bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of potential noise conflict zones on the construction and operation of the new Chile-Argentina Aguas Negras Interconection Road
Authors: Fingerhuth Sebastian , Araya Alejandro
Published: June 2017

As part of the infrastructure integration between Chile and Argentina there is the plan to build the Aguas Negras Interconexion Road. It seeks, finally, to improve the physical and commercial connectivity of the zones between the ports of Porto Alegre (Brasil) and Coquimbo (Chile). It passes the Andes Mountaines and includes the construction of a tunnel for vehicular traffic as well as the extension of the access road D-41CH on the Chilean side. This paper presents the result of a study done to establish those cities or communities that may be affected during construction or future operation of the route. It also presents the mitigation actions and solutions that could be used to reduce the noise impact. It was established that there are cities or towns linked to the current route of the D-41 CH route that will be affected directly or indirectly due to its proximity to the current route layout. Finally, it was concluded that the construction and future operation of the D-41 route will cause diverse sound impacts in the different communities along the route.
Classifying type of vehicles on the basis of data extracted from audio signal characteristics
Authors: Marciniuk Karolina , Kostek Bozena , Czyżewski Andrzej
Published: June 2017

The aim of this study is to find and optimize a feature vector for an automatic recognition of the type of vehicles, extracted form an audio signal. First, the influence of weather-based conditions of road surface on spectral characteristic of the audio signal recorded from a passing vehicle in close proximity to the road is discussed. Next, parameterization of the recorded audio signal is performed. For that purpose, the MIRtoolbox, designed for music parameter extraction, is used to obtain a vector of parameters. Correlation analyses are performed to check whether extracted parameters enable to separate selected types of vehicle-associated noise, e.g.: car, truck and motorcycle. Behrens-Fisher statistics is used to find the most suitable parameters that may be contained in the optimized feature vector. The last step is to build a decision system that allows for the automatic classification of a vehicle type. The results of automatic classification of prepared vehicle-noise related samples are shown and discussed. [Research was supported by the Polish National Centre for Research and Development within the grant No. OT4-4B/AGH-PG-WSTKT.]
Acoustic potentials of urban surfaces
Authors: Herget Wolfgang , Brandstätt Peter
Published: June 2017

Noise levels in larger cities have been increasing tremendously due to their growth and the concentration of population. These noise levels have to be controlled properly in order to reduce health hazards, lower the annoyance level for near habitants and work forces and improve life quality. For that purpose, the treatment of ambient sound by means of controlling sound transmission, diffraction, refraction and absorption from sources to receivers are of great importance. Besides reducing the sound radiation of sources, we can analyse and map the resulting sound fields and exploit the walls and surfaces of buildings or streets to reduce the sound level. But, it is a challenge employing currently existing surfaces with innovative concepts and technologies intelligently. Such acoustic urban design and a gain insight of acoustic measurements in the laboratory are shown in the paper. As a perspective to the future, related ideas, technologies and products will be introduced.
A wide-angle topography-capable parabolic equation using a non-transformed coordinate system
Authors: Swearingen Michelle E. , White Michael J. , McKenna Mihan H.
Published: June 2017

Low-frequency acoustic propagation for long ranges (up to 200 km) is of significant military interest, particularly for the purposes of persistent surveillance of denied areas and infrastructure/activity sensing. A deep understanding of the natural environment’s influence on the signal is critical for accurate interpretation of received signals at monitoring stations. Influenced by the underwater acoustics community, a flexible, wide-angle, finite-difference parabolic equation model has been developed. This model handles discontinuities and gradual variations in density and wavenumber, allowing terrain/topography to be represented as range-dependent density and wavenumber profiles. Traditional coordinate-transforming methods for propagation over topography require interpolations and/or extrapolations near the top of the computational boundary when transformed back into the original coordinate system, introducing potentially significant errors. These methods work well for shorter distances, where interpolations/extrapolations are minimized, and bounded systems, such as certain ocean conditions, but potentially produce questionable results as the propagation distances, and influences from the upper domain, increase. While not as computationally efficient, the method presented here does not require a coordinate transformation. An overview of the mathematical development, comparisons to benchmark cases, and a discussion of this method are presented. (Distribution Statement A—Approved for Public Release; distribution unlimited.)
Broadband transmission loss in the audible regime with a 3D sonic crystals by use of resonance overlap
Authors: Groby Jean-Philippe , Lardeau Alexandre , Romero-Garcìa Vicente
Published: June 2017

The acoustic properties of a three-dimensional sonic crystal made of square-rod rigid scatterers incorporating a periodic arrangement of quarter wavelength resonators are theoretically and experimentally reported in this work. The periodicity of the system produces Bragg band gaps that can be tuned in frequency by modifying the orientation of the square-rod scatterers with respect to the incident wave. In addition, the quarter wavelength resonators introduce resonant band gaps that can be tuned by coupling the neighbor resonators. Bragg and resonant band gaps can overlap allowing the wave propagation control inside the periodic resonant medium. In particular, we theoretically and experimentally show that this system can produce a broad frequency band gap exceeding two and a half octaves (from 590 Hz to 3220 Hz) with transmission lower than 3%. Finite element methods were used to calculate the dispersion relation of the locally resonant system. The visco-thermal losses were accounted for in the quarter wavelength resonators to simulate the wave propagation in the semi-infinite structures and to compare the numerical results with the experiments performed in an echo-free chamber. The simulations and the experimental results are in good agreement. This work motivates interesting applications of this system as acoustic audible filters.
What do ultrasound velocity and attenuation tell us about crystal nucleation?
Authors: Povey Malcolm J. , Holmes Mel , Sheng Fei
Published: June 2017

Akulichev and Bulanov showed that a coupling between ultrasound and crystals in equilibrium with their melt would occur leading to high attenuation. This phenomenon is well established. However, what happens in circumstances such as in the induction period where critical fluctuations occur and crystal embryos appear and disappear, i.e. under non-equilibrium circumstances? Evidence is presented that the mean solution adiabatic compressibility is altered by these transient phenomena, providing a unique insight into a poorly understood and industrially crucial process step. Fluctuations in adiabatic compressibility observed as a result of the high measurement rates available with high frequency pulsed ultrasound provide further insight into the early stages of crystal growth phenomena. Later on, when individual crystals begin to interact and sinter a frame modulus emerges which necessitates a semi-phenomenological interpretation.
Acoustical properties of nanoporous activated carbon fibres
Authors: Karpinski Hugo , Umnova Olga , Venegas Rodolfo , Hargreaves Jonathan A. , Nahil Mohamad
Published: June 2017

This work continues a series of studies on the link between the microstructure of multiscale materials and their acoustical properties [1]-[3]. Granular activated carbons are excellent low frequency sound absorbers. Two factors contribute to this. (i) They have three scales of heterogeneities: millimetric grains and micrometric and nanometric inner-grain pores. (ii) The presence of sorption in nanometric pores leads to a decrease of static bulk modulus and, consequently, of the effective low-frequency sound speed. Activated carbon felts also show promising low-frequency sound absorption but have simpler microstructure. They do not contain inner-fibre micrometric pores, but still have inner-fibre nanometric pores. This, combined with a relatively regular fibre arrangement, makes them ideal for studying the effect of sorption on their acoustical properties. In this work, parameters describing the microstructure and sorption kinetics are measured independently for several types of felts with different levels of activation. The predictions of a microstructure-based model [3] are compared with measurements of sound absorption, characteristic impedance and propagation constant. It is concluded that sound absorbers with controlled properties can be designed by varying the level of activation, fibre size and porosity. References: [1] Venegas, Umnova, J. Acoust. Soc. Am. 2011. [2] Venegas, Umnova, J. Acoust. Soc. Am. 2016. [3] Venegas, Boutin, Wave Motion, 2017.
Influence of porosity, fiber radius, and fiber orientation on anisotropic transport properties of random fiber structures
Authors: Luu Hoang Tuan , Perrot Camille , Panneton Raymond
Published: June 2017

The ability of fibrous media to mitigate sound waves is controlled by their transport properties that are themselves greatly affected by the geometrical characteristics of their microstructure such as porosity, fiber radius, and fiber orientation. Here, the influence of these geometrical characteristics on the anisotropic transport properties of random fiber structures is investigated. First, representative elementary volumes (REVs) of random fiber structures are generated for different triplets of porosity, fiber radius and fiber orientation. The fibers are allowed to overlap and are motionless (rigid-frame assumption). The fiber orientation is derived from a second order orientation tensor. Second, the transport equations are numerically solved on the REVs which are seen as periodic unit cells (PUCs). These solutions yield the transport properties governing the sound propagation and dissipation in the respective fibrous media. These transport properties are the tortuosity, the viscous and thermal static permeabilities, and the viscous characteristic length. Finally, relations are proposed to estimate the transport properties and the thermal characteristic length when the geometry of the fiber structures is known.
Towards the individualized estimation of the band importance function for Speech Intelligibility Index
Authors: Shen Yi
Published: June 2017

Speech Intelligibility Index (SII, ANSI S3.5-1997) is a widely used tool for predicting speech recognition performance based on the audibility of the speech stimulus across frequencies. The core of the SII model is the band importance function (BIF), which represents the contributions of different frequency regions to speech understanding. Potential problems associated with the classic approach to assess the BIF have recently been pointed out by a number of researchers, and novel psychophysical techniques have been developed consequently. This presentation presents adaptive psychophysical procedures for the efficient estimation of the BIF. These procedures estimate the spectral weights using either Bayesian or correlational approaches and optimize the stimulus presentation iteratively on a trial-by-trial basis. Initial experimental verification of the procedures using both word and sentence materials will be presented.
How pitch dynamically drives social judgments in speech
Authors: Ponsot Emmanuel , Burred Juan José , Belin Pascal , Aucouturier Jean-Julien
Published: June 2017

Human listeners in social interaction possess the remarkable ability to continuously form high-level social representations from very thin slices of behaviors, and notably from others' voice. However, it turns out to be particularly challenging to design experiments that allow uncovering mental representations of such complex dynamic auditory signals. Here we were able to show how voice’s pitch dynamically drives judgements of social dominance and trustworthiness, two most salient traits in first-impression personality evaluation. We used a specifically developed voice-processing algorithm to create, from a few recordings of brief utterances such as the word “hello,” thousands of novel voices presenting random intonations. These stimuli were then presented in several psychophysical experiments and reverse-correlation was deployed to assess the temporal processing of voice’s pitch underlying the judgments. We found that both dominance and trustworthiness rely on dynamic, not static, pitch contour processes, and that these processes were strikingly similar across both stimuli’ and observers’ gender. These results suggest that humans have developed a unique cross-gender dynamic code to go beyond the dimorphic characteristic of the voice and be able to infer social traits from intonation. The present approach constitutes a starting point to provide mechanistic accounts in population with impaired emotion recognition.
The use of accurate versus heuristic auditory and visual cues for time-to-collision judgments
Authors: Oberfeld Daniel , DeLucia Patricia R. , Keshavarz Behrang , Campos Jennifer L.
Published: June 2017

Estimating time-to-collision (TTC) is needed when pedestrians cross a road and a vehicle is approaching. An accurate auditory cue to judge the TTC of a sound source approaching at constant velocity is provided by the ratio of an object’s instantaneous sound intensity to its instantaneous rate of change in sound intensity (auditory τ). However, heuristic-based auditory cues might also be used, as suggested by research in vision. We presented auditory and visual simulations of approaching objects. Auditory and visual TTC cues were decorrelated by slightly shifting auditory TTC against visual TTC. This permitted the estimation of cue weights for auditory cues (e.g., auditory τ, final sound pressure level) and visual cues (e.g., visual τ, final optical size) in three sensory conditions: auditory-only, visual-only, and audiovisual. Results showed that TTC estimates in the auditory-only condition were primarily based on an auditory heuristic cue (final sound pressure level) rather than on auditory τ. In the visual-only condition, visual τ was more important than the heuristic cues. In the audiovisual condition, participants relied more strongly on visual cues than auditory cues. We discuss the need for more refined auditory simulations to gain further insight into the cue weighting in everyday situations.
Acoustic-phonetic encoding in the human auditory
Authors: Chang Edward F.
Published: June 2017

In this talk, I will address the functional organization of the human auditory cortex and its role in speech processing. I will describe new evidence for global partitioning of the auditory cortex into domains relevant for the encoding the temporal dynamics of connected speech. I will discuss new evidence demonstrating the neural representations of prosodic intonation, phoneme, and speaker identity.
Dual rate codes for the pitch of harmonic complex tones in the auditory midbrain
Authors: Delgutte Bertrand , Su Yaqing
Published: June 2017

Harmonic complex tones contained in speech and music evoke a pitch at their fundamental frequency (F0). This pitch can be produced through either patterns of harmonics individually resolved by the cochlear frequency analysis or periodicity in the amplitude envelope resulting from beating between neighboring harmonics. To investigate how these two pitch cues are coded in the auditory midbrain, we recorded from single units in unanesthetized rabbits in response to harmonic complex tones with varying F0 so as to create conditions where harmonics were likely resolved or unresolved. For F0 above 600 Hz, some neurons showed local maxima in firing rate when a low-order (<6-8) harmonic of F0 coincided with the neuron’s best frequency (BF), thereby providing a rate-place code to resolved harmonics similar to that found in the auditory nerve. For F0 below 800 Hz, some neurons showed rate tuning to a particular F0 unrelated to the BF. Altering the phase relationships among the harmonics showed that this nontonotopic rate code was sensitive to envelope repetition rate and therefore likely derived from temporal cues in the auditory nerve. Thus there are two complementary rate codes for distinct pitch cues, but neither of these codes provides a direct representation of pitch.
Temporal weighting of azimuthal cues in the free field and in headphone listening
Authors: Stecker G. Christopher , Hafter Ervin , Brown Andrew D. , Moore Travis M.
Published: June 2017

Dynamic aspects of binaural cue processing can be captured via several types of psychophysical measurements in human listeners. These include sensitivity measures with spatially dynamic stimuli, temporal integration measurements, and perceptual weighting measurement with stochastic spatial-cue variation. The latter approach has been adopted in a series of papers and ongoing studies. These assessed the time course of binaural lateralization and azimuthal localization as a function of stimulus frequency, bandwidth, modulation rate, temporal regularity, duration, envelope shape, and reverberation. The detailed temporal profile of perceptual weights, or “temporal weighting function,” can be captured psychophysically and through Monte Carlo simulations based on computational binaural model outputs. Among the results that will be reviewed in this talk are (1) demonstration of sparse temporal sampling of binaural cues at moments of positive envelope slope, (2) impacts of cochlear interference on low-frequency binaural cues, (3) evidence for leaky temporal integration of binaural information in late-arriving sound, (4) effects of temporal irregularity on enhanced ongoing-cue sensitivity, (5) distinct patterns in temporal weighting of interaural time and level differences, and (6) enhanced onset dominance in reverberation. [Work supported by R01DC011548.]
Intracranial electrophysiology of human auditory and auditory-related cortex during speech categorization tasks
Authors: Nourski Kirill V. , Steinschneider Mitchell , Rhone Ariane E.
Published: June 2017

Speech perception engages a large cortical network encompassing multiple regions within temporal and frontal lobes. This study examined spatiotemporal dynamics of speech processing using direct electrophysiological recordings from patients undergoing invasive monitoring for surgical treatment of refractory epilepsy. Words were presented in target detection tasks that required acoustic, phonemic and semantic processing. High gamma (70-150 Hz) activity was recorded directly from Heschl’s gyrus (HG), superior, middle temporal and supramarginal gyri (STG, MTG, SMG), and prefrontal cortex (PFC). Analysis focused on task effects (responses to non-target words in a control tone detection task vs. semantic categorization tasks) and target effects (target vs. non-target words in a semantic task). Responses within posteromedial HG (auditory core cortex) represented acoustic stimulus attributes, but did not show task or target effects. Non-core auditory cortex (anterolateral HG and lateral STG) primarily exhibited sensitivity to task. Auditory-related areas (MTG and SMG) and PFC showed both target and, to a lesser extent, task effects. Task and target effects were more prominent in the language-dominant hemisphere. Findings support hierarchical organization of speech processing at the cortical level, wherein acoustic, phonemic, and semantic processing are primarily subserved by core, non-core, and auditory-related cortex, respectively.
Neural representations of restored acoustic rhythm in noise
Authors: Cervantes Constantino Francisco , Simon Jonathan Z.
Published: June 2017

Factors influencing the dynamics of auditory restoration, where acoustically missing information is nevertheless perceived, remain unresolved despite their important contributions to sensory cognition. We present the case of perceptual restoration of acoustic rhythms subject to masking and removal. Neurally, in addition to expected acoustically-driven cortical rhythms, cortical rhythms are also observed in response to absent but expected acoustic rhythms, reflecting purely endogenous neural processes. Experimentally, brief noise masker probes were added to a prolonged 5-Hz rhythmic pulse train, and in half those cases the underlying rhythm was also removed. Listeners continually reported whether probes were perceived as rhythmic or not. Analysis of neural responses obtained by magnetoencephalography (MEG) shows that for cases where an absent rhythm was nonetheless perceived as present, the responses contained greater evoked rhythmic power than when the absent rhythm was perceived as absent. Moreover, such percept-specific neural modulations (at the target rate and others) predict behavioral sensitivity, suggesting that this neural variability in evoked rhythmic power is directly tied to variability in perception. Given the relevance to human communication in noisy environments, it is proposed that sufficiently synchronized neural dynamics may underlie the subjective experience of a sound as modulated, even if unsupported by sensory data.
Auditory attention detection: Application in neuro-steered hearing aids
Authors: Das Neetha , Van Eyndhoven Simon , Bertrand Alexander , Francart Tom
Published: June 2017

State-of-the-art hearing prostheses are equipped with acoustic noise reduction algorithms to improve speech intelligibility. However, cocktail party scenarios with multiple speakers pose a major challenge since it is difficult for the algorithm to determine which speaker it should enhance. To address this problem, electroencephalography (EEG) signals can be used to perform auditory attention detection (AAD), i.e., to detect which speaker the listener is attending to. Taking a step further towards realization of a neuro-steered hearing prosthesis, we worked on AAD-assisted noise suppression in a competing-speakers scenario in the presence of babble noise. We use an EEG-informed AAD module in combination with a blind source separation algorithm to extract the per-speaker envelopes from the microphone recordings, as well as a multi-channel Wiener filter to extract the denoised speech signal(s). Using a new algorithm pipeline, we obtain better AAD accuracies, and a better robustness to variations in speaker positions and signal-to-noise ratios (SNR), compared to previously reported results. Furthermore, the algorithm allows to switch more swiftly to the other speaker’s stream when there is a switch in attention.
Neural correlates of modulation masking release: The role of sound deprivation
Authors: Ihlefeld Antje , Ning Matthew , Chaubal Sahil S. , Alamatsaz Nima
Published: June 2017

It is well documented that for tone detection in background noise, normally-hearing (NH) listeners have better behavioral thresholds when that noise is temporally modulated as compared to temporally unmodulated, a perceptual phenomenon referred to as Modulation Masking Release (MMR). However, hearing impaired listeners often do not show a dramatic difference in performance across these two tasks. Behavioral evidence from Mongolian gerbils (Meriones unguiculatus) with conductive hearing loss (CHL) supports the idea that sound deprivation alone can reduce MMR. Here, MMR was assessed in core auditory cortex in three NH animals, and one animal with CHL. Trained, awake gerbils listened passively to a target tone (1 kHz) embedded in modulated or unmodulated noise while a 16-channel chronically implanted microelectrode array recorded multi-unit neural spike activity in core auditory cortex. Results reveal that rate code correlates with behavioral thresholds at positive, but not negative Signal-to-Noise ratios. Effect of sound deprivation on MMR will be discussed using a Wilson-Cowan neural network model of cortical function. [Work supported by NIH R03 DC014008.]
Multi-fiber coding on the auditory nerve and the origin of critical-band masking
Authors: Houde Robert A. , Hillenbrand James , Gayvert Robert T. , Houde John F.
Published: June 2017

Understanding the physiological mechanisms that underlie the exquisite frequency discrimination abilities of listeners remains a central problem in auditory science. We describe a computational model of the cochlea and auditory nerve that was developed to evaluate the frequency analysis capabilities of a system in which the output of a basilar membrane filter, transduced into a probability-of-firing function by an inner hair cell, is encoded on the auditory nerve as the instantaneous sum of firings on a critical band of fibers surrounding that filter channel and transmitted to the central nervous system for narrow-band frequency analysis. Performance of the model on vowels over a wide range of input levels was found to be robust and accurate, comparable to the Average Localized Synchronized Rate results of Young and Sachs [J. Acoust. Soc. Am. 1979, 66, 1381-1403]. Model performance in perceptual threshold simulations was also evaluated. The model succeeded in replicating psychophysical results reported in classic studies of critical band masking.
Examining the role of a medial olivocochlear reflex elicitor on the attentional modulation of cochlear function
Authors: Beim Jordan A. , Oxenham Andrew J. , Wojtczak Magdalena
Published: June 2017

Selective attention has been shown to modulate cortical and subcortical neural representations of sound in the auditory systems of humans and research animals. Neuroanatomy of the auditory system suggests that cortical activity is capable of modulating cochlear responses to sound via corticofugal projections to the medial olivocochlear (MOC) efferent system. Several human studies using otoacoustic emissions (OAEs) suggest that selective attention can modulate cochlear responses to sound, but results across studies typically show small and inconsistent effects. Recent work in our laboratory has demonstrated much larger effects of cross-modal selective attention on cochlear processing than previously reported, likely due to improved methods for measuring MOC effects. One unanswered question is whether selective attention can modulate cochlear function directly, or whether it only modulates stimulus-elicited MOC activity. Our current study compares OAE magnitudes measured while participants attend to auditory or visual stimuli to perform a behavioral task in the presence or absence of a MOC eliciting noise. Preliminary results indicate that the presence or absence of the MOC elicitor did not change the attentional effects on OAE magnitude.
Visually-guided auditory adaptation and reference frame of the ventriloquism after effect
Authors: Lokša Peter , Kopco Norbert
Published: June 2017

Ventriloquism aftereffect (VA) is observed as a shift in the perceived locations of auditory stimuli, induced by repeated presentation of audiovisual signals with incongruent locations of auditory and visual components. Since the two modalities use a different reference frame (RF), audition is head-centered (HC) while vision is eye-centered (EC), the representations have to be aligned. A previous study examining RF of VA found inconsistent results: the RF was a mixture of HC and EC for VA induced in the center of the audiovisual field, while it was predominantly HC for VA induced in the periphery [Lin et al., JASA 121, 3095, 2007]. In addition, the study found an adaptation in the auditory space representation even for congruent AV stimuli in the periphery. Here, a computational model examines the origins of these effects. The model assumes that multiple stages of processing interact: (1) the stage of auditory spatial representation (HC), (2) the stage of saccadic eye responses (EC), and (3) some stage at which the representation is mixed (HC + EC). Observed results are most consistent with a suggestion that the neural representation underlying spatial auditory plasticity incorporates both HC and EC auditory information, possibly at different processing stages. [Work supported by VEGA-1/1011/16.]
Figure/ground segregation enhanced by spatially directed attention
Authors: Reed Darrin K. , Toth Brigitta , Chait Maria , Shinn-Cunningham Barbara
Published: June 2017

We recently reported that detecting a “figure” of repeated chords amidst “background” tones was worse when the figure was spatially separated from the background, a counterintuitive result given the published studies of spatial unmasking. Because of the way we blocked trials and provided instructions/feedback, listeners may have directed attention to the front where most figures appeared. Here, we investigated whether spatial cues would improve figure detection when listeners were instructed that spatial cues could aid performance. Figure detection was recorded for a condition where both the background and figure were presented diotically and for two binaural conditions. In one binaural condition, the figure occurred as a brief token at a lateral position separated from the background. In the other binaural condition, the background was composed of both a diotic stream and a lateralized stream, which contained the target (if present). Figure detection accuracy was better for both binaural conditions than for the diotic condition. Accuracy was best for the binaural condition in which the background was diotic and the figure was a brief lateralized token. These results reinforce the idea that binaural cues can be used to direct attentional focus, enhancing detectability of a target object amidst competing sounds.
Development of an open source audio processing platform
Authors: Audette William , Clavier Odile , Rasetshwane Daniel , Neely Stephen T. , Murphy Joel
Published: June 2017

The Open-Source software movement has demonstrated the value and quality of open-source tools and includes well-established systems such the Android Operating System. This movement is expanding to hardware and when designed properly, open-source hardware combines the user-friendliness and dependability of commercial products with the high performance and flexibility of scientific tools developed by researchers in their own laboratories. In this research, we present a hardware and software platform entirely open-source, designed to spur innovation in sound and speech processing algorithms. The first prototype includes a Teensy 3.6 board which leverages the Arduino development environment while providing powerful computational capabilities. This processor board is paired with custom-designed electronics for audio control, power management and wireless communication. The software base is designed for multiple users: (1) “experts” who optimize new algorithms directly in firmware; and (2) researchers who interact with existing algorithms to modify parameters and evaluate their performance in different conditions. Hearing aid research and other audio signal processing fields will greatly benefit from the open sharing of algorithms on one common platform that is easily obtained from existing vendors. Here we present the current functionality of the platform, as well as how to access it and contribute to this exciting Open Source project.
Objective determination of backward masking
Authors: Smith Silas , Yonovitz Al
Published: June 2017

Backward Masking (BM) functions have been shown to relate to age, lead toxicity, and are differentiated in children with language disorders. These functions may be indicative of auditory processing deficits. This study investigated if Evoked Potentials (EP) could be utilized to obtain BM functions. A tonal stimulus, followed by an inter-stimulus interval (ISI) and a noise masker was the EP stimulus. All were studied individually in the appropriate temporal alignment. ISI”s of various durations to derive the BM function middle, and late auditory evoked potentials. This study randomly presented four different stimulus conditions, 1) tone alone, 2) noise alone, 3) tone and noise, and 4) silence. With a long inter-trial interval (1 sec) and high sample rate (31250 Hz) EP’s were obtained for 4000 trials. The stimuli were pure-tones (1000 Hz, 10 msec. duration with a Blackman function and noise bursts of varying intensity. Agreement was found for the behavioral and electrophysiological task. Results indicated that EP’s could be arithmetically combined to observe the differential electrophysiological responses and neurologic loci of evoked potentials during the BM effect.
Lossy compression of uninformative stimuli in the auditory system
Authors: Mlynarski Wiktor , McDermott Josh
Published: June 2017

Despite its temporal precision, the auditory system does not encode fine detail of some classes of natural sounds. For example, sounds known as “auditory textures” seem to be encoded and retained with a lossy, compressed representation consisting of time-averaged statistics. One explanation is that the auditory system compresses stimuli that exceed its informational bandwidth. Decreased sensitivity to temporal detail of sound would reflect a limit of the auditory system to transmit sensory information above a certain rate. Here we instead propose a normative explanation. We assume that to minimize energy expenditure, the auditory system compresses stimuli that do not carry novel information about the environment. We developed practical measures of stimulus coding cost (the number of simulated auditory nerve spikes required to encode the sound) and stationarity (degree of change to the sound spectrum across successive time windows). We found that coding cost is not predictive of the ability to discriminate exemplars of a sound. In a second experiment we found that human listeners are sensitive to temporal detail of sounds with high coding cost provided they are unexpected. Our results are consistent with the hypothesis that perceptual compression of auditory textures is a manifestation of an adaptive coding strategy.
Auditory perception of object properties as inverse acoustics
Authors: Cusimano Maddie , Traer James , McDermott Josh
Published: June 2017

Perception relies on regularities in sensory data that are caused by physical laws. In audition, physical laws governing object interactions constrain the structure of sounds. However, it remains unclear to what extent these constraints have been internalized by the brain to support auditory inferences about the world. To investigate whether physical constraints are modeled by the auditory system, we developed a Bayesian ideal observer for a physics-inspired generative model of impact sounds, and tested whether its judgments of the mass of a ball falling onto a board accorded with those of human listeners. To generate audio with the model, the time-varying impact force was convolved with measured impulse responses of the ball and board. The force varied parametrically with mass to simulate impacts involving balls of different masses. This relationship was fitted to measurements of a set of wooden balls with equal hardness. Inference was performed by Markov chain Monte Carlo sampling. The model accurately predicted most human judgments in a two alternative forced choice task using recorded audio. However, the model underestimated mass when the ball material was harder than wood. The results suggest that additional physical parameters (e.g., hardness) must be modeled to account for human perception.
Increased reaction time adherence to response criterion in a sample discrimination task
Authors: Berg Bruce G. , Bellato Michael
Published: June 2017

In a signal detection task with equal-variance distributions and an unbiased criterion, the distribution of reaction times typically has a peak near the point of overlap between the two distributions. A sample discrimination task is used to determine whether slower reaction times are associated with a likelihood ratio near unity or to the placement of the decision criterion. Listeners decide whether a single presented tone was sampled from a normal distribution with a mean of 1000 Hz or a mean of 1100 Hz, with each distribution having a standard deviation of 100 Hz. Base rates are varied across conditions so that the optimal decision criterion corresponds to respective likelihood ratios of .25,.67, 1, 1.5, or 4. In all conditions, the peak of the reaction time distribution as a function of frequency is near the optimal criterion for maximizing percent correct. In conclusion, slower reaction times are found when the frequency of the tone is near the selected criterion rather than near a point where stimuli from the two distributions are most similar. The results suggest that increases in reaction time are associated with the decision stage rather than an earlier perceptual processing stage.
Exponential modeling of frequency-following responses in American neonates and adults
Authors: Stump Kristin M. , Jeng Fuh-Cherng , Nance Brandie
Published: June 2017

Frequency-following response (FFR) has been widely used to assess the mechanisms of speech processing for speakers of tonal and non-tonal languages. For Chinese speaking adults, the characteristics of speech processing with increasing number of sweeps have been described with an exponential curve-fitting model; however, these characteristics for non-tonal language speakers have yet to be described in a similar manner. This study examined the characteristics of speech processing for both adults and neonates who speak a non-tonal language, to determine the goodness-of-fit of an exponential model to neonatal and adult FFRs, and compared the results between groups to determine if any differences exist. Twelve American neonates and 12 American adults were recruited for this study. Participants were native English speakers. The FFR was elicited using the English vowel /i/ with a rising pitch contour for a total of 8000 sweeps from each participant. From the three indices (Frequency Error, Tracking Accuracy and Pitch Strength) computed, the FFR trends were fit to an exponential curve-fitting model to estimate the frequency tracking acuity and neural phase-locking magnitude when the amount of sweeps increased in the averaged waveform. Significant differences between groups were found for the objective indices.
Envelope following responses to Schroeder-phase harmonic stimuli
Authors: Attigodu Chandrashekara Ganesh , Aiken Steven J. , Wang Jian
Published: June 2017

Recent studies suggest that peripheral nonlinearities only partially account for the envelope-following response (EFR) recorded at the scalp, with additional contributions from broadly tuned neurons in the central nervous system. The present study investigated this by measuring EFR to low and high-frequency stimuli designed to (1) optimize within-channel phase synchrony to produce maximal envelope modulation depth on the basilar membrane, or (2) optimize phase synchrony across multiple frequency channels to maximize envelope-related activity arising in the central nervous system. EFR was recorded in normal-hearing listeners using Schroeder-phase stimuli with harmonic components constrained to low and high-frequency ranges, as well to multi-frequency sinusoidally amplitude modulated tones as a function of component phase. Estimates of basilar membrane phase curvature varied across individuals. Response amplitudes and phase-locking values for the EFR varied as a function of carrier frequency range and component phase. The present results are consistent with an understanding of scalp-recorded EFR as a measure of central envelope processing extending beyond the initial encoding of the stimulus envelope arising in the periphery. The scalp-recorded EFR is thus not a direct index of envelope encoding in the auditory nerve.
Ripple-spectrum resolution in humans: Evoked-potential study
Authors: Nechaev Dmitry , Sysueva Evgeniya
Published: June 2017

Resolution of ripple spectra depending on spectral bandwidth was investigated in normal listeners using the phase reversal test in conjunction with recording slow auditory evoked potentials. The test signal had a band limited rippled spectrum. The central frequency of the spectrum was 2 kHz, and equivalent rectangular bandwidth was from 0.5 to 5 oct. The signal level was 80 dB SPL. The principle of the test was to find the maximum ripple density (rip/oct) at which the slow auditory evoked potentials (N1-P2 complex) to a ripple phase reversal could be recorded. The increasing of ripple density resulted in decrease of evoked potential amplitude. The ripple-density resolution was 8.5 rip/oct at spectrum bandwidth from 5 to 1 oct. This result is in agreement with psychophysical data. At a bandwidth of 0.5 oct, the ripple density resolution was 6.9 rip/oct, which was lower than has been shown in previous psychophysical studies. The difference between psychophysical and evoked-potential data is discussed. [Work supported by The Russian Foundation for Basic Research, grant № 16-34-00742.]
On the perception of audified seismic data
Authors: Boschi Lapo , Paté Arthur , Delcor Laurianne , LE CARROU Jean-Loïc , Dubois Daniele , Fritz Claudia , Holtzman Ben
Published: June 2017

Auditory display of scientific data has been applied successfully to several disciplines. Seismic recordings can be “audified” by accelerating them before playing them through an audio reproduction system. We present a suite of experiments, designed to help determining whether auditory display of seismic data can find practical research applications. Experiments consist of asking listeners to (i) categorize audified seismograms that are presented to them binaurally, and (ii) define with a few lines of text (that we later analyzed semantically) the features of audified signals that helped them in completing this task. In a first experiment listeners categorize freely, i.e., they form their own categories: they are found to follow similar categorization strategies, which suggests the existence of auditory clues perceived by most of them. From these results it is, however, hard to identify a simple correlation between such clues and the geophysical parameters that should control the data. In a second round of experiments, listeners are assigned a constrained categorization task, and ad-hoc data sets are selected to isolate some specific geophysical parameters: this way, the sensitivity of the auditory system, via our display method, to such parameters can be evaluated. Results suggest that listeners are able to categorize signals according to the parameters we had chosen, and that their performance can be improved by training. Our work opens the way to new applications of auditory display to seismology.
Learning-related improvements in auditory detection sensitivities correlate with changes in sensory- and decision-related components of the event-related potential
Authors: Ball Natalie J. , Wisniewski Matthew G. , Zakrzewski Alexandria C. , Iyer Nandini , Simpson Brian , Thompson Eric R. , Spencer Nathan
Published: June 2017

Listener performance in an auditory detection task can improve with practice (Zwislocki, Maire, Feldman, & Rubin, 1958). This could result from a selective attention process and/or sensory plasticity (e.g., if trained stimuli receive increased cortical representation). Here, listeners were trained to detect either an 861-Hz or 1058-Hz tone (counterbalanced across participants) presented in a noise masker. On the following day, high-density EEG was collected while listeners: 1) attempted to detect 861-Hz and 1058-Hz tones in noise at an SNR of -21 dB, and 2) passively heard the same tones presented in quiet. Listeners were significantly better at detecting tones at their trained frequency. In addition, P3 amplitudes were larger for trained than for untrained tones during the detection task. During passive exposure to the same tones, P2 amplitudes were similarly larger for trained than for untrained tones. The difference in P3 amplitudes suggests that training leads to more efficient decisional processing, perhaps related to an expectation for tones at the trained frequency. Differences in P2 amplitudes may reflect training-induced sensory cortical plasticity that is frequency specific. Further, the difference in P2 amplitudes suggests that training-induced improvements in detection are not merely related to attentional modulations.
Repeatability of non-invasive physiogical measures from the early auditory pathway
Authors: Bharadwaj Hari M. , Varghese Lenny A. , Shinn-Cunningham Barbara
Published: June 2017

Objective physiological measures such as otoacoustic emissions (OAEs) and evoked potentials (e.g., auditory brainstem responses, envelope-following responses) provide a non-invasive window into the function of specific early portions of the auditory pathway. However, both the clinical utility of such measures and our ability to reproducibly relate such measures to individual behavior are limited by many sources of variability. Indeed, variability may be introduced by confounding physiological and anatomical factors (e.g., individual differences in cochlear dispersion, head and brain tissue geometry, efferent effects), by the non-standardized nature of calibration techniques for acoustic stimulation and in-ear measurements (e.g., taking into account individual ear-canal properties), and by measurement-related factors (e.g., contact impedance, and noise from unrelated brain activity). Over the last five years, we have conducted several experiments to explore individual differences in suprathreshold hearing, which has forced us to address some of these sources of variability. In this presentation, summarizing the results from several unpublished “mini” experiments, we describe some methodological choices that we have employed, or plan to employ, to improve the test-retest reliability of physiological measures.
Effects of processing depth on lexically guided perceptual learning
Authors: Drouin Julia R. , Ose Jacqueline , Theodore Rachel M.
Published: June 2017

Listeners use lexical information to modify the mapping to representations for individual speech sounds. This mechanism, termed lexically guided perceptual learning (LGPL), results in long-lasting changes to speech sound categories and may be modulated by attention mechanisms. The literature on LGPL has demonstrated that learning may be influenced by explicit or implicit attention towards anomalous aspects of the input and may be affected by individual factors, such as cognitive abilities. The current study used three experiments to examine the degree to which graded lexical recruitment, indexed by explicit attention to the lexicon compared to other stimulus features, influenced the magnitude of LGPL. Listeners completed an exposure phase, where they heard an ambiguous phoneme, midway between /s/ and /ʃ/. Attention was manipulated across experiments through task instructions during exposure such that attention was shifted either towards lexical information (lexical decision task), surface variation (amplitude judgment task), or syntactic knowledge (syntactic decision task). Following exposure, all participants completed a phoneme identification task for members of an /s/-/ʃ/ continuum. Preliminary results indicate that LGPL occurred in each experiment; however, the magnitude of learning differed as a function of attention. The final results will be discussed in terms of constraints of the LGPL mechanism.