bluuebunny/crossref_metadata_2025 huggingface dataset:
Linking design decisions to speech intelligibility
Authors: Hulva Andrew , Ermann Michael , Hull Kirsten , Rehfuss Randall , Kanapesky Aaron , Reardon Alex
Published: May 2016

What is the largest classroom that will support unamplified communication? What design attributes and acoustical conditions contribute to speech intelligibility, and how much should each design attribute be weighted when predicting speech transmission index (STI)? This line of inquiry aims to correlate room design and mechanical equipment (HVAC) design to speech intelligibility (STI) in university lecture rooms. It seeks to link the STI of classrooms at Virginia Tech to ambient noise levels, reverberation time, impulse response characteristics, room volume, number of seats, distance to nearest HVAC terminal device, receiver location, and speaker source power. Ambient noise measurements and STI will be mapped on a 1 m x 1 m grid for a subset of the measured rooms to visualize the noise on the listener plane and better estimate the haptic component of signal-to-noise ratio in the spaces. The research also will explore quirks in the STI measurement itself, including differences between the direct and indirect measurement methods, differences permitted for test speech level, and differences from seat to seat within a single room.
Predicting and controlling heating, ventilating, and air conditioning systems noise: A comparison of computer noise control prediction tools and their potential pitfalls
Authors: Cuff Nicole
Published: May 2016

Appropriate background noise levels for mechanical systems are critical for a successful use of any project. There are several computer software packages that acousticians use to evaluate the background noise levels in a space; of course, the acoustician needs to understand all of the inputs into the programs to fully understand the outputs. We will discuss strategies to use these noise prediction tools successfully, including how to evaluate noise sources and translate manufacturer data to input into the programs, how to evaluate various noise paths together for one space, and how to consider sound propagation of different noise sources. We will compare several different and widely available computer noise prediction programs and discuss the positives and challenges of using each one, including the author's assessment of which circumstances lend themselves best to one program versus another.
Simulation of noise propagation through heating ventilation and air conditioning ductwork
Authors: Herrin David W. , Ruan Kangping
Published: May 2016

Noise primarily propagates through the airspace or breaks out through the walls of HVAC ductwork. Finite element analysis was used to assess the noise attenuation of each of these paths. Specifically, the insertion loss and breakout transmission loss were assessed for both bare and lined ductwork. Sound absorptive lining was modeled using poroelastic finite elements and the ductwork itself was modeled using shell and beam elements. A diffuse field was approximated at the source using a collection of monopole sources having random phase. Results were compared to measurement with good agreement. Several conclusions can be made regarding noise transmission in large ducts that should be transferable to other industries.
Relative abundance of sound scattering organisms in the Northwestern Hawaiian Islands is a driver for some odontocete foragers
Authors: Copeland Adrienne M. , Au Whitlow W. , Bradford Amanda , Oleson Erin , Polovina Jeffrey
Published: May 2016

Previous studies in the Northwestern Hawaiian Islands (NWHI) focused on shallower communities in and near reefs and did not investigate the organisms living in deeper waters that some apex predators rely on for food, e.g., some odontocetes forage at depths greater than 400 m. To examine the relationship between deep-diving odontocete predators and prey, a Simrad EK60 echosounder operating at 70 kHz collected acoustic abundance throughout the NWHI from May 7 to June 4, 2013. Visual and passive acoustic surveys for marine mammal presence were conducted concurrently with the echosounder. Two broad scattering layers were found, a deep layer from 325 to 670 m and a shallow layer from 0 to 195 m. The highest densities of both deep and shallow scattering organisms were associated with deep slopes of banks and atolls. Beaked and short-finned pilot whale sightings occurred in locations of high scattering density associated with slopes of atolls and banks. It is hypothesized that the high scattering organisms associated with these features are similar to the mesopelagic boundary community found in the Main Hawaiian Islands and support a food web representing the prey of the cetaceans.
Intensity difference limens in mice
Authors: Kobrina Anastasiya , Toal Katrina , Burke Kali , Dent Micheal L.
Published: May 2016

The ability to distinguish between sounds of differing intensities is a universal auditory process. Previous researchers have examined the intensity discrimination abilities of goldfish, parakeets, and several mammals including feral and house mice using behavioral approaches. CBA/CaJ mice are frequently used as a model for human hearing research, yet intensity difference limens (IDLs) have not been measured in this strain. The aim of the present study was to establish IDLs for 12, 16, 24, and 42 kHz tones at 10 and 30 dB SL. Eight adult animals were trained and tested in a discrimination task using operant conditioning procedures with positive reinforcement. IDLs were variable across all frequencies for 10 dB SL, but remained stable for 12, 16, and 42 kHz at 30 dB SL, with elevated IDLs at 24 kHz. Calculations of the Weber fractions at each sensation level tested showed that Weber’s law does not hold true for IDLs in CBA/CaJ mice. Overall, thresholds were comparable to those found in other animals.
Acoustical and vibratory characteristics of a synthetic mallard syrinx replica
Authors: Groom Taylor B. , Riede Tobias , Thomson Scott L.
Published: May 2016

The study of the physics of human voice production has benefited by the use of synthetic human vocal fold replicas. Extending this concept to avian vocalization, a functioning model of a male mallard syrinx for studying the relationship between syrinx anatomical features and vocalization characteristics is described here. The mallard syrinx is characterized by two sets of labia located at the tracheobronchial juncture, and vocalization is produced by the flow-induced vibration of these labia. Shape and histological composition of labia demonstrate similarities to mammalian vocal folds. In this study, life-sized synthetic replicas based on CT data of an adult male mallard syrinx, including airway and labia regions, are studied. The replicas are fabricated using exceedingly flexible silicone materials that have been previously used in synthetic human vocal fold replicas. The replicas are mounted in tube-like airways representing the trachea and bronchi, with flow generated by an adjustable air supply. In this presentation, the CT-based syrinx model, including fabrication process, will be introduced. The model response, including acoustical output and vibratory motion, will be described and compared to previous models and to existing data about mallard vocalization.
Neyman-Pearson detection of underwater bioacoustic signals
Authors: Dadouchi Florian , Huillery Julien , Gervaise Cédric , Mars Jérôme I.
Published: May 2016

The use of passive acoustic for the classification, localization, and density estimation of populations of marine mammals is a current area of interest. It is a cheap and an efficient alternative to visual surveys. However, the lack of an efficient automatic detector for unknown marine mammal calls greatly undermines the feasibility of those tasks, especially when dealing with species showing a great variability of calls. This study adds one more step toward the fully automatic detection of unknown bioacoustic signals in impulsive, non-stationary, and colored ocean noise. The detection procedure is a two-steps fully statistical method solely based on the knowledge of the background noise in the spectrogram. The first step models the noise power as a chi-squared distribution, which parameter is estimated. The signal is then detected using a Neyman-Pearson approach, providing a binary spectrogram that contains false and true detections. The second step removes a significant amount of false detections from the binary spectrogram. The time-frequency distribution of false detections is fitted with a correlated binomial distribution, which is used to discriminate patches of detections (signal) from uniformly distributed detections (false alarms). Examples showing the applicability of this method on several real underwater sounds are presented.
Size differentiation of a continuous stream of particles using acoustic emissions
Authors: Nsugbe Ejay , Starr Andrew , Foote Peter , Ruiz-Carcel Cristobal , Jennions Ian K.
Published: May 2016

Procter and Gamble (P&G) requires an online system that can monitor the particle size distribution of their washing powder mixing process. This would enable the process to take a closed loop form which would enable process optimization to take place in real time. Acoustic emission (AE) was selected as the sensing method due to its non-invasive nature and primary sensitivity to frequencies which particle events emanate. This work details the results of the first experiment carried out in this research project. The first experiment involved the use of AE to distinguish sieved particle which ranged from 53 to 250 microns and were dispensed on a target plate using a funnel. By conducting a threshold analysis of the peaks in the signal, the sizes of the particles could be distinguished and a signal feature was found which could be directly linked to the sizes of the particles.
Uncertainty estimates of psychoacoustic thresholds obtained from group test
Authors: Rathsam Jonathan , Christian Andrew
Published: May 2016

A common goal in laboratory psychoacoustic testing is determining the level, or threshold, at which a test signal is judged subjectively equivalent to a reference signal. Adaptive methods, in which the next signal level depends on the response to the previous signal, are most efficient and precise for determining thresholds but only accommodate one subject at a time. At NASA, testing one subject at a time to achieve a sample size representative of a larger population would exhaust testing resources. Instead, three or four subjects are tested simultaneously using preselected signal levels. When a threshold is estimated from a curve fit through group test data, techniques are required for assessing the threshold uncertainty. In this presentation, we examine the Delta Method, the Generalized Linear Model (GLM), the Nonparametric Bootstrap, and Bayesian Posterior Estimation (BPE). Each technique is first exercised on a manufactured, theoretical dataset. When we are confident we are using the methods correctly, we apply them to two psychoacoustic datasets. The Delta Method is the simplest to implement. The BPE is the most versatile, allowing the inclusion of prior information. While useful, the Nonparametric Bootstrap takes longer to calculate. The GLM is found to be least robust.
Numerical calculation of acoustic radiation force and torque on non-spherical particles in Bessel beams
Authors: Wijaya Felix B. , Lim Kian Meng
Published: May 2016

Manipulation of biological cells using acoustic radiation force has drawn a lot of attention in recent years. The force and torque acting on cells are usually estimated from analytical and semi-analytical solutions derived for simple shapes, such as spheres and ellipsoids, typically in an axisymmetric configuration. Since biological cells come in various shapes and sizes and they may have an arbitrary orientation in a microfluidic channel, there is a need for a more versatile and robust numerical model for evaluating the acoustic radiation force and torque. Motivated by this, a three-dimensional boundary element model is developed for calculating radiation force and torque on particles of arbitrary shapes and sizes subjected to arbitrary acoustic waves. The first order acoustic field is solved by using the boundary element method. The second-order, time-averaged tractions are then obtained from the first order field. Subsequently, the resultant radiation force and torque are calculated by integrating the tractions over the surface of a fictitious sphere that encapsulates the particle. The force and torque on non-spherical particles subjected to acoustic Bessel beams are obtained using this numerical model. The effects of the beam cone angle and particle orientation on the radiation force and torque are investigated.
Differences in cortical responses to spatial changes in foreground versus background auditory objects
Authors: Reed Darrin K. , Tóth Brigitta , Shinn-Cunningham Barbara
Published: May 2016

Identifying neural markers related to the integration of auditory features—such as spectrum, temporal coherence, and lateral position—can help to reveal the mechanisms underlying how the auditory system processes simultaneous sound sources. For a stimulus that is composed of randomly chosen successive inharmonic tone complexes, a subset of tones can perceptually segregate from the other simultaneous tones if the subset repeats for a sufficient number of tokens. Listeners can reliably detect this repeating pattern as a figure sound object amidst a randomly changing background. An electroencephalogram was recorded while listeners performed the detection of changes in interaural time difference (ITD) cues that were attributed to either the figure or the background. Detection of ITD changes for either auditory object elicited a fronto-central early negativity (100–200 ms) and P300 event-related potentials (ERP) associated with identification of a behaviorally relevant event. However, the ERP amplitudes were larger for the ITD changes associated with the figure compared those associated with an ITD change of the background. This illustrates that the manner in which spectro-temporal features combine to form auditory objects can modulate cortical responses to spatial information. The result supports the notion that spatial features integrate subsequent to object formation.
What would MacGyver do? Unconventional vibration testing for Mercy Sioux City helistop
Authors: Mooney Jon W.
Published: May 2016

A trip to Harbor Freight, a hardware store and some MacGyvering—these were essential to arriving at a vibration analysis for a hospital wanting to add a helistop to its roof. Normally not a challenging assignment, the analysis for this project was complicated by many factors, including: the existence of several functioning cath labs on the floor below the roof; unknown vibration and EMI sensitivity of the cath lab equipment; a limited budget— and only one week to prepare for the study. This presentation will explain in detail the goals and constraints of the project, and how three engineers—one an acoustician—developed relatively-simple-yet-ingenious, and low-cost, solutions.
Practical aspects of design, tuning, and application of dynamic vibration absorbers
Authors: Ryaboy Vyacheslav M.
Published: May 2016

Theory of dynamic vibration absorbers is a classic topic that has been thoroughly researched. Nevertheless, implementing the dynamic system in a structure and applying it properly still meet some challenges that have not been adequately addressed in the technical literature. Some of practical problems include achieving thermal stability, building a damped device with the desired undamped frequency, providing mechanisms for tuning or adjusting the dynamic absorber in situ, and effective tuning of multiple absorbers. The paper describes a new patented design of dynamic vibration absorber for optical tables together with the new method of tuning. The tuning procedure uses only one sensor and does not require access to the moving mass. Applications include suppressing flexural resonance vibrations of standard optical tables and the recent project on vibration control of large support bench for unique petawatt laser system at Lawrence Berkeley National Laboratory.
The problem of the noisy golf club
Authors: Kerrian Peter A. , Russell Daniel A.
Published: May 2016

Player perception of the quality of a hand-held sports implement is strongly influenced by the sound generated at impact with a ball. A recent innovative golf club driver design increased the moment-of-inertia of the club, making it more forgiving to hits off center and allowing players to hit balls with greater accuracy. However, this club has not been readily accepted because players hate the loud and annoying sound it makes when striking a golf ball. In this paper, we will discuss the acoustic and vibrational properties of this club as measured through experimental modal analysis, laser Doppler vibrometry, and acoustic field tests. Vibration and acoustic data correlate well and reveal that the annoying high amplitude components in the impact sound are due to vibrational modes in the sole of the club head, at frequencies below that of the “trampoline mode” of the club face. Implications resulting from this study will influence future golf club designs to make them sound more pleasing without altering performance.
Applications of speech intelligibility assessment
Authors: Payton Karen
Published: May 2016

There are many situations when it would be helpful to be able to predict how intelligible a talker will be to a specific listener in a specific environment. Metrics such as the Speech Intelligibility Index (SII) [e.g., Ricketts, Ear Hear. 17, 124–132 (1996)] and the Speech Transmission Index (STI) [e.g., Humes et al., J. Speech Hear. Res. 29, 447–462 (1986)] have been used for such purposes. This talk will review the history, philosophy, and effectiveness of these and other metrics in specific situations affecting the chain between talker and listener. Some of the situations include: hearing loss [e.g., HASPI: Kates and Arehart, Speech Commun. 65, 75–93 (2014)], degradations due to room acoustics [e.g., SRMR: Santos et al., Speech Commun. 15, 815–824 (2013)], and assistive communications technologies. The role of assumptions regarding speech in normal versus disorder populations will be briefly touched on.
Industry testing of voice quality output from mobile devices
Authors: Espy-Wilson Carol Y. , Zhou Xinhui , Akrouf Ali
Published: May 2016

In general, the commercial evaluation of speech for telecommunication is focused on what is called “speech quality” rather than intelligibility per se. This talk will discuss the current state-of-the-art in the context of the objective test model 3QUEST (3-fold Quality Evaluation of Speech in Telecommunications) developed by Head Acoustics. 3Quest is an objective evaluation of transmitted speech with background noise and we will discuss the new ETSI standard that it is based on. The particular improvement relative to previous objective methods (PESQ and POLQUA) is that influence of different background noises is taken into account and the calculation of three mean opinion score (MOS) values, one each for the speech-only regions of the signal (SMOS), the noise-only regions of the signal (NMOS), and the total signal (GMOS). These scores allow for a more meaningful statement regarding the causes for the impression of quality. Using examples, we will discuss how signal noise, intelligibility, and quality are interrelated as signals are affected by various parameters.
Lexical and nonlexical approaches to intelligibility in speech: An intermediate approach
Authors: Boyce Suzanne E.
Published: May 2016

Intelligibility is a continuum with a floor and a ceiling. In this session, we are concerned with different ways of defining and quantifying intelligibility for different acoustic applications. A major break point in the continuum is defined by lexical transcription. For most applications, such as evaluating clinical and non-native speaker populations, the focus is on whether a reasonably adept listener would come up with a correct transcription under ideal conditions. For other applications, as in telecommunications or clear speaking style, we consider the effects of less-than-ideal conditions, cognitive fatigue, or listener pleasure. In general, however, the quantification of intelligibility is either defined by listener estimates, listener transcription or by broad statistical trends. In this paper, we consider an intermediate method of measuring the likely intelligibility of speech using acoustic characteristics specific to syllable shape, but not tied to transcription. Examples from measuring speaker fatigue, clear speaking style, and disordered source characteristics will be provided.
Use of time reversal focusing to create a high amplitude focus of sound in air
Authors: Willardson Matthew L. , Clemens Miles , Anderson Brian E.
Published: May 2016

Time reversal is a technique that may be used to achieve intentional sound focusing. The purpose of this presentation is to explore how intense the focus of airborne sound energy can be using time reversal. Experiments utilize loudspeakers and a single microphone placed in a reverberation chamber. Various frequency ranges and loudspeaker orientations are explored along with different types of loudspeakers in order to experimentally determine the optimum conditions for generating the loudest focus possible. The overall purpose of this study is to create an acoustic focus at nonlinear sound pressure levels in order to create a controllable source of nonlinear acoustic sound.
Comparison of inverse techniques for reproducing an extended, partially coherent sound field above a reflecting plane
Authors: Leete Kevin M. , Neilsen Tracianne B. , Harker Blaine M. , Gee Kent L.
Published: May 2016

The relative abilities of two advanced array processing techniques to reconstruct a partially correlated noise source similar to a high-speed jet are compared. M-SONAH is a modification of statistically optimized near-field acoustical holography that includes multiple types of wavefunctions [A. T. Wall et al., J. Acoust. Soc. Am., 137, 963–975 (2015)]. The hybrid method may be described as an advanced cross-beamforming algorithm with regularization [T. Padois et al., AIAA Paper 2013-2212]. A numerical, multiple wavepacket-based source distribution provides a reasonable model of the frequency-dependent directivity and coherence properties of a jet noise sound. An image source was included to account for a reflecting ground plane and the numerically modeled sound field was used an input to both the M-SONAH and hybrid methods. For M-SONAH, the image source was handled using an additional set of cylindrical wavefunctions and for the hybrid method, sources were assumed to be located both above and below the reflecting plane. While both methods provide accurate reconstructions, for this test case, the hybrid method performs better at higher frequencies using a realistic measurement aperture and density. [Work sponsored by the USAFRL SBIR program.]
Time reverse imaging of tsunami waveforms
Authors: Hossen Jakir , Cummins Phil R. , Dettmer Jan
Published: May 2016

We consider the application of Time Reverse Imaging (TRI) to tsunami waveform data, in order to recover the initial sea surface displacement associated with the tsunami source. We use as a case study the tsunami triggered by the March 11, 2011, Tohoku-Oki earthquake, for which an unprecedented number of high-quality observations are available. The method represents the tsunami source by dividing the source region into a regular grid of “point” sources. For each of these, a tsunami Green’s function (GF) is computed using a basis function for sea surface displacement whose support is concentrated near the grid point. We apply the TRI method to estimate initial sea surface displacement at each source grid point by convolving GFs with time-reversed observed waveforms recorded near the source region. The result for initial sea surface displacement obtained via TRI agrees well with other models obtained using more traditional inversion methods. We show that the TRI method has potential for application in tsunami warning systems, as it is computationally efficient and can be used to estimate the initial source model using near-field data, and this TRI source model provides accurate and realistic predictions of far-field tsunami waveforms.
“Knocked Over!”: A visual demonstration of time reversal focusing using bending waves in a thin plate
Authors: Young Sarah M. , Heaton Christopher , Anderson Brian E.
Published: May 2016

The purpose of this research is to develop a visual demonstration of time reversal focusing in a thin plate to be used as a teaching tool. This presentation will discuss the various plate materials tested to provide the optimal conditions for time reversal focusing. Specifically, the reverberation time in each plate and the sensitivity of the source of vibrations are quantified to provide the best spatially confined focus as well as the highest focal amplitude possible. A vibration speaker and a scanning laser Doppler vibrometer (SLDV) are used to provide the time reversal focusing. A series of objects are placed on the plate in an attempt to knock over objects near the focal location and not elsewhere. Spatial mapping of the plate vibration using the SLDV will be shown to illustrate why some objects fall and others do not.
Application of time reversal mirror and minimum variance distortionless response technique for source localization
Authors: Too Gee-Pinn J. , Tzeng Yuling
Published: May 2016

Time difference of arrival (TDOA) and time reversal mirror (TRM) are commonly used in acoustic source localization. TDOA has excellent results in free field, but fair results in multiple reflections environment. TRM is applicable in multiple reflections environment and for multiple sources localization. The study continues the advantage of TRM and combines MVDR technique of noise reduction in order to find source locations. The results indicate that the combined MVDR technique gives better noise reduction than TRM in multiple reflections environment. From the drawing of energy diagram of acoustic waveguide, the combined MVDR technique will focus energy on signal source and it also reduces the noise energy in the other region. Comparing between TRM and the combined MVDR for source localization, the combined MVDR gives better resolution than TRM does. In addition to give better resolution, the combined MVDR will find the source location by finding the maximum energy location, on the other hand, TRM is unable to reduce reflection interference effectively which might lead to misjudge the source locations. However, the combined MVDR needs more computing time than TRM does.
Underwater acoustic communication in time-varying channel environment based on passive time reversal
Authors: Han Xiao , Yin Jingwei , Yu Ge , Zhang Xiao
Published: May 2016

Channels estimated from probe signal or training symbols will mismatch with the true channels in passive time reversal (TR) underwater acoustic (UWA) communication when the ocean environment is time-varying, leading to poor channel equalization performance. In order to solve this problem, this paper studies Block-based TR processing structure. The received data are divided into small blocks and the channel estimated from previously decoded symbols is used to match filter the current block to suppress the channel mismatch. Decision feedback equalizer (DFE) is also combined with Block-based TR to remove the residual inter symbol interference (ISI) and Doppler effect (Block-based TR-DFE). Mobile UWA communication experiment was conducted near Xiao Changshan island, Dalian in July, 2015. Though the received data are preprocessed by resampling, residual Doppler effect still exists due to ununiform motion between the receiver and transmitter, making the channel time-varying fastly. Block-based TR realized effective tracking and compensation for time-varying channels. The output signal-to-noise ratio (SNR) after equalization is greatly improved and the bit error rate (BER) is significantly reduced.
How reproducible are psychoacoustic listening tests on spatial impression in auditoria?
Authors: Witew Ingo B. , Vorlaender Michael , Pieczykolan Aleksandra
Published: May 2016

In three psychoacoustic experiments, it was shown that changes in frequency (pitch) and level (loudness) of stimuli lead to significant differences in the perception of apparent source width (ASW). Due to partially identical test conditions in two of the experiments, it is possible to analyze the collected data in regard to stability of ASW perception over repeated testing sessions and to study inter-individual differences. This analysis shows that intra-individual effects of stimulus loudness and pitch are consistent across participants, whereas the absolute level of ASW perception varies between individuals and between experimental sessions. Using this data, possible influences such as listener training effect over repetition of test sessions are discussed. The presented results provide insights into possible improvements of investigating ASW in future studies.
Perception of spatial impression changes due to source movement
Authors: Cho Sungbeen , Wang Lily
Published: May 2016

Few investigations have studied how spatial impression at a receiver position in a performing arts venue varies as a source moves across the stage. This paper reviews an evaluation method for spatial impression by studying the relative change in received sound energy due to source movement, using a proposed metric called the Interaural Level Difference Correlation Range (ILD-CR). Previous work by the authors indicated that this metric is able to quantify varying spatial impression changes as a source moves across a stage, better than standard spatial impression metrics. A subjective study is now being conducted to assess perception of different ILD-CR in assorted spaces. Can listeners perceive different ILD-CR, and consequently differentiate between spatial impressions linked to different performing arts venues as source position changes? Results from the preliminary study are presented.
Relating listener envelopment to specific time segments in early and late portions of sound fields
Authors: Dick David A. , Vigeant Michelle C.
Published: May 2016

Listener envelopment (LEV) in concert halls is a function of both the spatial and temporal properties of the room impulse response (IR). This study used measured spatial IRs that were modified to study which segments of the early and late parts of the IRs contribute the most to the perception of LEV. Measurements were obtained in the Peter Kiewit Concert Hall in Omaha, NE, using an Eigenmike 32-element spherical microphone array, and processed for third-order Ambisonic reproduction over a 30-loudspeaker array. A subset of the IRs were identified with either an exceptionally high or low amount of LEV. These IRs were modified such that some time segments of the IRs were reproduced in full 3D (e.g., the early energy), while other segments were played only through a single loudspeaker in front of the listener (e.g., the late energy). Additional stimuli were generated that contain time portions of both the highly enveloping IRs and the unenveloping IRs. A subjective listening test was conducted in which listeners rated the LEV of the modified IRs convolved with anechoic music. Results will be presented that compare the LEV ratings to objective measurements of the sound fields. [Work supported by NSF Grant 1302741.]
Using individually equalized playback of binaural recordings from an electronic orchestra to determine the effects of early reflections on proximity, localization, and loudness
Authors: Griesinger David H.
Published: May 2016

Reflections in the first 50 ms are often assumed to enhance sound quality, but data supporting the assumption are lacking. We need to know when reflections are beneficial, and when they are not. Work by Lokki et al. may help to answer this question, but we have developed a binaural recording and playback technique that yields as good or better results. The key is individual equalization from the microphone to the eardrum of a listener. We have developed a quick and non-invasive method of headphone equalization that produces accurate timbre and frontal localization without head-tracking. This enables binaural impulse responses from a number of instrument positions in real halls to be manipulated by adding or deleting individual reflections and then evaluated with blind listening tests. Data from Boston Symphony show that early lateral reflections in the front of the hall are typically inaudible, but early medial and lateral reflections in the rear of the hall can reduce or eliminate proximity, clarity, impact, envelopment, and the ability to localize individual instruments. Deleting one or two of the earliest and strongest reflections improves all of those perceptions with no effect on loudness.
Noise, national parks, and the wildlife therein
Authors: Fristrup Kurt M. , McKenna Megan F. , Buxton Rachel
Published: May 2016

Monitoring at more than 600 sites in National Park Service (NPS) units has shown that noise poses widespread concerns: a contaminant to the physical environment, an infringement on superlative visitor experience, and a sensory burden for wildlife. NPS acoustical data were generalized into maps predicting sound levels for the coterminous U.S. These maps document the spatial scope and intensity of noise burdens on wildlife for park and other protected areas in the U.S. Although NPS units and other protected areas generally have sound levels a few decibels lower than adjacent unprotected land, 15% of all protected areas have sound levels 10 dB higher than predicted natural levels (median A-weighted levels). Designated critical habitat for 20 threatened animal species (US Fish and Wildlife Service) also exceed this 10 dB noise exposure criterion. Wildlife responses to noise have been documented in a wide range of taxa and habitats, with the past six years witnessing rapid growth in this research. Notably, controlled playback studies have been performed in otherwise pristine habitats to demonstrate that noise alone affects habitat utilization, foraging effectiveness, and breeding success. Noise may still present underestimated threats to wildlife; it certainly presents underutilized opportunities for habitat restoration.
Recent advances in scientific understanding of the effects of sound from seismic surveys
Authors: Gisiner Robert , Miksis-Olds Jennifer , Tsoflias Sarah L.
Published: May 2016

The E&P Sound & Marine Life Joint Industry Programme (SML JIP), a partnership of 13 oil and gas companies and associations, funds independent scientific research to increase understanding of the potential effects of E&P sound on marine life. To advance understanding of the interaction between sound from oil and gas operations and marine life, the JIP identifies and commissions research to: (1) support planning of E&P projects and risk assessments, (2) provide the basis for appropriate operational measures that are protective of marine life, and (3) inform policy and regulatory development. SML JIP research categories include sound source characterization and propagation, physical and physiological effects and hearing, behavioral impacts and biological significant effects, and technologies for monitoring and mitigation. Highlights of projects to better characterize the source properties of seismic air sources, understand the hearing of Arctic pinnipeds, assess hearing recovery in marine mammals exposed to impulse sounds, and advance monitoring and mitigation technologies such as passive acoustic monitoring and alternative sound sources will be presented.
Ultrasound-mediated drug targeting to tumors: Revision of paradigms through intravital imaging
Authors: Rapoport Natalya
Published: May 2016

In collaboration with Dr. Brian O’Neill (Houston Methodist Research Institute), the intravital fluorescence microscopy was performed using a customized Nikon A1R system to monitor the effect of ultrasound on the extravasation and tissue diffusion of various potential drug carriers including individual polymeric molecules, polymeric micelles, phase-shift nanoemulsions, and nanoemulsion-encapsulated drug. Carrier and drug extravasation and tissue accumulation was compared for the normal and tumor tissue upon intravenous injections to pancreatic tumor bearing mice. This approach allowed for the first time discriminating vascular and tissue compartments in the processes of the ultrasound-mediated drug delivery. Nanoemulsion accumulation in the tumor tissue was much faster than in the normal tissue. Without ultrasound, extravasation coefficient was threefold lower while tissue accumulation rate was two orders of magnitude lower for perfluorocarbon nanodroplets than for polymeric micelles. However, ultrasound application induced a 4.7-fold local enhancement of nanodroplet extravasation (to be compared with a 1.5-fold enhancement for micelles) and resulted in higher nanodroplet concentration and more uniform distribution in the tumor tissue. A kinetic model was suggested that allowed discriminating between various kinetic regimes of nanocarrier internalization in tumors of various sizes, cell density, and rigidity.
Ultrasound-mediated transport of nanoparticles and the influence of particle density
Authors: Lea-Banks Harriet , Stride Eleanor , Coussios Constantin C.
Published: May 2016

A significant barrier to successful drug delivery in cancer therapy is the limited penetration of nanoscale therapeutics deep into tumors. Ultrasound mediated cavitation has been shown to promote nanoparticle transport, but achieving tumor wide distribution still represents a considerable challenge. The current study investigates the way in which nanoparticle drug-carriers may be designed to enhance penetration under ultrasound exposure. A computational model has been developed to predict the transport of a nanoparticle in an ultrasonic field in the presence of an oscillating microbubble, by a combination of primary and secondary acoustic radiation forces, acoustic streaming, and microstreaming. Experimental investigations were also performed in a tissue-mimicking phantom to study the transport of different types of particle, in the presence or absence of a microbubble ultrasound contrast agent, at ultrasound frequencies of 0.5 MHz and 1.6 MHz with peak pressures in the range of 0–2.0 MPa. Micro- and nanoparticles with contrasting density cores ranging from 1.0 g/cm3 to 19.3 g/cm3 were used for the study. Both the theoretical and experimental results showed that the denser particles exhibit significantly greater ultrasound-mediated transport than their lower density counterparts, indicating that this is a key consideration in the design of nanoscale therapeutics.
Accuracy requirements for unmanned aerial vehicle-based acoustic atmospheric tomography
Authors: Finn Anthony , Rogers Kevin
Published: May 2016

If the acoustic signature is measured onboard a propeller-driven unmanned aerial vehicle and by an array of microphones on the ground, comparison between the projected and observed signals allows the propagation delays—and hence effective sound speed values of the intervening medium—to be determined. As the ray paths along which energy travels intersect within the atmosphere at multiple locations and angles, temperature and wind velocity fields may be estimated using tomography. This paper describes signal processing strategies for determining propagation delays at sub-millisecond levels of precision; the inverse problem and a model that allows meteorological observations to be incorporated into the tomographic solution; and the algebraic iterative reconstruction technique used to overcome the ill-posed nature of the inversion. A weakly sheared daytime convective atmospheric boundary layer—synthesised through use of large eddy simulation code that utilises pseudo-spectral differencing and solves an elliptic pressure equation—is used to show sub-millisecond levels of observation noise permits faithful reconstruction of target atmospheres. Particular attention is paid to the atmospheric layer below 100 m as this region typically experiences the greatest spatio-temporal variation in temperature and wind speed.
Pulse scattering in a turbulent atmosphere with applications to acoustic remote sensing of the atmosphere with sodars
Authors: Ostashev Vladimir E. , Bradley Stuart , Wilson D. K.
Published: May 2016

A new, rigorous theory of acoustic pulse scattering in a turbulent atmosphere with spatial-temporal fluctuations in temperature and wind velocity is developed. The theory generalizes the classical theory of sound scattering to broadband signals and coupled spatial-temporal fluctuations of random fields. The scattered sound field is obtained as a Born approximation of a set of equations for the sound pressure and acoustic particle velocity. The spatial-temporal correlation function of the scattered field is calculated. These results are obtained without using the quasi-static approximation, which is employed in the classical theory, and enable analysis of this approximation. The spatial, temporal, and frequency coherences of the scattered signal are studied. The results obtained are applied to acoustic remote sensing of the atmosphere with sodars. It is proposed that the frequency spectrum of the temporal correlation function could be used to measure the wind velocity and the variance of the convective velocity fluctuations. An ad hoc approach for increasing the spatial resolution in acoustic sounding of the atmosphere is suggested. The theory developed is rather general and applicable to acoustic pulse scattering in other media such as the ocean with temperature, salinity, and current velocity fluctuations.
Results from the Humming Roadrunner ground truth experiment
Authors: Waxler Roger M. , Talmadge Carrick , Green David , LaLande Jean-Marie , Velea Doru
Published: May 2016

In August 2012, a ground truth infrasound experiment was performed in the American Southwest. Six large chemical explosions were detonated at the White Sands Missile Range in New Mexico. In TNT equivalents, there were two 10 ton charges, two 20 ton charges, and two 50 ton charges. In addition to an extensive near-field deployment to capture source waveforms, a large network of infrasound sensor arrays was deployed at ranges from about 50 km to about 500 km and along a variety of azimuths. Results from the experiment will be discussed.
Development of an anechoic wind tunnel
Authors: Mayoral Salvador , Khader Syed Zeeshan
Published: May 2016

The development of an anechoic wind tunnel is presented. The test section walls of a low-speed open-circuit wind tunnel have been acoustically treated in order to simulate an acoustically free field environment with forward flight. The dimensions of the test section are 0.86 m wide by 0.56 m tall and 1.32 m long. The four walls of the test section are lined with pretensioned Kevlar panels that permit the transmission of sound with less than 2 dB of attenuation. The top and bottom walls of the test section sandwich 4-in. thick acoustic foam between the pretensioned Kevlar and a wooden frame. The side walls of the test section consists of pretensioned Kevlar screens that separate the test section flow from adjacent anechoic chambers. In this fashion, the acoustic measuring equipment is not subjected to the flow inside the test section. Noise sources are modeled with a small loudspeaker that is connected to a signal generator and acoustic measurements are taken with quarter-inch condenser microphones. Preliminary results indicate that the test section is anechoic for frequencies greater than 1 kHz. This work ultimately aims to experimentally investigate the interaction between aeroacoustic noise sources and a momentum wake.
Monte-Carlo analysis of two logical premises to avoid the Probit algorithm for determination of sensory threshold by psychophysics
Authors: Biswas Amitava
Published: May 2016

An often confusing and usually avoided, Probit algorithm, is traditionally needed to iteratively calculate an optimal regression line for stimulus strength versus detection rate for psychophysical data that actually appears non-monotonous but supposed to be monotonous. Two logical premises are presented that enable monotonicity even with non-monotonous observed rates: (1) If a trial stimulus is above the threshold then a set of higher stimuli are detectable. (2) If a trial stimulus is below the threshold then a set of lower stimuli are undetectable. The time series in Fig1 has 15 trials of a conventional audiometric threshold tracking session, with 10 dB down for detecting and 5 dB up for missing a stimulus. Following from the two premises, the set of additional points are the predicted responses. Monte-Carlo simulation demonstrated that this strategy not only finds a monotonic relation between detection rate versus stimulus intensity, but also significantly improves accuracy of estimation of the 50% threshold level. In conclusion, two logical premises can help to obtain uniform monotonicity of the sigmoid shaped psychometric regression curve, even without using conventional probit iterations, leading to faster and simplified estimation of the 50% threshold point with greater accuracy. Further research is needed to evaluate clinical impact of this concept for improving current procedures of threshold estimation without increasing the number of actual observations for various psychophysical assessment of sensory thresholds.
Design optimization of a stiffened flexible panel under turbulent boundary layer excitation
Authors: Wu Kuangcheng , Stowe Nicholas , Brown Eric
Published: May 2016

The vibration and noise generated from turbulent boundary layer (TBL) flow are main design considerations in the Automotive, Aerospace, Shipbuilding industries, as well as many others. Simulation has been widely applied to help reduce TBL-induced vibration and noise; however, a fully coupled CFD + FEA analysis is still a computational challenge for high-fidelity models. On the other hand, when the block pressure assumption is applicable, a general approach applies the fluctuating pressure underneath the TBL as excitation to the structure to predict its vibratory response and noise. This paper first uses the general approach to predict the vibration and noise of a stiffened flat panel subjected to TBL excitation. The various methods, both empirical and numerical, that are used to estimate the TBL wall spectrum are outlined. Structural transfer functions from Energy Finite Element Analysis (N. Vlahopoulos, K. Wu, MAST Americas 2010) are calculated for the panel. The calculated TBL excitation (M. Goody, AIAA, 2004) and structural transfer functions are combined to predict the flow-induced vibration and noise. In addition, optimization algorithms are applied to evaluate the impacts of several parameters (i.e., varied plating thickness and local damping) and determine the best design of the panel within the set of parameters.