bluuebunny/crossref_metadata_2025 huggingface dataset:
Reverberation analysis and acoustical modeling for improved acoustical conditions within modern workplace phone rooms
Authors: Maurer Alex , Fullerton Jeffrey , Kim Kimteri
Published: April 2019

As open office floor plans have grown popular, phone rooms have become important for staff to conduct personal conversations in private. Varying in acoustic and holistic design, these rooms are intended to both isolate the occupant’s speech from being heard by others in the office and reduce intrusive noise from disrupting these phone conversations. The acoustical properties within the rooms are often ignored, even though these spaces can have rather reverberant conditions and be subjectively very bothersome and awkward to converse within. Several types of porous absorption can help to control the acoustics of these phone rooms which are commonly implemented today. We have studied a variety of absorptive panel samples, placements, and coverage areas to test the effect of absorption in the phone rooms. We measured the reverberation time and impulse response of the rooms with various acoustical finishes to better understand the effectiveness of porous absorption to control the acoustics of these phone rooms.
Better together—Combining acoustics and environmental DNA to understand ecosystems
Authors: Miksis-Olds Jennifer L. , Watts Alison
Published: April 2019

Acoustic signals have historically been and presently are the state-of-the-art for sensing the ocean at small to large spatial scales. Passive acoustics non-invasively assess sound levels, surface conditions, human activity, and the distribution of vocalizing marine life. Echosounders provide acoustic backscatter information that contribute not only critical information on biology but also physical components of the water column which has supplied invaluable knowledge on the community structure, organism size and distribution, and oceanic microstructure. Advances in DNA methods present an opportunity to harness a new technology and fundamentally improve our capacity to monitor habitats, communities, and individual species. Environmental DNA (eDNA) includes whole microorganisms, tissue fragments, reproductive and waste products, and other cellular material in a sample. eDNA methods, such as acoustics, allow for the identification of species without having to physically capture animals. While eDNA and acoustics are both powerful methods for identifying and describing organisms present in the environment, no single survey method can fully represent the “real” condition. We envision a future where remote platforms can gather and relay data in near-real time and can elicit a targeted response to information, such as launching a drone to survey additional locations or increasing the sampling frequency when key species are present.
Acoustic challenges of senior care facilities
Authors: Schilb Emily , Dugger Edward
Published: April 2019

The population of the US, Europe, and Asia is aging, and the rate at which individuals are developing neurodegenerative diseases is also increasing. As a result, we are seeing a rise in the number of senior living facilities, ranging from independent living for active seniors to memory care facilities aiding those suffering from Alzheimer’s and Dementia. Often these mixed levels of care are housed in one building, with the result being a dynamic facility with uses not limited to residential units and medical clinics but including fitness centers, pools, theaters, auditoriums, recreation rooms, dining rooms, and bars. With such a diverse range of often acoustically incompatible activities and uses, the challenges in designing these facilities quickly become apparent. During this presentation, we will explore the challenges of integrating residential suites with various amenities and the potential solutions for maintaining acoustic isolation without compromising architectural design or functionality.
Does noise sensitivity or attentional capacity predict cardiovascular responses to distracting sound?
Authors: Oliver Jordan N. , Sollmann Lea , Niehl Annika , Francis Alexander L.
Published: April 2019

Workplace noise may cause stress that has long-term implications for health. Employees in open-plan offices typically identify intermittently occurring background sounds as significant sources of stress, possibly because they distract attention away from intended tasks. Thus, individual differences in attention and noise sensitivity may explain individual differences in physiological responses to workplace noise. In previous research [Oliver, et al., in 176th Meeting of the Acoustical Society of America (2018)], we reported results from a preliminary analysis of 19 participants’ affective and electrodermal responses to working in background noise that included intermittent environmental sounds. Electrodermal responses were used as a measure of distraction because they constitute a primary component of the physiological orienting response, a multi-component response reflecting exogenous capture of attention. Our results suggested that individuals who are more sensitive to noise experienced greater frustration with the primary task, but there was no relationship between frustration and distraction as indexed by electrodermal responses. Here, we present additional analyses of an expanded dataset, focusing on attentional and cardiovascular measures (heart rate and pulse volume amplitude) previously linked to cognitive demand and noise annoyance (Francis et al., 2016) and relate these results to an overall characterization of the auditory orienting response.
Integrating acoustic shooter detection into a hearing protection device
Authors: Hengy Sébastien , Christoph Marcus , Duffner Pascal , Hamery Pascal , Zimpfer Veronique
Published: April 2019

Recent advances in the development of hearing protection devices open new fields of applications on the battlefield. While the TCAPS (Tactical Communication And Protective Systems) protect against acute acoustic traumas, they maintain information relative to the acoustic environment of the soldiers. Today, these systems are efficient for both hearing protection and communication. We propose to use the microphones equipping the TCAPS headsets in order to detect and localize shooters on the battlefield. The microphone underneath the hearing protection is used in order to detect the shock and muzzle waves generated by supersonic shots. A meshed network between the TCAPS deployed on the field allows transmitting asynchronous information relative to the detected waves to data fusion nodes that allow estimating the shooter’s position. Solutions are proposed in order to compensate the effects of the presence of the head between the microphones underneath the hearing protection. Results concerning the estimation of the time difference of arrival of a transient wave in free field and in the presence of an artificial head are presented. The data fusion process is tested thanks to simulations in various deployment configurations.
Characterization of digital MEMS microphone elements for usage in a hostile fire detection system on a multi-rotor drone
Authors: Prather Wayne E. , Frazier William G. , Di Xiao
Published: April 2019

Acoustic based Hostile Fire Detection Systems (HFDS) depend on multi-element arrays of microphones which are simultaneously sampled at sample rates often in the 10–50 ksps range. A driving component of the electronic hardware complexity of the system is the signal buffering, filtering, and analog to digital conversion required for each microphone channel. Digital MEMS microphones consolidate these functions to within the microphone element giving a digital output representative of the measured acoustic signal. Digital MEMS microphones allow for a completely digital hardware solution which reduces complexity and allows more flexibility in utilizing higher element number arrays if desired. The performance parameters relevant to HFDSs of current best-in-class digital MEMS microphones were measured and compared to current analog microphones commonly utilized in these systems. The purpose of these tests was to determine the viability of digital MEMS microphones as an alternate acoustic sensing element for a HFDS system being implemented on a multi-rotor drone.
Anomalous wave polarization through a 3D periodic auxetic lattice
Authors: Patil Ganesh U. , Matlack Kathryn H.
Published: April 2019

Solid media supports both longitudinal and shear wave polarizations, providing a rich platform for designing phononic materials with prescribed wave filtering, engineered mode conversions, negative refraction, and other unique properties. While longitudinal waves almost always propagate at a faster velocity than shear waves in natural materials, tailoring the polarization of the faster wave velocity could enable unique control over wave propagation properties. Here, we present a three-dimensional periodic “bowtie” lattice that exhibits a shift in the faster wave polarization from the quasi-longitudinal to quasi-transverse wave in an anisotropic plane. We observe that this shift, termed “anomalous wave polarization”, is possible when the lattice behaves auxetically. Using the finite element method, we show that the wave polarizations in the bowtie lattice depend on certain geometric parameters and the wave propagation direction. We use wave velocity information to evaluate the lattice effective properties using the Bloch-wave homogenization approach and confirm the required elastic condition for the polarization anomaly in an anisotropic plane. We also emphasize the importance of identifying the wave polarization along with the wave velocity classification for lattice effective property evaluation. This lattice behavior will be useful for designing mode-converting metamaterials that have potential application in non-destructive testing and bio-medical ultrasounds.
Partial activation of modular and foldable tessellated acoustic arrays for wave focusing
Authors: Zhao Ningxiner , Harne Ryan L.
Published: April 2019

Tessellated acoustic arrays inspired by origami structures are suggested to enable wave focusing by exploiting curvatures realized by folded configurations of the array transducer elements. The use of origami-inspired folding patterns also cultivates great portability for space-limited applications. Yet, maintaining curvatures may prohibit feasible implementation of a tessellated been studied for the acoustic energy focusing usage. This research proposes an alternative technique to achieve wave focusing with tessellated arrays that do not realize curvatures upon folding. Here, the partial activation of a tessellated array is exploited to result in constructive interference that realizes a nearfield focal region. The modeling approach to examine partially activated arrays is presented and verified against numerical simulations. Then, the changes in nearfield focusing characteristics are correlated with corresponding changes in partial activation and array folding extent. The opportunities to exploit the partial activation of relatively simple origami-inspired array structures are examined to identify strategies to simplify implementation of portable, folding acoustic arrays in applications.
Estimation of environmental parameters with machine learning using a compact tetrahedral array and sources of opportunity
Authors: Moore Jesse T. , Miller James H. , Potty Gopu R. , Tripathy Aditi , Tazawa Makio , Amaral Jennifer , Vigness-Raposa Kathleen J. , Newhall Arthur , Lin Ying-Tsong
Published: April 2019

In a previous paper, we showed that we could localize sound sources using a compact tetrahedral hydrophone array in a continental shelf environment south of Block Island, Rhode Island. The tetrahedral array of phones, 0.5 m on a side, was deployed to monitor the construction and operation of the first offshore wind farm in the United States. Directions of arrival (DOAs) for a number of ships were computed using a time difference of arrival technique. Given the DOAs, ranges are estimated using supervised machine learning techniques. Here, we extend this work to estimate a number of environmental parameters including water depth and sediment composition. Training sets of range-dependent ocean waveguides and sediment sound speeds were generated using a propagation model for a neural network. Data from the tetrahedral array were processed by the neural network, which provided estimates of the water depth and sediment parameters such as sound speed and density. These estimates are compared to bathymetric data and core data collected as part of the site characterization for the wind farm. [Work supported by the Office of Naval Research and the Bureau of Ocean Energy Management.]
Deep learning for automated detection of B-lines in lung ultrasonography
Authors: van Sloun Ruud J. , Demi Libertario
Published: April 2019

The application of ultrasound imaging to the diagnosis of lung diseases is gaining attention. Of particular interest are several imaging-artifacts, e.g., A and B line artifacts. A-lines are hyperechoic horizontal lines, which are substantially visualized across the entire image and parallel to pleural-line. They represent the normal pattern of the lung if pneumothorax is excluded. Differently, B-line artifacts correlate with pathology and are defined as hyperechoic vertical artifacts, which originate from a point along the pleura-line and lie perpendicular to the latter. Their presence has been linked to an increase in extravascular lung water, interstitial lung diseases, non-cardiogenic lung edema, interstitial pneumonia, and lung contusion. In this work, we describe a method aimed to support the clinicians by automatically identifying the frames of an ultrasound video where B-lines are found. To this end, we employ modern deep learning strategies and train a fully convolutional neural network to perform this task on b-mode images of dedicated ultrasound phantoms (Demi et al., Sci. Rep. 2017). We moreover calculate neural attention maps that visualize which components in the image triggered the network, thereby offering simultaneous localization. Future work includes characterization of the detected B-lines to enable adequate phenotyping of various lung pathologies.
Initial transients in free reed instruments: A survey of experimental results
Authors: Cottingham James P.
Published: April 2019

For free reeds in steady oscillation, the fundamental transverse beam mode dominates, but transverse modes and some torsional modes are also typically present. The motion of the free-reed tongue in early stages of the initial transient has been studied experimentally with the aim of determining the presence of higher modes and their possible role in the attack transient. These transients have been studied for free reeds mounted on a wind chamber with several methods used to initiate the attack transients. The resulting displacement and velocity waveforms have been studied using laser vibrometry, variable impedance transducer proximity sensors, and high speed video with the tracking software. The most realistic procedure used a pallet valve mechanism simulating the attack transient in a key-operated instrument. Short-term spectra derived from the waveforms have been analyzed, showing that both higher transverse modes and some torsional modes are observed in the initial transient, with the second transverse mode and the torsional mode especially prominent in the earlier stages of oscillation. Comparisons of reed tongues of different designs have been made to explore the role of these modes in the initial excitation.
Recognizing speech in the context of talker variability
Authors: Heald Shannon L. , Nusbaum Howard C.
Published: April 2019

The relationship of the acoustic patterns of speech to phonetic categories varies across talkers. A change in talker therefore requires listeners use this relationship which depends on determining the acoustic-phonetic mapping for a new talker. The work from our group has demonstrated that tuning the perceptual system to the acoustic-phonetic system of a new talker is associated with a redirection of attention and a momentary increased load on working memory. These empirical findings support the hypothesis that speech perception is best thought of as an active cognitive process, where the ambiguity of the acoustic signal determines the mobilization of cognitive resources needed to support accurate perception. In this talk, I will (1) discuss the implication of these results for both cognitive and neural models of speech perception and (2) make the argument that extant theories of speech perception must address recognition in the context of acoustic-linguistic pattern variability, such as talker variability, as it is central to the computational problem of understanding speech perception.
Who's talking and what are they saying: Phonetic cue distributions link speech and talker recognition
Authors: Kleinschmidt Dave F.
Published: April 2019

On the one hand, talker variability is one of the fundamental challenges for speech recognition: each talker has their own mapping from linguistic units to sounds, which means that an effective listener must use a different recognition function for each talker. On the other hand, talker variability means that speech is a source of rich information about who the talker is. This dual nature of talker variability means that speech and talker recognition are inextricably linked: knowing something about who is talking makes it easier to understand what they are saying, and knowing something about how someone talks unlocks the rich social meaning of speech. I argue that the concept of a talker's generative model, or the probabilistic distributions of sounds associated with each phonetic/linguistic category, is a useful general purpose conceptual tool for understanding the link between talker variability, speech recognition, and social identity. With such phonetic cue distributions, we can use information theoretic tools to quantify both the extent and structure of talker variability across different phonetic systems and establish in-principle consequences of talker variability for both speech recognition and socio-indexical inferences from speech.
Sound scattering from targets in shallow water by finite element method combined with normal-mode method
Authors: Li Jinyu , Shang Dejiang , Liu Jinpeng , Zhang Chao
Published: April 2019

A hybrid method to calculate the sound scattering field of the target in waveguide is presented, combining the theory of the normal mode with the finite element method (FEM). Although FEM used only can provide accurate results, it is deeply restricted by the property of the computers and does not have a satisfying computing speed, for its calculation is closely related to the size and complexity of the target. The hybrid method presented in this paper can calculate the sound scattering field of more arbitrary and more complicated target over farther ranges in oceanic waveguide at low frequencies. First, separate the sound field into two parts, domain A, containing the target in the nearer range, and domain B meaning the rest domain of the field. In domain A, the sound field was calculated via FEM. Then, apply the normal mode theory to forecast the sound scattering field over farther ranges, using the pressure data on the intersection area between domains A and B obtained by FEM. The method has been used to calculate the sound scattering field of a rigid sphere in waveguide and based on the results, it is demonstrated that this hybrid method is accurate and efficient.
Rethinking libraries—Three case studies
Authors: Way Evelyn , Doria Damian
Published: April 2019

As the nature of library usage changes, traditional book stacks and individual workspaces are giving way to group activities, informal meetings, classes, and makerspaces. In the past, distraction was managed not through the acoustic environment, but operationally through behavior enforcement and having separate physical spaces for different activities. Now excessive reverberation and inappropriate background noise levels significantly inhibit the usability of a library. Conversations from the café must not disturb small group work areas or instruction on the three-dimensional printer, community meetings need to happen at the same time as classes on digital photo processing, and childrens' story time occurs while the local entrepreneur researches how to register their business. We examine the acoustic design for a community library as collaboration center, a community library as recreation center, and a school library integrated into the common space.
Design of carotid bifurcation phantoms for integrative imaging investigations of arterial wall and flow dynamics
Authors: Chee Adrian J. , Yiu Billy Y. , Yu Alfred C.
Published: April 2019

Vascular phantoms are well regarded as essential experimental tools in the development of new ultrasound techniques for assessing wall mechanics and blood flow. However, existing phantoms are ill-suited for evaluation of integrative imaging methods that seek to concurrently assess biomechanics and hemodynamics. Here, we present a novel design protocol for acoustically-compatible anthropomorphic walled phantoms with artery-like vessel elasticity of carotid bifurcation with stenotic-narrowing. Our protocol involved a set of three-dimensional printed mold parts (consisted of a vessel core and an outer mold) for investment casting of polyvinyl alcohol solution to construct the elastic vessel tube. Agar-gelatin slab was formed around the vessel tube mimicking surrounding tissue. For demonstration, a set of healthy and stenosed (25%, 50%, and 75%) carotid bifurcation phantoms were developed. Imaging experiments were performed on these phantoms to visualize complex blood flow (recirculation and flow jet formation observed) and pulse wave dynamics (derived pulse wave velocity = 4.67 ± 0.71 m/s). Integrative imaging of wall motion and blood flow in our phantoms also revealed fluid-structure interaction differences between healthy and diseased models. These findings show that phantoms developed with our new protocol are useful in vascular imaging studies that individually or jointly assess wall motion and flow dynamics.
Acoustic droplet vaporization with microfluidic droplets results in dissolved oxygen scavenging
Authors: Benton Rachel P. , Jahanpanah Newsha , Warner Emilee , Srivastava Rohan S. , Anand Ishan , Haworth Kevin J.
Published: April 2019

Acoustic droplet vaporization (ADV) is the ultrasound-mediated phase transitioning of liquid perfluoropentane (PFP) droplets into gas microbubbles resulting in dissolved oxygen scavenging from the surrounding fluid. The objective of this study was to determine how droplet diameter influences oxygen scavenging. Droplets of 12 μm and 6 μm diameters were manufactured using a microfluidic system, which were diluted in saline to obtain concentrations of 0.48 Χ 10-3 Â± 0.12 Χ 10-3 ml/ml and 1.11 Χ 10-3 Â± 0.13 Χ 10-3ml/ml, respectively. Samples were pumped through a 37 °C flow phantom at 10 ml/min. A 5 MHz transducer insonified droplets at 5 MPa for 20 cycles with a 500 Hz repetition frequency. Oxygen partial pressure (Po2) was measured with a distal sensor. Samples of 12 μm and 6 μm droplets had an average volume-weighted transition efficiency of 5.8% ± 4.5% and 5.3% ± 4.6%, respectively. The initial Po2 was 169 ± 7 mmHg for all samples. ADV with 12 μm and 6 μm droplets reduced the Po2 to 113 ± 21 mmHg and 101 ± 9 mmHg, respectively. An oxygen scavenging model based on the PFP phase transitioned volume yielded a final Po2 of 121 ± 27 mmHg for 12 μm droplets and 106 ± 29 mmHg for 6 μm droplets. There was no statistically significant difference (p > 0.05) between the experimentally measured and modeled Po2 values after ADV.
Graduate acoustics at Brigham Young University
Authors: Neilsen Tracianne B. , Sommerfeldt Scott D. , Leishman Timothy W. , Gee Kent L. , Anderson Brian E. , Blotter Jonathan , Thomson Scott L. , Strong William
Published: April 2019

Graduate studies in acoustics at Brigham Young University prepare students for industry, research, and academia by complementing in-depth coursework with publishable research. Graduate-level coursework provides students with a solid foundation in core acoustics principles and practices and measurement skills, including a strong foundation in experimental techniques and writing technical memoranda. Labs across the curriculum cover calibration, directivity, scattering, absorption, laser Doppler vibrometry, lumped-element mechanical systems, equivalent circuit modeling, arrays, filters, room acoustics, active noise control, and near-field acoustical holography. Recent thesis and dissertation topics include active noise control, directivity of acoustic sources, room acoustics, radiation and directivity of musical instruments, energy-based acoustics, time reversal, nondestructive evaluation, flow-based acoustics, voice production, aeroacoustics, sound propagation modeling, nonlinear propagation, high-amplitude noise analyses, machine and deep learning applied to ambient noise level prediction, crowd noise interpretation, underwater acoustic source localization, and ocean environment classification. The graduate students are expected to present research at professional meetings and publish in peer-reviewed acoustics journals. Graduate students often serve as peer mentors to undergraduate students on related projects and may participate in field experiments to gain additional experience. For update, follow us @BYUAcoustics
Nonlinear generation of sum frequencies in Sitka spruce
Authors: Case Jade , Neldner Lauren , Moore Thomas
Published: April 2019

It has been known for several decades that there are anomalous frequency components in the sound of a piano. These occur at the sum and difference frequencies of the overtones attributable to string motion, and are commonly referred to as phantom partials. Recent work has shown that, contrary to the generally accepted theory, the majority of power in these frequency components originates in the wooden parts of the piano and not the string. However, the etiology of the nonlinearity is not clear. To determine if the source of the nonlinearity is the stress caused by the pressure of the strings on the soundboard, experiments were performed on isolated pieces of Sitka spruce. The results indicate that stress can significantly increase the nonlinear response of the wood. [Work supported by NSF Grant #PHY-160749.]
Comparative study of oboe and clarinet
Authors: Fitzgerald Laura , Ramsey Gordon P.
Published: April 2019

The oboe and clarinet are relatively similar instruments in their size and shape yet create such different sounds. This study is an exploration of the reasoning behind their differences through a detailed acoustical analysis and geometrical study of these instruments, comparing and contrasting their properties. The oboe and clarinet are comparable in size but have some key differences. The oboe’s conical shape allows for all the harmonics to be present, while the clarinet is mostly cylindrical, except for the bell, so that mostly odd harmonics are present. The oboe’s keys have holes much smaller than those of the clarinet. Looking to find differences in acoustical spectra based on their geometric differences, samples of low, medium, and high ranges on both instruments using the same concert pitches have been taken. Data have been taken in a regular lab setting as well as an anechoic chamber in order to look for differences in harmonic content for each instrument. The data are consistent with the notion that the shape of the instruments does contribute to the spectra.
Stucture-borne noise from a pool
Authors: Doggett Felicia
Published: April 2019

A problem arose at a recently completed high-rise condominium building in Philadelphia. Tenants on many levels above a pool located on the second level of the building stressed that they could hear low-frequency sound when an early-morning swimmer was doing laps. Looking through literature, we found nothing to attest to the phenomenon that presented itself. To investigate, we used a 15 lb rubber medicine ball to simulate the cavitation caused by the swimmer, which also provided a repeatable source. Cavitation in the water created by the arm strokes of the swimmer was exciting the pool shell and transmitting through the structure ultimately converting to audible sound via the lightweight partitions in the living units. Our measurement system included time synchronized triaxial accelerometers to determine the transmission paths through the building, which identified two significant peaks at 35 Hz and 62 Hz. This case study details this unique problem, the identification of structural transmission, and the successful outcome after our recommendations were implemented.
Case study of acoustic disturbances in pencil towers due to building movement
Authors: Harkin Sean , Scinto Jennifer , Schnitta Bonnie
Published: April 2019

Pencil structure high-rise residential towers are becoming increasingly prevalent in major city centers as the demand for housing increases in urban centers with limited available property for development. The narrow footprint of these structures, combined with the efforts to build subsequent structures higher than the last, lead to unique acoustic issues within these buildings, which impact the residents’ quality of life and affect the value of the properties. During periods of high, and even medium wind speeds, these structures deflect more than traditional skyscraper buildings and the resulting moment force on the internal building assemblies creates disturbing acoustic events that have been measured to be significantly higher than ambient sound levels in select octave bands. This paper presents two case studies in one such pencil structure building in New York City, from diagnosis, to proposed and implemented innovative acoustic treatments, to client satisfaction.
Too many Cooks in the kitchen?: A review of noise and vibration challenges in mixed-use buildings for the session: Structure-borne noise in buildings and what we can do about it
Authors: Taubitz Sarah
Published: April 2019

Several projects with rooftop structural vibration and/or noise transmission through structures, and footfall impact issues will be shared, along with a review of recommendations and outcomes of the example projects. We plan to discuss noise/vibration challenges such as: (1) Design, or re-design, of Heating, Ventilation, and Air-conditioning (HVAC) and kitchen exhaust fan (KEF) on rooftops and within building envelopes. (2) Finding noise leaks in structure. (3) Is it the MRI machine’s vibration, or the Variable Air Volume (VAV) box causing noise and vibration in the office upstairs? (4) Discussion of resonance of different floor/ceiling assemblies.
Measurements of rail vibration in a residential building behind a wave barrier trench
Authors: Dong David W. , LoVerde John
Published: April 2019

The authors have previously reported on a wave barrier trench that was constructed to reduce vibration transmission from railroad to a multifamily residential building [J. Acoust. Soc. Am. 139, 2159]. The reduction in ground vibration levels due to the trench was measured in several site conditions [J. Acoust. Soc. Am. 140, 3281]. This paper extends the study with additional measurements of vibration transmission into the building and structure-borne propagation within the building.
Estimating the acoustic power of sources in semi-reverberant enclosures using generalized energy density
Authors: Hoyt Travis N. , Sommerfeldt Scott D. , Blotter Jonathan
Published: April 2019

Sound power measurements of acoustic sources are typically performed in anechoic or reverberation chambers using acoustic pressure according to international standards. The anechoic chamber creates a free-field environment where the sound power is estimated from the squared pressure integrated over some enveloping surface. The reverberation chamber produces diffuse-field conditions, where sound power is proportional to the spatially averaged squared pressure. Since most acoustic sources exist in rooms that are neither anechoic nor entirely reverberant, it is desirable to estimate the sound power within these non-ideal, semi-reverberant spaces. In such environments, the direct and reverberant energies each contribute to the total measured field. If the kinetic and potential components of acoustic energy density are weighted appropriately, the spatial variation of the field can be significantly reduced compared to squared pressure. This generalized energy density allows an adaptation of the sound power formulation by Hopkins and Stryker to be used to make an efficient and accurate in situ sound power estimate of a noise source in a non-ideal acoustical environment. Since generalized energy density optimizes the spatial uniformity of the field, fewer measurement positions are needed compared to traditional standards. The experimental results and practical limitations of this method will be discussed.
Overturning of nonlinear compressional and shear waveforms subject to power-law attenuation or relaxation
Authors: Cormack John M. , Hamilton Mark F.
Published: April 2019

Model equations for plane nonlinear wave propagation that do not account for energy loss inevitably predict waveforms that are multivalued. Referred to as waveform overturning, this reveals that essential physics is not represented in the mathematical model. Energy loss from thermoviscous absorption keeps waveform steepening in check and prevents overturning for all source amplitudes, thus ensuring physical relevance of solutions. This is not the case for every energy loss mechanism, and waveform overturning may still occur above a critical source amplitude despite the presence of losses. The present work determines the critical source amplitude associated with two loss operators, one for power-law attenuation and the other for relaxation, and for both compressional waves (quadratic nonlinearity) and shear waves (cubic nonlinearity) [Cormack and Hamilton, Wave Motion 85, 18 (2019)]. Reformulation of the model equations in intrinsic coordinates enables numerical solution of waveform evolution up to and beyond the distance at which waveform overturning occurs. It is found that attenuation and dispersion resulting from a power law with exponent less than unity, or the attenuation and dispersion due to relaxation, is insufficient to prevent waveform overturning at all amplitudes. [Work supported by the ARL:UT McKinney Fellowship in Acoustics.]
Jet crackle: From production to propagation to perception
Authors: Gee Kent L.
Published: April 2019

The sound of a crackling jet is unusual. It is an irregular, popping noise that gives a distinct impulsive quality to the broadband noise from military jet aircraft, rockets, and even volcanoes. What are its possible causes? Which factors influence its propagation—and it perception? This presentation reviews historical and recent research into a phenomenon that lies at the crossroads of fundamental physical and psychoacoustics.
Comparison of sonic boom propagation models with measurements above the Earth’s turbulent boundary layer
Authors: Lonzaga Joel B.
Published: April 2019

NASA conducted the Sonic Booms in Atmospheric Turbulence (SonicBAT) overflight campaign at Armstrong Flight Research Center in 2016 and Kennedy Space Center in 2017. The sonic booms were generated by F-18 aircraft flying at nearly constant altitudes and at nearly constant, supersonic speeds. Although the primary objective of the campaign was to investigate the effects of turbulence on the propagation of sonic booms from the aircraft, a subset of the SonicBAT datasets can be used to validate sonic boom propagation models. This dataset is obtained from the recording using a microphone mounted at a wingtip of a TG-14 glider flying above the Earth's turbulent boundary layer. With this dataset, effects due to turbulence and ground impedance, which are still poorly understood, are effectively eliminated. Consequently, comparison is made between measurements and models which only account for the nonlinear and absorption effects. Such models are obtained using NASA's PCBoom sonic boom propagation code, which has recently been updated to incorporate the full wind effects and improve the code's accuracy and efficiency. Additionally, near-field signatures of the aircraft using PCBoom’s near-field approximant are also compared with those generated by The Boeing Company using computational fluid dynamics.
Enhancing dynamic positioning performance inside mid-air acoustic levitator
Authors: Fushimi Tatsuki , Marzo Asier , Hill Thomas L. , Drinkwater Bruce W.
Published: April 2019

Acoustic levitators are devices which generate converging acoustic radiation forces and thus can trap objects in mid-air. Acoustic levitators have found applications in the fields of chemistry and biology as a non-contact transportation method. The trapping of objects can be achieved using a phased-array in which the phase of the signal sent to each transducer is varied to generate a trap that stably holds the particle at the target three-dimensional position. The transducer phases can be changed over time to translate the acoustic field in space, thereby transporting the trapped particle. Here, we describe an open-loop spatial calibration scheme which increases the positioning accuracy of a particle in an acoustic levitator. The effectiveness and the performance of the spatial calibration was determined using a single-axis standing wave levitator with 60 ultrasonic transducers (40 kHz), and a levitated particle (EPS particle of radius 0.7 mm). Our calibration method is shown to significantly improve the positioning accuracy of the particle inside the acoustic levitator and reduced RMS error down to 0.11 and 0.03 mm in x and z axes, respectively. Although the calibration approach only considers the static response, the trajectory when the particle moves at a relatively high velocity (≈1 cm/s) was also improved. Increasing the precision and velocity of a moving particle will enhance the capabilities and reliability of acoustic levitators and open up possibilities for novel applications.
Effects of noise-induced hearing loss on speech-in-noise envelope coding: Inferences from single-unit and non-invasive measures in animals
Authors: Parida Satyabrata , Heinz Michael G.
Published: April 2019

Speech-intelligibility models (SIM) can be used for systematic fitting of hearing-aids and cochlear-implants, potentially improving clinical outcomes in noisy environments. Existing SIMs are suitable for predicting performance of normal-hearing subjects, but not for hearing-impaired subjects due to our limited understanding of the effects of cochlear hearing impairment on speech-in-noise coding. In this work, we collected auditory-nerve (AN) single-unit responses and envelope following responses (EFR) in normal- and hearing-impaired chinchillas to speech, spectrally-matched stationary-noise, and noisy-speech. Our data show increased correlation between AN-fiber response envelopes of noisy-speech and noise-alone for hearing-impaired fibers in speech-relevant modulation-frequency bands, suggesting a greater degree of distraction from inherent envelope fluctuations following cochlear hearing loss. This novel finding is significant given the emphasis recent SIMs [e.g., Jørgensen and Dau, JASA (2011)] have placed on the importance of inherent noise-envelope fluctuations in addition to speech-coding fidelity in predicting noisy-speech perception. Preliminary data also show enhanced fundamental-periodicity coding at the expense of place-specific formant coding, and a degradation of burst envelopes of high-frequency fricatives for the hearing-impaired group. EFRs show evidence for degraded tonotopic coding, as observed in single-unit responses [e.g., Henry et al., J. Neurosci. (2016)]. [Work supported by Action on Hearing Loss (UK).]
Passive music listening: A modulation of resting-state functional connectivity to better dissociate tinnitus
Authors: Shahsavarani Somayeh , Tai Yihsin , Schmidt Sara , Khan Rafay , Husain Fatima
Published: April 2019

Previous fMRI studies have shown tinnitus-related changes in resting-state functional connectivity (rs-fc) and have the potential for serving as biomarkers of tinnitus. In this study, we further investigated the effect of tinnitus on three intrinsic neural networks—the auditory network, the dorsal attention network (DAN), and the default mode network (DMN) while the participants were at rest or under a passive music listening condition. Our results indicated that listening to music altered the auditory network in both groups, with increased connectivity between inferior frontal gyrus and auditory areas in controls. This alternation was observed only in the patients with mild tinnitus handicap and was absent in the patients with severe tinnitus handicap. The effect of music on the DAN hinged upon hearing sensitivity: decreased connectivity between the lateral occipital cortex and the DAN, and increased connectivity between the precuneus and the DAN was observed in controls and patients with normal hearing, compared to those with hearing loss. Furthermore, passive music listening modulated the coherency of the DMN based on tinnitus status and/or hearing sensitivity. Our findings highlight the efficacy of rs-fc in dissociating the relatively heterogeneous tinnitus population and its subgroups from controls, using rest and listening to music.
Simultaneous measurement of electrocochleography and ear canal pressure in normal-hearing adults
Authors: Chen Jessica , Simpson Michael , Jennings Skyler G.
Published: April 2019

The auditory system is regulated by various adaptive mechanisms that modify sound as it passes upstream to the cortex. Studying these adaptive mechanisms, such as the middle ear muscle (MEM) reflex and the medial olivocochlear (MOC) reflex, reveals how the normal auditory system adjusts to challenging listening tasks and how abnormal reflexes may contribute to perceptual difficulties experienced by patients with sensorineural hearing loss. Studies in laboratory animals reveal that MOC and MEM reflexes result in neural antimasking at the output of the auditory nerve. Antimasking effects at the level of the middle ear and at the level of the cochlear hair cells should carry over to effects observed at the output of the auditory nerve. Antimasking due to MEM and MOC reflexes has been difficult to study in humans since measurement approaches are limited to non-invasive techniques with only a single output variable (e.g., ear canal pressure). In these studies, we assess MEM and MOC function by simultaneous measurements of ear canal pressure and electrocochleography, including the cochlear microphonic potential and compound action potential. Simultaneous measurements are expected to reveal the antimasking effects of MEM and MOC reflexes to middle ear, hair cell, and auditory nerve responses.
The effect of broadband elicitor duration on transient-evoked otoacoustic emissions and a psychoacoustic measure of gain reduction
Authors: Salloom William , Bharadwaj Hari M. , Strickland Elizabeth A.
Published: April 2019

Physiological and psychoacoustic studies of the medial olivocochlear reflex (MOCR) in humans have often relied on long elicitors (> 100 ms). This is largely due to previous research using otoacoustic emissions (OAEs) that found MOCR time constants in the 100s of milliseconds when elicited by broadband noise. However, Roverud and Strickland (2014), using a psychoacoustic measure of gain reduction, found differential effects of duration for on- and off-frequency tonal elicitors. For the on-frequency elicitor, thresholds increased with increasing on-frequency duration up to about 50 ms, and then plateaued. In contrast, thresholds with off-frequency elicitors continued to increase with elicitor duration. These results are consistent with cochlear gain reduction, possibly by the MOCR, in which the on-frequency elicitor is affected by gain reduction at the signal frequency place, but the off-frequency elicitor is not. The effect of the duration of broadband noise elicitors on similar psychoacoustic tasks is currently unknown. Additionally, the relationship between gain reduction measured psychoacoustically and using OAEs as a function of elicitor duration are unknown. This study will measure the effects of ipsilateral broadband noise elicitor duration on transient-evoked OAEs and psychoacoustic gain reduction estimated from a forward-masking paradigm. [Work supported by NIH R01 DC008327 (EAS) and NIH R01DC015989 (HMB).]
Influence of viscous boundary layer on wave propagation on isolated tectorial membranes
Authors: Wen Haiqi , Lemons Charlsie , Boatti Elisa , Meaud Julien
Published: April 2019

The tectorial membrane is an extracellular matrix located in the cochlea. The tectorial membrane is often hypothesized to play an important role in hearing mechanics. Measurements of wave propagation on isolated tectorial membranes have been used in the literature to characterize the intrinsic mechanical properties of tectorial membranes in the auditory frequency range. While most previous studies have made an implicit assumption regarding the width of the tectorial membranes in order to find the properties of the TM using a simple model, we have recently used a more accurate model that takes into account the finite width of the TM and its anisotropy. However, experiments are conducted in an artificial endolymph bath, which we neglected in our previous analysis. In this work, we study the influence of the viscous boundary layer due to the fluid on wave propagation on isolated tectorial membranes. The boundary layer adds damping and mass to the tectorial membrane, which we model using a commercial finite element software. The influence of the boundary layer on the space constant and wave speed of the longitudinally propagating radial motion, and on the spatial patterns of the longitudinal motion, are analyzed.
Implementing an efferent signal into an auditory pathway model for tone-in-noise detection
Authors: Farhadi Afagh , Carney Laurel H.
Published: April 2019

Simultaneous tone-in-noise detection has been studied extensively, but typically without consideration of the medial olivocochlear (MOC) efferents. We are testing hypotheses for masked detection using a central auditory model with a signal from midbrain to MOC. Masked tones are encoded in the rate profile of band-enhanced (BE) inferior colliculus (IC) neurons, which are excited by a range of modulation frequencies. Peripheral responses to noise are characterized by large fluctuations, an effective stimulus for BE IC neurons. In contrast, peripheral channels tuned near the tone have smaller fluctuations: addition of the tone flattens the signal envelope and also pushes the inner hair cell (IHC) transduction nonlinearity further into saturation. Excitatory projections to MOC from noise-driven BE IC cells would decrease cochlear gain, reducing IHC saturation, and resulting in larger fluctuations and IC rates. In contrast, tone-plus-noise-driven channels would reduce MOC excitation, resulting in relatively higher cochlear gain, more saturation, and ultimately lower IC rates. Thus, the descending signal from IC BE cells to MOC is hypothesized to enhance contrast in the IC rate profile. Because efferents have slow dynamics, timing is an important factor. Therefore, we focus on model sensitivity to masked tones of different durations for comparison to psychophysical trends.