bluuebunny/crossref_metadata_2025 huggingface dataset:
A new lumped parameter model for the design of the free-flooded ring transducer
Authors: Been Kyounghun , Nam Seungwon , Lee Haksue , Seo Hee-seon , Moon Wonkyu
Published: April 2018

The free-flooded ring (FFR) transducer is the well-known low-frequency sound sources in underwater because of its broad operating frequency bandwidth and relatively small size. Many previous studies have been performed that predict the characteristics of an FFR transducer using an equivalent circuit model (ECM), a type of lumped parameter model (LPM) because an ECM is widely used to understand the properties of such transducers in the design process. However, it is quite difficult to predict the characteristics of an FFR transducer because the acoustic field is generated from its top and bottom openings, connected by the inner fluid, as well as the cylindrical ring surface. In this study, the authors investigated an ECM of an FFR transducer. The ECM consists of three parts: the piezoelectric ring, the cylindrical cavity, and the radiation load. In addition, an LPM which can consider mutual radiation loads was proposed to improve the accuracy of the model. The proposed models were compared and verified using commercial finite element method (COMSOL Multiphysics). We confirmed that LPM can predict characteristics of FFR transducer more accurately than ECM. [This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (Grant No. 2016R1E1A2A02945515).]
Interactive (adjustable) plots and animations as teaching and learning tools
Authors: Russell Daniel A.
Published: April 2018

Interactive plots, such as are made possible with the Manipulate[ ] command in Mathematica, can be useful as teaching tools in the classroom, as well as learning aids for students outside of class. The use of adjustable sliders to change parameter values for an equation or system of equations allows for quick visual exploration of the effects of those changes on the resulting plot. Sometimes this visualization can help students understand difficult conceptual meaning hidden in mathematical expressions. Similarly, an adjustable interactive animation can effectively facilitate an understanding of concepts that are sometimes difficult to grasp from words or equations, or even “fixed” animations. This talk will demonstrate the creation of interactive plots and animations, and showcase several examples which the author has developed and used for teaching acoustics at the graduate and undergraduate levels. In addition, we will also discuss ways that students can be encouraged to create their own interactive plots or animations to aid in their own understanding.
An interactive simulation of the filtered-x least-mean-squares algorithm for active noise control
Authors: Gee Kent L.
Published: April 2018

As part of a graduate acoustics course at Brigham Young University, students learn about principles of active noise control (ANC). One of the concepts covered is how a basic ANC algorithm functions. This presentation describes an interactive simulation of the filtered-x least-mean-squares (FXLMS) algorithm implemented in MATLAB. Available user-selected inputs include sampling frequency, type of signal to be controlled, number of filter coefficients, convergence coefficient, and system model parameters. As outputs, the students are able to observe the different signals, the attenuation, and the filter coefficients. Altering inputs and observing the simulation results motivates classroom discussion and facilitates students' gaining a working understanding of an ANC algorithm.
Traditional polyphony: Multipart singing in world cultures
Authors: Wheeler Paul A.
Published: April 2018

Vocal polyphony has been part of the western musical culture since the 11th century. There are other cultures in the world, however, that use multipart singing in their traditional music that is not based upon the European classical style with parallel thirds and triad chords. This paper will discuss the use of vocal polyphony in several well-established traditions in the world, such as the Aka Pygmies from Central Africa, Canto a tenore from Sardinia, and iso-polyphony of Albania. It will contrast polyphonic types like parallel, drone, canonic, ostinato, and heterophonic polyphony. It will also illustrate how sound quality differs from the European classical style. An understanding of polyphonic traditions can assist us in understanding people whose cultures differ from our own.
Development of a dual temporal-spatial chirp method for the generation of broadband surface acoustic waves
Authors: Duquennoy Marc , Fall Dame , Ouaftouh Mohammadi , Benmeddour Farouk , Hebaz Salah-eddine , Samgin Nikolay , PIWAKOWSKI Bogdan , JENOT Frederic
Published: April 2018

This study deals with the optimization of transducers for Rayleigh-type Surface Acoustic Waves (SAW) generation. These transducers are based on Interdigital Transducers (IDT) and are specifically developed to characterize properties of thin layers, coatings, and functional surfaces. In order to characterize these coatings and structures, it is necessary to work with wide bandwidths IDT operating in the high frequencies. Therefore, in this study a spatial chirp-based on an IDT are realized for wideband SAW generation. The use of impulse temporal excitation (Dirac-type negative pulse) leads to a wide band emitter excitation but with significantly limited SAW output amplitudes due to the piezoelectric crystal breakdown voltage. This limitation can be circumvented by applying a temporal chirp excitation corresponding in terms of frequency band and duration to the spatial chirp transducer configuration. This dual temporal-spatial chirp method was studied in the 20 to 125 MHz frequency range and allowed to obtain higher SAW displacement amplitudes with an excitation voltage lower than that of the impulse excitation.
Experimental measurement and analysis of acoustic wave propagation in water-filled steel pipeline using the iterative quadratic maximum likelihood algorithm
Authors: Li Zhao , Jing Liwen , Wang Wenjie , Li Yue , Dubey Amartansh , Lee Pedro , Murch Ross
Published: April 2018

Acoustic wave propagation (up to 50 kHz) within a water-filled steel pipeline is studied using laboratory experiments. The experiments were carried out in a 6 m length of cylindrical stainless steel pipeline using acoustic transducers to acquire signals from 100 locations uniformly spaced along the longitudinal axis of the pipe. By applying the iterative quadratic maximum likelihood algorithm (IQML) to the experimental results, parameters such as wavenumbers, attenuations, and mode amplitudes were accurately extracted for individual modes from the measurement data. We found that the IQML algorithm could extract these parameters more accurately in situations where the measurement data had low signal to noise ratio as compared to other algorithms such as Prony’s method. A very good match was obtained between the experimental results and predictions from an analytical waveguide model for the wavenumber dispersion curves, attenuations, and acoustic power characteristics of the axisymmetric and non-axisymmetric modes. Additional physical explanations of the propagation phenomena in the pipeline waveguide were obtained using the experimental results and analytical model.
Acoustical and optical resonances of two-sphere systems
Authors: Dean Cleon E.
Published: April 2018

Two sphere systems show strong morphology dependent resonances even for two spheres of identical composition [G. W. Kattawar and C. E. Dean, Opt. Letts. 8, 48–50 (1983).]. How do analogous fluid spheres respond in the analogous situations? Do they show similar or different resonances? Preliminary investigations suggested that the response of fluid bispheres do not show as rich a panoply of resonances [C. E. Dean and J. P. Braselton, JASA, 141, 3735 (2017).]. How much do these systems differ? Would alternate boundary conditions restore some lost resonances? This talk attempts to answer these and other questions through the use of theoretical computational acoustics models.
Inferring atmospheric surface-layer properties from wind noise in the nocturnal boundary layer
Authors: Hart Carl R. , Lyons Gregory W
Published: April 2018

Uncertainties in the state of the atmosphere, to a large extent, limit the prediction accuracy of outdoor sound propagation. In particular, event sound propagation requires accurate knowledge of wind speed and temperature profiles, spatially averaged over the path of propagation. In a stable quasi-steady nocturnal boundary layer, wind speed and temperature gradients follow a scaling that is asymptotically independent of altitude and depends on Monin-Obukhov similarity parameters. Since these parameters describe the near-surface profiles of wind speed and turbulent intensity, which in turn are known to govern wind noise, it is anticipated that a connection exists between Monin-Obukhov parameters and the statistics of wind noise. It is expected that these parameters may be inferred from wind noise sensed by screened microphones. Ambient noise data collected in the southwest U.S. are analyzed for the purpose of examining whether Monin-Obukov similarity parameters may be inferred from wind noise. We explore the consequences of establishing inferences with a priori distributions for the similarity parameters, and utilizing wind noise data from microphones at one or more altitudes.
Neural bases of complex sound perception: Insights from an avian speech mimic
Authors: Henry Kenneth S. , Carney Laurel H.
Published: April 2018

Many complex sounds including speech contain periodic fluctuations in signal level known as amplitude modulation (AM). Auditory-nerve fibers encode AM primarily through response synchrony to signal modulation. In contrast, neurons of the midbrain encode AM through both response synchrony and substantial changes in average discharge rate. Specifically, many midbrain neurons with band-pass modulation tuning show enhanced discharge activity in response to a limited range of modulation frequencies. Here, we describe several recent studies on the relative importance of envelope synchrony vs. average rate coding in the midbrain for AM perception. Behavioral and neurophysiological experiments were conducted in the budgerigar, an avian species with the unusual capacity to mimic speech. Budgerigars were found to exhibit human-like behavioral sensitivity to a variety of complex sounds including AM stimuli and synthetic vowels with triangular and natural spectral envelopes. Most neurons in the budgerigar midbrain showed band-pass modulation tuning. Whereas either response synchrony or average discharge rate was sufficient to account for behavioral performance in some cases, only response synchrony could explain behavioral thresholds for (1) detection of low modulation frequencies and (2) formant-frequency discrimination in noise. These results highlight the significance of midbrain envelope synchrony for perception of complex sounds. [R00-DC013792 and R01-DC001641.]
Transient developmental hearing loss leads to disruption of striatal function in adults
Authors: Mowery Todd M.
Published: April 2018

Transient hearing loss during development can lead to deficits in the auditory perceptual abilities of children. These deficits arise from both peripheral ear and central neural dysfunction along the auditory neuraxis. Even if hearing loss resolves or is treated, persistent learning deficits and language impairments can occur. This suggests that regions downstream of the primary auditory neuraxis can be disrupted by brief auditory deprivation. One such region, which is highly involved in language development, is the auditory striatum. Thus I asked how the development of cellular properties in the auditory striatum are affected by hearing loss, and how these changes affect the learning of an auditory task. I used the gerbil and a brain slice preparation to assess how the expression of long term potentiation (LTP), which is a biomarker of learning, correlated with behavioral performance in adult animals that had undergone developmental hearing loss. I found that the cellular expression of LTP corresponded with the rapid acquisition of the behavioral task, and that developmental hearing loss delayed both the expression of LTP and the correlated behavioral acquisition. This suggests that striatal dysfunction could play a role in language acquisition impairments in children with hearing loss.
Understanding pitch perception through physiological, modeling, and behavioural methods
Authors: Walker Kerry M.
Published: April 2018

Pitch is a salient perceptual quality that underlies our musical experience, interpretation of speech, and ability to attend to one of multiple speakers. Yet the brain mechanisms that support this key percept remain unclear. We have measured the pitch discrimination of humans, ferrets, and mice on a 2-alternative forced choice task. These experiments show that species differ in their weighting of harmonic and temporal envelope cues for pitch judgments. By applying existing computational models, we demonstrate how cochlear filter properties can explain some of these species differences. We have also used microelectrode recordings in behaving ferrets to understand how individual cortical neurons represent pitch. We find that: (1) cortical activity correlates better with ferrets’ pitch judgements than stimulus f0; and (2) inhibition can shape neural representations of f0 when animals are actively engaged in a pitch discrimination task, compared to when they are passively listening to the same sounds. We are now using 2-photon calcium imaging, during which we can measure the precise spatial position and responses of large numbers of individual neurons simultaneously, to better understand how and where pitch is extracted within the cortical microcircuit.
When infants encounter infant speech
Authors: Polka Linda
Published: April 2018

Over the past four decades, we have learned a great deal about how infants perceive and decode the speech spoken around them and directed to them. Yet we know very little about how infants perceive their own vocalizations or speech with the unique vocal properties of an infant talker. This leaves a serious gap in our understanding of infant language development. In this talk, I will present findings from a new line of research that begins to address this neglected aspect of infant speech development by exploring how infants perceive speech with infant vocal properties. The findings suggest that access to infant speech has a broad and significant impact—influencing receptive, expressive, and motivational aspects of speech development. I will highlight some of the valuable lessons I learned under the mentorship of James J. Jenkins that have steered me along this rich and exciting line of research.
Voice quality: Speaker identification across age, gender, and ethnicity
Authors: Trent-Brown Sonja
Published: April 2018

Listeners can perceptually identify speaker gender and ethnicity at better than chance guessing for adult speakers (Lass et al., 1978; Thomas & Reaser, 2004; Trent-Brown et al., 2012). These findings are supported across varying levels of phonetic complexity and across temporal manipulations that impact perceptual processing. There is less evidence regarding the extent to which these patterns hold for child speakers and whether listener gender/ethnic background and experience influence accuracy of identification. African American and European American male and female adult speakers were recorded producing passage-, sentence-, and word-length (/hVd/) stimuli including 11 General American English vowels. African American and European American male and female child speakers, ages 8–12, were recorded producing sentence and word stimuli. A temporal manipulation introduced to distort perceptual expectations presented stimuli to listeners in both forward and reversed conditions. Listeners were male and female African American and European American undergraduate students. Significant outcomes were observed for accuracy across speaker gender, speaker ethnicity, phonetic complexity, and temporal condition. In addition to accuracy of identification, listener confidence ratings, identification reaction times, and confidence reaction times also showed differential outcomes with respect to speaker age, gender, and ethnicity.
Investigations on n-tuple coprime arrays
Authors: Bush Dane R. , Xiang Ning
Published: April 2018

Coprime arrays so far combine two sparsely-spaced subarrays, undersampled by factors of M and N, in order to achieve MN degrees of freedom. To ensure that the grating lobes of each subarray can be largely eliminated, M and N must be coprime. In number theory, sets of pairwise coprime numbers can exceed just two numbers. The current work extends the theory to include coprime linear arrays with an arbitrary number, n, of subarrays. A triple coprime array comprised of n = 3 equal-aperture subarrays with M, N, and O elements, undersampled by factors of NO, MO, and MN, respectively, may use just M + N+O-1 shifts to observe MNO directions. The design frequency of such an array not only exceeds the Nyquist spatial sampling limit, but is also greater than that of a standard (double) coprime array with equivalent aperture and number of elements. A triple coprime array is constructed with subarrays of M = 3, N = 4, and O = 5 and measured in a simulated free field condition. Experimental validation of the array confirms that the triple coprime array can also observe lower frequencies up to the design frequency. This paper discusses advantages and practical significance of n-tuple coprime microphone arrays over conventional double coprime linear arrays.
Time difference of arrival-based acoustic source localization and separation technique for sparse arrays
Authors: Bai Mingsian R.
Published: April 2018

An acoustic source localization and separation technique intended for sparse arrays is suggested in this paper. Unlike conventional beamforming approaches, the proposed technique is based on time difference of arrival (TDOA) information. This effectively eliminates the spatial aliasing problem due to overly large inter-element spacing of sensors. This method begins with estimation of the TDOAs between at least 4 sensors for 3-dimensional sound fields, with the aid of the generalized crosscorrelation-phase transformation (GCC-PHAT) algorithm and the subspace-based time delay estimation algorithm. Next, a constrained least squares (CLS) algorithm is applied to locate the source based on the above-estimated TDOAs. Once the source location is found, the source signal is extracted by using the Tikhonov regularization (TIKR) algorithm and minimum variance distortionless response (MVDR) beamformer. Regularization parameter is selected with a special search procedure to best preserve the audio quality in the inverse solution process. Experiments and listening tests are undertaken to validate the proposed TDOA-based localization and separation technique.
Quantitative ray methods for scattering by tilted cylinders
Authors: Marston Philip L.
Published: April 2018

After a review of ray methods and phenomena associated with high frequency scattering by spheres and cylinders in water viewed broadside, generalizations to tilted cylinders relevant to spectral and imaging domains will be summarized. These extensions were found to be useful for meridional as well as helical ray backscattering enhancements associated with leaky (or supersonic) waves on shells [F. J. Blonigen and P. L. Marston, J. Acoust. Soc. Am. 112, 528–536 (2002)]. For such enhancements, Fermat’s principle is useful for identifying ray paths of interest. In the case of helical waves (and in the broadside special case) the scattering amplitude can be expressed in terms of a Fresnel patch area where the guided wave is excited on the shell. Fresnel patches also give insight into the relatively large magnitude of meridional ray contributions. The coupling coefficient is proportional to the radiation damping of the leaky wave. For some shells it is necessary to take into account the anisotropy of the phase velocity. Computational benchmarks include scattering into the meridional plane by tilted infinite cylinders. Related phenomena include time-frequency domain features and enhancements from waves crossing truncations and from subsonic and negative group velocity guided waves. [Research supported by ONR.]
Experimental study on characteristics of echoes reflected by a cylindrical object in underwater multi-path channel
Authors: Wang Fangyong , Du Shuanping , Su Jiao
Published: April 2018

Research work on characteristics of echoes scattered by a cylindrical object located in underwater multi-path is introduced in the paper. A sound scattering experiment of a cylindrical object in water-filled tank is carried out, the purpose of which is to give answers to questions of how the multi-path channel corrupt the characteristics of echoes from an elastic body in underwater multi-path channel and how many target-related features can still be extracted in both time and frequency domain which can be used for classification or feature-based detection. Detailed data processing results are shown and analyzed, which may be useful to research on signal processing method of sonar target detection and classification.
Use of time, space, frequency, and angle data products in understanding target-in-the-environment scattering physics
Authors: Williams Kevin , Kargl Steven G. , Espana Aubrey L.
Published: April 2018

Broadband, multi-aspect time domain data of scattering from targets placed on sediment interfaces contains a wealth of information about the target and the modifications to the target scattering due to its location in the ocean environment. Different data products derived from the data can be used together to gain a better insight into the overall physical processes at play. We use a 2:1 aluminum cylinder and a 2:1 aluminum pipe to demonstrate the utility of different types of data products. Domains examined include imaging in the horizontal plane, frequency response as a function of look angle, and time domain response as a function of look angle. We then examine these same domains using relatively narrow windows of time with varying start times. This analysis allows visualization of the evolution of the physical mechanisms involved. [Sponsored by the Office of Naval Research and the Strategic Environmental Research and Development Program.]
Representation trade-offs for the quality assessment of acoustic color signatures
Authors: Park J. D. , Cook Daniel , Hunter Alan J.
Published: April 2018

Acoustic color is a representation of the spectral response over aspect, typically in 2-D. This representation aims to characterize the structural acoustic phenomena associated with an object with frequency and aspect as the two axes of choice. However, the strongest acoustic color signatures are typically the geometric features of an object due to geometric scattering. Naturally, these geometric features are well-represented as straight-line signatures in the spatial spectrum representation with the axes horizontal and vertical wavenumbers. Elastic responses due to other scattering mechanisms such as Rayleigh scattering or Mie scattering are typically smaller in magnitude, and are not easily recognizable or separable from the stronger responses. This work explores variants of acoustic color, to find intuitive representations for these types of scattering responses, and to assess their signature quality.
Synthetic aperture sonar speckle noise reduction performance evaluation
Authors: Bruna Marsal A. , Pate David J. , Cook Daniel
Published: April 2018

SAS (Synthetic Aperture Sonar) imagery always contains speckle, which is often thought of as a kind of multiplicative noise with respect to the underlying scene reflectivity. Speckle arises from the coherent interference of waves backscattered by rough surfaces within a resolution cell. Numerous image processing algorithms have been proposed to reduce speckle while preserving image features. Frequently, these algorithms are evaluated using actual SAS imagery; where the underlying noise-free image is unknown. The lack of noise-free images along with a limited number of images can lead to an incomplete estimation of algorithm performance. The use of various image quality and speckle reduction metrics is also required to accurately assess performance. In this paper, a unified framework using both simulated and real imagery is used to analyze the performance of prominent algorithms, such as multilook and anisotropic diffusion methods.
Simulating an object response with synthetic aperture sonar inverse imaging
Authors: Prater James
Published: April 2018

Synthetic aperture sonar (SAS) algorithms were developed in order to produce high resolution imagery from wide-beam wideband data. The high data rates associated with SAS data have fostered the development and implementation of efficient beamforming algorithms, many of which were originally developed for synthetic aperture radar. Some of these beamforming algorithms are invertible, and inverse beamforming techniques have been developed for SAS data analysis, where imagery is inverted in order to produce aspect-dependent data. Since imagery is invertible, this process can also be used as a simulation to produce stave-level data from a simulated image. This paper describes a modeling approach where inverse imaging techniques are applied in order to generate simulated stave-level sonar data. Using this approach, an image is generated from assumed object geometry and reflectance and inverted in order to generate stave-level data. The stave level data is then beamformed specifically to produce frequency vs. aspect data products. Since the inverse imaging process assumes specular reflection, features present in the frequency vs. aspect data are solely due to the surface reflectance and object shape. Comparison of inverse image simulated data with physics based simulations or field-collected data are shown and the limitations of the comparison are discussed.
Characterization of internal waves in synthetic aperture sonar imagery via ray tracing
Authors: Pate David J. , Cook Daniel , Lyons Anthony P. , Hansen Roy E.
Published: April 2018

Synthetic aperture sonar imagery often captures features that appear similar to sand waves but are actually pockets of denser water traveling as isolated waves along the seafloor. These pockets of cold water refract acoustic waves like a lens, causing intensity peaks and shadows that resemble medium to large scale sand waves. This work uses dynamic ray tracing to predict the intensity return as affected by refraction. First, we explore the nature of the intensity pattern created by internal waves of various shapes and sizes. Then, we use an optimization-based approach to solve the inverse problem: given an intensity pattern, determine the size, shape, and location of the internal wave that created it.
Architectural acoustics short course presentation material
Authors: Hoover K. Anthony
Published: April 2018

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects, called “Architectural Acoustics.” An architect can earn one continuing education unit (CEU) by attending this short course, if it is presented by a qualified member of TCAA. The course covers topics in sound isolation, mechanical system noise control, finish treatments, and implementation of quality acoustical spaces. This paper will cover the course material in order to prepare and qualify potential presenters. In order to qualify as an authorized presenter for this AIA/CES short course, attendance at this special session and membership in TCAA are required.
Insect ear biomechanics: Passive and active processes that can inspire acoustic sensors
Authors: Windmill James F.
Published: April 2018

Biological systems provide an incredible wealth of archetypes that have emerged through evolutionary processes. Hearing organs are a good example of how different solutions, and adaptions, across different animal taxa, can often converge to solve similar sensory problems. Hearing has evolved independently multiple times across the insects, and the diversity of these biological solutions therefore provides a wealth of inspiration for the creation of novel acoustic sensors. Some biological solutions can be considered as purely passive mechanical constructs that accomplish some processing of the incoming sound. This talk will consider examples of this, including the frequency discrimination of the locust ear, and the directionality and wideband response of different moth ears. Several insects also display active hearing processes, whereby energy is used to actively change the hearing response, bearing some similarity to the processes found in the mammalian inner ear. This talk will thus discuss how some moths actively tune their ear, and how the mosquito ear actively utilizes gain and compression. Finally, the talk will discuss some examples of different acoustic sensors from the University of Strathclyde that take inspiration from these passive and active biological processes.
Correlation of cavitation activity with ultrasound-enhanced delivery of compounds to erythrocytes ex vivo
Authors: Murphy Emily M. , Priddy Mariah C. , Janis Brett R. , Menze Michael A. , Kopechek Jonathan A.
Published: April 2018

Blood transfusions are one of the most common medical procedures in hospitals, but shortages of erythrocytes often occur due to their limited shelf life (6 weeks) when refrigerated. Preservation of erythrocytes in a dried state offers a potential solution to challenges faced with blood storage, and preservative compounds such as trehalose have been identified in organisms that survive desiccation in nature. However, these compounds do not readily cross mammalian cell membranes. Therefore, we are exploring the use of sonoporation to facilitate their delivery into erythrocytes ex vivo. In this study, we assessed the effect of cavitation activity on delivery of a fluorescent compound similar in size to trehalose (fluorescein) to human erythrocytes. Microbubbles were added to erythrocyte solutions and sonicated (2.5 MHz, 4 cycles) at various pressures and durations. Fluorescence was quantified with flow cytometry. The amplitude of broadband emissions in the first 8 seconds of sonication did not correlate with delivery (r2 = 0.23), whereas after 8 seconds the broadband emissions amplitude was associated with increased delivery to erythrocytes (r2 = 0.97). These results suggest that the timing of cavitation activity, rather than the amplitude alone, may be an important factor in ultrasound-mediated delivery of compounds into erythrocytes.
On amplification of radial oscillations of microbubbles due to bubble-bubble interaction in polydisperse microbubble clusters under ultrasound excitation
Authors: Haghi Hossein , Jafari Sojahrood Amin , Kolios Michael C.
Published: April 2018

Optimizing the performance of microbubbles (MBs) in applications not only requires a good understanding of the dynamics of individual MBs, but also knowledge of their interactions with each other within polydisperse clusters. However, the behavior of acoustically driven MB clusters is not well understood. Most studies have been limited to cases of a few interacting MBs for a limited range of acoustical parameters. We use a numerical method to simulate the dynamics of clusters of (20–50 MBs) randomly distributed MBs. MBs with the size distribution of 2–8 micron were sonicated with pressures between 1 and 250 kPa, frequencies between 0.5 and 10 MHz and concentrations between 2e3 and 2.5e6 MBs/mL. Bifurcation structures of radial oscillations of each MB within a cluster were studied. Results show that in a polydisperse MB cluster, larger MBs (even in small numbers) can amplify the radial oscillations of smaller MBs. Amplification occurs if the resonance peaks of larger MBs coincide with the resonance peaks of smaller MBs. Additionally, there is an optimum number density at which amplification is maximized. Results suggest that the presence of bigger MBs may enhance the superharmonic oscillations of the smaller MBs which can be applied in superhamonic ultrasound imaging using MBs.
Ultrasound, human health, safe levels, and Cuba: What do we know?
Authors: Leighton Timothy
Published: April 2018

While definitive statements are impossible, a slim evidence base suggests the following on weight-of-probabilities regarding ultrasonic adverse effects in humans. One study at extremely high intensities reports physical effects (notably burning between fingers/nostrils). At lower intensities, adverse psychological effects occur in only a subset of the population (susceptibility possibly decreasing with age), are restricted to frequencies below ~25 kHz, probably result from the extraordinary sensitivity of our hearing/balance systems, and can be difficult to separate from (and may be causally related to) adverse effects of anxiety and annoyance. This does not remove the need for protection, especially for increasingly common public exposures, where the exposure and exposed person are often uncharacterised. Only one interim guideline from 1984 addresses maximum permissible levels (MPLs) for public exposure. It is based on scant evidence, and may or may not be appropriate. All other guidelines relate to occupational exposure. These MPLs are a legacy of decades of copying previous guidelines, which were themselves based on inadequate sampling (usually a small cohort of adult men), and averaging practices which obscured the particular sensitivities of a subset of the population. Against this background, the likelihood, or not, of an ultrasonic weapon in Cuba will be discussed.
Adverse effects of very high-frequency sound and ultrasound on humans
Authors: Fletcher Mark D. , Lloyd Jones Sian , Dolder Craig N. , White Paul , Leighton Timothy , Lineton Ben
Published: April 2018

For many years, workers have reported adverse symptoms resulting from exposure to very high-frequency sound (VHFS) and ultrasound (US), including annoyance, dizziness and difficulty concentrating. Recent work showing the presence of a new generation of VHFS/US sources in public places has reopened the debate about whether adverse effects can be caused by exposure to VHFS/US. Our field measurements of VHF/US sources in public places have identified devices producing up to 100 dB SPL at 20 kHz. Nearly all of the sources measured, including those in places occupied by tens of millions of people each year, are likely to be clearly audible to many young people. We have conducted two studies. The first looked at adverse symptoms resulting from exposure to audible VHFS/US, and the second was a double-blind study of adverse symptoms resulting from exposure to inaudible VHFS/US. In each study, both symptomatic participants, who reported previously experiencing symptoms, and asymptomatics participants, who did not, were tested. We found evidence that symptoms were produced by exposure to audible VHFS/US but not by inaudible sound. It is possible that the substantial effects reported for inaudible VHFS/US exposure were not reproduced because of ethical restrictions on stimulus level and duration.
Low power wireless communication between personal electronic devices and hearing aids using high frequency audio and ultrasound
Authors: Miegel Jonathon , Branch Philip , Blamey Peter
Published: April 2018

Hearing aids continue to be the main intervention for hearing loss but their ease of use and control is of concern due to their small size. While technological advances in Bluetooth Low Energy have allowed for improved wireless control, in particular, between personal electronic devices, its use for communication with hearing aids is problematic due to their limited battery life. This research investigates the implementation of acoustic wireless communication between personal electronic devices and hearing aids using multiple modulation schemes utilizing frequencies between 16 and 20 kHz. The performance of each modulation scheme is assessed over a 3 metre range and the power consumption compared to that of Bluetooth Low Energy.
Auditory, cognitive, and linguistic processing skills in individuals with hearing loss
Authors: Appaiah Konganda Shivali , Sharma Mridula , Monaghan Jessica J. , Keidser Gitte , Valderrama Valenzuela Joaquin Tomas , Newall John , Beach Elizabeth
Published: April 2018

Hearing impairment affects a person’s ability to communicate effectively. People with hearing loss (HL) report difficulty communicating in noise, even when the HL is compensated by conventional amplification. This study aims to investigate factors that contribute to understanding speech in noise. Nine adults with HL and nine controls participated in the study. The test-battery include auditory, cognitive and linguistic tests. For the HL group, auditory stimuli were filtered with NAL-RP prescription to compensate for their HL. Results indicate a significant difference in performance between the groups on the Modulation Detection Threshold (MDT) test [F (1, 15) = 3.24, p =0.04] and the speech recognition in noise test [f (1, 15) = 25.6, p<0.001]. HL group performed better on the MDT and poorer at recognising speech in noise possibly due to broadening of auditory filters. With the broadened auditory filters in mind, this result supports the fact that they would have poor frequency specificity, detrimental for speech recognition. HL group performed better than the control group on the cognitive spare capacity test [f (1, 15) = 4.72, p= 0.04]. Preliminary data suggests that adults with HL may compensate for hearing-related difficulties in certain situations by using their cognitive skills.
Perceptual and neural representation of consonants in hearing impaired listeners
Authors: Su Yaqing , Sankaran Narayan , Swaminathan Jayaganesh
Published: April 2018

Difficulties in perception of consonants have been associated with speech perception difficulties in hearing-impaired (HI) listeners. However, the neural bases underlying such difficulties have not been clearly explored and understood. The goal of this study was to use scalp electroencephalography (EEG) recordings to better understand the neural mechanisms that contribute to the consonant perception difficulties in HI listeners. Such a psychophysiological approach can lead to the development of improved hearing-aid fitting and speech enhancement strategies. Perceptual and EEG responses to vowel-consonant-vowel speech were measured in 8 HI listeners with and without amplification. A machine-learning classifier was trained to discriminate the EEG signal evoked by each consonant. The performance of the classifier was compared to the HI listeners’ psychophysical performance. For all subjects, consonant intelligibility was better in aided compared to unaided listening condition, but overall performance was well below ceiling. An information transmission analysis showed that place and manner of articulation were more affected than voicing and nasality. EEG waveform showed different response patterns for each consonant, and the machine-learning classifier was able to successfully “decode” consonants from the EEG signal. However, a straightforward relationship between the neural and perceptual representation of consonants could not be established in HI listeners.
Characterizing cortical auditory networks in bilateral cochlear implant users using electroencephalography
Authors: Smieja Daniel , Dunkley Benjamin , Papsin Blake , Gordon Karen
Published: April 2018

Objective: This research aims to characterize the cortical network involved in listening with bilateral cochlear implants (CIs) through measures of functional connectivity. Rationale: A better understanding of the underlying cortical network involved in hearing will help elucidate remaining challenges experienced by children who received bilateral cochlear implants early relative to their peers with normal hearing. This work extends our previous focus on plasticity in temporal regions to include multiple cortical areas and considers the phase relationships between neural source signals. Methods: The data were collected using 64-channel electroencephalography in response to click stimuli in a passive listening condition. Source reconstruction was applied using the TRACS beamformer in order to localize the underlying neural generators. Sources were mapped to regions in the Automated Anatomical Labeling atlas and connectivity analyses were performed to examine statistical relationships between the atlas regions in order to generate network models. Results: Preliminary data show that in addition to the primary auditory areas, regions in the precuneus and frontal areas are activated in response to sound. The connectivity analyses are ongoing. Significance: Differences in the cortical auditory networks will help to understand how the auditory system is integrated in the cortex in bilateral cochlear implant users.
Tone-evoked acoustic change complex (ACC) in an animal model
Authors: Presacco Alessandro , Middlebrooks John C.
Published: April 2018

The auditory change complex (ACC) is a cortical evoked potential complex generated in response to a change (e.g., frequency or level) within an ongoing auditory stimulus. The ACC has been recorded in both normal-hearing human subjects and in cochlear implant users, suggesting that the ACC would be useful in clinical applications. Here, we investigate the feasibility of recording ACC in response to frequency or level changes in sedated cats. Five purpose-bred cats were sedated with ketamine and acepromazine. Continuous tones alternated between high and low frequencies or levels in 500-ms blocks. Frequency and level steps were varied parametrically. Scalp potentials were recorded with needle electrodes (two active electrodes = one on each hemisphere, reference: mastoid, ground = back of the cat). ACC was successfully elicited in all cats by both frequency and level steps. In many cases, ACCs were markedly greater for increasing or for decreasing stimulus steps. The discrimination thresholds measured were in good agreement with previous behavioral studies in which cats where trained to perform similar frequency or level discriminations. The results indicate that the ACC will be a useful tool for evaluating novel acoustical or electrical stimulation modes that are not yet feasible in humans.
Estimation of emotional arousal from speech with phase-based features
Authors: Guoth Igor , Darjaa Sakhia , Trnka Marian , Rusko Milan , Ritomský Marian , Jarina Roman
Published: April 2018

The most commonly adopted approaches in speech emotion recognition (SER) utilize magnitude spectrum and nonlinear Teager energy operator (TEO) based features while information about phase spectrum is often omitted. The information about phase has been frequently overlooked in approaches applied by speech processing researchers due to the signal processing difficulties. We present study of two phase-based features: The relative phase shift (RPS) based features and modified group delay features (MODGDF) that represents phase structure of speech in the task of emotional arousal recognition. The evaluation is performed on the CRISIS acted speech database which allows us to recognize five levels of emotional arousal from speech. To exploit these features, we employ concept of deep neural network. The efficiency of the approaches based on features mentioned earlier is compared to baseline platform using Mel frequency cepstral coefficients (MFCCs) and all pole group delay features (APGD). The combination of another phase-based types of features with our baseline platform led to the overall improvement of performance of the system for different levels of emotional arousal. These results confirm that combination of phase information and magnitude information leads to the overall improvement of performance of such system and also that combination of different types of features representing phase information brings additional increment of the performance.
Creation and characterization of an emotional speech database
Authors: Moriarty Peter M. , Vigeant Michelle , Wolf Rachel , Gilmore Rick , Cole Pamela
Published: April 2018

Paralinguistic features of speech communicate emotion in the human voice. In addition to semantic content, speakers imbue their messages with prosodic features comprised of acoustic variations that listeners decode to extract meaning. Psychological science refers to these acoustic variations as affective prosody. Most studies of affective prosody obscure semantic content, although the resulting stimuli are less representative of naturally occurring emotional speech. The presented works details the creation of a naturalistic emotional speech database on which both acoustical analysis and a listening study were conducted. To this end, 55 adults were recorded speaking the same semantic content in happy, angry, and sad voices. Based on prior acoustic analyses of affective prosody, classic parameters were extracted including pitch, loudness, timing, as well as other low-level descriptors, and compared the acoustic features of each emotion with published evidence and theory. Preliminary results indicate that this naturalistic speech samples yielded acoustic features that are congruent with prior experimental stimuli of anger and happiness, but was less consistent with sadness. The results of the listening study indicated that listeners discriminated the intended emotions with 92% accuracy. The dataset therefore yielded a database of emotionally salient acoustical information for further analyses. [Work supported by NIH-R21-104547.]
Effects of a mask rim leak on AC airflow measurement
Authors: May Nicholas A. , Scherer Ronald
Published: April 2018

Studies in airflow during speech production typically use a pneumotachographic mask system to measure expired airflows. Accurate measures of airflow using the Glottal Enterprises MSIF-2 aerodynamic system require a complete seal of the mask rim to the face. Literature frequently cites mask rim leaks as causing flow measure inaccuracies, but quantitative studies of inaccuracies are needed. Prior work (May & Scherer, in press) provided a general empirical equation relating mask rim leak flow, the cross sectional area of the rim leak, and upstream airflow. The current empirical bench research extends this DC flow work to an AC flow situation as in the case of vibrato and/or tremor using 3 and 6 Hz, 2 leak areas, 50 and 200 cm3/s peak-to-peak variations, and an upstream flow of 200 cm3/s. Results: smaller leak area, higher AC frequency, and higher AC airflow extent resulted in the lowest mask rim leak airflow.
Separation of closely-spaced acoustics sources in an under-determined system with convex optimization
Authors: Shi Tongyang , Bolton J. S.
Published: April 2018

The ability to identify acoustical source locations accurately is critical when performing sound field reconstructions. In previous work, a monopole-based, iterative equivalent source method, wideband acoustical holography, has proven able to provide accurate noise source location in complex machines even when the number of measurements was far smaller than the number of parameters that needed to be determined in the model (see: Tongyang Shi, Yangfan Liu and J. Stuart Bolton, “Diesel engine noise source visualization with wideband acoustical holography,” SAE paper 2017-01-1874). However, at some stage, when acoustical sources are too closely spaced, the current algorithm has difficulty in separating them. This is true, especially at low frequencies, in which case current holography methods tend to visualize two closely-spaced acoustics sources as a single large source, thus losing the accuracy of the source location. In the present work, the equivalent sources were still modeled as an array of monopoles, but the source strength parameter estimation and regularization problem was formulated as a convex function and turned into an iterative convex optimization problem that can be solved by an open source code. It will be demonstrated that the new procedure is capable of reconstructing very closely-spaced acoustics sources.