bluuebunny/crossref_metadata_2025 huggingface dataset:
Directional cues for sound source segregation in birds, crocodilians, and lizards
Authors: Carr Catherine E. , Christensen-Dalsgaard Jakob
Published: May 2014

Sound source segregation depends on neural mechanisms that enhance directionality. The main directional cues are interaural time difference (ITD) and interaural level difference (ILD). Birds, crocodilians, and lizards have a brainstem circuit used for detection of ITDs. In birds and crocodilians, this circuit forms a map of ITD by delay lines and coincidence detection. The physical range of ITDs for these maps are small in animals with small heads, which should make detection of ITDs difficult. Both birds and crocodilians have coupled ears, however, which extend the range of ITDs available as well as enhancing ILD. Lizards have even more strongly coupled ears, extending the ITD range by a factor 3, but ITD and ILD covary, and a large part of the ITD is a constant delay created by filtering by interaural cavities, chiefly producing enhanced lateralization. All lizard auditory nerve fibers show strongly directional responses, and effectively every neuron in the lizard auditory pathway is directional, enhancing the already strong lateralization by simple EI-type neural processing, but with no clear maps of auditory space. Thus, the processing of sound direction in the bird, alligator, and lizard CNS is different, but all three groups have mechanisms for enhancing sound source directionality.
Soundscape evaluation on Mississippi State University campus
Authors: Yildirim Yalcin
Published: May 2014

The term soundscape, used first time at the end of 1970s, refers to the sum of the sounds which can be heard and perceived by people in a specific environment (Schafer). The concept of soundscape has recently paid attention to planning and design disciplines where the focus point is commonly placed on the visual, rather than the acoustic aspect. The perception of an outdoor environment does not only depend on the physical features of a site, but also relies on the characteristics of the users. Thus, this research will examine how objective measurement of soundscape might be different from subjective perceptions of users in the Mississippi State University Campus as a public open space due to demographic and climatic variations. Stage one, as a pilot or a preliminary study, was a soundscape walk with a small group in four selected sites. Stage two will include more detailed interviews in these sites with a much larger sample size from the general public. At the end of the study, the research findings will help to characterize soundscapes of different types of urban open spaces and to understand how a person perceives and evaluates the sound qualities in these areas.
Acoustic measurements based on a soundscape analysis in an open-plan classroom in a primary school
Authors: Shin Sang Bong
Published: May 2014

It is critical to fully understand the acoustic environment in open plan classrooms because there is a current increasing popularity of a new type of classrooms and because it has been reported that the open plan classroom has a serious problem of noise. Since the architectural features of the open plan classrooms are different from those of traditional classrooms, traditional measurement methods are not sufficient to investigate the new type of classrooms. In this study, a new type of open-plan classroom combined with small classrooms is examined with soundscape approaches. Acoustical events occurring in the open-plan classroom in a primary school were analyzed, and the activities that created the specific acoustical events were observed using methods of soundwalks, focus group discussions, and narrative interviews. Also acoustic measurements were conducted with measurement sets from soundscape analysis and from traditional methods in the building. The results of measurements were compared to determine the differences in the effects of measurement methods on the acoustical events in open plan classrooms. The study found that the results of the acoustical measurements based on soundscape analysis are different from those of traditional measurement methods. The differences among the measurement sets demonstrate that it is useful to use soundscape analyze to understand open plan classrooms.
Solutions to cocktail-party-like problems in acoustic insects
Authors: Römer Heiner
Published: May 2014

Insects often communicate by sound in mixed species choruses; like humans and many vertebrates, in crowded social environments, they thus have to solve cocktail-party-like problems in order to ensure successful communication. This is a particular problem in species-rich environments like tropical rainforests with background noise levels of up to 60 dB SPL. I describe three “bottom-up” mechanisms in cricket receivers, which contribute to an excellent neuronal representation of conspecific signals under such conditions. First, more sharply tuned frequency selectivity of the receiver reduces the amount of masking energy around the species-specific calling song frequency, resulting in a signal-to-noise ratio (SNR) of −8 dB, when masker and signal were broadcast from the same side. Second, spatial release from masking improved the SNR by further 6 to 9 dB. Neurophysiological experiments carried out in the nocturnal rainforest yielded a further improvement of SNRs by 8 dB compared to the laboratory. Finally, a neuronal gain control mechanism enhances the contrast between the responses to signals and the masker, by inhibition of neuronal activity in inter-stimulus intervals. The results indicate that without knowledge of receiver properties and the spatial release mechanisms the detrimental effect of noise may be strongly overestimated.
Cross-modal integration and non-linear relationships: What can frogs tell us about solving cocktail party problems?
Authors: Taylor Ryan C.
Published: May 2014

Courtship in most anuran amphibians occurs in noisy environments, analogous to human communication at cocktail parties. Female frogs express strong mating preferences for particular properties of male vocalizations, but how they identify individual callers within the noisy chorus environment remains unclear. One possible mechanism is cross-modal integration, whereby females attend to both acoustic and visual cues (male vocal sac inflation). In choice experiments, we used a robotic frog with an inflating vocal sac, combined with acoustic playbacks, to test the role of cross-modal integration in female tüngara frogs. In nature, male tüngara frogs produce a two-note courtship call and the vocal sac inflates synchronously during production of both notes. We tested female mating preferences when we artificially varied the temporal synchrony of the vocal sac inflation relative to the two call notes. Some combinations elicited a strong preference from females, some combinations generated a strong aversive response, and other combinations were neutral. These data show that females conduct cross-modal assessments of male callers. The temporal combinations that elicited positive, negative, or neutral responses were not predictive in a linear fashion, however, suggesting that the integration of visual cues may strongly modulate auditory perception in females.
Comparative perception of temporally overlapping sounds
Authors: Neilans Erikson G. , Dent Micheal L.
Published: May 2014

Parsing the auditory scene is a problem faced by humans and animals alike. Characteristics such as frequency, intensity, and location all help organisms assign concurrent sounds to specific auditory objects. The timing of sounds is also important for object perception. When sounds totally overlap in time, ascribing separate sounds to individual objects is difficult. However, slight temporal separations make this task slightly easier. In humans, synchronous streams of high and low frequency tones are heard as a single auditory stream. When the tones are slightly offset in time from one another, a second stream emerges. Here, we compared the perception of simultaneous, asynchronous, and partially overlapping streams of tones, human speech sounds, and budgerigar (Melopsittacus undulatus) contact calls in budgerigars and humans using operant conditioning methods. Human and bird subjects identified the partially overlapping stimuli differentially. Both species required less temporal separation to identify the sounds as “asynchronous” for the complex stimuli than for the pure tones. Interestingly, the psychometric functions differed between the two species. These results suggest that both humans and nonhumans are capable of using temporal offsets for assigning auditory objects, and that the ability to do this depends on the spectrotemporal characteristics of the sounds.
Neural correlates of hearing in noise in macaque auditory cortex
Authors: Cohen Yale , Bennur Sharath
Published: May 2014

The perception of sound in a noisy environment is a critical function of the auditory system. Here, we describe results from our study into the link between neural activity in the auditory cortex and the hearing-in-noise tasks described above. We recorded neural activity from single neurons in the core auditory cortex (i.e., A1) while monkeys were participating in these tasks. Neural recordings were conducted with tetrodes, and the frequency of the target matched the best frequency of the recorded auditory neuron. We found that the relative intensity of the target tone in the presence of the noise masker significantly modulated the response of A1 neurons. In contrast, the presentation of the target sound alone did not elicit a significant response from A1 neurons. This suggests a task-relevant contextual modulation of A1 responses during hearing in noise. Additionally we found no correlation between the monkey's behavioral choices—as assessed by their responses on choice trials—and A1 activity. Our results suggest that the encoding of a sound of interest in the presence of a noise masker is an active process, providing new insights into the neural basis for hearing in noise in the auditory system.
Observations of fission/fusion processes in fish aggregations using a multibeam echosounder
Authors: Weber Thomas C. , Grunbaum Daniel , Stanton Timothy K.
Published: May 2014

Models of fish behavior within aggregations typically incorporate a fish's ability to sense near neighbors. Some newer models also include a cognitive functionality that allows the fish to understand not only the action of the near neighbors but also their intent. This cognitive function might be manifested, for example, in some stochastic estimate of the movement of a local population rather than at the individual level. Inherent in such a function are the temporal and spatial scales at which a fish's cognitive function operates. To help constrain these scales we have analyzed acoustic backscatter from walleye pollock collected with a multibeam echosounder as part of the NOAA Alaska Fisheries Science Center survey. During this survey, repeat passes that were approximately 1 nmi long were collected at approximately 15 mi intervals over an aggregation of fish. In at least one case, we have been able to acoustically observe an initial group of fish that undergoes both fission (splitting) and fusion (recombining) behaviors. In doing so, we are able to track the net movement, speed, and size of various parts of the group, thereby providing some ground truth for cognitive functionality models. [Research supported by the U.S. Office of Naval Research.]
Bioacoustic absorption spectroscopy measurements at the shelf beak off Oregon
Authors: Diachok Orest
Published: May 2014

This paper describes the results of a Bioacoustic Absorption Spectroscopy (BAS) experiment, which was conducted at a biological hot spot at the shelf break off Oregon in August 2012. The location of the hot spot was identified by a NW Fisheries Science Center survey. This experiment included coincident measurements of transmission loss (TL), fish layer depths, fish length distributions, and continuous temperature profiles. The objective was to derive the bioacoustic parameters of hake (a physoclist), the dominant species in this region and other species from measurements of TL vs. range (0–10 km), frequency (0.3–5 kHz), depth (0–260 m), and time of day, and demonstrate consistency with trawl and echo sounder data. TL measurements were conducted between a moving, ship-deployed, broadband source and a 24 element, water column-spanning vertical array, which were provided by the Naval Research Laboratory. This was the first BAS experiment that targeted a physoclist. Previous BAS experiments targeted physostomes. The TL data exhibited absorption lines that were as high as 2 dB/km. Absorption lines at relatively high frequencies, which were observed on near-surface and mid-ocean hydrophones, are attributed to myctophids. Absorption lines, which were observed at relatively low frequencies on near-bottom hydrophones, are attributed to hake.
Three-dimensional ultrasound computer tomography at Karlsruhe Institute of Technology (KIT)
Authors: Ruiter Nicole V. , Zapf Michael , Hopp Torsten , Kretzek Ernst , Gemmeke Hartmut
Published: May 2014

The KIT 3D USCT surrounds the breast with ultrasound transducers on a 3D aperture and emits and receives nearly spherical wave fronts for synthetic aperture focusing. This full 3D system achieves isotropic 3D resolution, has a nearly spatial invariant point spread function, and allows fast data acquisition. The 3D USCT device is equipped with 2041 ultrasound transducers. The acquisition is carried out by sequentially selecting a single emitter, sending a chirp at 2.5 MHz center frequency and recording the transmitted and reflected waves with all receivers. Rotational and translational movement of the aperture is applied to enhance the image contrast. Up to 40 GB of raw data is acquired with 480 parallel channels for digitization at 12 bit and 20 MHz sampling frequency. In a first pilot study, ten patients with different lesions were imaged. Speed of sound, attenuation, and reflection images of each patient were derived from the raw data. Overlaid volumes of the modalities show qualitative and quantitative information at a glance. The results are promising because the breasts' tissue structures and cancerous lesions could be identified in the USCT images.
Boundary conditions in quantitative elastic modulus imaging
Authors: Seidl Daniel T. , Babaniyi Olalekan A. , Oberai Assad A. , Barbone Paul E.
Published: May 2014

Quantitative elastic modulus imaging from quasistatic strain fields has several advantages over other approaches. It requires no specialized hardware, provides spatial resolution nearly commensurate with Bmode, and may be extended to quantitative nonlinear modulus imaging in a straightforward way. It has the drawback, however, of requiring the solution of a complex inverse problem with an ultrasound measured displacement field. The most common approach to solving the inverse problem is iterative optimization. To solve the inverse problem, the experimental configuration is simulated. Material property distributions in the simulated experiment are then varied until the simulated deformation field matches the observed deformation field. The weak link in this process is uncertainty in the experimental conditions. In the context of iterative inversion, this translates into uncertainty in the boundary conditions of the forward model. In this talk, we discuss how different choices of displacement and/or traction boundary conditions affect the inverse problem's solution using phantom and clinical breast data. We show that a Bayesian estimate of the displacement field in the face of uncertain boundary conditions can be implemented by spring finite elements on the domain boundary. [Authors gratefully acknowledge funding from NSF and NIH (NSF SI2 Grant No. 1148111; NIH NCI-R01CA140271).]
Relationship between pitch and rhythm perception with tonal sequences
Authors: Guzman Sandra J. , Almeida Robert , Glass Karson , Elston Cody , Shafiro Valeriy , Sheft Stanley
Published: May 2014

Past work has shown varying degrees of relationship between pitch and rhythm perception. Current work investigated the relationship between pitch and rhythm processing in a four-tone sequence-reconstruction task which places additional demands on short-term memory. Sequence tones either had a fixed duration (212 ms) with frequency randomly selected from a logarithmically scaled distribution (400–1750 Hz), a fixed frequency (837 Hz) with a randomly selected log scaled duration (75–600 ms), or a random frequency and duration. In initial conditions, the task was to assemble sequence elements to recreate the target sequence for each of the three sequence types. To evaluate effect of extraneous randomization, both frequency and duration were randomized in the final two conditions with only one of the two attributes defining the target sequence. When only one stimulus attribute was randomized, performance was significantly better with sequences defined by pitch rather than rhythmic variation. Combining pitch and rhythmic variations led to a slight improvement in performance, while the introduction of extraneous variation had little to no effect when either pitch or rhythm defined the target sequence. Overall, there was a wide performance range across listeners with listeners clustered primarily by ability to use pitch information. [Work supported by NIH.]
Examining the influence of forward, backward, and simultaneous notched noise on the mid-level hump in intensity discrimination
Authors: Roverud Elin , Strickland Elizabeth A.
Published: May 2014

Psychoacoustical intensity discrimination limens (IDLs) for high frequency, short duration pedestals are poorer at mid levels than at lower and higher levels. It has been theorized that this so-called midlevel hump (MLH) may reflect mid-level cochlear compression, whereas the improvement at higher levels may be due to spread of excitation cues. To characterize intensity discrimination within a single frequency channel, researchers (e.g., Plack, 1998) have used simultaneous notched noise (NN) to limit cues from the spread of excitation to other channels. However, additional effects of the NN on the pedestal remain a matter of debate. The NN may provide a reference against which intensity judgments are made. Additionally, the NN may produce excitatory masking in the pedestal frequency channel, suppress the pedestal, and evoke cochlear gain reduction via the medial olivocochlear reflex. These latter two mechanisms change the basilar membrane compression slope, but operate over different time courses. In the present study, we examine the MLH with different durations of forward, backward, and simultaneous NN and pure tone maskers to isolate these potential mechanisms. Results will be interpreted using a computational model of the auditory system. [Research support provided by grants from NIH (NIDCD): R01-DC008327 and the Purdue Research Foundation.]
Gap detection in school-age children and adults: Effects of marker center frequency and ramp duration
Authors: Porter Heather , Buss Emily , Hall Joseph W. , Grose John H.
Published: May 2014

Data on the development of auditory temporal processing varies widely across studies, depending on the particular stimulus (e.g., marker center frequency) and the methods used to quantify performance. Recently, gap detection thresholds were observed to be adult-like later in childhood for narrowband low-fluctuation noise (with 40-ms ramps) than wideband Gaussian noise (with 4-ms ramps; Buss et al., 2013). These results could reflect relatively protracted development of the ability to detect gaps in spectrally narrow stimuli compared to broader stimuli, irrespective of inherent stimulus fluctuation. That is, the use of across-channel cues that benefit gap detection for wideband stimuli could develop early in childhood. Alternatively, age effects in gap detection may depend on center frequency or ramp duration. The present study measured gap detection for low-fluctuation narrowband noise with either a low (500 Hz) or a high (5000 Hz) center frequency, and for wideband noise with short (4 ms) or long (40 ms) ramps. Listeners were normal-hearing 4- to 16-year-old children and adults. Results will be discussed in terms of the effect of center frequency, ramp duration, and across-frequency cues on gap detection for children and adults.
The effects of amplitude envelope and context on auditory duration perception
Authors: Chuen Lorraine , Schutz Michael
Published: May 2014

Here, we extend research indicating that a sound's amplitude envelope (changes in intensity over time) affects subjective duration (Grassi and Darwin, 2006). Specifically, we explore whether amplitude envelope affects the strategies underlying duration perception by comparing “flat” (abrupt onset, sustain, abrupt offset) and “percussive” (abrupt onset followed by exponential decay) envelopes. Participants performed a two alternative forced choice task: judging which of two tones sounded longer. Trials were divided into blocks organized by envelope: (a1) uniform flat-flat, (a2) uniform percussive-percussive, and (b) mixed (uniform, percussive-flat, and flat-percussive). This was designed to either permit (a) or prohibit (b) envelope-specific listening strategies. Block order was counterbalanced across participants. An analysis of the first block (a between-subjects comparison of uniform and mixed block performance) indicated that performance on flat-flat trials was not significantly different for the two block types, whereas percussive-percussive trial performance was significantly worse for the mixed block. This suggests that participants optimally employ an envelope-specific strategy for the uniform block (a) when able to predict envelope, and a generalized strategy in the mixed block (b) when unable. Interestingly, there was no performance advantage for the uniform block when presented second, suggesting that contextual order effects may affect auditory duration perception.
Infants ability to perceive changes in timbre
Authors: Lau Bonnie K. , Werner Lynne A.
Published: May 2014

Recent studies have demonstrated that infants can ignore spectral changes in sequentially presented complex tones and categorize them on the basis of missing fundamental pitch. However, infants' ability to discriminate these spectral changes is unknown. This study investigated the ability of adults, 7- and 3-month-olds to perceive changes in the spectral centroid of harmonic complexes using an observer-based method. Stimuli were 500-ms complex tones, with 20-ms raised cosine onset/offset ramps presented at 70 dB SPL. All harmonics were generated up to 10 000 Hz then bandpass filtered with a -24 dB/octave slope around the center frequency (CF). The experiment consisted of five phases that presented complexes with a 15, 10, 5, 2, or 0.5% ΔCF. To demonstrate timbre discrimination, participants were required to ignore changes in the fundamental frequency of complexes which randomly varied between 170, 180, 190, 200, 210, and 220 Hz, and to respond only when the CF of the spectral centroid changed. Infants were tested on three conditions (15, 10, 5%, or 15, 2, 0.5%). Adult participants were tested on all phases until they reached a phase they could not discriminate. Preliminary results indicate that infant performance is comparable to adults, suggesting discrimination of timbre at 3 months.
Pitch shifts in scale alternated wavelet sequences and the prediction by auditory image model and spectral temporal receptive field
Authors: Tsuzaki Minoru , Irino Toshio , Takeshima Chihiro , Matsui Tohie
Published: May 2014

SAWS's are acoustic stimuli in which an impulse response of vocal tract and its scaled version are alternately placed in the time domain at a constant periodic rate. When the scale factor is close to unity (1.0), the perceived pitch corresponded to the original periodicity. As the difference in the scaling became large, the pitch tended to be matched to what corresponds to be lower than the original by an octave. One of the characteristics of this pitch shift was that the pitch chroma did not change. This sort of pitch continuum could not be realized by changing the fundamental frequency of harmonic complex tones, but could be realized by attenuating the odd harmonics of them. Two auditory models were used to predict this pitch shift phenomenon, i.e., AIM by Patterson's group; STRF by Shmma's group. Both models could predict the pitch shift by an octave, but AIM predicted the pitch ambiguity better than STRF. While it is easy to find the secondary local peak of periodicity besides the primary peak, the peak activity in STRF was singular in most cases. The results suggested that AIM could preserve the temporal fine structure better than STRF.
The sharp frequency selectivity of low- and medium- spontaneous rate auditory nerve fibers might allow for rate-place coding up to 5 kilohertz
Authors: Cantu Marcos A.
Published: May 2014

One feature that might differentiate the three types of spontaneous rate (SR) auditory nerve fibers (ANFs) is the sharpness of frequency tuning at comparable sound pressure levels. My hypothesis, prior to modeling the tuning curves for each fiber type, was that low-SR fibers have a higher threshold for stimulation and thus have sharper frequency selectivity than medium-SR fibers, which in turn have sharper frequency selectivity than high-SR fibers. The results of the simulation support this framework. I used the Zilany et al. (2014) model of the auditory periphery and the cochlear tuning parameters from Shera et al. (2002) to generate tuning curves and neurogram raster plots for each of the three fiber types. The results of the simulation suggest that the sharp frequency selectivity of low-SR and medium-SR ANFs might allow for resolved rate-place coding up to 5 kHz. At frequencies below 1500 Hz, high-SR fibers were seen to have very different response properties than low-SR and medium-SR fibers. It is conceivable that the different fiber types constitute parallel pathways and mediate two different coding schemes. We should consider whether these sharply tuned low-SR and medium-SR ANFs, while fewer in number than High-SR ANFs, might be especially important for rate-place frequency coding.
Neural discrimination of degraded speech
Authors: Steadman Mark , Sumner Christian J.
Published: May 2014

Cochlear implants provide a degraded input to the auditory system. Despite this, cochlear implant users are able to discriminate speech sounds in quiet with a degree of accuracy comparable to that of normal hearing listeners. The neural bases of this phenomenon is not well understood. A set of vowel-consonant-vowel phoneme sequences, each produced by multiple talkers, were parametrically degraded using a noise vocoder. Neural responses were recorded in the guinea pig midbrain and cortex, and auditory nerve responses were generated using a computational model. The discriminability of these responses was quantified using a nearest neighbor classifier. When envelope modulations were limited to 16 Hz, classifier performance was qualitatively similar to that of human listeners for all brain regions. However, in the auditory nerve and the midbrain, the preservation of high rate envelope cues enabled the near perfect discrimination of speech tokens even for heavily spectrally degraded speech. High rate envelope cues do not appear to increase discriminability of auditory cortex responses. High rate envelope cues, represented up to the midbrain, are useful for discriminating speech tokens. However, qualitatively more consistent with perception, high rate envelope cues do not contribute to the discriminability of cortical neural responses.
Shear-wave velocity estimation from different type of sediments
Authors: Dong Hefeng
Published: May 2014

This paper presents estimates of shear-wave velocity profiles for different types of sediments by inverting the dispersion curves of interface waves. Data used in this study were collected at different locations with different recording devices in different experiments. Four data sets were analyzed. Data from one set were recorded by hydrophone array, and data from other three sets were collected by multi-component ocean bottom seismic cables. The configuration of the experimental setup and the environmental conditions were different for the different experiments. Water depth varied from 2 m to 365 m. The frequency range of the interface-wave data was from 1.5 Hz to around 20 Hz. The phase-velocity dispersion curves of the interface waves were extracted using different time-frequency analysis methods. The maximum penetration depth of the interface waves to the sediments varied from 15m to 180 m. A Bayesian nonlinear inversion approach was used for estimating shear-wave velocity profiles as a function of depth in the sediments and the uncertainties. The estimated shear-wave velocity profiles from different experiment and different sediment type were discussed and compared.
Biosonar auditory model for target shape perception and clutter rejection
Authors: Simmons James A. , Warnecke Michaela , Gaudette Jason E.
Published: May 2014

Big brown bats (Eptesicus fuscus) emit widely beamed biosonar sounds that contain two prominent harmonics (FM1, FM2). They exploit the ripple spectrum of multiple-glint echoes to perceive target shape and the relative weakening of higher harmonic FM2 frequencies in lowpass echoes from the surrounding scene to suppress clutter. Delay discrimination experiments using electronically generated echoes show that (1) flat-spectrum or ripple-spectrum echoes are perceived as having sharply focused delay images, (2) lowpass filtering causes defocussing of perceived delay, and (3) masking release occurs between defocused images of lowpass echoes and focused images of full-band echoes. A time-frequency auditory model for the decomposition of FM echoes into temporal and spectral dimensions, followed by reconstitution of object images in terms of delay alone accounts for both shape perception and the release from clutter masking. The model's structure resembles a neuronal spectral pattern-recognizing network grafted onto a neuronal delay-line/coincidence-detection delay-determining network. The categorical segregation of focused target shape from defocused clutter emerges from a novel anticorrelation process that depends on the auditory system's restricted range of lateral interactions across adjacent frequencies. [Work supported by ONR, NSF, BIBS, and JSPS.]
Biosonar dynamics in horseshoe and old-world leaf-nosed bats
Authors: Mueller Rolf , Gupta Anupam K. , He Weikai , Pannala Mittu
Published: May 2014

Horseshoe bats (family Rhinolophidae) have evolved a capable biosonar system to allow the pursuit of prey amid dense vegetation that produces large amounts of clutter echoes. Horseshoe bats have long been known to employ dynamic effects such as Doppler effect compensation and large-scale rotations of their pinnae to realize these capabilities. Recent research has produced evidence of even more pervasive dynamical biosonar properties in horseshoe bat biosonar as well as in the related Old World leaf-nosed bats (family Hipposideridae). On the emission side, these animals employ elaborate baffle shapes that surround the exit points of their ultrasonic pulses (nostrils). During echolocation, multiple parts of these noseleaves such as the anterior leaf and the lancet in horseshoe bats are set in motion, typically in synchrony with pulse emission, hence creating a time-variant channel for the exiting wave packets. Similarly, the pinnae which diffract the incoming echoes on the reception side are frequently in motion while echoes impinge on them. These motions include non-rigid changes in shape. All these effects add a dynamic dimension to the interface of the bats' biosonar with the external world, which could allow the animals to enhance the quantity and quality of the sensory information they receive.
Model-based and in-situ observations of high-frequency (10s–100s kHz) acoustic scattering from multiple targets
Authors: Urmy Samuel S. , Warren Joseph D.
Published: May 2014

The biomass of many fish and plankton stocks is estimated using active acoustics and the echo-integration method. This method relies on the assumption that the acoustic energy backscattered by schools or aggregations varies linearly with the number of scattering targets. While accurate under most circumstances, theory predicts this assumption will break down at high scatterer densities, a prediction that has been confirmed experimentally in previous studies. The number of studies exploring these effects, however, remains small. Departures from linearity may be caused by multiple scattering, shadowing effects, and/or resonant spacing of targets at the ensonifying frequency. We explored these effects on different configurations of scatterers using a combination of theory, computer modeling, and in-situ measurements on standard targets. The computer model in particular facilitated controlled testing on scattering configurations that would be difficult to achieve in-situ. We found that the linearity assumption is supported at most densities commonly encountered in fisheries surveys, but that there are some situations where nonlinear effects become important and should be considered. These results will be useful in the interpretation of echo-integration data from a variety of species and ecosystems.
Time domain investigations of acoustical scattering from schools of swim bladder fish
Authors: Raveau Maria P. , Feuillade Christopher
Published: May 2014

Recent studies of time independent scattering from schools of swim bladder fish reveal important differences between the predictions of a mathematical model, which fully incorporates multiple scattering processes between the fish, and a second approach which treats the school as an effective medium with complex sound speed determined by the swim bladder resonance function. In back scattering, both modeling and data comparisons show that the effective medium approach underestimates the scattering amplitude when the fish separation is greater than about a quarter of the incident wavelength. In contrast, comparisons in the forward scattering direction show good agreement. These results are critically significant for time domain investigations of fish school scattering, aimed at using spatial and temporal variations in the acoustic field to study the stochastic behavior of the distribution and motion of the fish ensembles. A simple approach, using the inverse FFT of the school model and effective medium harmonic solutions, again reveals the limitations of the effective medium approach in back scattering. However, to obtain high resolution time sampling, more sophisticated time domain solution techniques based upon numerical integration and perturbation theory approaches are necessary. Both computational studies and data comparisons will be presented. [Research supported by ONR.]
Optimization of the aperture and transducers of a three-dimensional ultrasound computer tomography system
Authors: Gemmeke Hartmut , Zapf Michael , Hopp Torsten , Ruiter Nicole V.
Published: May 2014

In previous work we optimized the aperture of our 3D Ultrasound Computer Tomography (USCT) system with emphasis on reflection tomography. Based on the promising clinical results with speed of sound and attenuation images, the next generation aperture will be upgraded to contain also optimization for transmission tomography. The main changes to be implemented in aperture, transducers, and transducer arrays are: (1) Overall 3D aperture: due to the shape of the buoyant breast a simpler hemispherical aperture can be applied. (2) The diameter of the aperture will be increased and the diameter of the transducers will be decreased for further homogenization of the illumination. (3) The disjunctive sampling of the transducers will be increased and the transducers will be distributed randomly to enhance the uniformity of transmission tomography. (4) Transducers will be connected both as emitters and receivers to decrease the need for mechanical movement of the aperture.
Using higher-order scattering in seismic imaging
Authors: Verschuur Dirk J.
Published: May 2014

For seismic exploration, acoustic sources and receivers are positioned at the earth's surface in order to measure the reflection response from the subsurface inhomogeneities. However, in most current imaging algorithms, only the primary reflections are being taken into account and multiple reflections are being discarded as noise. In the recently proposed method of full wavefield imaging, the higher-order scattering is taken into account in the imaging process where they contribute to extend the illumination area and no longer produce spurious imaging artifacts. This method involves an inversion process, where a recursive modeling method is used to predict the measured reflection response—including all its higher-order scattering effects—based on estimated reflectivity values and background velocity model. Because the background velocity cannot be assumed to be homogeneous in the earth, background velocity model estimation is a crucial component of the imaging process. It appears that automatic estimation of velocity models can be accomplished within the concept of full wavefield migration, in which higher-order scattering events can also be fully accommodated. Finally, the results of full wavefield imaging can be combined with localized, target-oriented full waveform inversion in order to get the final details, being the elastic properties, at the target zone.
Highlights of the Underwater Acoustics Technical Committee at the 167th Meeting of the Acoustical Society of America
Authors: Isakson Marcia
Published: May 2014

The underwater acoustics (UW) technical committee (TC) is a dynamic group of investigators researching such varied fields as acoustic tomography, underwater acoustic communications, and shallow water waveguide propagation. In this overview of the UW TC, a brief introduction of the goals and interests of the community will be followed with a series of highlights of what one can expect at the UW sessions.
Introduction to the Structural Acoustics and Vibration Technical Committee
Authors: Phillips James E.
Published: May 2014

The Structural Acoustics & Vibration Technical Committee (SAVTC) includes the study of motions and interactions of mechanical systems with their environments and the methods of their measurement, analysis, and control. This talk will provide a broad overview of the many research areas of interest to SAVTC. A few topics will be explored in more depth to provide background on some of the more common analysis methods used by members of the technical committee.
Architectural Acoustics-Space for sound, and you
Authors: Case Alexander U.
Published: May 2014

The discipline of Architectural Acoustics consistently produces more than 100 papers across six or more special sessions, at each meeting of the ASA. Student paper awards, student design competitions, and Knudsen lectures augment these activities. Joint sessions, particularly with Noise, Musical Acoustics, Psychological and Physiological Acoustics, and Signal Processing in Acoustics, add more still to the architectural acoustics goings-on at every ASA conference. The sphere of influence is not limited to ASA alone, as TCAA members participate in the Green Construction Code of the International Code Council, Society of Motion Picture and Television Engineers Study Group: Movie Theater Sound System Measurement and Adjustment Techniques, Classroom Acoustics Standards, the American Institute of Architects Continuing Education System, and more. This busy committee also produces a steady stream of publications documenting recent work and deciphering standards for key stakeholders. Anyone with an interest in the field will find many opportunities to advance their own expertise, build a network of colleagues, friends, and mentors, and contribute to the essential activities of the Technical Committee on Architectural Acoustics.
Psychological and Physiological Acoustics: Investigating the auditory system and its responses to sound
Authors: Gallun Frederick J.
Published: May 2014

Psychological and physiological acoustics concerns the investigation of the auditory system and its responses to sound in humans and other species. This encompasses perception and perceptual organization of simple and complex sounds, including speech; anatomy and function of the auditory pathways, including all physical and biological responses to auditory stimulation; hearing disorders, hearing loss, and auditory prostheses; vibrotactile and vestibular sensation, and the interaction of hearing with other sensory modalities; developmental, aging, learning, and plasticity effects in auditory function; and theories and models of auditory processes. This talk describes several current areas of research, including the benefits of having two ears, how intense noise can damage the auditory nerve, and how computational models of the auditory system can complement behavioral and physiological experiments to broaden our understanding of how the auditory system responds to sound.
Sound power levels of the Caxirola and different types of caxixis
Authors: Pozzer Talita , Paul Stephan
Published: May 2014

In 2014, Brazil will host the FIFA World Cup and Brazilian Musician Carlinhos Brown created the caxirola as the official music instrument, adapting an old African instrument—the caxixi. In both instruments, the sound is generated by hard particles impacting on the walls of a closed basket. While the caxirola is made of environmental-friendly polymer, the caxixi is handcrafted of natural components. At a previous ASA meeting [Pozzer and Paul, J. Acoust. Soc. Am. 134(5), 4187 (2013)], we presented both instruments and sound pressure levels measured at users ears. Being handmade makes the caxixi to be highly variable in size and proportions, in contrast to the caxirola which is an industry product. We now present sound power level (SWL) measurements made by the hemi-anechoic room method and the reverberation chamber method. The SWL measured for the caxirola was 79 to 86 dB (80 to 85 dBA) for transversal and longitudinal use, respectively. The SWL of four different caixixis measured ranged between 69 and 80 dB (70 to 79 dBA). Octave band SWLs were found to be higher for the caxirola compared to all four caxixi in the 500 Hz to 4 kHz bands.
Perception of combination tones correlated to cochlear activity
Authors: Suha Victoria , Epstein Michael
Published: May 2014

String players producing double stops at certain intervals perceive a third note that is not physically present (combination tone). This experiment was designed to determine whether or not this combination tone is a result of measurable cochlear activity. Young, normal-hearing musicians matched the pitch and rated the loudness of combination tones perceived in the presence of pairs of pure tones. These matches and ratings were compared with distortion-product otoacoustic emissions (DPOAEs) generated by the same tone pairs. While there was some variability in listener performance, with some listeners making inconsistent pitch matches across trials, listeners who gave consistent responses pitch matched the combination tone to a frequency close to the strongest DPOAE. This suggests that the perception of combination tones is associated with physical activity within the cochlea.
The need for a soundscape taxonomy
Authors: Schulte-Fortkamp Brigitte
Published: May 2014

It is for some time now that the standardization process in Soundscape in the ISO/TC 43/WG 54 12913 has started. Meanwhile, it has reached the level of decisions regarding evaluation approaches. Hence, as perception is the foreground of any assessment procedures here, on the one hand interviews do play a major role, but also procedures as sound walks. On the other hand, a time to evaluation related psychoacoustic measurement is needed to bring relevant datasets into triangulation. This paper will present the current state of the art in Soundscape and will discuss further input that is needed in this field.
Cross-modal soundscape mapping: Integrating ambisonic field recordings with high dynamic range spherical panoramic photography to produce interactive maps
Authors: Carter J. Parkman , Braasch Jonas
Published: May 2014

We cannot “measure” the soundscape any more than we can “measure” the ocean, the city, or the wilderness. Being comprised of myriad complex elements, conditions, and relationships between sound sources and sound perceivers, the soundscape—and any sufficient description of it—must account for several different, but significantly interrelated, dimensions: physical, spatial, temporal, perceptual, cultural, and historical. How, then, are we to meaningfully document the soundscape? If we are to begin to understand the soundscape's impact on us—and our impact upon it—we need new methods to capture and represent the multisensory extents of a soundscape without reverting to one-dimensional quantitative abstractions. This project proposes an interdisciplinary method to record a soundscape's multisensory attributes by combining aural and visual information in a structured way which links the directionality of view and sound arrival. This method integrates multi-directional Ambisonic audio recordings with high dynamic range (HDR) spherical panoramic photography in the form of interactive maps and virtual tours. Case studies using the cross-modal soundscape mapping method will be presented.
Measurement of hearing-protector attenuation using auditory steady state responses
Authors: Valentin Olivier , John Michael Sasha , Laville Frédéric
Published: May 2014

There is a need to assess hearing protection device (HPD) attenuation to ensure that individuals receive adequate protection from noise. Present methods of attenuation measurement have limitations. Objective measurements such as field microphone in real ear (F-MIRE) do not assess bone conducted sound. Psychophysical measurements such as real ear attenuation at threshold (REAT) are biased due to the low frequency masking effects from test subjects' physiological noise, and the variability of measurements based on subjective response. We explored using auditory steady state responses (ASSR) as a technique that may overcome these limitations. ASSRs were recorded in ten normal hearing adults, using both “normal” and “occluded” conditions. Stimuli included both narrow band noises and pure tones (500 and 1000 Hz), amplitude modulated at 40 Hz. Stimuli were presented through either loudspeakers or headphones, at 45, 55, and 65 dB SPL. “Physiological attenuation” was calculated as the difference between ASSR values (both amplitude and phase) for normal and occluded conditions. Physiological attenuation estimates were compared to in-ear (objective) and psychophysical (subjective) measurements. Grand mean ASSR data complied well with in-ear and subjective measurements. Further work is needed to provide accurate assessment of ASSR-based physiological attenuation for individual subjects.
A public science experiment on the link (if any) between hearing loss and a lifetime of loud music exposure
Authors: Akeroyd Michael , Whitmer William , Mackinnon Robert , Fortnum Heather , Moore David R.
Published: May 2014

It is well known that a lifetime of exposure to loud industrial noise can lead to substantial amounts of hearing damage. The effect of a lifetime of loud music exposure is far less certain, however. To assess if there is such a link, we have launched a public science experiment that combines (a) a questionnaire on the amount of listening to loud music over one's life as well as standard questions on their hearing, and (b) a triple-digit speech-in-noise test specifically crafted for high-frequency hearing losses. The experiment has a dedicated website and takes advantage of the 2013 Centenary of the Medical Research Council to act as a “pull” for the public to participate. Over the 100 years, the MRC has been funding research, there has been revolution after revolution in the technology for music reproduction for the home or stage and in the volumes they can reach. The talk will describe the design of the experiment, the results so far, and our experience-based suggestions for running future web-based, public-science experiments. [Work supported by the Medical Research Foundation, the Medical Research Council, and the Chief Scientist Office, Scotland.]