bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic ranging and waveguide invariant parameter estimation using virtual arrays.
Authors: Turgut Altan
Published: October 2013

A method for estimating the range of an unknown broadband acoustic source in a waveguide [Thode et al., J. Acoust. Soc. Am. 108(4), 1582–1594 (2000)] is revisited and extended to estimate both waveguide invariant parameter “beta” and source range in shallow water. In the new method, two or more vertical arrays are used without requiring a signal sample from a guide-source. It was shown that both methods are mathematically identical and they both provide robust range estimation even when the reference signal sample is used from different time and/or different vertical array location. It was also demonstrated that an image processing tool, Hough Transform method, provides robust parameter estimation from virtual array output data. In addition, the parameter estimation method was validated under both summer and winter conditions by using incoherent noise data to localize and track merchant vessels and to estimate waveguide invariant parameter. [Work supported by the Office of Naval Research.]
Perceptions and expectations of speech privacy in healthcare environments.
Authors: Good Kenneth , Rineer Nikki
Published: October 2013

Most methods for evaluating speech privacy were developed for offices and corporate environments and from the point of view of productivity and distraction impacts on the listeners. How do these methods translate to healthcare and other environments where confidential containment of information is required by law? This case study will look at the objective measurements of speech privacy along with patient subjective impressions and expectations surveyed.
Safe and sound? Sleep disruption in healthcare facilities.
Authors: Solet Joanne , Buxton Orfeu , Carballeira Andy , Ellenbogen Jeffrey
Published: October 2013

National healthcare quality surveys have found that noise in hospitals is an urgent concern, showing negative impact on patient satisfaction. The purpose of this study was to develop sleep arousal probability threshold curves to specific hospital-based sounds, demonstrating their impact on all stages of human sleep. Recordings were captured of hospital sound sources corresponding to specific categories identified as salient in the American Institute of Architects' Draft Interim Guideline on Sound and Vibration in Healthcare Facilities. Fourteen sounds were calibrated for dynamic presentation through a speaker array at the sleep lab to deliver rising 5 decibel-step exposures from 40 to 70dB(A). Noise-related EEG arousals were quantified using current AASM criteria and summed for each sleep stage by sound type and decibel level to calculate arousal probability threshold curves. The tested stimuli evoked a range of arousal thresholds. At the 50% arousal probability level, stimuli spanned 15 dB(A) Leq in Stage 2 sleep, 17 dB(A) Leq in REM sleep, and 30 dB(A)Leq in Stage 3, the deepest sleep. The findings provide evidence that repeated arousals in all sleep stages occur even in healthy young adults when hospital sounds exceed 45dB(A); responses vary widely by stimulus types.
Using indoor room criteria when the “room” is outside.
Authors: Harrison Byron W.
Published: October 2013

Indoor noise criteria have applicability in the analysis of outdoor performance spaces. The presentation will provide an overview of the environmental noise issues at the Jay Pritzker Pavilion in Chicago, IL. The project design was largely influenced by noise concerns, in its physical form, audio design strategy, and building systems design. During the postconstruction tuning of the audio system a number of parameters were adjusted to contend with the unusually low signal-to-noise ratio, including the overall loudness of amplified music, audio signal compression, the content and level of the acoustic enhancement system, and the approach to the active in-house mix of the audio system. An investigation was also undertaken to investigate the continuous and impulsive noise levels and frequency content at various times of day as compared with traditional environmental noise criteria and indoor room criteria. Subsequent studies regarding the impact of nearby construction noise on rehearsals and performances were influenced by the use of indoor noise criteria methods.
The room noise criteria (RNC) metric.
Authors: Schomer Paul
Published: October 2013

The recent ANSI S12.2:2008 room noise criteria contains both a survey and an engineering method to specify room noise criteria. The methods use A-weighting and extended NC, respectively. A new metric, titled like the standard, room noise criteria (RNC) is included as a diagnostic tool. It is based on human hearing and more correctly assesses low-frequency sound. In particular, it is sensitive to the standard deviation to random noise and/or low-frequency surging in the 16–125 Hz octave bands such as the sound that can be produced by HVAC systems or other devices. It provides a bridge between the NC and RC criteria by correctly predicting the need for the less stringent (at low frequencies) NC criteria when the HVAC system is well designed (no surging, moderate standard deviation) and also correctly predicting the more stringent (at low frequencies) RC criteria when the HVAC system noise has a large standard deviation and/or surging.
Equine vocalizations: The start of a search for happiness.
Authors: Browning David A. , Scheifele Peter M. , Pond Rebecca L.
Published: October 2013

As with all perissodactyls, the vocalizations of equines, specifically a horse’s whinny, has a variable frequency (or melodic) component as well as just simple tonals. This appears to provide a primitive means of expression, simpler than any song or language but potentially more informative than the purely tonal moos or baahs of cattle or sheep (but a long way from the complexity of some birdsong). Sonograms are compared from in-barn whinnies recorded under apparently stressful (departure of a foal) and pleasant (arrival of the morning feed wagon) circumstances, with the same horse and various horses, to determine if distinctive patterns can be identified. We also compare these with greeting whinnies and departure whinnies. The ultimate goal is to be able to acoustically identify an expression of happiness.
A vocal repertoire of Asian elephants (Elephas maximus) and comparison of call classification methods.
Authors: Glaeser Sharon S. , Klinck Holger , Mellinger David K. , Ren Yao , Clemins Patrick J. , Johnson Michael T. , Cook Mandy L. H. , Zelick Randy
Published: October 2013

This study compares classification methods applied to an acoustic repertoire of the Asian elephant (Elephas maximus). Recordings were made of captive elephants at the Oregon Zoo in Portland, OR and of domesticated elephants in Thailand. Acoustic and behavioral data were collected in a variety of social contexts and environmental noise conditions. Calls were classified using three methods. First, calls were classified manually using perceptual aural cues plus visual inspection of spectrograms for differentiation of fundamental frequency contour, tonality, and duration. Second, a set of 29 acoustic features was measured for nonoverlapping calls using the MATLAB-based program Osprey, then principal component analysis was applied to reduce the feature set. A neural network was used for classification. Finally, hidden Markov models, commonly used for pattern recognition, were utilized to recognize call types using perceptually-weighted cepstral features as input. All manual and automated classification methods agreed on structural distinction of six basic call types (trumpets, squeaks, squeals, roars, rumbles, and barks), with two call types (squeaks and squeals) being highly variable. Given the consistency of results among the classification methods across geographically and socially disparate subject groups, we believe automated call detection could successfully be applied to acoustic monitoring of Asian elephants.
Recent insights on the mechanisms of frequency discrimination in cicadas (Hemiptera, Cicadoidea).
Authors: Fonseca Paulo J. , Michelsen Axel
Published: October 2013

Mate finding in cicadas is usually mediated by acoustic communication. Males produce a loud acoustic signal that is used to guide females toward singing males. The calling songs are frequently complex with changes in rhythm, amplitude modulation and, in many species, frequency modulation. Therefore, it is likely that the auditory organ encode some of those characteristics and that the nervous system may process the information and extract some species-specific parameters. The tympanic vibrations are transferred to the onion-shaped auditory organ, localized at some distance from the tympanum within the auditory capsule, through a stiff schlerotized apodeme. This configuration has raised problems to the understanding of how the different frequencies of the song, that Fonseca et al. (2000) have shown to be finely encoded at the level of the auditory interneurons in the cicada Tettigetta josei, are passed on to the auditory organ by the structures of the receptor. Using biophysical, electrophysiological, and anatomical measurements from the receptor structures of the cicada Tettigetta josei, a functional model that may allow for the above-mentioned frequency discrimination will be presented [Fonseca, P.J., Münch, D., and Hennig, R.M., “How cicadas interpret acoustic signals,” Nature 405,297–298 (2000)].
Bayesian model-based technique for termites detection.
Authors: Mehmood Asif , Tahaineh Orwa , Seiner John
Published: October 2013

This paper presents a model-based approach to detect termites from their head banging acoustic signals, and is derived from Bayesian probability theory. The termite head banging is the loudest and most diagnostic sound that termites make, and can be utilized for termite detection. The laser Doppler vibrometry system is used to obtain the termite head-banging signals from infested wood. An algorithm based on Bayesian probability theory is developed to detect termites’ presence. The atomic model that represents the termites’ data is the sum of decaying sinusoidal signals. First the model selection is performed that tells us about the number of vibration frequency components present in the data under observation. Once the correct model is known, then the vibration frequency that corresponds to termites’ head banging frequency is determined. The calculations are performed using the Markov chain Monte Carlo method. Monte Carlo integration is then used to approximate the marginal posterior probabilities for all the parameters, including the number of exponentials and whether a constant offset is present. The performance of this algorithm is evaluated by testing it on experimental data, and the results obtained reveal the excellent performance of the algorithm.
A new high frequency microultrasound system with applications in cardiovascular research.
Authors: Foster F. Stuart
Published: October 2013

The development of preclinical imaging using micro-MR, CT, PET, SPECT, optical, and ultrasound technologies has created a new paradigm for imaging in the laboratories of biomedical researchers. Once considered a luxury for isolated multiuser centers, microimaging platforms are now becoming mainstream in bioresearch where quantitative in vivo imaging measurements of biomarkers and other endpoints are becoming a requirement of these investigations. Microultrasound has come a long way from its inception in the mid-1990s. This paper will detail the progression of preclinical microultrasound from mechanical to array based imaging systems. The technology of high frequency array based ultrasound imaging will be reviewed including details on the transducers and beamformer used in the first commercially available system. Applications of this system in the areas of cancer and cardiovascular disease will be described. The development of high frequency microbubble contrast modes based on linear and nonlinear signal processing will be discussed with relevant examples including imaging of VEGFR-2 and CD31 expression in disease models. All experiments with animals were done under a protocol approved by the Sunnybrook or VisualSonics Animal Care Committees. [The author declares a significant financial interest in VisualSonics Inc.]
Identifying and controlling acoustic bioeffects.
Authors: Schlicher Robyn K. , Hutcheson Joshua D. , Hallow Daniel M. , Prausnitz Mark R.
Published: October 2013

Ultrasound exposure causes internalization of a wide variety of molecules in cells and tissues, especially in the presence of acoustic cavitation. However, high levels of uptake are often accompanied by cell death. This study first analyzed intracellular uptake and cell viability after exposure of porcine carotid arteries to ultrasound ex vivo by confocal microscopy and found that at moderate ultrasound pressure, there was extensive uptake by endothelial cells with little uptake by underlying smooth muscle cells, whereas at high ultrasound pressure there was extensive endothelial cell death and increase uptake by smooth muscle cells. To understand the mechanisms involved in cell uptake and death, sonicated DU145 cells were analyzed by high level microscopy, flow cytometry, and chemical analyses. This work showed that uptake was caused by transient wounds created in the cell membrane that resealed within minutes after sonication. It also identified and quantified seven different cellular responses to this wounding, including cell repair modes and four different death modes. To save cells from apoptotic death, which was found to be mediated by calcium, cells were exposed to a calcium chelator, which rescued approximately half of the apoptotic cells from death.
Diagnostic ultrasound combined with targeted microbubbles improves recovery following acute coronary thrombosis.
Authors: Unger Evan , Matsunaga Terry , Xie Feng , Porter Thomas
Published: October 2013

Forty-five pigs with acute coronary artery occlusions—low MI pulse sequence (CPS) to guide high MI (1.9 MI) pulses during infusion of platelet-targeted MBs or non-targeted MBs. Third group received no ultrasound/MB. All groups received pro-urokinase, heparin, and aspirin. Angiographic recanalization rates, resolution of ST elevation, and wall thickening were analyzed. Pigs receiving MB had more rapid replenishment of risk area (RA) (80% versus 40% for MB; p=0.03) and higher epicardial recanalization rates (53% versus 7% for pro-urokinase alone; p=0.01). Replenishment of contrast within RA with MB showed higher recanalization rates and higher rates of ST resolution (82% versus 21% for pro-urokinase alone; p=0.006). ST resolution occurred in six pigs (40%) with MB who did not have epicardial recanalization; five had recovery of wall thickening. Conclusions: IV MB with brief high MI DUS guided by CPS improves both epicardial recanalization rates and microvascular recovery.
Acoustic characterization of echogenic liposomes: Attenuation and quantitative backscatter.
Authors: Kopechek Jonathan A. , Porter Tyrone M. , Coussios Constantin-C. , Perrin Stephen R. , Huang Shaoling , McPherson David D. , Holland Christy K.
Published: October 2013

Echogenic liposomes (ELIPs) are being developed for use as ultrasonic contrast agents and as drug carriers for ultrasound-targeted drug delivery. Physical and acoustical characterization of ELIPs is necessary in order to determine the optimum parameters for diagnostic and therapeutic applications. In this study, ELIP samples at concentrations of 10, 20, and 50 μg/ml were exposed to ultrasound in pulse-echo mode at center frequencies of 2.25, 3.5, 7.5, 10, 15, and 30 MHz. The received echoes were analyzed to determine the attenuation and backscatter coefficients and the results were compared to a theoretical computational model. The sample chamber contained two 50-μm tungsten wires as reference scatterers. The echoes from the wires were acquired before and after addition of ELIP to determine the attenuation coefficient. The backscatter coefficient was determined by averaging the square of the RF amplitude between the wires and accounting for transducer parameters. Each transducer was calibrated and characterized in deionized water using PVDF hydrophones. The peak attenuation coefficient occurred at 7.5 MHz while the backscatter coefficient increased with frequency. This was in agreement with the computational model. These results provide important information for determining the optimum acoustical parameters for ELIP exposure in diagnostic and therapeutic applications. [Work supported by NIH 2RO1 HL059586-04A2 and ASA Hunt Postdoctoral Research Fellowship.]
Modelling of oscillations of a microbubble in an elastic vessel.
Authors: Martynov Sergey , Stride Eleanor , Saffari Nader
Published: October 2013

Encapsulated microbubbles have been extensively investigated as contrast agents for diagnostic ultrasound imaging and more recently for therapeutic applications such as drug delivery. However, theoretical models for microbubble dynamics exist either for encapsulated bubbles in an infinite volume of liquid, or for unencapsulated bubbles in a confined volume. In the present study, a finite-element method is applied to quantify the effects of both encapsulation and confinement in a blood vessel upon a microbubble’s response to ultrasound. The effect of encapsulation is examined for polymeric and surfactant coatings. Elastic deformations of the vessel wall are described using a lumped-parameter model, treating the wall as a thin membrane. It will be shown that even at low acoustic pressures (10 kPa), the bubble oscillations can be significantly modified as a result of confinement. In particular, the frequency spectrum of the oscillations of a confined bubble is characterized by two modes. For relatively soft vessels, a high-frequency mode dominates, with the eigenfrequency increasing with the vessel stiffness. The eigenfrequency of the low-frequency mode decreases with the vessel length. The results will be discussed in the context of diagnostic and therapeutic applications.
Soundscaping the aesthetic—Beyond measurement and assessment.
Authors: Case Alexander U.
Published: October 2013

Soundscape in the context of community noise alone risks missing the important subjective reactions people have to the aesthetic value of any sound environment. The music recording and film sound industries have been recording sounds for art and entertainment, without regard for objective assessment, for more than a hundred years. Soundscape design has the opportunity to borrow from the time-tested recording, signal processing, and playback techniques developed by recording engineers where appropriate, learning from their search for emotional, intellectual, and uniquely human reactions. An introduction to nonobjective recording techniques is presented, with emphasis on some of the more counter-intuitive parts of the recording craft.
Overview of on-going Federal Aviation Administration and National Park Service collaborative research efforts in support of the National Parks Air Tour Management Act.
Authors: Lee Cynthia
Published: October 2013

In support of the National Parks Air Tour Management Act of 2000 (NPATMA), the FAA and NPS are developing air tour management plans (ATMPs) for approximately 100 national parks. ATMP objectives are to develop acceptable and effective measures to mitigate or prevent significant adverse impacts, if any, of commercial air tour operations upon the natural and cultural resources of and visitor experiences in national parks and abutting tribal lands. In accordance with NPATMA, any methodology adopted by a federal agency to assess air tour noise under this Act shall be based on reasonable scientific methods. Both agencies acknowledge that additional research is needed. This paper presents an overview of Volpe Center contributions to the collaborative effort by the FAA and NPS to develop improved methods to (1) quantify park soundscapes (natural and non-natural); (2) enhance computer modeling capabilities through aircraft source noise database expansion and advanced research into the factors which affect aviation noise propagation for complicated environments, such as national parks; and (3) assess the effects of aircraft overflights on park visitor experience, including the metrics used in these assessments. Improved methods developed in these efforts will also be used to support other agency projects related to aviation noise.
Visitor perception of park soundscapes: An approach and research plan.
Authors: Schomer Paul , Stanley G. Randy
Published: October 2013

In the United States, much of the research on the soundscape in national parks and wilderness areas has centered on so-called dose-response relations with the aim of stating: How much manmade noise is unacceptable? Based on their experience in urban areas, this approach has been advocated primarily by the aviation noise community. But there is another school of thought. Visitors to national parks are guests and patrons of what the park has to offer. Just as juries of listeners are used to judge the sound quality of automobiles and home-appliances, juries of listeners could also be used to judge the sound quality in national parks. The current plan is to develop outdoor sound quality measurement and prediction methods and standards by which the U.S. National Park Service can accomplish their assessments of the acoustic ambient. This paper discusses the plan for this measurement protocol development and indicates some standards to be developed.
Sonar material acoustic property measurements using a parametric array.
Authors: Humphrey Victor F. , Robinson Stephen P. , Beamiss Graham A. , Hayman Gary , Smith John D. , Martin Michael J. , Carroll Nicholas L.
Published: October 2013

The use of a parametric array as an acoustic source for measuring the acoustic properties of materials for use in sonar systems is considered. Techniques of measuring the wideband transmission and reflection properties of limited size test panels are described and the advantages of using a parametric array in terms of reducing edge diffraction errors are discussed. Results for a range of materials under ambient pressure over the range 10–200 kHz are presented to illustrate the potential of the technique. The implementation of the approach in a pressure vessel at the UK National Physical Laboratory is also described and illustrated with example results obtained over the frequency range 2–50 kHz for two test objects that have predictable behavior. The potential of the technique is also illustrated with experimental results for viscoelastic test panels for hydrostatic pressures up to 2.8 MPa.
Parametric array application for long range ocean sounding.
Authors: Naugolnykh Konstantin , Esipov Igor
Published: October 2013

The parametric array (PA) is a nonlinear transducer that generates narrow, sidelobe-free beams of low frequency sound, through the interaction of high frequency pump waves. PA was suggested by Peter J. Westervelt, winner of the Lord Rayleigh Medal, at the same time this devise invention was underway in the Soviet Union made by Zverev and Kalachev. Remarks of PA applications for long distance ocean sounding is presented in the present paper. Experimental test of a high-frequency PA was made on the Black Sea coast by Esipov et al., and investigations of powerful PA characteristics was performed in a ocean by Andebura et al., in 1990. Then large-scale ocean vortices sensing at a distance of 1000 km was realized by Esipov et al. [Acoust. Zh., 40(1), 71–75 (1994)]. In both experiments, the transducer of R/V “Boris Konstantinov” was used with parameters: pump wave power W=20 kW, pump wave frequency f=3 kHz, parametric signal frequency F=230–700 Hz. Obtained results indicate the efficiency of PA application for long distance ocean sounding. [Work supported by ISTC project 3770 and NATO Grant No. ESP.NR.NRCLG 982524.]
Observing Atlantic herring by parametric sonar.
Authors: Godø Olav Rune , Foote Kenneth G. , Dybedal Johnny , Tenningen Eirik
Published: October 2013

Atlantic herring (Clupea harengus) has been observed in situ by the Kongsberg TOPAS PS18 parametric sub-bottom profiling sonar, with nearly horizontal transmit and receive transducer arrays mounted flush on the hull of R/V G. O. Sars, at N71.4 E16.3. The primary frequencies are in the band 15–21 kHz, with nonlinearly generated difference frequencies in the band 0.5–6 kHz. The beamwidths are 6–10 deg depending on frequency and range, but with exceedingly low sidelobes. The observation of herring in schools and layers was accomplished with the vessel both at rest and sailing at its ordinary survey speed of 10 knots. The observations with the parametric sonar were confirmed by concurrent, synchronized observations with the Simrad EK60/38-kHz scientific echo sounder and by trawling with a pelagic net. The herring length varied from 28.0–36.5 cm. Present work suggests that parametric sonar will become a powerful new tool in marine ecosystem studies, enabling the numerical density of schooling and shoaling fish to be determined, and the size of swimbladder-bearing fish to be estimated by detection of swimbladder resonance. [Work partly supported by Norwegian Research Council Grant no. 184705.]
Resonant mode conversion in superfluid 4 helium and in solids.
Authors: Garrett Steven L.
Published: October 2013

One component of the success of the Westervelt analysis of the parametric array was that sound propagation in most gases and liquids exhibit very little dispersion. Therefore, the pump waves and their nonlinearly generated product propagate at very nearly the same speed. When an acoustic medium can support more than one sound mode with different propagation speeds, then a parametric array can be created by the nonlinear interaction of the two slower sound waves to produce the faster wave, if the slow wave propagation directions are not collinear. Bulk superfluid helium, at temperatures below 2.1 K, will support a slower (thermal) sound mode and a faster (mechanical) sound mode. An experiment performed in 1977 will be described that used a waveguide to create thermal (temperature-entropy) sound waves while controlling their angle of intersection. A mechanical (pressure-density) wave was produced and its amplitude determined the thermodynamic coupling constant between density changes and the Galilean invariant square difference in the normal and superfluid particle velocities that characterize the thermal sound wave amplitude. An earlier experiment will also be described that demonstrated the nonlinear conversion of two shear waves to a longitudinal wave in aluminum. [Work supported by the Office of Naval Research.]
Quantum acoustics, the second law and the end fire array.
Authors: Putterman Seth , Roberts Paul H.
Published: October 2013

The fundamental nonlinear interaction which leads to the scattering of waves and to the end fire array yields a Boltzmann equation for sound, a one fluid theory of superfluid helium [S. Putterman, P. H. Roberts, Physics Letters, 89A, 444 (1982)] and a route to the quantum theory of interacting phonons [M. Cabot, S. Putterman, Phys. Lett. 83A, 91 (1981)]. Along with a review of these consequences of nonlinear classical acoustics the conundrum of the consistency of the second law of thermodynamics with the Hamiltonian nature of the end fire array will be exposed but not resolved [S. Putterman, P. H. Roberts, Phys. Rep., 168, #4 (1988)].
Effect of stimulus onset delay on auditory cortex neural responses to voice pitch feedback perturbation.
Authors: Behroozmand Roozbeh , Larson Charles R.
Published: October 2013

It has previously been shown that the auditory neural responses to voice F0 feedback perturbation are suppressed during active vocalization compared to passive listening to the playback. However, a study in primates showed that the vocalization-induced suppression enhances auditory sensitivity to feedback perturbation. This evidence suggests that the cortical neural responses to self-vocalization reflect suppression to vocal onset and excitation in response to perturbations in voice pitch feedback. In this study, we investigated the effect of stimulus onset delay on cortical neural responses to voice F0 feedback perturbation. Event-related potentials (ERPs) were recorded in human subjects in response to simultaneous (0 ms) and delayed (500 ms) PSS (+200 cents) during active vocalization and passive listening conditions. Results showed that, for the delayed PSS, the P200 peak magnitude was larger during vocalization compared with passive listening. This finding suggests that vocalization enhances auditory cortex responsiveness to deviations in voice pitch feedback following the onset of vocalization. This enhancement might be due to changes in tuning properties of auditory neurons by the vocal motor system that helps to detect and correct for vocal errors during speech production.
Event-related potential correlates of online monitoring of auditory feedback during vocalization.
Authors: Hawco Colin S. , Jones Jeffery A. , Ferretti Todd R.
Published: October 2013

When speakers hear the fundamental frequency (F0) of their voice altered, they shift their F0 in the direction opposite to the perturbation. The neural mechanisms underlying this response are poorly understood. In the present study, event-related potentials (ERPs) were used to examine the neural mechanisms used to detect alterations in auditory feedback during an ongoing utterance. Participants vocalized for 3 s, and heard their auditory feedback shifted by 0, 25, 50, 100, or 200 cents for 100 ms midutterance. In two sessions, participants either vocalized at their habitual pitch, or matched a target pitch. A mismatch negativity (MMN) was observed, with the amplitude positively related to the size of the perturbations. No differences were found between sessions. The F0 compensation response was found to be smaller for 200 cent shifts than 100 cent shifts, and a positivity was observed in the ERPs for a 200 cent shift. This result suggests that a 200 cent shift may be perceived as externally (rather than internally) generated. Thepresence of an MMN, and no earlier (N100) response suggests that the underlying sensory process used to identify and compensate for errors in midutterance may differ from feedback monitoring at utterance onset.
Ictal and interictal changes in central auditory processing.
Authors: Daly David B. , Daly David M.
Published: October 2013

Disordered functioning manifest in seizures can also give rise to subtle, pervasive interictal changes. We have used sets of synthesized acoustic stimuli, concurrent EEG and AED blood-level monitoring to evaluate changes in a 24-year old female with focal seizures. During ictus patient becomes mute, she can hear but not comprehend, and may then be briefly amnestic. EEG revealed sharp/slow waves over left anterior temporal regions, with occasional bilateral discharges. Levels of two AED fluctuated 50%, with peaks 2 h apart. Performance on 4-min sets of auditory testing with ge-ye and be-de-ge fluctuated from well defined (p<0.001) near either peak AED, to near-chance levels; three-choice vowel sets were well defined throughout. Disruptions, which involved contralateral homologous areas as well as surrounding ipsilateral areas, are consistent with augmented inhibition.
Comparison of measurements at ambient pressure on clinical immittance and wideband acoustic transfer function systems.
Authors: Schairer Kim , Morrison Brooke , Steininger Ellyn , Fowler Cynthia
Published: October 2013

The purpose of the study was to compare acoustic admittance recorded using probe tones of 226, 678, and 1000 Hz on a clinical immittance system with admittance and reflectance recorded on a wideband acoustic transfer function (WATF) system. The WATF system uses a click probe, which yields measurements across a broad range of frequencies with one test, whereas multiple tests are required at individual frequencies on the clinical system. Thus, the WATF system has the potential to provide more information in a shorter amount of time. The hypothesis was that admittance would be comparable between the two systems, which would provide support for clinical use of the WATF system. Measurements were taken at ambient pressure (i.e., 0 Da Pa) in the ear canals of adults with normal hearing and middle-ear function. Because the clinical system reports only information at the tympanometric peak by default, the data at 0 Da Pa were manually recorded by entering the cursor mode. In general, the results at all three probe frequencies support the hypothesis, although the relationship was stronger for the two higher probe tone frequencies. The clinical implications and effect of analysis bandwidth on the WATF system will be discussed.
An electroacoustical analog for estimating sound pressure level at the tympanic membrane at high frequencies.
Authors: LoPresti Janice L. , Recker Karrie , Zhang Tao
Published: October 2013

For various applications, it is useful to know the sound pressure level (SPL) at the tympanic membrane (TM). However, measuring the SPL close to the TM is not clinically feasible, due to safety and discomfort concerns. Therefore, it is desirable to estimate the SPL at the TM using measurements away from the TM. This is challenging at high frequencies where the effect of canal geometry becomes significant as the wavelength of the acoustical source becomes comparable to the dimensions of the canal. In this study, an electroacoustical analog was used to estimate the SPL at the TM for ten participants. The analog is comprised of a transducer (i.e., sound source), occluded ear canal, and the middle ear [Pascal et al. (1998)]. The ear model was optimized for each individual using a 2-parameter fit using real ear measurements further away in the canal. The optimization did not require inputs that may be difficult to obtain such as the exact canal geometry. A simulated transfer function was created and applied to each measured real-ear response to generate the estimated response at the TM. The model was verified using the SPL measured at the TM.
The sensitivity of hearing by the resonance in in vivo human ear canal.
Authors: Cheng Wei-De , Yu Jen-Fang , Huang Kuo-Wei , Chang Shang-Peng , Chen Chin-Kuo
Published: October 2013

This study is to discuss the sensitivity of human hearing sounds at different depths of ear canal, and to construct the measurement scales which can be the reference for the sound measurement and research in the future. Eighteen subjects aged from 20 to 30 years old with normal hearing and middle ears were studied. The pure tone audiometer and impedance audiometer were utilized to exam the frequency threshold of subjects. The real ear measurement was also utilized. The intensities of stimuli were 40, 50, 60, 70, and 80 dB SPL. The measured depths to the tympanic membrane were 0.5, 1.0, 1.5, and 2.0 cm, respectively. The gain of ear canal by different frequencies at 500, 1000, 2000, 4000 Hz was measured. Based on the results, there was moderate negative correlation between the resonance of ear canal and hearing. The larger the gain of ear canal was, the better the hearing of the subject would be. Consequently, the sensitivity of hearing for normal people would be affected by the resonance of ear canal. The resonance of each subject would be changed similarly at different measurement depths.
Behavioral responses to harmonic complex tones with missing fundamental frequencies by chinchillas in the presence of low-pass masking noise.
Authors: Shofner William P.
Published: October 2013

The pitch associated with the missing fundamental (F0) is one of the principal psychological attributes of human pitch perception. Behavioral responses to missing F0 stimuli were measured in chinchillas using operant conditioning and stimulus generalization. Animals were trained to discriminate between harmonic complex tones having a 500-Hz F0 and a 125-Hz F0. When animals were tested with tone complexes having the same F0s, but where the F0s were missing, responses were similar to those obtained when the F0s were present, suggesting that missing F0 sounds were perceptually equivalent to F0 present sounds. In the presence of low-pass masking noise, responses to F0 present and missing F0 stimuli were similar, suggesting that the percept was not due to the reinsertion of the F0 through cochlear nonlinearities. When the F0s of test stimuli were systematically varied, gradients in behavioral responses were observed, suggesting the existence of a psychological dimension related to F0. When the F0 and spectrum were varied independently, responses were related to the F0 rather than to spectral differences among test stimuli. The results indicate that chinchillas possess a pitchlike perception of the missing F0 that is unlikely to arise from cochlear distortion products. [Work supported by NIDCD R01 DC005596.]
Temporal modulation transfer functions in listeners with real and simulated hearing loss.
Authors: Desloge Joseph G. , Reed Charlotte M. , Braida Louis D. , Delhorne Lorraine A. , Perez Zachary D.
Published: October 2013

Temporal modulation transfer functions (TMTFs) were obtained in nine listeners with moderate to profound sensorineural hearing loss (age range of 21 to 69 years). The hearing loss of each impaired listener was simulated in a group of three age-matched normal-hearing listeners through a combination of spectrally-shaped masking noise and multi-band expansion. TMTFs in both groups of listeners were measured in a broadband noise carrier as a function of modulation rate in the range of 2 to 1024 Hz using a 3I, 2AFC procedure. The presentation level for the unmodulated broadband noise (whose duration was 500 ms) was set to be the maximum of either 70 dB SPL or the level such that noise was 10 dB above the lowest hearing threshold. The listeners with simulated hearing loss thus received signals at the same SPL and SL as their hearing-impaired counterparts. The shape of the TMTF curves (defined as the measured threshold of modulation in dB as a function of frequency of modulation) and the interpolated DC values of the function (using an exponential fitting procedure) were generally similar for listeners with real and simulated hearing loss. [Work supported by NIH-NIDCD R01 DC00117.]
Effects of several variables on temporal-order identification in young and elderly listeners.
Authors: Fogerty Daniel , Kewley-Port Diane , Humes Larry
Published: October 2013

Four measures of temporal-order identification were completed by young (N=35, 18–31 years) and elderly (N=151, 60–88 years) listeners under various stimulus conditions. Experiments spaced over several months used forced-choice constant-stimuli methods to determine the smallest stimulus onset asynchrony (SOA) between brief (40 or 70 ms) vowels that enabled identification of the stimulus sequence. Vowels in four words (pit, pet, pot, put) served as stimuli. The four measures of temporal-order identification were: (1) monaural two-item sequences; (2) monaural four-item sequences; (3) dichotic two-item vowel-identification sequences; and (4) dichotic two-item ear-identification sequences. All listeners identified the vowels in isolation with better than 90% accuracy. Results indicated that elderly listeners performed significantly poorer on monaural and dichotic temporal-order identification tasks than young listeners, although a large overlap in group distributions was observed. For both groups, the two-item dichotic task was significantly harder than two-item monaural. Increasing the attentional demands of the monaural task by randomizing the stimulus ear did not explain this difference. Using shorter duration stimuli did not alter performance in the monaural task but did improve performance in the dichotic task. Significant learning occurred for elderly listeners but not enough to eliminate the age-group differences. [Work supported, in part, by NIA.]
Minimum audible angles in children who use bilateral cochlear implants.
Authors: Zettler Cynthia M. , Godar Shelly , Litovsky Ruth Y.
Published: October 2013

Over 5000 children worldwide have received bilateral cochlear implants (CI) so that the auditory skills that rely on inputs to both ears, such as sound localization, may be improved. In this study, localization acuity was measured with minimum audible angles (MAA), the smallest discriminable distance between two locations in the frontal azimuth plane. It is unclear whether children who use bilateral CIs can attain MAAs comparable to their acoustically hearing peers, and if so, the extent to which exposure to bilateral hearing is necessary. Children having 3–36 months of bilateral experience participated. Stimuli were spondaic words presented at an overall level of 60 dB (± 4 dB rove). Every child with >5 yrs of auditory experience performed the task, whereas some of the children with <5 yrs of experience could not perform the task. In the former group, children with >2 yrs of bilateral experience were the best performers (MAA thresholds <15°), compared to children in the latter group who completed the task (MAA thresholds >30°). Results suggest that in children who receive bilateral CIs the two overall factors that impact performance are overall time in sound and amount of time with bilateral experience. [Work supported by NIH DC R01008365.]
A speech quality metric based on a cochlear model.
Authors: Kates James M. , Arehart Kathryn H.
Published: October 2013

Noise, distortion, nonlinear signal-processing algorithms, and linear filtering can all affect the sound quality of a hearing aid. The sound quality, in turn, can have a strong impact on the success of the device. The general approach in designing a quality metric is to compare the degraded signal with a clean (unprocessed) reference signal; the comparison generally involves comparing one or more features extracted from the signals. In this presentation, features are extracted from a computationally efficient model of the auditory periphery. The model includes the middle ear, an auditory filter bank, dynamic-range compression, two-tone suppression, and loudness scaling. The first step is a metric for noise, distortion, and nonlinear signal processing. The noise and nonlinear metric focuses on differences in the short-time signal behavior. The second step is a metric that focuses on the changes in the long-term average spectrum caused by linear filtering. The third and final step is to merge the noise and nonlinear metric with the linear filtering metric to produce a composite sound quality metric that can be applied to an arbitrary signal-processing system. The metrics give correlation coefficients better than 0.94 in comparison with quality ratings made by normal-hearing and hearing-impaired listeners.
A cochlearlike model of equal loudness levels for impaired and normal hearing: A new basis for hearing-aid gain-compression prescriptions.
Authors: Goldstein Julius L
Published: October 2013

Mean psychophysical data on most comfortable and uncomfortable tone levels as a function of hearing loss [Pascoe, 13th Danavox Symp. 153–183 (1988); D. M. Schwartz et al., The Hearing J. 41, 13–17 (1988)] is interpolated for other loudness levels by representing impaired auditory response as a modification of the idealized normal cochlear mechanical response to tones: linear at low and high sound levels joined by power-law compression of the low level “tip” gain. Denoting the low- and high-level nonlinear transitions as stimulus thresholds for compression and decompression, hearing loss elevates the compression threshold without changing the decompression threshold, until the compressive region is eliminated. Further hearing loss converts the compression threshold into a threshold for power-law “tail” expansion. Mean psychophysical data, represented by multiple regression lines, are fit exactly by an analytical solution for the normal model parameters. Estimates for thresholds of approximately 15 and 95 phons and tip gains of 40–52 dB are physiologically plausible for the normal cochlea. Normal equal loudness levels updated by Suzuki and Takeshima [Y. Suzuki and H. Takeshima, J. Acoust. Soc. Am. 116, 918–933 (2004)] allow reliable extension of the model to low frequencies with estimates of auditory high-pass linear acoustic processing and of normal low-frequency tip gains. [Work supported by NIDCD.]
A weighting-function-based approach to subjectively modify the frequency response of a hearing aid.
Authors: Sabin Andrew T. , Marrone Nicole , Dhar Sumitrajit
Published: October 2013

While approaches that modify the frequency response of a hearing aid based on a listener’s subjective preference have demonstrated some success, they also have several limitations. Namely, these approaches (1) consider a small set of potential frequency-gain curves (FGCs) and (2) they converge on the final FGC, which makes the outcome dependent upon the starting point. Here we present a new approach that addresses these problems by (1) considering a much larger initial set of FGCs, and (2) using a method that is not convergence based. First, the listener rates the clarity of short samples of speech filtered by a set of maximally different probe FGCs. A weighting function is then computed, where the weight given to each ∼1/3 octave frequency band is proportional to the normalized slope of the regression line between the listener’s rating and the within-band gain of the probe FGC. Next, the listener rates the clarity of speech samples filtered by the weighting function, which is multiplied by one of several, randomly ordered, scaling coefficients. The final FGC is the scaling coefficient that receives the maximum rating, multiplied by the weighting function, added to a hearing-loss-specific correction factor. Results will be compared to current fitting strategies.
Experimental validation of alternate integral-formulation method for predicting acoustic radiation based on particle velocity measurements.
Authors: Ni Zhi , Wu Sean
Published: October 2013

This paper presents experimental validation of an alternate integral-formulation method (AIM) for predicting acoustic radiation from an arbitrary structure based on the particle velocities measured by a laser Doppler anemometer (LDA) and double hotwire sensor over a hypothetical surface enclosing a target source. Both the normal and tangential components of the particle velocity on this hypothetical surface are measured and taken as input data to AIM codes to predict acoustic pressures in the exterior region. The results thus obtained are compared with those measured by microphones at the same locations. Measurement limitations are discussed and an error analysis of LDA measurement is presented.
Acoustic features and inteilligibility of American-English vowels for English, Chinese, and Korean talkers.
Authors: Jin Su-Hyun , Liu Chang , Kamdar Sangeeta
Published: October 2013

Sixteen American-English vowels including 12 monothongs and 4 diphthongs were recorded in a phonetic context of /hVd/ from young English (E), Chinese (C), and Korean (K) talkers. The Chinese and Korean talkers were bilingual and had stayed in United States up to 6 years. Two sets of experiments will be discussed: acoustic analysis and intelligibility of English vowels produced by the three groups of talkers. Results of acoustic analysis showed that there was no significant difference in F1×F2 vowel space among the three groups of talkers. In addition, the three groups of talkers showed great similarity in F2/F1 ratio across the 12 monothongs. Vowel durations had significantly greater variability across vowel categories for the Chinese and Korean talkers than for the English talkers, indicating that, besides producing spectral differences among vowels, Chinese and Korean talkers also attempted to generate durational difference among vowels to make each vowel distinguishable from others. More acoustic features such as spectral tilt and formant transition in the diphthongs and the effects of acoustic features on vowel perception by native English listeners will be discussed. Furthermore, the relationship between the vowel intelligibility and the second language experience of non-native talkers will be examined.