bluuebunny/crossref_metadata_2025 huggingface dataset:
An acoustic source model for the signal produced by ground motion over an underground event in mountainous terrain
Authors: Waxler Roger M. , Hetzer Claus
Published: April 2018

A confined, large explosion underground launches an infrasonic signal into the atmosphere generated by the heaving of the ground over the explosion. For example, the last three North Korean nuclear weapon tests produced infrasonic signals detected at great distances form the test site. Under flat terrain, modeling the acoustic source from a confined explosion is a classical problem, similar to that of a baffled loudspeaker. In mountainous regions, the problem is more difficult. A boundary element method has been developed to this end. Given the vertical motion of the ground surface, the model predicts an the acoustic pressure on a spherical section centered over the source. From this, a source function for far field propagation can be extracted. The methods used to produce such a model will be presented.
Active cochlear mechanics and outer hair cells
Authors: Ashmore Jonathan F.
Published: April 2018

David Kemp’s discovery of otoacoustic emissions signalled a new era in cochlear modelling and neurobiology. After Bekesy, the emphasis on cochlear processing had centered on the physics of frequency selectivity with any underlying physiological or cellular contributions taking a back seat. Since then, many lines of evidence have revealed that the (at the time) enigmatic population of outer hair cells (OHCs) within the cochlea plays a central role in modifying the basilar membrane mechanics: OHCs act as fast actuators up to at least 80 kHz in order to cancel fluid damping of the partition. The active mechanical feedback due to OHCs appears to be delicately poised so that small variations from section to section provides a substrate for the inhomogeneities required for OAEs. Metabolically labile, the intrinsic non-linearities of the system can be traced to the hair cell mechano-electrical transduction step itself. Mammalian OHC “motor” function has an identified molecular basis, and only recently have structural studies partially clarified how it this molecule (“prestin”/SLC26A5) works. A further contemporary concern is whether the mammalian cochlea employs the same, but scaled, mechanism of sound amplification for high as well as for low frequencies and this issue will be discussed.
David Kemp’s impact on cochlear modeling and otoacoustic emission measurement and modeling
Authors: Talmadge Carrick L. , Long Glenis R.
Published: April 2018

Between 1990 and 1998, Drs. Carrick Talmadge, Glenis Long and Arnold Tubis worked together in the field of Hearing Science at Purdue University on a diverse number of topics, including the measurement and modeling of spontaneous otoacoustic emissions, measurement and modeling of stimulus frequency and distortion product otoacoustic emissions (SFOAEs and DPOAEs respectively), and on cochlear modeling. We will explore here linkages between Dr. Kemp’s work and our research. This includes his sweep method for measurement of SFOAEs, which lead to the least-squares-fit based method for recording and analyzing SFOAEs and DPOAEs developed by our group. His emphasis on the clinical relevance of otoacoustic emissions implied a linkage between otoacoustic emission data and the underlying function of the cochlea, and this became a main focus of our cochlear modeling efforts. His evidence for two-sources for DPOAEs and his study of the so-called DPOAE “filter shape” were highly influential in the direction of our research at Purdue University.
Interrelationships among microstructures of otoacoustic emissions and hearing thresholds
Authors: Dewey James , Dhar Sumitrajit
Published: April 2018

Otoacoustic emission (OAE) amplitudes, phases, and delays often exhibit ripples with small changes in stimulus frequency. Similar microstructure patterns are observed in behavioral hearing thresholds and loudness judgements for pure tones. Here, we summarize work demonstrating that there is a common microstructure in hearing thresholds and OAEs elicited by single tones—referred to as stimulus-frequency OAEs (SFOAEs)—when presented at near-threshold levels. The periodicity and strength of this microstructure are related to SFOAE delay and magnitude, respectively. Such relationships are consistent with this microstructure arising from multiple intracochlear reflections of SFOAE energy between its region of generation and the middle ear boundary—an idea proposed by David Kemp in his first reports describing the discovery of emissions from the ear. The details of OAE generation and propagation explain why similar but not identical microstructures are also observed in the ear canal pressure in response to tones (which is the vector sum of the stimulus and SFOAE pressures) and in two-tone evoked distortion-product OAE spectra, as well as why microstructures shift in frequency as the result of cochlear or middle ear manipulations.
Role of expectancy in front-back confusions during sound source localization
Authors: Yost William
Published: April 2018

Front-back confusions (FBCs) often occur in laboratory experiments. Stimulus complexity, especially for high-frequency sounds, and head motion significantly reduce FBCs, so that in the everyday world FBCs probably do not often influence sound source localization. There is a small literature suggesting that listeners “expectancies” (based on experience or other sensory inputs) for where sound sources might be also affect FBCs. A low-pass noise that produces a large number of FBCs and a high-pass noise that does not were used. Listeners indicated the location of sound sources on the azimuth plane. The study aimed to investigate FBCs and not sound source localization accuracy. For one condition, listeners were told that the noises would all be coming from in front, that in another condition from in back, and in a third condition from the full 360° azimuth circle. In the first (front) and second (back) conditions, most of the sounds came from the front or back respectfully, but 20% did not. The expectancy that sounds would be in front or in back had a large influence on FBCs as compared to when sounds were presented from the entire azimuth circle. (Work supported by grants from NIDCD and Oculus VR, LLC.)
Portable Automated Rapid Testing (PART) measures for auditory research
Authors: Gallun Frederick J. , Seitz Aaron , Eddins David A. , Molis Michelle R. , Stavropoulos Trevor , Jakien Kasey , Kampel Sean , Diedesch Anna C. , Hoover Eric , Bell Karen , Souza Pamela , Sherman Melissa , Calandruccio Lauren , Xue Gretchen , Sebena Rene , Srinivasan Nirmal Kumar
Published: April 2018

This presentation will focus on data collected across the globe on tablet computers using applications available for free download, built-in sound hardware, and calibrated consumer-grade headphones. Tests involve spatial release from speech-on-speech masking, binaural sensitivity, gap discrimination, temporal modulation, spectral modulation, and spectrotemporal modulation. The data will be compared across sites and with data from the published literature. The similarity of the obtained data to the expected values and the consistency across sites will help evaluate the potential of this relatively inexpensive and easily disseminated approach to psychoacoustical data collection. The extent to which valid performance can be obtained is a metric of the possibility that in the future such test methods could be used by researchers without access to a full laboratory, clinicians interested in evaluating auditory function beyond the audiogram, and students as part of their training, as well as many other uses not yet imagined.
Is there an auditory identification “pop-out” for moving speech targets?
Authors: Pastore M. Torben , Yost William
Published: April 2018

Stationary visual targets are often far more salient when the target moves against an otherwise static background—the so-called “pop out” effect. In the first of two experiments, we tested for a similar effect in the auditory domain. Listeners were asked to identify a single word, spoken by a female, in the midst of two or four masking words spoken by males. Listener performance was estimated in terms of percentage of correct responses and compared between conditions where target and maskers were co-located or located at different locations. For some conditions, the target word was amplitude-panned across the loudspeaker array and in others the target remained stationary. Results showed a spatial release from masking for all conditions where the target and maskers were at different locations. The presentation of a stationary versus moving target stimulus yielded no statistically significant difference in identification performance, suggesting that the visual “pop-out” effect may not have a direct corollary in the auditory domain.
Is there an auditory detection “pop-out” for moving tones in the presence of static noise maskers?
Authors: Pastore M. Torben , Yost William
Published: April 2018

Stationary visual targets often become far more salient when they move against an otherwise static background—the so-called “pop out” effect. In the second of two experiments, we tested for a similar pop-out effect in the auditory domain. Tone-in-noise detection thresholds were measured using a 2-down 1-up adaptive procedure under conditions where the target was stationary or moved via amplitude-panning. Target frequencies of 500 Hz and 4 kHz were tested. Maskers (2–4, depending on the condition) were independent Gaussian noises filtered to have equal energy per octave. All target and masker stimuli were 500-ms duration. Listener performance was compared between conditions where target and maskers were co-located or positioned separately for conditions when the target word was amplitude-panned across the loudspeaker array and in others when the target remained stationary. Results will be presented and discussed.
Effect of auditory stream segregation cues on binaural pitch fusion
Authors: Oh Yonghee , Gallun Frederick J. , Reiss Lina
Published: April 2018

Binaural pitch fusion, the fusion of dichotically presented tones that evoke different pitches across ears, can be influenced by temporal envelope cues such as coherent amplitude modulation (Oh and Reiss, ASA 2017). This suggests that binaural pitch fusion may be governed at least in part by top-down processes involved in auditory grouping. The current study was designed to investigate how temporal streaming cues either prior or posterior to a fused dichotic tone pair can influence binaural pitch fusion. Six normal-hearing (NH) listeners and six bilateral hearing-aid (HA) users were tested in a modified auditory streaming paradigm (Steiger and Bregman, 1982). A pair of simultaneous, dichotic reference and comparison stimuli was placed in rapid alternation with a third binaural (diotic) capture stimulus, for a total of 10 alternations. The binaural fusion ranges, the frequency ranges over which binaural pitch fusion occurred for dichotic stimuli, were smaller when measured with the streaming paradigm than with static, spectral-only stimuli of equivalent durations. HA users showed greater reductions in fusion ranges with streaming than NH listeners. The findings suggest that temporally flanking stimuli suppress fusion between dichotic stimuli. [Work supported by NIH-NIDCD grant R01 DC013307 and F32 DC016193.]
Differential effects of hearing loss on neural and behavioral measures of speech perception in noise
Authors: Koerner Tess K. , Zhang Yang
Published: April 2018

Understanding speech in background noise is difficult for many listeners, and those with hearing impairment tend to show considerable variability in performance. Event-related potentials (ERPs) and associated cortical oscillations are useful for examining neural responses to speech in various listening conditions and may represent neurophysiological markers of auditory perception. The present study examined the effects of hearing impairment on the neural coding and perception of speech in noise in a group of adult listeners with varying degrees of sensorineural hearing loss. This work was also designed to determine whether cortical ERPs and oscillatory rhythms in various frequency bands can predict the effects of hearing impairment on sentence recognition in noise. Passive N1-P2 and MMN responses were elicited with a double-oddball paradigm containing a consonant and vowel change in background noise. Speech perception was evaluated using phoneme discrimination and sentence recognition in noise tasks. Analysis showed that hearing impairment significantly impacted the MMN response but not the obligatory, sensory N1-P2 complex. Results showed that these objective neural responses may be promising neurophysiological markers of perception in noise across listeners. This work has important implications regarding the use of electrophysiological measures for assessing speech perception in complex auditory environments in clinical populations.
Human recognition of environmental sounds is not always robust to reverberation
Authors: Traer James , McDermott Josh
Published: April 2018

Reverberation is ubiquitous in natural environments, but its effect on the recognition of non-speech sounds is poorly documented. To evaluate human robustness to reverberation, we measured its effect on the recognizability of everyday sounds. Listeners identified a diverse set of recorded environmental sounds (footsteps, animal vocalizations, vehicles moving, hammering, etc.) in an open set recognition task. For each participant, half of the sounds (randomly assigned) were presented in reverberation. We found the effect of reverberation to depend on the typical listening conditions for a sound. Sounds that are typically loud and heard in indoor environments, and which thus should often be accompanied by reverberation, were recognized robustly, with only a small impairment for reverberant conditions. In contrast, sounds that are either typically quiet or typically heard outdoors, for which reverberation should be less pronounced, produced a large recognition decrement in reverberation. These results demonstrate that humans can be remarkably robust to the distortion induced by reverberation, but that this robustness disappears when the reverberation is not consistent with the expected source properties. The results are consistent with the idea that listeners perceptually separate sound sources from reverberation, constrained by the likelihood of source-environment pairings.
3D-printing and vibration (including resonance)
Authors: Virgin Lawrie
Published: April 2018

The material contained in this paper focuses on using 3D printing of relatively simple, flexible structural components and plane frames. The relatively high resolution of modern 3D printers facilitates the production of slender structures, and thus provides an opportunity to exploit geometric parameter variations to enhance a practical understanding of stiffness and vibration. This approach has proved successful in initial inclusion in both the classroom via demonstration models, as well as in the lab in which elementary facilities can be utilized to acquire data. An especially useful facet of this approach is the assessment and justification for modeling simplifications, e.g., judging the circumstances under which the familiar sway assumption is valid in portal frames. Furthermore, minor parametric variations can be easily incorporated into sensitivity studies, and the production of multiple copies of essentially the same geometry promotes an effective use of statistical measurement uncertainty. We then extend this approach to forced vibration, with examples including the vibrating reed tachometer and sympathetic resonance.
The acoustic guitar as an experimental platform to teach vibration measurements, modal parameter estimation, and data management
Authors: Shepherd Micah R. , Dare Tyler P.
Published: April 2018

The laboratory class required by Penn State’s Graduate Program in Acoustics teaches general experimental methods for acoustics. Students learn the basics of data acquisition, sensor calibration and excitation methods through lectures and performing experiments. This talk will discuss the lab experiment used to teach vibration measurements, basic modal parameter estimation and data management using an acoustic guitar as the experimental testbed. Students are required to develop their own test plan for accelerometer and impact hammer locations and then collect the data using a custom-written LabVIEW data acquisition program. Since the data acquisition involves multiple impact and response locations, the students are required to manage their data in a way that allows for easy mapping of data files to spatial locations. They then estimate the guitar body mode shapes by decomposing the measured mobility matrix into its singular values and right- and left-singular matrices. Finally, the students visualize their results by creating a mesh in MATLAB using the impact locations. By completing all of the steps to perform a modal analysis of an acoustic guitar, the students gain experience in both the practical considerations of modal analysis and experimentation in general.
Seismic-infrasound-acoustic-meteorological sensors to dynamically monitor the natural frequencies of concrete dams
Authors: Diaz-Alvarez Henry , De Jesus-Diaz Luis A. , Chiarito Vincent P. , Simpson Christopher , McKenna Mihan H.
Published: April 2018

The U.S. Army Engineer Research and Development Center (ERDC) is leading research using seismic-infrasound-acoustic-meteorological (SIAM) arrays to determine structural characteristics of critical infrastructure. Large infrastructure, such as dams, emit infrasound (acoustic energy below that of human perception) at their natural modes of vibration, which are related to their structural condition. To validate the concept and its potential use for monitoring flood control structures, a structural evaluation was conducted at the Portuguese Dam in Ponce, Puerto Rico. The dam’s dynamic properties were studied prior to the deployment of SIAM arrays using detailed finite element (FE) models assembled in COMSOL Multiphysics software. The principal natural frequencies of the dam were identified and the fundamental modes were confirmed in the infrasound pass-band. The natural frequencies of 4.8 Hz, 6.7 Hz, and 10.2 Hz, respectively, were determined for the lower modes of vibrations. A total of three SIAM arrays were deployed multiple times over the course of three years. This provided a wide range of data to help understand how the dam’s natural frequencies changed due to different loading conditions such as the different reservoir levels. Infrasound test results were compared to resonant frequencies calculated from the dam’s transient responses produced by ambient and external load excitations.
Classroom demonstration of nonlinear tuning curve vibration and two-tone tests using a column of glass beads vibrating over a clamped elastic plate
Authors: Santos Emily V. , Korman Murray S.
Published: April 2018

A soil plate oscillator (SPO) apparatus consists of two circular flanges sandwiching and clamping a thin circular elastic plate. The apparatus can model the acoustic landmine detection problem. Here, uniform spherical glass beads—representing a nonlinear mesoscopic elastic material—are supported at the bottom by the acrylic plate (4.5 inch diam, 1/8 inch thick) and stiff cylindrical sidewalls of the upper flange. A magnetic disk centered and fastened below the plate is driven by an AC coil placed below the magnet. Nonlinear tuning curves of the magnet’s acceleration are measured by driving the coil with a swept sinusoidal signal applied to a constant current amplifier. Ten (separate) tuning curve experiments are performed using a fixed column of 350 grams of beads using 1,2,3,…,10 mm diameter beads. The backbone curves (peak acceleration vs. corresponding resonant frequency) exhibit a linear region with comparable slopes, while the detailed curvature vs. bead diameter reveals more structure. A bilinear hysteresis model is useful for characterizing results. In two-tone tests, air-borne sound from two 3 inch diameter speakers drives the bead column surface at closely spaced frequencies near the fundamental resonance. Nonlinearly generated combination frequency tones are compared for each of the ten bead diameter experiments.
The relationship between reading ability and categorical perception of spectrotemporal and spectral contrasts in children
Authors: O'Brien Gabrielle , Kubota Emily , Yeatman Jason D.
Published: April 2018

Behavioral evidence suggests that dyslexic readers are impaired in processing rapid temporal changes such as formant transitions. It is unclear if this possible impairment is attributable to the dynamic nature of a formant transition, the brevity of the cue, or a general deficit in categorical decision making. We tested categorical perception of speech in 30 children between the ages of 8 and 12 with a range of reading abilities (dyslexic, below average and above average readers) on two stimulus continua: (1) a /ba/-/da/ continuum, in which a 100-ms formant transition provides a spectrotemporal cue, and (2) a /sa/-/sha/ continuum with a purely spectral contrastive cue also lasting 100 ms. Two test conditions probed the interaction of working memory and categorical perception: a single-interval condition and an ABX paradigm. Children with dyslexia showed shallower psychometric functions and more lapses at the continuum endpoints compared to controls. There was no effect of stimulus continuum or test condition. This suggests that dyslexic children are not specifically impaired in their perception of formant transitions. Rather, dyslexic children may be subtly challenged in auditory coding of, or decision making about, temporally brief cues that may be either spectral or spectrotemporal in nature.
Recovering prosody of a case of foreign accent syndrome
Authors: Kuo Grace
Published: April 2018

Foreign Accent Syndrome (FAS) is a rare disorder characterized by the emergence of a perceived foreign accent following brain damage. In this case study, acoustic analyses were performed on the speech of a Mandarin-speaking female FAS patient at her four doctor’s appointments. The reading materials included news in newspaper and a tongue twister. The acoustic analyses include sentence-level intonation and rhythmic measures including %V and PVIs. Results reveal a gradual recovery trajectory from a disfluent stressed-timed pattern to a fluent syllable-timed pattern. A heritage Mandarin speaker and an advanced nonnative speaker recorded the same reading materials. Same acoustic analyses were performed on their speech for comparison.
Linguistic type-frequency in preschool boys and girls with and without hearing loss
Authors: VanDam Mark , Anderst Jenna , Olds Daniel , Saur Allison , De Palma Paul
Published: April 2018

Linguistic type-frequency, how many different lexical types are used, has been examined in usage-based models of child language acquisition. In general, it has been shown that exposure to greater type-frequencies increases children’s productive use of language and that language in turn bootstraps later development including language and literacy. It is not currently known if pediatric hearing loss impacts the type-frequency of those children’s early communicative productions. In this study, we used a public database available via HomeBank [http://homebank.talkbank.org] to examine the type-frequency in 53 cognitively intact children, 37 with mild to moderate hearing loss (HL) and 16 peers who were typically-developing (TD). For each child, we analyzed 15 minutes of high volubility from a representative daylong recording collected in a natural family setting via an audio recorder worn by the child. Results indicate a main effect of sex favoring girls, but no main effect of HL. There were, however, interaction effects in which TD-boys had a greater type-frequency than HL-boys, but TD-girls were lesser than HL-girls. Within the HL group, HL-girls had greater type-frequency than HH-boys, but within the TD group TD-boys had greater type-frequency than TD-girls.
Processing speed and age predict recognition of spectro-temporally degraded speech
Authors: Tinnemore Anna R. , Evans Lauren , Gordon-Salant Sandra , Goupell Matthew
Published: April 2018

Cochlear implants (CIs) provide a listener with the temporal envelope of an acoustic signal, but not the spectral fine structure. Speech recognition performance is highly variable among individuals and is often assessed clinically in ideal conditions (over-articulated, clean speech) rather than real-world listening environments. This study examined the effects of age and processing speed on understanding of time-compressed speech by listeners with normal hearing (NH) presented with vocoded speech of varying spectral resolution and listeners with CIs. NH listeners repeated sentences that had been time-compressed to varying degrees (no compression, 20%, 40%, or 60% time compression ratios) and then noise vocoded with various channels (4, 8, or 16 channels or unprocessed), while CI participants repeated unprocessed time-compressed sentences. Performance of age-matched NH listeners on the 4-channel vocoded speech most closely matched CI listeners’ performance at each level of time-compression. For NH listeners, age effects were observed on conditions featuring time compression and reduced spectral resolution. Both NH and CI listener groups showed a significant interaction between age and time compression. As difficulty increased (greater time compression for all, fewer channels for NH), cognitive measures of processing speed were correlated with speech recognition performance across all age and listening groups.
Directional emphasis in ambisonics
Authors: Kleijn W. Bastiaan , Allen Andrew , Skoglund Jan , Lim Felicia S.
Published: April 2018

We describe an ambisonics enhancement method that increases the signal strength in specified directions at a low computational cost. The strengthening method is referred to as a utilization of an enhancement operator. The operator can be used in a static setup to emphasize the signal arriving from a particular direction or set of directions, much like a spotlight amplifies the visibility of objects in one direction. It can also be used in an adaptive arrangement where it sharpens the directionality and reduces the distortions in timbre associated with low-degree ambisonics representations. The enhancement operator can be applied directly to time-domain ambisonics representations but also to time-frequency ambisonics representations.
Achieving realism and repeatability of an orchestra simulated within a concert hall
Authors: Neal Matthew T. , Vigeant Michelle C.
Published: April 2018

Virtual acoustic techniques can allow for direct comparison between concert halls, but care must be taken to ensure the virtual reconstruction connects back to the subtle perceptions of the real environment. To achieve better realism with repeatability between measured halls, a compact spherical loudspeaker array is being used to simulate an orchestra. This sound source is placed at twenty different source locations around the stage. For each instrument measurement position, a swept-sine signal is processed to radiate from the source with a particular instrument’s directivity, and the spatial room impulse response (RIR) is measured. This processing is accomplished through filters designed from an instrument directivity database measured with 32 microphones. For each instrument, a set of full-frequency filters, one for each loudspeaker driver, were designed from one-third octave band spherical harmonic weights. These processing techniques are directly analogous to higher order Ambisonics (HOA). In the audience, a 32-element spherical microphone array is used to capture the spatial RIR, and each measurement is convolved with single-instrument anechoic recordings and auralized using HOA. Separate auralizations of each instrument are combined together into a full-orchestral auralization. The measurement setup, filter design, and equalization techniques will be presented. [Work supported by NSF Award 1302741.]
Effects of non-individual head-related transfer functions and visual mismatch on speech recognition in virtual acoustic environments
Authors: Ward Kristi M. , Peng Z. Ellen , Grieco-Calub Tina M.
Published: April 2018

There is widespread research and clinical interest in quantifying how the acoustics of real-world environments, such as background noise and reverberation, impede a listener’s ability to recognize speech. Conventional methods used to quantify these effects include dichotic listening via headphones in sound-attenuated booths or loudspeakers in anechoic or low-reverberant environments, which lack the capability of manipulating room acoustics. Using a state-of-the-art Variable Room Acoustics System housed in a virtual sound room (ViSoR), this study aims to systematically assess the effects of non-individual head-related transfer functions (HRTFs) and mismatched visual perception on speech recognition in virtual acoustic environments. Young adults listened to and repeated sentences presented amidst a co-located two-talker speech competitor with reverberation times ranging from 0.4 to 1.25 s. Sentences were presented in three listening conditions: through a loudspeaker array in ViSoR with the participants’ own HRTFs (Condition 1); via headphones in a sound-attenuated booth with non-individual HRTFs(Condition 2); and using the same binaural reproduction as Condition 2 in ViSoR (Condition 3). Condition 3 serves as a control condition, allowing us to quantify the separate effects of non-individual HRTFs and visual mismatch on speech recognition. Discussion will address the validity and use of virtual acoustics in research and clinical settings.
VSLM—The virtual sound level meter
Authors: Muehleisen Ralph T.
Published: April 2018

Inexpensive sound level meters and low cost or free apps for smart phones and tables have made it much easier to introduce the concept of sound levels to a wide audience at very low cost. However, there are times when it is preferable to be able to take more complicated measurements that are generally only available on more expensive sound level meter. With fairly low cost digital recorders, one can now take a calibrated recording of an acoustic event and analyze the recording later. In this presentation, a free software package called VSLM: The Virtual Sound Level Meter is described. VSLM allows users to calibrate a recording and do many types of analysis including mimicking a sound level meter on fast, slow, Leq, octave, and 1/3 octave band analysis using fast FFT or digital meters that meet ANSI standards, high resolution spectral analysis, and create spectrograms.
Determining the mass of gas in large collection volumes with acoustic and microwave resonances
Authors: Gillis Keith A. , Pope Jodie G. , Moldover Michael , Mehl James B.
Published: April 2018

We characterized a 1.8 m3, quasi-spherical resonator, a pressure vessel informally known as the “big blue ball” or “BBB.” The BBB will be the collection volume of a NIST-designed gas-flow standard that will operate at pressures up to 7 MPa. Using microwave resonance frequencies, we determined the volume of the BBB filled with argon as a function of pressure (up to 7 MPa) and temperature (near ambient). The measured pressure- and temperature-dependences of the BBB’s volume are consistent with the published properties of carbon steels. We filled the BBB with 220 kg of argon in weighed increments of approximately 20 kg. We also determined the mass macoust of argon in the BBB by measuring the pressure, the acoustic resonance frequencies facoust of 3 modes, and using the known thermophysical properties of argon. The values of macoust were within ±0.03 % of the gravimetrically determined masses. In a typical application, the BBB will never be isothermal. Nevertheless, the acoustic resonance frequencies quickly and accurately determine the average temperature and mass of the gas in the BBB despite significant, long-lived thermal gradients that are created by pressure changes. A theoretical model for effect of temperature gradients on the acoustic resonance frequencies is presented.
Frequency-wavenumber analysis with a sparse array
Authors: Choi Yonghwa , Kim Donghyeon , kim Jea Soo
Published: April 2018

In underwater acoustics, there has been many studies for finding the target direction using beamforming technique. When receiving a signal with a frequency higher than the design frequency of the array, it is difficult to estimate the direction of the signal due to spatial aliasing. In this study, we propose a method of estimating the direction of the frequency signal higher than the design frequency of the array by using frequency-wavenumber analysis. When the frequency-wavenumber analysis is performed, the striation pattern appears, and it is confirmed that the slope of the striation remains constant even if the spatial aliasing occurs. The direction of the signal was estimated by visual inspection and it was verified with SAVEX15 data.
On the prediction of sound diffusion coefficient
Authors: Azad Hassan , Siebein Gary W.
Published: April 2018

Acoustic diffusers are one of the key elements in architectural acoustic design. The shape, placement and combination with absorbers along with the physical characteristics of the room such as the volume, size, and geometry make a complex design scenario full of variables and dependencies. The Prediction of scattered reflections with the help of computer modeling is one of the most recent areas of research. Currently the only software package that exist for the simulation of the scattered sound is Reflex [1] from AFMG which can predict scattering and diffusion coefficients of 1D acoustics diffusers using their cross sections. It employs Boundary Element Methods for the calculation purposes. This study intends to develop a sound diffusion prediction software that simulates the measurement laboratory environment of the diffusion coefficients in accordance with 17497-2 ISO standards to predict diffusion coefficients of different type of 2D and 3D acoustics diffusers such as Schroeder, fractal and volumetric diffusers. For the calculations, wave-based room acoustics modeling techniques such as FDTD and BEM will be used. There are plenty of partial differential solvers available that are used for acoustics purposes which will be used in this paper as well. [1] http://reflex.afmg.eu/
Use of transition and abstract rules by budgerigars in auditory pattern processing
Authors: Fishbein Adam , Ball Gregory F. , Dooling Robert
Published: April 2018

Budgerigars, a small species of parrot, are open-ended vocal learners that produce a long, rambling warble song. Past work has shown that these birds are sensitive to changes in the order of their song elements but it is not clear what rules they may use to process changes in sounds sequences. Here, we used operant conditioning and psychophysical techniques to ask how budgerigars discriminate among patterned auditory sequences. In these experiments, auditory sequences of the form AAB, composed of pure tones or natural warble elements, were played to the bird as a repeating background until the bird pecked a key to initiate a trial. During a trial, either a target sequence played that differed from the background in the order of the elements or a sham trial occurred where there was no change. Results show that budgerigars use rules about the transitions between elements to detect targets. Further experiments using multiple background sequences show that the birds are also sensitive to the underlying abstract pattern of sounds (same-same-different). Thus, with their ability to attend to surface transition rules (phonology-like) and deeper abstract patterns (syntax-like), budgerigars are a useful vocal learning model for studying the neurobiology and evolution of language.
Optical coherence tomography reveals complex motion between the basilar membrane and organ of corti in the gerbil cochlea
Authors: Strimbu Clark E. , Lin Nathan C. , Olson Elizabeth S.
Published: April 2018

The mechanical basis of auditory transduction within the mammalian cochlea is not fully understood but relies on complex mechanical interactions between different structures within the Organ of Corti (OoC). We used spectral domain phase microscopy, a functional extension of optical coherence tomography (OCT), to measure the sound-evoked motion in response to “Zwuis” frequency complexes, in vivo, in the basal region of the gerbil cochlea. Because OCT allows for measurements from multiple axial positions along the optical path, we are able to simultaneously record vibration at different points within the OoC between the basilar membrane (BM) and tectorial membrane. Imaging through the round window membrane, we could record from several longitudinal locations along the cochlea and at each location, we measured from several radial positions. Both the BM and intra-OoC vibrations are tuned and show nonlinear amplification, or compressive growth, with the applied sound pressure level. Similar to recent reports (Ren et al, PNAS 2016; Ren and He, MoH 2017), we find that the motions of surfaces within the OoC can exhibit a greater degree of compressive nonlinearity (amplification) and physiological vulnerability than the motion of the BM. Additionally, some responses show sharp notches near the onset of the nonlinear regime.
Effect of broadband chirp signal on the sonic behavior of the /kwa/ fishes inhabiting Posidonia oceanica seagrass meadow
Authors: Hermand Jean-Pierre , Velardi Laura
Published: April 2018

Early experiment to study acoustics of Posidonia oceanica seagrasses (USTICA99) transmitted acoustic chirp signals (0.2-16 kHz, 15.8 s) every minute during 3 days over a meadow. Receiving hydrophones recorded vocalizations from unknown fish inhabitants, which sound like /kwa/. Here, we address the impact of our measurements on this fish population. The authors’ ears analyzed the recordings to identify all fish vocalizations and attempt to recognize /kwa/ individuals based on timbre. A comparative analysis of the /kwa/ sound production within time intervals between and during chirp transmission was made to understand if and how the sonic behavior is affected. As in few similar studies for other anthropogenic noise sources on a limited number of species, there was an observable effect. The major part of the vocalization patterns that were identified within the chirp time interval started near the onset of the frequency sweep, which first spans the range of /kwa/ sound production (0.4-2 kHz). The number of single vocalizations per unit time during that period was close to that during the no-chirp time interval while during higher swept frequencies was markedly smaller. This suggests the fish detection range may extend toward ultrasound to avoid dolphin predators. Quantitative results will be presented.
Multi-resolution rank analysis for non-contrast ultrasound imaging of slow flow
Authors: Bayat Mahdi , Alizad Azra , Fatemi Mostafa
Published: April 2018

While conventional filtering techniques can effectively exclude tissue-related Doppler shifts from those resulting from blood motions in large vessels (flow rates ~ cm/s), significant spectral overlap can hinder proper clutter filtering in imaging slow flows (flow rates ~ mm/s or tenths of mm/s). Recently, several groups have proposed clutter filtering via processing of echo ensembles in the rank space instead of frequency domain. Though significant Doppler content can result from fast moving tissues, global coherence of the induced variations enables a low rank representation. In this talk, we first provide a brief overview of the low rank clutter removal methods. We then present a new framework for the analysis of Doppler ensembles using multi-linear decomposition of a tensor comprising Doppler ensembles at different rates. The model results in a high dimensional tensor from which, after proper rank selection, images of flow at different speeds can be extracted along different fibers. Using simulation models, we demonstrate the superior performance of the proposed method over singular value clutter filtering in imaging small vessels embedded in moving tissue undergoing both translational and shearing motions. We also present in vivo examples where the proposed method provides significant blood to clutter + noise ratio enhancement compared to singular value clutter filtering.
High power evaluation of textured piezoelectric ceramics for SONAR projectors
Authors: Shankar Arjun , Meyer Richard
Published: April 2018

Textured Ceramics of the relaxor ferroelectric PMNT have shown exceptional piezoelectric properties suitable for high power SONAR projectors. The piezoelectric coefficient (d33>800pm/V), the electromechanical coupling coefficient (k33>0.80), and the mechanical quality factor (Qm>90) in various forms of PMNT showcase the potential for these textured ceramics to be implemented in a high power, broad bandwidth acoustic projector. This work attempted to devise a set of experiments to quickly characterize the electromechanical performance of these materials in relevant devices in order to provide feedback to both the material developers and the user community. In this effort, textured PMNT and Manganese doped PMNT (Mn:PMNT) were compared to the performance of conventional lead zirconate titanate (PZT) ceramics. Linearity and harmonic distortion measurements were made in a high pressure test facility to measure source levels of these SONAR projectors. In addition, isothermal measurements were made at 50 degrees Celsius to monitor source levels as a function of duty cycle. The results from these measurements were then compared to modeled results and appropriate recommendations on material composition improvements were made.
SII—Speech intelligibility index standard: ANSI S3.5 1997
Authors: Pavlovic Caslav
Published: April 2018

The Speech Intelligibility Index Standard (SII) defines a method for computing a physical measure that is highly correlated with the intelligibility of speech. The SII is calculated from acoustical measurements of speech and noise. In this talk the activities of the Working Group for the Speech Intelligibility Standard will be reviewed including the issues to be resolved, the changes, and the additions under consideration. The general framework of the current standard (ANSI S3.5-1997) is such that new methodologies for specifying the effective (“equivalent”) speech and noise can be easily incorporated as long as they have been tested and found valid for a well specified set of circumstances. The history of the Speech Intelligibility Index (SII) Standard and its relationship to the Articulation Index (AI) and the Speech Transmission Index(STI) will also reviewed. The general philosophy of Speech Intelligibility Index will also be discussed including the definition and specification of its fundamental variables: dynamic speech and noise spectra, information transmission by different bands, and their biologic/evolutionary compatibility with both the threshold of hearing, and the neural tuning.
Switch of synchronization states of aeroacoustical coupled organ pipes
Authors: Fischer Jost L. , Bader Rolf
Published: April 2018

The separation distance of two equally tuned, aeroacoustically coupled organ pipes is varied stepwise in a synchronization experiment. At distances of multiples of about half the wavelength of the fundamentals, abrupt changes of SPL and fundamental frequency of the coupled and synchronized system can be observed. Frequency jumps also occur at higher harmonics. The nonlinear coupling function of the system implicitly takes into account the time delay of the system caused by the separation distance and therefore plays an important role for the observed phenomenon. The effect can be explained as a switch of synchronization states from in-phase to anti-phase and vice versa.
Total hearing health for preventing occupational hearing loss
Authors: Murphy William J.
Published: April 2018

The National Institute for Occupational Safety and Health (NIOSH) developed the Total Worker Health program that encourages health and safety professionals to consider more than just a particular exposure. Workers can suffer hearing loss due to both workplace, but due to a wide range of activities outside of work. Training workers in the proper use and application hearing protection can extend the effectiveness of hearing loss prevention efforts and promote the concept of Total Hearing Health. Awareness of hazardous activities such as the use of power tools, firearms, and chemical exposures, can instill a safety culture beyond the workplace. Hearing protector fit testing gives workers an increased self-efficacy and assurance that they can safely enjoy noisy activities without the need to sacrifice their ability to hear. This presentation will describe the work that NIOSH has undertaken to promote hearing protector fit-testing for the workplace and describe ways in which the Centers for Disease Control and Prevention has promoted hearing health.
Earplug comfort: From subjective assessment on the field to objective measurement and simulation using augmented artificial heads
Authors: Doutres Olivier , Sgard Franck C. , Benacchio Simon , Terroir Jonathan , Perrin Nellie , Trompette Nicolas , Negrini Alessia , Gaudreau Marc-André , Jolly Caroline , Berry Alain , Gauthier Philippe-Aubert , Padois Thomas , Gauvin Chantal
Published: April 2018

For several years, lack of comfort has been pointed out as a major reason of earplug poor efficiency as noise control solution. The great complexity of comfort makes it difficult to predict it in the earplugs design phase. It is rather considered in an empirical way by the manufacturers using trial-and-errors approaches based on subjective assessment over a panel of subjects. Furthermore, because comfort is not quantified, Occupational Health and Safety (OHS) practitioners cannot select earplugs ensuring wearer comfort. To address these issues, a major international research project funded by two OHS institutes (IRSST in Canada and INRS in France) and involving several Universities (in Canada and England) started in 2017. The main objectives are to: (1) improve the understanding of earplugs comfort as perceived by field workers with consideration of all comfort components, (2) develop laboratory tools (augmented experimental and virtual artificial heads) to measure physical design variables related to the auditory, physiological, and functional components of comfort and (3) design a battery of hybrid objective/subjective comfort indices to quantify / measure / predict the different components of comfort. The aim of this presentation will be to present the project and first results.
Sonic boom carpet widths for NASA’s Low Boom Flight Demonstrator using realistic atmospheric profiles in the western hemisphere
Authors: Doebler William , Loubeau Alexandra , Sparrow Victor
Published: April 2018

NASA is developing and building a Low Boom Flight Demonstrator (LBFD) within the next five years to study public reaction to low amplitude, shaped sonic booms. Understanding the potential land area ensonified by sonic booms is critical for the upcoming community tests, and is not well known outside of using the 1976 US Standard Atmosphere which assumes zero wind. Using atmospheric profiles from NOAA’s Climate Forecast System Reanalysis (CFSR) for a span of many months, the sonic boom carpet widths and Stevens Mark VII Perceived Levels (PL) at the edge of the carpet were calculated using NASA’s sBOOM augmented Burgers Equation propagation code. The LBFD’s near field pressure cylinder calculated using NASA’s LAVA CFD code was used as the input to the sBOOM code. Atmospheric profiles were sampled from several regions with varying climate in the western hemisphere. Preliminary results indicate that sonic boom carpets will be widest during winter months, and will have highest carpet edge PL values during summer months. [Work supported by the NASA Education AS&ASTAR Fellowship Program.]