bluuebunny/crossref_metadata_2025 huggingface dataset:
The Newman Student Award Fund, a major contributor to architectural acoustics education.
Authors: Coffeen Robert C.
Published: July 2011

The creation of the Newman Student Award Fund in honor of Bob Newman by Mary Newman and some of Bob Newman’s friends and colleagues has been of considerable help in interesting and rewarding students who intend to pursue a career in professional acoustical consulting. The Fund provides the Robert Bradford Newman Student Medal for Merit in Architectural Acoustics and the Schultz Grant for educators in architectural acoustics, and it is a sponsor of the Annual Acoustical Society Student Design Competition. From the architecture and the architectural engineering programs at the University of Kansas and during the past 14 years, over 30 KU students plus several students from architectural engineering at Kansas State University have been guided into acoustical consulting or closely related fields. KU students have received at least one of the five awards from the student design competition since its beginning in 1994, and a number of Newman medals have been awarded. As a member of the Newman Student Award Fund Advisory Committee, it is a privilege to assist with the continuation of this excellent organization.
Influence of Robert B. Newman on education.
Authors: Egan M. David
Published: July 2011

Professor R. B. Newman’s 4.43 course at MIT followed the scholarly legacy of W. C. Sabine, V. O. Knudsen, and C. P. Boner, but featured irreverent observations, succinct admonitions, case histories of BBN projects, and field trips (which stressed importance of sensory observations to understand principles of physics). In the late 1960s, the presenter, a former student of Newman, developed teaching aids at Tulane University which evolved into architectural acoustics, now in print for its 41st year. In the first 7 years of Newman Award Fund, the number of participating schools grew due to face-to-face communication with faculty and school administrators. The presenter and W. J. Cavanaugh facilitated the initial growth primarily at Clemson University (6 medalists), University of Florida (6), Rhode Island School of Design (5), and Oklahoma State University (4). Examples will be cited to show how Newman Award enhanced status of acoustics educators in designer-dominated academic cultures.
An international perspective on the work of the Newman fund.
Authors: Dance Stephen
Published: July 2011

Since 2007 London South Bank University has been involved with the Newman Fund through their Masters programe in Environmental and Architectural Acoustics. This link has lead to closer relations between London South Bank University and the Acoustical Society of America starting with a Schultz Grant award, followed by attendance at the fourth Concert Hall Research Group Summer Institute, and recently in Dr. Dance becoming the first international member of Newman committee. Each year the best dissertation has been submitted to the Newman committee, and fortunately nearly every year one of our acoustic students has been awarded the Newman medal. The Acoustics Group has used the Newman fund to encourage the award-winning students to go on to our Ph.D. research programe. The most effective inducement has been found to be sending the prospective Ph.D. student to an international conference, where a research paper is presented based on their Masters dissertation. Case studies of the awarding winning projects are briefly outlined, emphasizing the link between the Masters dissertation and the subsequent student selected Ph.D. topic.
The Newman medal: A recipient’s recollections after 20 years.
Authors: Madaras Gary
Published: July 2011

Gary Madaras received the Newman medal 20 years ago (1991) for his Master of Architecture thesis work at Kent State University, OH. It was awarded at a pivotal time, as his academic and professional direction was changing from designing the visual environment to designing the aural environment. Dr. Madaras reflects on the circumstances that contributed to this lifelong redirection and on the studies for which he received the Newman medal. An overview of his career in architectural acoustics since receiving the Newman medal is followed by a heartfelt thank you to those that made, and still make, the program possible two decades later.
From Portugal to Florida, and the Newman award.
Authors: Carvalho Antonio
Published: July 2011

I was 31 years-old when, in 1991, I left the University of Porto to study architectural acoustics at the University of Florida with Professor Gary W. Siebein. In 1994, I finished my Ph.D., I got the Robert Bradford Newman Award, and my career changed. In fact, that 1994 would be the “big bang” of my future life. Personally, academically, and scientifically, my Universe blew up and began expanding. What I learned and what I taught in the 17 years after that (and what the architectural acoustics changed in Portugal and Southern Europe) is the subject of this paper.
Acoustics as a factor of ergonomics: Communication behavior and workload of pupils and teachers in highly absorbent classrooms.
Authors: Oberdoerster Markus , Tiesler Gerhart
Published: July 2011

This lecture refers to an interdisciplinary research project carried out from 2000 to 2006 by the Bremen University, Germany. A mixed team of acousticians, occupational and medical scientists, and pedagogues investigated the kind of work and communication behavior in classrooms in two elementary schools. Using a database of 175 examined lessons an analysis is made of how different kinds of work (frontal lessons versus differentiated lessons) affect the basic and working sound level in the classroom. Parameters are discussed, which can describe classroom acoustics appropriately. Also discussed are how altered room characteristics (e.g., increased absorption, shortened reverberation time, and improved speech intelligibility) affect the sound level in the context of each kind of work. A methodical examination of the database allows not only an assessment of mean values but also of the detailed teaching phases, as characterized by certain pedagogical factors. The results provide the basis for discussion of stress and work demands of teachers: Based on recordings of teacher’s heart rate the effects of noise level on the workload of the teachers as a stress reaction and a factor of fatigue are analyzed.
The nature and nurture of seeing with sound: The role of learning in biosonar.
Authors: Gisiner Robert , Reichmuth Colleen
Published: July 2011

Echolocating dolphins achieve performances in detecting and classifying components of their environment that rival the performances we typically associate with vision. Many researchers have referred to dolphins “seeing with sound” or forming internal “images” of the world via acoustics, implying a presumed isomorphy of sensory inputs and a common representation at higher levels of processing in the brain. But some aspects of acoustics do not translate into visual equivalents (hollow objects and objects of different materials) and some visual aspects of an object do not translate into acoustic equivalents (color and brightness). So, how is this cross-modal sensory translation achieved? Is it hard-wired into the anatomy of the brain, learned through association, or is it some combination of the two? Experimental tests of nature versus nurture in cross-modal sensory performance are reviewed, as first explored by Schusterman and Kastak. Further studies are suggested to reveal the respective roles of neuroanatomy and associative learning in the formation of a dolphin’s perceptual and conceptual world.
Auditory evoked potential audiometry in fish.
Authors: Ladich Friedrich
Published: July 2011

A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fish. More than 90% of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. Applying and further developing the AEP-technique enabled the investigation of a wide range of scientific questions. First, it was possible to describe and compare basic hearing abilities in a large number of species. Subsequently, the ontogenetic development of hearing as well as the influence of various accessory hearing structures (Weberian ossicles and swimbladder) were studied. The technique was also successfully utilized to analyze the temporal resolution ability of the auditory system. The AEP-technique is suitable for studying threshold shifts after exposure to (TTS) and in the presence of (masking) various noise types (white, ambient, and anthropogenic). Comparison of AEP-audiograms with sound spectra, along with the analysis of AEPs in response to conspecific sounds, enabled us to assess the ability to communicate acoustically in general, and during ontogeny and in the presence of noise in particular. Finally, various factors potentially influencing hearing such as temperature, albinism, and cave dwelling were investigated. [Work supported by the FWF.]
A new connection: Enhanced hearing ability in the New Zealand bigeye, Pempheris adspersa.
Authors: Radford C.A. , Caiger P. , Ghazali S. , Higgs D.M.
Published: July 2011

Recently the bigeye, Pempheris adspersa, has been found to be one of the few sound producing fish found in the temperate marine waters of New Zealand. An initial crude morphological examination of this species found a special connection, analogous to that of the well-defined laterophysic connection, between the otic capsule and the lateral line recess. The aim of the present study was to characterize the hearing ability of the bigeye using auditory evoked potentials, understand the role of this special connection, and describe the morphology of the hearing structures using microCT and MRI techniques. The novel connection consists of a robust ligament directly connecting the otic capsule to the lateral recess, with the swim bladder running directly posterior to the ligament. Pempheris adspersa could hear in the frequency range 100–1000 Hz, with greatest sensitivity between 100–800 Hz. Cutting the connecting ligament resulted in a 15–20 dB threshold shift, with a further 5–10 dB shift after swim bladder puncture. This connection represents a completely novel hearing specialization and shows that the lateral line is directly connected to the otic capsule, enhancing the hearing ability of this species especially at low frequencies (100–200 Hz).
Directional and frequency saccular sensitivity of the little skate, Raja erinacea.
Authors: Sisneros Joseph A. , Fay Richard R.
Published: July 2011

Although a number of previous behavioral studies have demonstrated that elasmobranch fishes can detect and are attracted to low frequency sounds, few physiological studies have characterized the auditory response properties of the elasmobranch inner ear to such low frequency sounds. In this study, we examined the directional and frequency responses of the inner ear saccule in the little skate, Raja erinacea to low frequency stimuli. Evoked microphonic potentials were recorded from the middle region of the saccule while sound was generated using a shaker table designed to mimic the particle motion vector component of sound. 8 test frequencies (50, 64, 84, 100, 140, 185, 243, and 303 Hz) and 11 directions were used to characterize the displacement sensitivity, frequency response and directional response properties of the skate saccule. Saccular potentials were evoked and measured at twice the stimulus frequency in vivo using a wave analyzer while stimuli were generated via the shaker table system. The right and left saccules appeared to have an omnidirectional response based on initial measurements, and the frequency response of the skate saccule had lowest displacement thresholds from 100 to 185 Hz.
Experimental investigation of the Krysl–Cranford–Schilt model for the otolith vibration of a teleost fish.
Authors: Rodgers Gwendolyn V. , Rogers Peter H.
Published: July 2011

The Krysl–Cranford–Schilt model [Schilt, et al., J. Acoust. Soc. Am. 127, 1754 (2010)] for the response of a teleost otoith to sound makes some unexpected predictions, which, if true, would have significant implications for our understanding of the mechanisms of hearing in fish. It has been believed for over 60 years that the otoliths function like the inertial mass of an accelerometer, which, in the absence of attachments to the skull (or a swimbladder), would vibrate back and forth in the direction the acoustic particle velocity but with a smaller amplitude. The KCS model, however, predicts that the otolith motion is highly dependent on both the frequency and direction of the incident sound wave and involves significant rocking motion as well as translation. If this is true, then the particle-motion-vector models for directional hearing in fish, which have held sway for over 40 years are incorrect. The validity of this model is experimentally tested in a direct and simple manner. An otolith is suspended in a sphere of low-shear-modulus tissue phantom in a large acoustic test tank. The motion of the acoustically excited otolith is measured using an ultrasonic vibrometer.
Ontogenetic development of hearing and sound communication in catfishes.
Authors: Lechner Walter , Ladich Friedrich
Published: July 2011

Catfish possess a high diversity in accessory hearing structures, hearing sensitivities, and sound-generating mechanisms. Nevertheless, the ontogeny of their hearing and sound communication remains unknown. We investigated the development of Weberian ossicles and hearing sensitivity in the African bullhead catfish from postlarval stages up to adults and also examined the ontogenetic development of hearing and sound production in the yellow marbled squeaker catfish. In the smallest bullhead catfishes, the Weberian ossicles and interossicular ligaments are not fully developed. They are unable to detect sounds at low levels and high frequencies. In later stages of both species tested, hearing sensitivity increases with size at low frequencies and decreases at high frequencies. In the squeakers, the duration of stridulation sounds, sound pressure level, and pulse period increase, whereas the dominant frequency decreases with size. The most sensitive frequencies correlate with the dominant frequencies of stridulation sounds in all size groups, enabling all stages to detect communication sounds. Our studies show two different trends of changes in hearing sensitivity in catfishes: one prior to and the other after full development of the Weberian ossicles. Squeakers of all sizes are able to communicate acoustically. These results contrast with prior findings in teleosts. [Work supported by FWF.]
Saccular-specific, seasonal differences in hair cell density in a vocal fish with seasonal auditory plasticity.
Authors: Coffin Allison B. , Mohr Robert A. , Sisneros Joseph A.
Published: July 2011

Plainfin midshipman fish (Porichthys notatus) rely on acoustic communication for courtship. Courting males build nests in rocky intertidal areas and emit low-frequency hums to attract reproductive females. There is surprising physiological plasticity in the female midshipman’s auditory system, with reproductive (summer) females exhibiting greater sensitivity to higher frequencies than non-reproductive (winter) females. Recent work demonstrates that this physiological plasticity occurs at the level of the saccule, which is the primary hearing organ in this species. This research examines potential morphological correlates of this physiological plasticity. Summer females have greater saccular hair bundle density than winter females and there is a corresponding increase in net cell addition as determined by quantification of dividing and dying cells and by counts of immature hair bundles. No seasonal differences are seen in the other inner ear end organs. Saccular hair cell number is not correlated with fish size, suggesting that the hair cell increase is not due to differences in fish size between sampling seasons. These data suggest that the hair cell increase in summer females may contribute to the greater auditory sensitivity seen in reproductive females. Future studies will examine morphological and molecular differences between saccular hair cells in winter and summer females.
Monoamine innervation of vocal and auditory circuits in the plainfin midshipman fish.
Authors: Forlano Paul M. , Nielsen Lilja , Timothy Miky
Published: July 2011

Monoamines, which include catecholamines (e.g., dopamine and noradrenaline) and serotonin, are important regulators of reward, motivation and reproductive-related behaviors across vertebrates. Studies in tetrapods have demonstrated that monoamines can also serve a modulatory function for vocalization and audition. Antibodies directed against serotonin (5-HT) and tyrosine hydroxylase (TH) (the rate limiting enzyme in catecholamine synthesis) were employed to investigate monoamine innervation of known central vocal and auditory nuclei and the sensory epithelium of the saccule, the main endorgan of hearing, in the plainfin midshipman fish, Porichthys notatus. Both 5-HT and TH-immunoreactive (-ir) terminals are abundant in hindbrain (dorsal descending octaval nucleus), midbrain (torus semicircularis), thalamic (central posterior nucleus), and ventral telencephalic auditory nuclei. In addition, very robust TH-ir is found in the octavolateralis efferent nucleus, and prominent TH-ir projections travel along the eighth nerve and terminate within the hair cell layer of the saccular epithelium. Aside from the midbrain periaqueductal gray, TH-ir is much more pronounced than 5-HT-ir throughout the descending vocal motor system, particularly in the tuberal hypothalamus and the hindbrain-spinal vocal motor nucleus, which directly innervates vocal musculature on the swimbladder. These data provide anatomical evidence that monoamines are modulators of vocal and auditory-driven behaviors in fishes.
In vivo tissue emulsification using millisecond boiling induced by high intensity focused ultrasound.
Authors: Khokhlova Tatiana D. , Simon Julianna C. , Wang Yak-Nam , Khokhlova Vera A. , Paun Marla , Starr Frank L. , Kaczkowski Peter J. , Crum Lawrence A. , Hwang Joo Ha , Bailey Michael R.
Published: July 2011

Shock-wave heating and millisecond boiling in high intensity focused ultrasound fields have been shown to result in mechanical emulsification of ex-vivo tissue. In this work, the same in situ exposures were applied in vivo in pig liver and in mice bearing 5–7 mm subcutaneous tumors (B16 melanoma) on the hind limb. Lesions were produced using a 2-MHz annular array in the case of pig liver (shock amplitudes up to 98 MPa) and a 3.4-MHz single-element transducer in the case of mouse tumors (shock amplitude of 67 MPa). The parameters of the pulsing protocol (1–500 ms pulse durations and 0.01–0.1 duty factor) were varied depending on the extent of desired thermal effect. All exposures were monitored using B-mode ultrasound. Mechanical and thermal tissue damage in the lesions was evaluated histologically using H&E and NADH-diphorase staining. The size and shape of emulsified lesions obtained in-vivo agreed well with those obtained in ex-vivo tissue samples using the same exposure parameters. The lesions were successfully produced both in bulk liver tissue at depths of 1–2 cm and in superficial tumors at depths less than 1 mm without damaging the skin. [Work supported by NIH (DK070618, EB007643, and DK007742) and NSBRI through NASA NCC 9-58.]
A Markovian approach to the modeling of sound propagation in complex urban environments.
Authors: Oldham David
Published: July 2011

[The use of the radiosity method as a means of modeling sound propagation in complex urban environments has been extensively employed by a number of researchers over the past decade. A basic assumption for this approach is that all reflections at building facades are diffuse and hence sound is scattered rather than reflected specularly. The approach employed in the work described in this paper uses the same basic assumption of diffuse surface reflections as the radiosity method but combines this with a Markovian approach in which the sound scattered from small area elements on the facades to similar elements on another facade is treated in terms of probability. It is thus possible to construct a probability matrix describing the entire propagation process for a specified urban geometry. It can be shown that significant reductions in computational requirements can be achieved by considerations of factors such as reciprocity. The method is applied to an investigation of sound propagation for a variety of different urban forms.
Acoustics research in Nanjing University–In memory of Professor Rong-jue Wei.
Authors: Zhang Shu-yi
Published: July 2011

Acoustics research in Nanjing University was initiated by Prof. Rong-jue Wei in 1954, and developed as an Institute of Acoustics of Nanjing University in 1978, and then also a National Laboratory of Modern Acoustics in 1990. Under the leadership of Prof. Wei, the research of acoustics developed widely from audio acoustics to physical acoustics and ultrasonics, including electro-acoustics, architectural acoustics, speech signal processing, molecular acoustics, atmospheric acoustics, acousto-electronics, low temperature acoustics, nonlinear acoustics, photoacoustics, biological acoustics, environmental acoustics, and noise control. Most of the research fields and works were initial and creative in the country, and some of them have been continued and developed greatly. Up to now, the researches of the institute include five fields as follows: (1) Intensive acoustics: ultrasonic cavitation, somoluminescience, soliton and chaos; (2) Photoacoustics and laser ultrasonics: photoacoustic spectroscopy and imaging, characterization of nanoscaled materials, biological materials, and metamaterials; (3) Ultrasonics: phonon crystals, surface acoustic wave technique, and devices; (4) Biomedical ultrasonics: nonlinear ultrasonic phenomena and imaging of biological tissues; (5) Audio acoustics: electroacoustics, architectural acoustics, environmental acoustics and noise control, and acoustic signal processing.
Unresolved mysteries of acoustic solitons.
Authors: Putterman Seth
Published: July 2011

High amplitude motion in a continuous medium often results in localized states caled solitons. These nonlinear dynamical states can exist at amplitudes that are larger and widths that are smaller than are accessible to perturbation theory. A new type of nonlinear mathematics is needed to approach these stable structures.
To improve the outcome of intracellular delivery by microbubble-facilitated sonoporation.
Authors: Deng Cheri X. , Fan Zhenzhen
Published: July 2011

Microbubble-facilitated sonoporation, or the ultrasound-induced disruption of plasma membrane, provides new opportunities for intracellular delivery of therapeutic agents. However, ultrasound mediated microbubble-cell interaction is difficult to control due to the very nature of unconfined microbubbles in solution, resulting in relatively low delivery efficiency and often variable delivery outcome. It is desirable to develop techniques in order to achieve reproducible, robust delivery outcome. By utilizing targeted microbubbles to control and confine microbubbles near the cells and examine the detailed biophysical and cellular processes of the interaction of ultrasound-driven microbubbles with cells, we seek to obtain improved understanding of the disruption of cell plasma membrane, cellular uptake, and subsequent downstream effects in sonoporation. In this presentation, we describe our studies that examined these aspects and the important factors involved in sonoporation outcome using multidisciplinary approaches and at the single cell level.
Acoustic cavitation assisted vascular endothelial growth factor transfection in vitro.
Authors: Tu Juan , Zhang Dong , Zhang Chunbin , Li Qian , Gao Feng , Guo Xiasheng
Published: July 2011

Angiogenesis is a complex process that is mediated by growth factors such as vascular endothelial growth factor (VEGF). Researchers have reported that therapeutic ultrasound (US) is able to promote VEGF production in vitro, with the acoustic cavitation-induced sonopration. Here, with the presence of ultrasound contrast agents, the vascular endothelia cells mixed with VEGF165 were exposed to 1-MHz US pulses with varied acoustic parameters. The inertial cavitation (IC) activities accumulated during US exposure were quantified as IC dose (ICD) based on passive cavitation detection. The US sonoporation pores were examined with electron scan microscopy. The VEGF expression and the proliferation of the treated cells were evaluated based on ELISA and MTT assessments, respectively. The results show that (1) the ICD could be affected by US parameters (e.g., pressure, total treatment time, and PRF) and (2) the sonopration pore size, VEGF expression, and the cell proliferation were initially increased with the increasing ICD, then tended to saturate instead of achieving a maximum while the ICD kept going up. The results indicated that IC should play an important role in stimulating VEGF expression through sonopration, and ICD could be used as an effective tool to monitor and control the US-mediated drug delivery outcomes. [This work was funded by the National Basic Research Program of China (2011CB707900) and NSF of China (11074123 and 10974093).]
On the acoustic performance of hybrid mufflers.
Authors: Bi Rong , Chen Jun , Li Kai Ming , Bi Rong , Liu Zheng Shi
Published: July 2011

The acoustic attenuation of hybrid mufflers including perforated screens and sound-absorbent materials is investigated in the current study. An analytical method based on a 2-D mode matching technique is used to model an axisymmetrical hybrid muffler. In the theoretical analysis, the hybrid muffler is divided into a number of sections in different homogeneous media with different acoustical characteristics. The acoustic properties of sound absorbent materials and perforated screens are taken into account to obtain eigenfunctions for wave propagation through the air and sound absorbent materials. A system of equations can be solved by matching the acoustic pressure and axial velocity across different sections, which leads to the solution for the determination of the muffler’s transmission loss (TL). The numerical predictions of TL show good agreements with published experimental data. The developed analytical approach is then used to examine the effect of the inner structure of the hybrid mufflers on their acoustic performance. Finally, a hybrid muffler with mixed absorbent materials is investigated. The predicted results show that the hybrid muffler with full packed housing can lead to an improved acoustic attenuation at broad band frequencies. [Work sponsored by the China Scholarship Council.]
Frequency dependence of the interaural time difference thresholds in human listeners.
Authors: Dunai Larisa , Hartmann William M.
Published: July 2011

Interaural time difference (ITD) thresholds for sine tones were measured as a function of frequency with unprecedented resolution along the frequency axis. The tone level was 70 dB SPL, and the method was a two-interval forced-choice, three-down one-up staircase. Overall, the lowest thresholds occurred near 1000 Hz. At lower frequencies, thresholds varied more rapidly than the expected 1/f law, suggesting a growing deficit in elemental ITD processors as characteristic frequency decreases. At higher frequencies, thresholds increased dramatically with increasing frequency. Measurements at 50-Hz increments were able to obtain a threshold for only one listener at 1500 Hz, but no threshold at 1550 Hz. In summary, performance varied from best to impossible over a range of about half an octave. In that sense, ITD thresholds appear to show the most dramatic frequency dependence of any auditory quantity. [Work supported by the Vice-rectorate for Faculty and Academic Planning, Universidad Politécnica de Valencia and by the US NIDCD Grant No. DC-00181.]
Human underwater and bone conduction hearing in the sonic and ultrasonic range.
Authors: Qin Michael K. , Schwaller Derek , Babina Matthew , Cudahy Edward
Published: July 2011

Several investigators have reported that high-intensity bone-conducted sounds in the ultrasonic range (>20 kHz) can produce auditory sensations in individuals with normal hearing. Underwater hearing threshold studies performed at the Naval Submarine Medical Research Laboratory have found audibility curves similar to those previously reported in bone conduction studies. Human underwater and bone conduction behavioral thresholds in the frequency range between 20 Hz and 200 kHz are presented. Accelerometry measurements made with a mechanical human-head simulator are also presented. The present findings support the argument that the primary mechanism for human underwater hearing is bone conduction. Possible mechanisms for the underwater ultrahigh frequency hearing will be discussed.
Lateralized processing of audiovisual speech: Combining dichotic listening with visual hemifield effects.
Authors: Boettiger Marianne , Hertrich Ingo
Published: July 2011

The perception of acoustically presented speech syllables can be influenced by simultaneous visual presentation of a speaker’s face uttering different syllables. Furthermore, previous studies have shown that the visual influence on the phonetic percept depends on the video signal being presented to the left or right hemifield, indicating lateralized processing of visual phonological information. The present study, combining a dichotic listening paradigm (/pa/ and /ta/ syllables) with visual hemifield presentation, investigated the interactions between auditory right-ear advantage, visual hemifield effects, and participants’ gender. Most of the items were perceived as /ta/, /pa/, or /pta/. Apart from a strong and highly significant right-ear advantage, single consonant responses showed a right-hemifield advantage, irrespective of place of articulation and gender. By contrast, /pta/ responses were more frequent in females than males and showed an interaction of video side with place of articulation. The largest number of double articulations was perceived if right-ear /ta/ was combined with labial left-hemifield presentation and left-ear /pa/. These results can be taken as an indicator that the mechanisms resulting in a fused single-consonant percept are different from the ones leading to more complex responses requiring cross-modal combinations of phonological information.
Accurate sound localization via head movements in listeners with precipitous high-frequency hearing loss.
Authors: Macpherson Ewan A. , Cumming M. Alasdair , Quelch Robert W.
Published: July 2011

Information about sound source location in the vertical plane is available via the direction-dependent filtering performed by the outer ears, but errors of localization such as front/rear reversals can occur when stimuli contain a limited range of frequencies or when high frequencies are inaudible due to hearing impairment. Information about front/rear sound source location is also available in the relationship between the rotation of the head and the resulting changes in interaural time and level differences. We have shown previously [Macpherson, J. Acoust. Soc. Am. 125, 2691(A) (2009)] that in normally hearing listeners, a minimum head movement angle (MHMA) of 5–10 deg is sufficient for accurate front/rear localization of low-frequency (0.5–1 kHz) noise-band targets. In the present study, we measured MHMAs for low-frequency and wideband (0.5–16 kHz) targets in listeners with near-normal low-frequency thresholds but precipitous hearing loss above 1–2 kHz. Neither stimulus could be localized accurately by these listeners without head movement, but for both stimuli, MHMAs of 5–10 deg sufficed for accurate localization at a rotation velocity of 50 deg/s. MHMAs increased with increasing rotation velocity similarly to those of normally hearing listeners. The results suggest that listeners with normal hearing and with high-frequency loss benefit similarly from dynamic localization cues. [Work supported by the NSF.]
Binaural synthesis of virtual moving sound sources.
Authors: Hamil James T. , Krishnamurthy Ashok K. , Feth Lawrence L.
Published: July 2011

Limitations in the movement of physical sources for motion related studies motivate the creation of a processing chain for accurate placement of moving sound sources in a three-dimensional virtual auditory space over headphones. Monaural and binaural cues normally available to listeners are accurately reproduced in the ear waveforms. Head-related transfer functions (HRTFs) are updated at a high rate to reflect each individual source’s changing directional information. A time-varying propagation delay is implemented for linear motion to account for the Doppler frequency shift that occurs when either the source or listener is moving in virtual space. The performance of the system is characterized through psychoacoustic measures of spatial resolution and compared to the existing literature. System constraints and potential future experiments are addressed.
Using spiking onset neurons and a recurrent neural network for sound identification.
Authors: Newton Michael , Smith Leslie
Published: July 2011

Physiological evidence suggests that specific neurons within the cochlear nucleus specialize in sound onset detection. These are innervated by type 1 spiral ganglion fibers covering a relatively wide spectrum. Sudden increases in sound energy (e.g., during the initial portion of a sound) result in an increased firing rate in a downstream onset neuron. Onset timing and spectral location are thought to play a role both in auditory stream separation and sound identification and interpretation. Onset neurons are modeled using leaky integrate-and-fire units innervated by spiking data streams produced using a passive gammatone filterbank followed by positive-going zero-crossing detection. Signal level is coded using multiple spike trains per filter channel. The model is presented with a succession of 607 musical samples selected from the McGill dataset and the pattern of onset spikes recorded for each sound. Groups of onset spikes occur close to the beginning of each note. The objective is to use the pattern of spikes, produced by the onset neuron model, as a fingerprint of the original acoustic signal. These onset fingerprints are presented to a recurrent neural network (reservoir network) to attempt to classify them. The results are compared with a sound classification scheme based on cepstral coefficients.
The precedence effect: Spatial versus cue specificity.
Authors: Brown Andrew D. , Stecker G. Christopher
Published: July 2011

Normal-hearing listeners effectively localize sound in everyday environments by responding to the directional cues carried by the early-arriving direct signal rather than the spurious cues carried by its reflected copies. This so-called precedence effect is known to depend strongly on the stimulus context. In a previous study, we demonstrated a divergence of echo thresholds for interaural time difference (ITD) and interaural level difference (ILD) under conditions of repeated stimulation. Specifically, while buildup and re-buildup effects were evident for both cues, a breakdown effect occurred for ILD only. This result suggests that dynamic precedence in the free field might depend on sensitivity to discrete ITD and ILD images. The present study assessed whether echo thresholds built up by ITD or ILD conditioner stimuli would remain elevated for subjectively matched ILD or ITD test stimuli. Stimuli were pairs or slow trains of broadband clicks presented over headphones. Echo thresholds were estimated from subjects’ judgments of fusion and lateral position. To the extent that buildup depends specifically on the spatial character of the stimulus, built-up echo thresholds should transfer between spatially equivalent cues. Echo thresholds measured at baseline levels following a change in cue type, however, suggest that buildup occurs in a cue-specific manner. [Work supported by NIH Grant Nos. F31-DC010543 (A.D.B.) and R03-DC009482 (G.C.S.).]
Influence of a single reflection on speech intelligibility in simulated electric-acoustic stimulation.
Authors: Helms Tillery Kate , Brown Christopher A. , Yost William A. , Bacon Sid P.
Published: July 2011

In reverberant environments, reflections occurring within 30–50 ms of the direct speech assist intelligibility by perceptually fusing with the source, effectively increasing its level. Fusion occurs at similar delays in monaurally deaf and normal-hearing listeners, suggesting an independence from binaural processes [Litovsky et al., J. Acoust. Soc. Am. 106, 1633–1654 (1999)]. Its effects can thus be examined in unilateral cochlear implant (CI) users. Simulated CI listening shows little benefit from early reflections, and a detriment when delays exceed 20 ms [Whitmal and Poissant, Conference on Implantable Auditory Prostheses (2009)]. Data from our laboratory show that CI users with residual acoustic hearing benefit from electric-acoustic stimulation (EAS) in reverberation. The role of early reflections in this EAS benefit remains unclear. The present study examined the effect of a single unattenuated reflection at ten delay times on intelligibility in simulated EAS. Target stimuli consisted of sentences combined with unattenuated copies delayed by 0–66 ms. Four-talker babble was added to increase difficulty. A four-channel vocoder simulated electric stimulation; low-pass filtered speech represented residual acoustic hearing. Monaural intelligibility scores from normal-hearing listeners under anechoic and reflected conditions with electric and electric-acoustic processing suggest that EAS may facilitate a benefit from early reflections. [Work supported by the NIDCD.]
Learning of reverberation cues for auditory distance perception in rooms.
Authors: Kopčo Norbert , Tomoriová Beata , Silvera Pierre , Tskhay Konstantin , Seitz Aaron
Published: July 2011

Listeners must calibrate to the room acoustics in order to judge source distance using reverberation. A learning process underlies this calibration, resulting in improved performance when auditory distance is examined repeatedly in the same room over the course of days. The processes of calibration and learning are spontaneous, not requiring any feedback about the actual target location. The current study examined whether the amount of spontaneous learning in rooms is dependent on the relative strength with which the reverberation cue is used for the distance judgments. Listeners judged distance of broadband noise bursts presented from distances ranging from 0.15 to 2 m directly ahead of the listener in a small rectangular classroom. The stimulus presentation level was either roved from trial to trial (R runs) or it was fixed within an experimental run (F runs). The subjects performed several experimental sessions over multiple days. One subject group was trained on the F runs, one on the R runs. Learning was observed in the R group but not in the F group, confirming that focusing on the reverberation cue is required for the learning and room calibration to occur. [Work supported by NIH and the European Community.]
Localizing amplitude-modulated, high-frequency tones in free field: Perceptual.
Authors: Macaulay Eric J. , Rakerd Brad , Hartmann William M.
Published: July 2011

High-frequency sinewave-amplitude-modulated (SAM) tones can be lateralized in headphone experiments based on the interaural level difference (ILD) and the interaural time difference in the envelope (eITD). Because of the vagaries of diffraction by the human head, the eITD may be an unreliable cue for localizing SAM tones in free field [Hartmann et al., J. Acoust. Soc. Am. 128, 2454 (2010)]. Localization experiments were done using a 13-loudspeaker array covering 90 deg of azimuth while binaural ear canal recordings were made to accompany each localization judgement. Parallel experiments for pure sine tones and SAM tones revealed the differences in localization judgements attributable to the modulation. These difference were compared with the differences in ILD and with the eITD for SAM tones, and also with differences in compressive functions of those interaural parameters. Correlations for eITD were low for most listeners, suggesting that the role played by eITD in azimuthal localization is not expressible by a monotonic function. Apparently localization of high-frequency SAM tones is quite different from lateralization. [Work Supported by the NIDCD, Grant No. DC-00181.]
Age-related changes in the binaural temporal window.
Authors: Eddins David A. , Eddins Ann Clock , Frisina D. Robert
Published: July 2011

Substantial data indicate that monaural temporal processing, sound localization ability, and spatial release from masking decline with advancing age. Physiological and psychophysical evidence indicate that the auditory system is quite sensitive to patterns of interaural cross correlation (IACC) as determined by the combined input from the two ears. Here we test the hypothesis that age-related changes in temporal processing lead to an elongation of the binaural temporal window as measured with an interaural correlation change interval (ICCI) task. The ICCI threshold was measured as a function of the duration change in interaural correlation. Band pass (400–3200 Hz) noise bursts were separated into three segments. Initial and final segments were interaurally uncorrelated while central segments were interaurally uncorrelated in the standard intervals and interaurally correlated in the signal interval. The duration of the central segment was adaptively varied to determine ICCI threshold. The just noticeable difference in static interaural correlation also was measured. The perception of static and dynamic changes in interaural correlation as well as estimates of the equivalent rectangular duration of the binaural temporal window will be compared across groups of younger and older adult subjects.
Effects of non-simultaneous modulated maskers on amplitude-modulation depth discrimination.
Authors: Millman Rebecca E.
Published: July 2011

Wojtczak and Viemeister [J. Acoust Soc. Am. 118, 3198–3210 (2005)] demonstrated that detection thresholds for amplitude modulation (AM) can be increased in the presence of an AM forward masker. In the present study, the effects of forward-masking on AM detection thresholds were extended to AM processing for easily detectable (suprathreshold) AM modulation depths by measuring the effects of nonsimultaneous AM maskers on AM modulation depth discrimination limens (AM DLs). Signal AM DLs were measured for a range of standard modulation depths. In one experiment the temporal delay between the masker and signal was varied. Consistent with the effects of AM forward maskers on AM detection thresholds [Wojtczak and Viemeister (2005)], the effects of the non-simultaneous AM maskers on AM DLs were greatest for short masker-signal delays. In another experiment, the masker-signal delay was fixed, the signal modulation frequency was fixed, and the modulation frequency of the non-simultaneous masker was varied. AM DLs for the signal were usually greatest when the signal modulation frequency was equal to the masker modulation frequency. The results of these experiments suggest that non-simultaneous AM maskers can affect suprathreshold AM processing but non-simultaneous AM maskers become less effective as the modulation depth of the standard increased.
Spectro-temporal specificity of learning on modulation depth discrimination.
Authors: Sabin Andrew T. , Eddins David A. , Wright Beverly A.
Published: July 2011

Most natural sounds are composed of peaks and valleys of sound energy spread across both frequency (spectral modulations) and time (temporal modulations). Here a perceptual-learning paradigm was used to explore how these modulations are encoded. Three groups of normal-hearing listeners were trained to discriminate the depth of either spectral, temporal, or spectro-temporal modulation 1 h/day for 7 days. Each group improved on their trained condition by an amount greater than a group that received no training. However, this training did not lead to improvement on untrained modulation depth discrimination conditions, even when those conditions shared the spectral or temporal modulation frequency with the trained condition. Further, the influence of discrimination training on the detection of spectro-temporal modulation differed across the three trained modulations: spectral training yielded improvement, temporal training had no effect, and spectro-temporal training actually led to worsening on spectro-temporal modulation detection. These results imply that each training regimen led to a different modification. Critically, the specificity of the depth discrimination learning suggests that some aspect of the training-induced modification was selective for the combined spectro-temporal properties of the trained modulation and is therefore consistent with the idea that filters with combined spectro-temporal selectivity underlie modulation perception. [Work supported by NIH/NIDCD.]
Dynamic range compression effects on modulation detection interference.
Authors: Lee Jungmee , Souza Pamela , Sabin Andy , Kwon Bomjun , Brennan Marc , Poling Gayla , Petersen Carla
Published: July 2011

Some evidence suggests that perceived amplitude modulation (AM) depth may be exaggerated for listeners with cochlear hearing loss (HI) compared to listeners with normal hearing (NH) due to a less compressive auditory system. Consistent with this, several researchers have demonstrated that interfering AM causes more masking of a target AM [modulation detection interference (MDI)] in HI than NH listeners. This effect might be due to the exaggerated perceived modulation depth in HI listeners. There is also evidence that the modulation depth of amplitude envelope fluctuations will be reduced by dynamic range compression (often used in hearing aids). MDI should therefore be smaller with a compressed interferer, due to the reduced modulation depth of the interferer. However, Shen and Lentz [(2010)] showed the opposite result. Specifics of that study included a processor that resulted in some artifacts and somewhat extreme compression parameters. The present study uses a low-distortion compressor with a range of compression parameters to investigate the effect of compression representative of wearable aids on MDI. We will report the influence of input level (re kneepoint) and attack/release time on MDI in NH and HI listeners.
Stimulus-based diotic and dichotic models that combined cues for detection of tones in reproducible noise.
Authors: Mao Junwen , Vosoughi Azadeh , Carney Laurel H.
Published: July 2011

Understanding speech in noisy backgrounds is a classical problem for people with hearing loss. The mechanisms for detection of pure tones in noise are still not fully understood. In this study, models that combined cues across epochs were constructed to predict binaural psychophysical experimental results. The data came from previous experiments, in which listeners were required to detect a 500-Hz tone in either narrowband or wideband reproducible noise waveforms in both diotic and dichotic conditions. For the diotic condition, cues were correlated and could be described by a multivariate distribution. Cues were combined using the covariance matrix. Decision variables based on the likelihood ratio of the tone presence were compared to the listeners’ detection patterns. Energy, envelope-slope, and fine-structure cues were combined optimally in the model. For the dichotic condition, the same strategy was applied by combining interaural level and interaural time differences. Better predictions were obtained from this model compared with models that relied on a weighted sum of the two cues. In addition, a modified envelope-slope model that computed the slope of the difference of the envelopes at the two ears yielded better predictions than models based on interaural time and level differences for the dichotic condition. [NIH-NIDCD-R01DCO1O813.]