established that the primary acoustic features of vowels are formant frequency, fundamental frequency, speech dynamics and naturalness. For speech perception research, precise control of the features in vowel stimuli was required. Starting in the 1980s, the Klatt formant synthesizer was the first important tool, and by 2000 Kawahara’s STRAIGHT synthesizer generated nearly natural speech. As a baseline for vowel perception, my research sought to determine psychophysical thresholds for F1 and F2 under ideal conditions. This talk reports contributions from my vowel perception studies on three questions. First, how do formant thresholds change with speech context (isolated vowels up to sentences), across age and with hearing impairment? Second, do vowels or consonants contribute more to intelligibility in noise-interrupted sentences? Third, given formant dynamics, how is intelligibility affected as consonant-vowel boundary conditions are manipulated across age and hearing impairment? Significant results include: (1) Vowels carry more information about sentence intelligibility than consonants for both young and older listeners; (2) Even though older listeners’ performance is reduced compared to young, hearing impairment has a greater negative impact than age-related cognitive decline.
Augmenting sparse arrays in ocean acoustics: A Gaussian Process approach
Authors: Michalopoulou Zoi-Heleni , Gerstoft Peter
Published: July 2024

Source localization and geoacoustic inversion performance depends on the location of receiving phones, their spacing, their number, and the array aperture. Performance suffers when practical design issues limit the capabilities of the array. In this work, sparse arrays are augmented leading to the generation of virtual arrays for better sampling of the ocean and, thus, improved estimation performance. To that effect, Gaussian Processes are employed, which are shown to create high-fidelity field “measurements” at virtual, densely spaced hydrophones. Kernel functions are key building blocks in the implementation of Gaussian Processes, as they quantify the field coherence at neighboring spatial points. Functions of interest are the squared exponential, Matern, and plane wave kernels. We validate our method with application to synthetic data as well as data collected during the Seabed Characterization Experiment conducted in 2022. [Work supported by ONR.]
Increasing the accuracy of ISO 354 and ASTM C423 through modal identification
Authors: D'Orazio Dario , Zaccarini Andrea , Falciano Fiorella
Published: July 2024

Measuring the acoustic properties of materials is a highly challenging task. Previous studies have highlighted errors in the absorption coefficient above 200 Hz, leading to absorption coefficient values higher than one. These errors are often attributed to differences in modal decays with and without the specimen. This effect is amplified in the case of highly reactive materials, such as innovative materials, that significantly impact the acoustic field and, consequently, the modal behaviour of the room. This work aims to reduce the difference between measured reverberation time values, with and without the specimen, through Data Augmentation. Modal identification was performed on measured impulse responses of porous specimens, where the alpha is known, allowing the determination of modal decay times and reverberation times within the frequency range of 70–180 Hz. A statistical analysis of natural modes and numeric solutions enables the identification of outliers. In this way, even in a non-well-optimized reverberation room, it is possible to enhance the accuracy of acoustic absorption measurements.
Acoustical investigations of multipurpose spaces at community facilities
Authors: Chan Mandy , Kundakcioglu Michael , Lorimer Alex
Published: July 2024

Multipurpose spaces in community and recreational facilities hold significant value, catering to a variety of uses and accommodating users of diverse age groups. This article discusses investigations conducted at nine municipally owned facilities including community centres, arenas, and a senior centre related to reportedly poor acoustic conditions in multipurpose spaces. The acoustical measurements of the as-found conditions, relevant criteria, and analysis are outlined. The sound isolation, acoustical treatment for interior reverberation control, and background noise from HVAC are discussed as the contributing factors for the subjective acoustic concerns.
Dissecting recorded gunshot sounds
Authors: Beck Steven D.
Published: July 2024

Gunshot audio recordings are composites of multiple sound sources, including blast, ballistic, mechanical, and environmental sounds. The existence of each sound and its distinguishing features depend on the source characteristics, the propagation environment, and the recording system. Controlled recordings show the situational dependence of these sound sources and the recording system. Knowledge of the physics and these dependences is critical in forensic analysis and the ability to dissect, separate, and identify sources in recorded gunshots. Multiple blast sources (muzzle blast, gas jet, mechanical impact, and primer explosion), ballistic sources (shockwave and subsonic flow), and environmental sources (reflections and terminal impact) will be shown from both controlled experiments and uncontrolled forensic recordings.
Source characterization of afterburning laboratory-scale jet noise with vector acoustic intensity
Authors: Eggleston Michele L. , Gee Kent L. , Mathews Logan T. , Olaveson Tyce W. , Pratt Hunter J. , Kumar M. G. Ashwin , Meadows Joseph W.
Published: July 2024

This paper presents an intensity-based characterization of noise sources in a highly heated laboratory-scale jet with a 3-inch exit diameter. Run conditions had nozzle pressure ratios between 2.7 and 3.5 and temperature ratios of ∼7. Measurements were performed using a microphone scanning rig containing 8 four-microphone intensity probes. Probes were separated by 1.5 nozzle diameters and the microphones were spaced 0.5 nozzle diameters apart. Each scan mapped out over 3,000 measurement locations to produce an intensity field map. Vector intensity was processed over a 200 Hz to 20 kHz bandwidth using the phase and amplitude gradient estimator (PAGE) method [D. C. Thomas, et al., J. Acoust. Soc. Am. 137, 3366–3376 (2015)]. Results show the dominant source region as a function of frequency and are compared to the acoustical holography source reconstruction of the T7-A afterburner engine condition [L. T. Mathews and K. L. Gee, AIAA J., in press (2024)]. Additionally, the intensity-derived source locations are connected to the jet’s supersonic and subsonic flow regions. [Work supported by ONR Grant No. N00014-21-1-2069].
Revisiting a classic experiment in violin acoustics as a classroom demonstration or laboratory activity
Authors: Morrison Andrew C.
Published: July 2024

In 1982, Carleen Hutchins built a violin to conduct experiments largely to learn about the role of air cavity resonances on the overall sound produced by the violin. This violin was of a standard design except for 65 holes 5 mm in diameter drilled into the ribs. The holes could be selectively plugged with corks for experimentation. Carleen Hutchins was a skilled luthier, and this violin, playfully called “Le Gruyère,” was a finely crafted musical instrument. For an introductory acoustics general education laboratory course, a version of Hutchins' Swiss cheese violin was created by drilling holes in the ribs of a factory-made student-model violin. Students in the course have the opportunity to replicate classic acoustics experiments or this violin can be used for class demonstration purposes. In this presentation, the advantages and challenges of implementing this activity as a laboratory or classroom demonstration are discussed.
Flame suppression due to acoustic streaming by using time reversal
Authors: Cliftmann Jay M. , Anderson Brian E. , Patchett Brian D.
Published: July 2024

Using high amplitude time reversal focusing to extinguish small flames is a novel demonstration of transient acoustic streaming. Typically, others have placed a low frequency acoustic source near the flame in order to generate a high enough particle displacement to extinguish it. In this study, we move the sources far from the flame and demonstrate that the time reversal method can focus transient waves to the flame. The peak acoustic overpressure level needed to extinguish a candle flame in free space is 191 dB peak when using a frequency range of 300 to 15000 Hz. This momentary focus causes acoustic streaming at the flame location after the focusing, which extinguishes the flame. By tracking the flame in high-speed video, we show the displacement of the flame due to the passing acoustic wave and subsequently due to the acoustic streaming. We further show that acoustic streaming extinguishes the flame, not the acoustic particle displacement.
Demonstration of nonlinear tuning curve vibration response using a homemade analog sweep spectrum analyzer
Authors: Paulenich III John , Korman Murray S.
Published: July 2024

A super-heterodyne sweep spectrum analyzer has been designed (using analog circuitry), built and tested to cover the 5 to 1000 Hz range. The analyzer employs a linear ramp voltage versus time, driving a voltage-controlled oscillator VCO that generates a sweep from 32.768 kHz to 33.768 kHz in 70 s. An analog AD734 multiplies the VCO signal by a sinusoidal signal (generated by a watch crystal 32.768 kHz oscillator). The “mixer” signal is low-pass filtered and amplified to generate a 5-1000 Hz swept tone using a 2-in. speaker. The accelerometer (mounted on a thin circular clamped acrylic plate) vibration response involves multiplying this signal by the VCO, then filtering this “mixer” signal using a 4-stage watch crystal ladder filter with a 1 Hz bandwidth. This signal is squared and low-pass filtered to generate the time (converted to frequency) vs. mean-squared voltage response on an oscilloscope. In the demonstration, 300 g of 6 mm diameter glass beads are supported by the 11.4 cm diam, 3.2 mm thick plate and upper rigid cylindrical wall column. The nonlinear tuning curve vibration response is recorded for various incremental drive amplitudes to demonstrate that the tuning curve resonant frequency significantly decreases with increasing drive amplitude.
Exploring comb filtering effects in the recording studio: A lesson on room acoustics
Authors: Bulla Wesley , LaFountaine Lisa , Plasse Raymond
Published: July 2024

A common practice during a live music-recording session is to position microphones, so-called, “room mics” to capture the ambient characteristics of the recording space. An in-class, hands-on experiment was conducted at Belmont University’s Historic Columbia Studio A in order to measure and observe the effect of comb filtering on the signal captured by an on-axis room microphone placed at various heights from the floor. A total of seven positions were recorded, spanning from just above the floor to twelve feet in the air. Sine sweep measurements and musical samples from a live virtual jazz-quartet were taken at each position. Students were then asked to listen back and discuss their preferences for each microphone height, comparing their observations to the matching frequency response analysis. A majority of students enjoyed the recording with the microphone positioned at the floor corresponding with the least amount of comb filtering. Although listener preference data was not collected, this experiment demonstrated the use of interdisciplinary examples as an educational tool in the field of acoustics.
Teaching concepts of acoustics in air—Part 3, reverberation
Authors: Gastmeier William J.
Published: July 2024

This paper has been written to participate in the “Education in Acoustics” session at the 2024 joint conference of the Canadian Acoustical Association and the Acoustical Society of America. It is written to build on Parts 1 and 2 of this series and similarly contains materials extracted from 30 years of teaching to Architects at the University of Waterloo and Dalhousie University in Halifax. Part 1 dealt primarily with sound propagation in air and the concepts of longitudinal wave motion, speed, frequency and wavelength and related effects which relate to what we perceive as pitch. Part 2 expanded on those concepts by discussing superposition and the definition and measurement of sound pressure, decibels and the decibel scale and how to manage decibels, all of which we perceive as loudness. Part 3 deals with reverberation, which is arguably the most important aspect of how sound propagates in indoor spaces. It affects both our ability to communicate and how we experience and perceive the quality of the acoustical environment. Practical demonstrations are provided to enhance learning of the concept of Reverberation. These include “hands on” demonstrations including physical experimentation, an audio demonstration and written materials to advance the concept.
The effects of vowel, pitch, and dynamics on the emotional characteristics of the Mezzo-Soprano, Countertenor, and Baritone Voices
Authors: Chang Bing Yen , Chan Hiu Ting , Law Man Hei , Horner Andrew B.
Published: July 2024

Previous research on the soprano, alto, tenor, and bass voices have shown that their emotional characteristics change with different vowel, pitch, and dynamics. This work continues the investigation with the mezzo-soprano, countertenor, and baritone voices. Listening tests were conducted whereby listeners gave absolute judgements on the voice tones over ten emotional categories, with the data analyzed using logistic regression. High-arousal categories were stronger for loud tones, whereas low-arousal categories were stronger for soft tones. The categories Happy, Heroic, Romantic, and Comic had an upward trend across the pitch range, whereas Calm, Mysterious, Shy, and Sad had a downward trend. Angry and Scary had different trends among the voices. For most categories, all five vowels were mostly similar in terms of emotional expressiveness, with exceptional cases for the baritone voice. Overall, pitch had the strongest effect and was almost twice as strong as dynamics and vowel, with dynamics slightly stronger than vowel. Vowel O had the largest strength-of-expressiveness overall, closely followed by vowels U and A, and finally vowels I and E last. These results give a quantified preliminary perspective on how vowel, pitch, and dynamics shape emotional expression in the voices across a wide range of voice types.
One-dimensional acoustic modeling of the şimşal considering the external Interaction of the open finger holes
Authors: Kaboodi Diako , Laurendeau Denis , Scavone Gary , Liu-Rosenbaum Aaron
Published: July 2024

A one-dimensional model in Python was developed to analyze the acoustic behavior of the Kurdish wind instrument, the şimşal. This model was developed using the Transmission Matrix Method (TMM), which was refined by taking into account the external interactions between the open tone holes. This research focuses on the acoustic resonator part of the şimşal with the lattice of finger holes in different cross-fingering patterns. The results were validated by measurements using an impedance probe, CapteurZ, which was developed by LAUM[1] and CTTM[2] The results are in good agreement with the measurement and despite the possible sources of error, which are discussed, the deviations are within an acceptable range. [1] The Acoustics Laboratory of the University of Le Mans [2] Le Mans Technology Transfer Center.
Tony Embleton and the ASA Standards Program
Authors: Brooks Bennett M. , Lind Stephen J.
Published: July 2024

Tony F. W. Embleton had a distinguished career as a researcher in acoustics, and as a leader in the ASA and CAA. Yet, he was keenly aware of the importance of standardization to practical applications in acoustics. Tony served as ASA Standards Director from 1993 to 1997, when the organization was going through a tough period, even facing abolishment by the ASA Executive Council. Tony reinvigorated the ASA Standards Program, including increasing its connection to the Technical Committees, as well as its administrative operations [T. F. W. Embleton, “Standards and the Acoustical Society,” J. Acoust. Soc. Am. 98, 691–693 (1995); S. Blaeser and C. J. Struck, “A history of ASA standards,” J. Acoust. Soc. Am. 145 (1), (2019)]. Tony also was instrumental in founding CAA’s Standards program. Tony’s legacy of engagement with the ASA technical and administrative leadership is still evident today. An overview of how Tony’s ideas remain a guiding force in the current ASA Standards Program is given.
The effect of eye-gaze direction on speech intelligibility
Authors: Taotong Tongthai , Dau Torsten , Ahrens Axel
Published: July 2024

In many daily situations we move our eyes to capture different visual information. Previous studies have shown interactions between the eye-gaze direction and auditory perception. The eye-gaze direction has been shown to modulate activity to acoustic stimuli in the auditory cortex of monkeys. In humans, decreased thresholds of binaural lateralization cues and improved accuracy of understanding series of digits in the presence of other speech has been shown. Here, we investigated the effect of the eye-gaze direction on speech perception of single-digit and 4-digit streams while directing the gaze at different directions containing either speech or non-speech stimuli. The speech interferers were also digits but a different gender than the target speech. The non-speech interferers consisted of speech-modulated speech shaped noise. The results showed improved speech intelligibility when the gaze direction and the auditory target direction were matching, in comparison to conditions where the gaze is pointed at a non-target direction. No differences were found comparing single-digit and 4-digit streams. Presenting speech or non-speech stimuli at the gaze direction did not affect the speech intelligibility results. These findings further clarify the influence of the gaze direction on speech perception.
Front-back bias and the 1000-Hz interaural intensity anomaly
Authors: Hartmann William
Published: July 2024

Free field measurements were made of the level differences, as measured in an ear canal, for a noise source in front of the head compared to a source in back. The measurements were made on a Kemar manikin for 19 lateral angles over the complete 180-degree range for front-back comparisons. There were 7 octave bands, 125–8000 Hz, and two horizontal planes. Front-back level differences were generally positive except for the dramatic case of 1000 Hz, where the differences were negative over an azimuth range of 120 degrees. When the head-related elevation of the sources was increased from zero to 10 degrees, the range of the negative front-back differences grew to 140 degrees. These physical results are consistent with the strong tendency for listeners to identify a one-third octave noise band in a narrow range near 1000 Hz as a source in back. This tendency may be the origin of the often-observed Grantham effect, wherein the difference limen for the interaural level difference is larger near 1000 Hz than at higher or lower frequencies. The connection is that sources in back of the listener, whatever their frequencies, are not localized nearly as well as sources in front.
Implicit and explicit responses to infant sounds: A cross-sectional study among parents and non-parents
Authors: Alonso Arteche M. Fernanda , Ramloll Leatisha , MENARD Lucie , Polka Linda
Published: July 2024

This research investigates the infant schema in auditory perception by examining how different demographics, including males, females, parents, and non-parents, respond implicitly and explicitly to baby vocalizations in comparison to adult, cat, and kitten sounds. Utilizing a single category implicit association task (SC-IAT) and a detailed questionnaire, we analyzed participants' responses to synthesized vowel sounds from infants, adults, cats, and kittens. The questionnaire focused on participants' liking and perception of cuteness for these sounds. Findings reveal a universal positive implicit preference for baby vocalizations across all groups (p = 0.01), without a similar effect for other sound sources. In contrast, explicit responses varied significantly. While all groups showed a preference for the sounds of cats, babies, and kittens over adults, only mothers demonstrated a statistically significant explicit preference for infant sounds over those of cats and kittens. This study highlights the discrepancy between unconscious and conscious attitudes towards infant sounds. It underscores that while an implicit affinity for baby vocalizations is widespread, explicit preferences, particularly in terms of cuteness and likeability, are markedly stronger in mothers. These insights contribute to our understanding of the auditory dimension of the infant schema, emphasizing the role of gender and parental status in shaping responses.
American English diphthong transitions and the acoustic vowel space: A pilot comparison of two tasks
Authors: Kuo Christina
Published: July 2024

The purpose of the present study is to evaluate the potential relationship(s) between diphthong transitions and the acoustic vowel space parameters in two speaking tasks. Diphthongs are associated with acoustic changes that reflect changes in vocal tract configurations, affording unique opportunities for investigating the articulatory-acoustic link. The acoustic vowel space, a representation of monophthong vowels in a two-dimensional plane defined by the first and second formant frequencies (F1 and F2), has been widely used to interpret articulatory-acoustic consequences and to index articulatory integrity. Nevertheless, limited is known as to how diphthongs and monophthong vowels account for the acoustic working space together [Lee et al., JASA 136(4), 1880–1894 (2014)]. To add to this inquiry, transitions of American English diphthongs /ei/, /ɑɪ/, /ɑʊ/, /oʊ/, and /ɔi/, defined by the primary F2 transition, are examined with respect to the quadrilateral vowel space anchored by /i/, /æ/, /ɑ/, and /u/. The speech sounds were obtained from four male speakers in two tasks, sentence reading and connected speech, that have been shown to elicit vowel space changes. It is hypothesized that greater diphthong transitions are associated with parameters corresponding to a larger vowel space. Findings will be discussed within the framework of the acoustic theory.
Effects of exposure to dialect-specific allophonic variation on perceptual similarity ratings of vowels
Authors: Bissell Marie , Clopper Cynthia G.
Published: July 2024

Dialect exposure affects listeners’ lexical processing. In this study, we examined whether listeners’ exposure to dialect-specific allophonic variation in two linguistic variables in American English (nasal split /æ/ system and pre-voiceless /ɑɪ/ raising) affects their perceptual similarity ratings of matching versus mismatching allophones. Listeners from the U.S. North were assumed to have more exposure to pre-voiceless /ɑɪ/ raising and less exposure to a nasal split /æ/ system, while listeners from the U.S. Midland were assumed to have more exposure to a nasal split /æ/ system and less exposure to pre-voiceless /ɑɪ/ raising. We analyzed Northern and Midland listeners’ perceptual similarity ratings on a 1–5 scale for three types of auditory vowel pairs: match (e.g., ban-bang or bike-bite), allophonic mismatch (e.g., ban-bat or bike-bide), and phonemic mismatch (e.g., ban-bike). We predict that listeners with more exposure to dialect-specific allophonic variation should rate allophonic mismatches as more different than allophonic matches compared to listeners with less exposure. Preliminary results suggest that listeners rate allophonic matches as more similar than allophonic mismatches, and both of these types are rated as more similar than phonemic mismatches, consistent with existing literature. There was no effect of dialect exposure to allophonic variation on perceptual similarity ratings.
A lucky covariance estimator using cumulative coherence
Authors: Brooker Daniel J. , Edelmann Geoffrey F.
Published: July 2024

This talk demonstrates a technique to improve covariance estimation using the principles of lucky signal processing and the cumulative coherence. Lucky processing, popularized in astro-photography, is a technique that increases signal quality by selectively keeping only a small fraction from a pool of potential snapshots. Cumulative coherence, a measure of how well a set of vectors is described by its subsets, provides the measure of “data quality” that enables the lucky processing. This approach was applied to covariance estimation on an acoustic array by taking a fixed duration sample of data and creating a dense set of snapshots with higher than usual overlap. From these densely sampled snapshots, the “luckiest” ones were found using cumulative coherence, and the covariance was averaged as normal. It was found that the lucky covariance estimate was successful at adaptive matched field processing and produced a less ambiguous processor output than the conventional estimator. The lucky covariance estimate had a higher estimated signal-to-noise ratio, especially when the source was at longer ranges from the array. [This work is supported by the Office of Naval Research.]
The crucial role of granular packing structure in marine sediment acoustics
Authors: Clark Abe , Olson Derek R. , Swartz Andrew
Published: July 2024

Motivated by the acoustic properties of marine sediments, we study via discrete-element method simulations the frequency dependence of dispersion and attenuation in model marine sediments. By numerically solving for the motion of each grain in a packing, rather than solving a continuum wave equation, we find that the granular packing structure, which is not explicitly considered in existing sediment-acoustics models, plays a crucial role in determining how attenuation and wave speed vary with frequency. Prior work has typically postulated a wave equation that is motivated by grain- scale forces, including viscous effects from the interstitial fluid, without explicitly considering the disordered packing structure of the grains. However, the packing structure is known to produce complex, nonlinear behavior (e.g., during shear or quasistatic compression), and how it affects dispersion and attenuation is not known. We consider linearized forces between particles (i.e., springs and dashpots), and demonstrate that the disordered packing structure leads to emergent scaling laws that do not agree with PDE-based approaches. Our results demonstrate that the granular packing structure must be explicitly considered when constructing theories for the acoustic properties of marine sediments.
Revisiting the Seattle Opera House
Authors: Levins Jennifer
Published: July 2024

Jerry Christoff played an integral part of the Seattle Opera House design in the early 1960s. An overview of the acoustic design elements for this space was published in 1964 in a paper co-authored with Paul Veneklasen. Many of the concepts presented in this paper, like reverberance, clarity, and envelopment, still influence acoustical design today. We will highlight the key points from this paper and share anecdotes from Jerry’s career.
Enhancement of virtual acoustics rendering using boundary mounted dipole loudspeakers
Authors: King Richard , Woszczyk Wieslaw , Oikonomidis Michail
Published: July 2024

The Immersive Media Lab at McGill University hosts a Virtual Acoustics Technology (VAT) system incorporating a suspended array of omnidirectional loudspeakers. Using a convolution reverb engine, acoustic simulations of real spaces can be realized via a catalog of Room Impulse Response measurements. Reflected sound in the room helps to disguise the location of the sound emitters rendering virtual acoustics. One limitation of the system, however, is the interference between the lab’s natural acoustics and the virtual environment generated by the VAT system. The improvement under consideration is to enhance diffusion along the walls of the lab, in order to mask the acoustical characteristics related to the physical dimensions of the room. Dipole loudspeakers are installed on the room boundaries and used to scatter reflections and reverberation along the wall surfaces enlarging the effective radiation surface of the walls. The scattered energy may mask specular reflections and reduce localization of the virtual acoustic sources. Investigations compare the result of scattering reflected sound vertically as opposed to horizontally across the boundaries. Measurements illustrate the effect of the dipole loudspeaker system when used on its own as well as working in conjunction with the existing omnidirectional loudspeaker array.
Using soundscape to monitor population size, demographics, and antipredator behavior in a dense aggregation of colonial seabirds
Authors: Eddington Valerie M. , Brosseau Joseph , Craig Liz , White Easton , Kloepper Laura
Published: July 2024

Migratory seabirds are vulnerable to decline due to climate change and anthropogenic disturbances. Common terns (Sterna hirundo) are highly vocal colonial seabirds that serve as bioindicators of their foraging grounds throughout their migratory range. Historically, monitoring colonial seabirds is invasive and time-consuming, and traditional acoustic approaches are complicated by high amounts of call overlap. Monitoring the behavioral ramifications of disturbance, as well as overall colony size and health, is crucial to implementing effective management decisions. However, methods are needed to do so efficiently and with minimal disturbance. In this study, we demonstrate that population size, demographics, and behavior can be assessed acoustically through changes in acoustic energy across varying temporal scales. To do this, we compared acoustic energy to in-person observations of nest density, chick-hatching, and investigator disturbance. We found that trends in acoustic energy align with observations of nest density, and the distribution of acoustic energy across frequency bands is indicative of colony demographics. Furthermore, we found a significant relationship between acoustic energy and investigator disturbance within 20 meters of an acoustic recorder. Overall, our findings suggest that colony-wide trends in population size, demographics, and behavior can be monitored via acoustic energy without the time-consuming analysis of individual calls.
Subharmonics are not the full story—Searching for acoustic signatures of cavitation and other fantastic beasts
Authors: Wu Qiang , Gray Michael , Smith Cameron , Cleveland Robin O. , Coussios Constantin , Stride Eleanor P.
Published: July 2024

Cavitation induced bio-effects are being exploiting in a wide range of applications from physiotherapy to brain surgery. The acoustic emissions generated by bubble activity are extremely useful in enabling real time treatment monitoring. The relationship between the spectral characteristics of these emissions and bubble dynamics is, however, complex. Here we report data from experiments with simultaneous ultra-high-speed optical imaging and passive acoustic mapping of individual microbubbles exposed to 50 cycles of ultrasound at 0.5 MHz with varying peak negative pressures. The spectral content of the acoustic emissions from individual microbubble was compared to the bubble dynamics observed by the imaging. As expected from prior work, both the number of discrete harmonics and broadband content in the emissions increased with increasing amplitude of bubble oscillation. There was no clear correlation, however, between the presence of ultra and sub-harmonic components and bubble behaviour. Indeed, these components were frequently absent. Moreover, phenomena such as microjetting, fragmentation and coalescence, that could produce very different effects in tissue, were indistinguishable acoustically. The results thus indicate that the definition of cavitation thresholds or doses should be very carefully considered depending on the therapeutic effect (or avoidance of unwanted bioeffects) required for a particular application.
Sound synthesis applications using a physical model of a single-reed woodwind instrument
Authors: Chatziioannou Vasileios , Hofmann Alex , Pàmies-Vilà Montserrat
Published: July 2024

Physical modeling can be used to analyze and predict the vibrations of a musical instrument. This also enables to numerically synthesize sounds as if they were produced by a real instrument. Focusing on single-reed woodwind instruments, a physical model should incorporate the actions of the player in order to synthesize realistic sounds. This interaction mostly takes place at the instrument mouthpiece—toneholes opened by the player's fingers may be approximated by changing the instrument geometry. A physical model is presented that is able to take embouchure effects into account, in order to reliably simulate note transitions. Regarding physical modeling synthesis, the numerical efficiency of the underlying algorithms should also be considered. Capturing as many physical phenomena as possible may lead to models that require longer running times. Omitting less significant phenomena may lead to models suitable for real-time performance, while retaining most of the sound characteristics of the real instrument. In either case, it is of utmost importance to prove that the simulation algorithms are numerically stable. Sound examples are presented in an attempt to imitate real recordings, as well as in a live performance setting (examples available at https://iwk.mdw.ac.at/sound-synthesis/)
Bowling alleys in residential buildings—Noise control and measurements
Authors: Du Guangsheng (Sam) , Levkoe Mark , Tsang Jessica , Li Qiang (Richard)
Published: July 2024

In the competitive world of residential development, developers are striving to construct residential buildings that will be more desirable to occupants by providing a diverse range of amenity spaces, such as a bowling alley. Understandably, noise concerns from the addition of bowling alleys in residential buildings were raised during the design stage of various projects. To address the issues, a jack-up floating floor system was proposed for the bowling alley to mitigate the noise impact from the pin setting machine, initial ball impact on the bowling alley lanes, rolling on the lanes, and ball impact with the pins. Apparent Impact insulation class (AIIC) and heel drop testing were completed at various stages during the floating floor construction to confirm the impact sound isolation performance of the floating floor system. Testing results concluded that the implemented floating floor system reduced impact noise significantly and satisfactory sound levels resulted in the closest occupied spaces.
Background noise and reverberation time in a college classroom
Authors: Ruhala Richard J. , Ruhala Laura , Packer Charles , Patino Antonio
Published: July 2024

A sound survey of noise levels in unoccupied classrooms on the Marietta Campus of Kennesaw State University identified one classroom as the most problematic in terms of background noise levels. This level is mostly associated with heating, ventilation, and air-conditioning equipment. Excessive background noise in learning spaces diminishes the speech intelligibility from the speaker to the listeners and can cause stress and fatigue. The overall A-weighted average sound levels are compared with ANSI-ASA S12.60-2010/Part 1 (Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools). In addition, frequency analysis of the background sound and time variations are studies. Binaural headset microphone measurements are compared to the single microphone measurements. Reverberation time is measured using the engineering survey method and compared to the ANSI guidelines.
A theory for the emission of infrasound from Tornadoes
Authors: Liang Bin , Waxler Roger M. , Markowski Paul
Published: July 2024

Tornadoes have been shown to radiate infrasound to great distances, however convincing fundamental sound mechanisms are still absent. After using vortex sound theory to study sound generated by two numerical tornadoes, we found that there is a significant low-frequency signal between 0.1 Hz and 1 Hz. The sound is closely related to rotation of the non-axisymmetric vorticity field and its frequency depends on the rotational frequency. The non-axisymmetric vorticity field is represented by a Kirchhoff vortex-like flow in baseline tornado model and by multiple-vortex flow in eddy injection tornado model. Interestingly, there also exist high-frequency components in the later model which are hypothesized to originate from vortex merging process. Field detection data of tornado infrasound provides some support for the low-frequency sound.
Low gain hearing aids use and benefit: A viable management option for those with hearing sensitivity within the normal range
Authors: Davidson Alyssa , Ellis Gregory M. , Brungart Douglas
Published: July 2024

Low (or mild) gain hearing aids (LGHAs) are increasingly considered for individuals with normal peripheral hearing but self-reported auditory complaints. The Tinnitus and Hearing Survey-Hearing Subscale (THS-H) offers a normative cutoff, aiding identification of significant self-reported hearing difficulties (SHD). This research assesses the benefits of LGHAs as a management option for individuals with normal hearing sensitivity and significant SHD, comparing LGHA use and benefit to individuals without SHD and those with peripheral hearing loss. 186 participants across four groups, including those with or without SHD and peripheral hearing loss were recruited. Participants completed questionnaires that addressed hearing aid usage, benefit, SHD and tinnitus. Individuals with significant SHD and hearing sensitivity within the normal range (NHT) reported higher LGHA usage and benefit than individuals with normal hearing difficulties (NHD) and NHT. Comparable use and benefit were noted between groups with significant SHD regardless of peripheral hearing loss status. The findings support LGHAs as a suitable management option for individuals with NHT and SHD, as indicated by hearing aid use and benefit. Quantifying the level of perceived auditory processing deficits (i.e., SHD), notably with the THS-H, enhances sensitivity in identifying those who may benefit from this management option.
Don’t say “modal analysis:” A backdoor introduction to vibrations via programming and numerical methods
Authors: Wallen Samuel P.
Published: July 2024

As an undergraduate degree requirement, The Walker Department of Mechanical Engineering at the University of Texas at Austin teaches a lower-division, introductory course on computer programming and numerical methods. The enrollment consists primarily of second-year mechanical engineering (ME) students, approximately half of whom enter the course with no prior programming experience. Due to its relatively early position in the ME curriculum, the course presents the unique challenge of teaching students to apply numerical methods to ME-relevant problems, with little background about the physics involved or the contexts in which they are likely to occur in practice. This talk presents an end-of-term project in which students use two numerical methods discussed earlier in the course, singular value decomposition and Runge-Kutta methods, to construct, simulate, and benchmark a reduced-order, dynamic model of a vibrating guitar string. In addition to reinforcing course outcomes associated with programming, mathematics, and data visualization, this project provides an introduction to acoustics, vibration, and modal analysis at a level that belies its position in the overall curriculum.
Probabilistic multiphysics inference with flexible coupling and data covariance estimation
Authors: Dettmer Jan , Shahsavari Pejman , Gosselin Jeremy
Published: July 2024

We consider combining complementary information contained in multiple data types recorded from distinct physical processes interacting with the Earth’s subsurface. Such multiphysics inference of non-invasive geophysical observations can improve the resolution of Earth structure and processes, but is plagued by many subjective choices that practitioners are commonly required to make. We present the method of probabilistic multiphysics inference that employs Bayesian statistics to overcome several requirements for subjective choices. To ensure appropriate data weights, full data covariance matrices are estimated during Markov chain Monte Carlo sampling. The layering structure of the subsurface is estimated with flexible coupling, where the number of homogeneous layers is treated as unknown and the number of geophysical parameters for each layer are unknown. The latter permits flexible coupling such that parameters for different physical processes are not required to share the same layering structure, which avoids over-parametrization. We consider two examples with elastic and electromagnetic waves. In the first example, the thicknesses of shallow (tens of meters) active and permafrost layers are better constrained by probabilistic multiphysics inference. The second example resolves cratonic structure, with reduced uncertainty of a sedimentary basin and for the depth of the lithosphere-asthenosphere boundary. [Work supported by an NSERC Discovery Grant.]