bluuebunny/crossref_metadata_2025 huggingface dataset:
Current perspectives on children’s auditory perception and consequences of noise exposure effects
Authors: Fredriksson Sofie , Fels Janina , Persson Waye Kerstin
Published: May 2013

Exposure to high sound pressure levels is well known to cause auditory damage, regardless of age. There is however limited knowledge of the effects on hearing due to noise exposure early in life. In addition, no well-established model is used to describe how children perceive and experience their sound environment compared to adults. New studies of children’s hearing have revealed different directivity pattern especially at high frequencies given by the head-related transfer functions due to the anthropometric data of the children and also an ear canal resonance at considerable higher frequencies compared to adults. Recent studies also describe children feeling a great deal of discomfort when exposed to sounds with high frequency characteristics. Children today are exposed to high sound levels from an early age at preschool, school and during leisure time. Few studies have looked at general health effects or hearing in particular. It is being discussed whether age related hearing loss, regarded as an inevitable part of life, to a large extent may be caused by a lifetime of noise exposure starting early in life. This paper will review available studies on noise induced hearing damage among children and give suggestions for future studies within this field.
The effects of noise disturbed sleep on children’s health and cognitive development
Authors: van Kamp Irene , Gidlöf-Gunnarsson Anita , Persson Waye Kerstin
Published: May 2013

Undisturbed sleep is essential for physiological and psychological health. Children have a special need for uninterrupted sleep for growth and cognitive development. Noise is an environmental factor that affects most children. In addition to noise in schools and preschools, many are exposed to potentially disturbing traffic related noise at night. The knowledge of how children's health, wellbeing and cognitive development is affected by noise disturbed sleep due to road traffic is very incomplete. Nor do we know how children are able to handle noisy situations (coping) and if a learned noise-related behavior in the long term has a negative influence on children's health and learning. The need for a restorative home environment can be particularly important when the child is simultaneously exposed to noise in the school environment. Moreover, it has been shown that although children are less sensitive for awakenings and sleep cycle shifts due to nighttime exposure, they are more sensitive for physiological effects such as blood pressure reactions and related motility during sleep. This paper aims to review existing knowledge on how children's health and cognitive development are affected by noise in the home and school environment, with special focus on the importance of noise-disturbed sleep.
Ballistic shock wave localization estimation of shooter position and velocity using difference of time of arrival DTOA algorithm in orthogonally arranged discrete acoustic arrays
Authors: Korman Murray S. , Sarkady Antal A.
Published: May 2013

A mathematical algorithm was developed using the difference in time of arrival, DTOA, of the ballistic shock wave cone at each position of an N-element array. The array is thought to be made up of orthogonally arranged discrete wide-band point like microphone or piezo-electric elements. The algorithm is used to estimate the parameter space involving both the displacement of the shooter with respect to the array and the velocity of the projectile. The algorithm utilizes a nonlinear least squares parameter fit of a difference in time of arrival equation that involves a lengthy Taylor series expansion of the exact “difference in time of arrival” theoretical equation. Results are presented showing that the model has good versatility in estimating displacement (location) and velocity in simulated trials that are presented. The method does not require any muzzle blast wave information or knowledge of the absolute time of arrival of the shock wave. Therefore, the orthogonal array located far from the shooter will be able to estimate the localization parameters as long as the projectile miss distance is not so large that ambient noise does not mask the detection of the shock wave pressure signature.
Statistical properties of nonlinear N-wave propagating in thermal or kinematic turbulence
Authors: Yuldashev Petr V. , Ollivier Sébastien , Khokhlova Vera , Blanc-Benon Philippe
Published: May 2013

Nonlinear propagation of high amplitude N-wave through turbulent layer is studied using 2D KZK-type nonlinear parabolic equation. The incident acoustic wave is assumed to have a plane wavefront and the waveform is a classical symmetrical N-wave. The turbulent layer is synthesized using a method of random Fourier modes. The modified von Karman spectra with the same values of outer and inner scales are considered for both scalar-type (temperature fluctuations) and vector-type (velocity fluctuations) turbulent fields. The rms value of the refraction index fluctuations μ is varied as a parameter. It is shown that statistical characteristics of N-wave propagating in vector-type or scalar-type turbulent fields are equivalent when μ in scalar-type turbulence is almost two times greater. The distance of most probable occurrence of caustics obtained in the KZK simulations, which account for diffraction effects is demonstrated to be inversely proportional to μ while the geometrical acoustics approach predicts the inverse proportionality to 2/3 power of μ. An effect of the initial N-wave amplitude on the peak pressure in random caustics is analyzed. The enhancement of focusing efficiency is observed for moderate initial amplitudes, whereas strong nonlinearity is shown to reduce pressure amplitudes. [Work supported by PICS RFBR 10-02-91062/CNRS 5603 grants.]
Radiation of finite-amplitude waves from a baffled pipe
Authors: Bodon K. J. , Thomas Derek C. , Gee Kent L. , Bakaitis Rachael C. , Blackstock David T. , Wright Wayne M.
Published: May 2013

The radiation of finite-amplitude waves from the open end of a baffled, circular pipe is considered as a direct continuation of work begun by Blackstock and Wright more than three decades ago [Kuhn et al., J. Acoust. Soc. Am. 63, (1978), S1, S84]. Band-limited Gaussian noise, as well as 1, 1.5, and 2 kHz sinusoidal pulses, with initial sound pressure levels ranging from 552 to 1186 Pa, have been propagated down a 6.1 m pipe, whose open end (5.1 cm inner diameter) has been placed off-center in a large rectangular baffle. As the steepened or shock-like waves exit the pipe, the measured waveforms are comprised of sharp impulses that are delta function-like in nature, particularly on axis. Although linear piston theory predicts similar waveform shapes, there is also evidence that nonlinear propagation of these impulses, which can exceed 150 Pa near the pipe opening, is occurring. http://asadl.org/jasa/resource/1/jasman/v63/iS1/pS84_s5
Mechano-acoustical measurement and modeling of the outer and middle ear
Authors: Funnell W. Robert J.
Published: May 2013

Mechano-acoustical measurement and modeling have evolved together. Most early measurements of the behavior of the outer and middle ear produced either spatial averages or single-point observations, which were amenable to modeling with uniform transmission lines and lumped circuits. A major step forward was the measurement of displacement patterns on the eardrum, which called for the use of finite-element models. Other major experimental steps forward included measuring spatial sound-pressure distributions, 3-D displacement patterns, and intracochlear pressures. Use of the finite-element method made it desirable to obtain detailed 3-D shape measurements, which were made much easier by the introduction of magnetic-resonance microscopy and x-ray microCT. The finite-element method has also made it possible to exploit measurements of material properties, and several different approaches have been used recently for making such measurements. The greatest challenges may be in dealing with very small dimensions and non-linear visco-elastic behavior. There is a need for more and better 3-D multipoint vibration measurements, and for material-property measurements that are more localized and that span a broader frequency range. Important directions for modeling include better use of available shape and material-property data, more attention to experimental animals and to variability, and better integration with cochlear models.
Carhart’s notch: A window into mechanisms of bone-conducted hearing
Authors: Kim Namkeun , Steele Charles R. , Puria Sunil
Published: May 2013

Otosclerosis is a disease process of the ear that stiffens the stapes annular ligament and results in footplate immobilization. This produces a characteristic loss in bone-conducted (BC) hearing of about 20 dB between 1 and 2 kHz, known as “Carhart’s notch,” for which the specific mechanisms responsible have not yet been well understood. In this study, it is hypothesized that this observed pattern of hearing loss results from interactions between compressional and inertial mechanisms of BC hearing. Differences in the basilar-membrane velocity between a normal and otosclerotic human ear were calculated in response to compressional vibration of the cochlear capsule, translational vibration of the skull bone in various directions, and combinations of the two, using an anatomically accurate 3-D finite element model of the middle ear, cochlea, and semicircular canals. Compressional and inertial BC stimuli were found to both be necessary to capture the full behavior of clinical data, with the compressional component dominating below 0.75 kHz, the inertial component dominating above 3 kHz, and the notch between 1 and 2 kHz resulting from the suppression of an ossicular resonance due to stapes fixation. [Work supported by grant R01-DC07910 and R01-DC05960 from the NIDCD of NIH.]
Differences in masked localization of speech and noise
Authors: Heo Inseok , Gilbertson Lynn , Chang An-Chieh , Stamas Jacob , Lutfi Robert
Published: May 2013

Dichotic masking studies using noise are commonly referenced in regard to their implications for “cocktail party listening” wherein target and maskers are speech. In the present study masker decision weights (MDWs) are reported suggesting that speech and noise are processed differently in dichotic masking. The stimuli were words or Gaussian-noise bursts played in sequence as masker-target-masker triads. The apparent location of words (noise bursts) from left to right was varied independently and at random on each presentation using KEMAR HTRFs. In the two-interval, forced-choice procedure listeners were instructed to identify whether the second-interval target was to the left or right of the first. For wide spatial separations between target and masker noise-MDWs were typically negative, indicating that target location was judged relative to the masker. For small spatial separations between target and masker noise-MDWs were typically positive, suggesting that target location was more often confused with the masker. For both spatial separations, however, word-MDWs were close to zero, implying that the masker served to distract attention from the target without itself being given significant weight. The results are consistent with an interpretation in which spectral dissimilarities among words generally serve to reduce confusions and relative comparisons among words.
Perceived elevation cued by images rotating in horizontal planes
Authors: Qu Tianshu , Sun Haoze , Wang Ning , Wu Xihong , Hartmann William M.
Published: May 2013

The sense of elevation perceived by human listeners is normally attributed to high-frequency spectral structure above 4 kHz, caused by anatomical filtering. Our research began with the conjecture that elevation information might be available below 4 kHz when it is linked to a quasi-continuous set of azimuthal cues through measured (KEMAR) head related transfer functions. In an elevation discrimination test, listeners heard two successive azimuthal rotations of 90 degrees, each in a different horizontal plane. The elevations of the horizontal planes differed by as little as 10 degrees and as much as 110 degrees. Listeners reported which rotation had the higher elevation. Results of the rotation experiments were compared with the results from experiments with fixed azimuths, similar to those of Algazi et al. [J. Acoust. Soc. Am. 109, 1110–1122 (2001)]. A rotation from 0 to 90 degrees led to negligible improvement compared to a fixed azimuth of 45 degrees. By contrast, a rotation from 45 to 135 degrees appeared to be particularly advantageous. [Work supported by the National Natural Science Foundation of China Grant Nos. 61175043 and the AFOSR.]
Threshold interaural time differences and the centroid model of sound localization
Authors: Hartmann William M. , Brughera Andrew
Published: May 2013

The centroid display model of sound lateralization hypothesizes an array of brain-stem cells with wide ranges of best frequencies (f) and best interaural time delays (ITD, τ). The cells are distributed according to function p(f,τ), and images are lateralized according to the centroid of an excitation pattern on this array, the rate-ITD function. The centroid display was tested by calculations using model cells for the medial superior olive, as the origin of the rate-ITD function. The cells had excitatory inputs, membrane potential increments, and time constants established by physiological measurements. Cells were driven with realistic frequency-dependent synchrony. The predictions were compared to the measured frequency dependence of ITD thresholds for human listeners. It was found that for high frequencies, 750 Hz and greater, the model could successfully account for the thresholds by making appropriate adjustments to p(f,τ). For lower frequencies, the model greatly underestimated thresholds for any reasonable p(f,τ) because integration over the wide range of τ reduced the variability in the rate-ITD function to unreasonable values. It is concluded that the centroid model fails to account for human thresholds at low frequency. [Work supported by the AFOSR and NIDCD.]
An original paradigm to investigate pure informational masking using complex tones
Authors: Calcus Axelle , Agus Trevor , Colin Cécile , Kolinsky Régine , Deltenre Paul
Published: May 2013

Most usual speech masking situations induce both energetic and informational masking. Energetic masking (E.M.) arises because both signal and maskers contain energy in the same critical bands. Informational masking (I.M.) prevents the listeners from disentangling acoustical streams even when they are well separated in frequency, and is thought to reflect central mechanisms. In order to quantify I.M. without E.M. contamination in complex auditory situations, target and maskers can by presented dichotically. However, this manipulation provides the listeners with important lateralization cues, which dramatically reduces I.M. Therefore, the current study aimed at restoring a fair amount of I.M. using complex tones in a new dichotic paradigm. Regularly repeating signals and random-frequency multitone maskers were presented dichotically, but switched from one ear to the other within a 10s sequence. Switches could either appear at a slow or rapid rate. We compared listeners’ detection performance in these switching situations to that elicited in traditional diotic and dichotic situations. Results showed that the amount of I.M. induced when signal and maskers were rapidly switching throughout a sequence was significantly higher than in classical dichotic situations, and appeared to be comparable to the diotic listening situation. Therefore, this paradigm provides an original tool to evaluate auditory perception in situations of pure I.M. using complex tones.
Lateralization of noise targets with interaural level differences presented within a noise interferer
Authors: Reed Darrin , van de Par Steven
Published: May 2013

The interaural level difference (ILD) of a lateralized target source is reduced when the target is presented together with background noise containing no ILD. It is unknown whether listeners simply use this reduced aggregate ILD or are still able to utilize the target ILD in a lateralization task. Behavioral experiments revealed that the temporal asynchrony between the onsets/offsets of the target and the background noise resulted in the population of listeners actually perceiving a larger ILD than the target ILD. For synchronous onsets/offsets, however, the perceived ILD depended on the coherence of the background noise. With coherent background noise, the population of subjects perceived a reduced ILD near the aggregate ILD. In contrast, the population of subjects made a reasonable estimate of the target ILD when the background noise was diffuse. Implementation of an Equalization Cancellation model and taking the compensatory level equalization that yields the lowest output as an estimate for the ILD results in the reduced ILD of the aggregate stimulus being reported regardless of the background noise coherence. However, application of an appropriate normalization factor to the model's output results in a dependence on background noise coherence for ILD lateralization as seen in the behavioral experiments.
Effects of the stimulus spectrum on temporal weighting of binaural differences
Authors: Stecker G. Christopher
Published: May 2013

The influence, or “perceptual weight” of binaural information typically varies over the duration of a brief sound, as characterized by the temporal weighting function (TWF). Here, TWFs were measured for binaural lateralization of Gabor click trains (GCT) varying in carrier frequency from 1 to 8 kHz, and of broadband noise-burst trains (NBT) with repeated (“frozen”) or newly sampled (“fresh”) noise across bursts. Interclick intervals (ICI) ranged from 2 to 10 ms. On each of many trials, human listeners judged the lateral position of a singly presented GCT or NBT, and indicated the position on a touch-sensitive display. Lateral positions varied with the overall interaural time (ITD, ranging +/− 500 µs) and level (ILD, ranging +/−5 dB) differences applied to each stimulus. Additional random variation in ITD (+/−100 µs) and ILD (+/−2dB) was applied independently to each click within a train. TWFs were calculated by multiple linear regression of normalized position judgments onto the individual click ITD and ILD values, and indicated large ICI-dependent weights on the initial click (“onset dominance”), elevated weights near offset, and lower weights for interior clicks. Flatter TWFs with reduced onset/offset weights were observed for “fresh” NBT stimuli than for GCT or “frozen” NBT stimuli. The results corroborate previous reports of temporal asymmetries in the binaural processing of periodic stimuli across frequency. [Work supported by R01 DC011548.]
Individual differences in auditory-motor integration revealed by speech fluency manipulations
Authors: Loucks Torrey M. , Chon Heecheong , Kraft Shelly , Ambrose Nicoline
Published: May 2013

A role for auditory feedback in maintaining fluency appears less specific than for pitch control, as one example, but delayed auditory feedback (DAF) clearly provides a potent manipulation of fluency. As most speakers are susceptible to DAF, we predicted DAF is particularly suited to identifying individual differences in auditory-motor integration. We conducted a series of studies to probe susceptibility to DAF-induced disfluency in 60 normally fluent speakers during conversation and oral reading. We further contrasted DAF effects on fluency with dual-task effects on fluency. During conversation and reading under DAF (250 ms delay), multivariate cluster classification indicated speakers show high, low, or intermediate susceptibility to disfluency. In contrast, dual-task effects on fluency appeared bimodal with individuals showing high or low susceptibility. DAF susceptibility was not related to dual-task disfluency in 41/60 speakers, but the remaining speakers were disfluent under DAF and dual-task conditions. When the DAF paradigm was extended to adults who stutter, most were classified as highly susceptible. The findings provide compelling evidence that individual differences need to be considered in auditory-motor integration research. Fluency is influenced by both auditory feedback and cognitive factors related to attention, which can inform theories of normal and disordered speech.
Speech production in amplitude-modulated noise
Authors: MacDonald Ewen N. , Raufer Stefan
Published: May 2013

The Lombard effect refers to the phenomenon where talkers automatically increase their level of speech in a noisy environment. While many studies have characterized how the Lombard effect influences different measures of speech production (e.g., F0, spectral tilt, etc.), few have investigated the consequences of temporally fluctuating noise. In the present study, 20 talkers produced speech in a variety of noise conditions, including both steady-state and amplitude-modulated white noise. While listening to noise over headphones, talkers produced randomly generated five word sentences. Similar to previous studies, talkers raised the level of their voice in steady-state noise. While talkers also increased the level of their voice in amplitude-modulated noise, the increase was not as large as that observed in steady-state noise. Importantly, for the 2 and 4 Hz amplitude-modulated noise conditions, talkers altered the timing of their utterances, reducing the energetic overlap with the masker by approximately 2%. However, for the 1 Hz amplitude-modulated condition, talkers increased the overlap by approximately 4%. Overall, the results demonstrate that talkers are sensitive to the temporal aspects of noisy environments and will alter their speech accordingly.
Auditory plasticity and sensorimotor learning in speech production
Authors: Shiller Douglas M. , Lametti Daniel R. , Ostry David J.
Published: May 2013

Numerous studies have shown the speech motor system to be highly flexible and responsive to changes in sensory input, revealing a central role for both auditory and somatosensory feedback in the acquisition and maintenance of speech motor control. Consistent with these studies, models of speech production have highlighted the role of accurate, stable sensory representations that serve, in part, as the goals of speech movements. A separate (and considerable) body of work has demonstrated that auditory-sensory representations of speech sounds are not perfectly stable, but rather exhibit rapid adaptation to changing input conditions in both children and adults. The plasticity of auditory representations has important implications for the control of speech production, both in early speech motor development and in the sensory-based maintenance of speech accuracy that characterizes adult speech motor control. In this talk, I will describe a series of studies that explore the link between sensory and motor plasticity in the speech motor system. The studies combine the paradigm of sensorimotor adaptation (altering auditory feedback during speech production) with measures and manipulations of auditory-perceptual representations of speech sounds. The results reveal not only that auditory speech targets are flexible under conditions of altered auditory feedback, but that changes in sensory representations can have a direct impact on speech motor learning and performance.
Speech motor learning alters auditory and somatosensory event-related potentials
Authors: Ito Takayuki , Coppola Joshua H. , Ostry David J.
Published: May 2013

Speech motor learning is dependent upon changes to motor function, but it also results in changes to sensory systems. However, the neural mechanisms of sensory plasticity associated with speech motor learning are little understood. We here examined whether auditory and somatosensory cortical processes are changed in conjunction with speech motor learning. We tested native speakers of American English. Altered auditory feedback (AAF) training was used as a motor learning task. As subjects repeated aloud the speech utterance “head,” the produced sound was feedbacked through headphones while the first formant of /ea/ was gradually decreased over 50 repetitions and held at a maximum change for 110 repetitions. In order to evaluate the effects of the resulting adaptation on cortical sensory processes, we recorded auditory and somatosensory event-related potentials (ERPs) using 64-channel electroencephalography before and after AAF training. Auditory ERPs were elicited by using the synthesized vowel sound “e.” Somatosensory ERPs were elicited by facial skin deformation. We found changes to auditory and somatosensory ERPs following AAF training in individuals who showed adaptation to altered auditory feedback. The changes in ERPs were correlated with the amount of adaptation. This suggests that speech motor learning alters somatosensory and auditory cortical processing.
The relative contribution of rhythm, intonation, and lexical information to the perception of prosodic disorder
Authors: Olejarczuk Paul , Redford Melissa A.
Published: May 2013

Acoustic studies suggest that children with autism spectrum disorder (ASD) produce atypical rhythm and intonation [Diehl and Paul (2011)]. Behavioral studies indicate that children with ASD combine prosody with lexical content in atypical ways [Peppé et al. (2007)]. The current study assessed the relative contribution of rhythm, intonation, and language context to perception of prosodic disorder. Short excerpts were taken from narratives produced by 18 children with ASD and 18 typically developing controls. Prior study indicated that listeners easily distinguished groups on the basis of these excerpts. Here, the excerpts were resynthesized to control for voice quality and to allow for selective inclusion of F0, duration, intensity, and lexical information. Experiment 1 investigated listeners’ ability to distinguish the groups based on delexicalized samples that preserved only rhythm (duration + intensity), only intonation, or a combination of both. Experiment 2 investigated the contribution of lexical information to the judgments, and the interaction of lexical information with intonation. Results indicated that (1) listeners were less able to distinguish between groups in the Intonation Only condition, and (2) intonation had a negligible effect on performance when lexical content was present. We conclude that rhythm cues and lexical information contribute more to perceived disorder than intonation.
Towards a vocal typology for American English
Authors: McPeek Tyler , Harnsberger James
Published: May 2013

Prior work in the field of speaker identification has shown that individual voices are not uniformly dissimilar from one another: when misidentified, the errors are not randomly distributed but, in fact, indicate the existence of vocal stereotypes, or groups of voices that share identifiable features. Popular labels for such groups can include “rich,” “droning,” “gravelly,” and many others. In this study, 100 American English male and female voices were separately rated for interspeaker similarity and the ratings used to posit nine vocal types for each gender. Acoustic properties corresponding to speaking rate, pitch variability, and mean pitch were the most predictive in classifying voices into types in discriminant analyses using a total of 23 measures. For female voices, chronological age strongly influenced the resulting taxonomy. Male voice types were not blocked by age, and unlike the female voices, a single type constituted a plurality (26%) of the voices in the database. The implications of this work for the modeling of other indexical properties of speech will be discussed, along with its implications in the applied area of forensic voice identification.
The correlation between perceptual saliency and acoustic parameters of dysarthrias
Authors: Wang Emily , Verhagen Leo
Published: May 2013

Dysarthria is a group of speech disorders resulting from neurological disturbances in central or peripheral systems. There are six single types of dysarthria and all present with deviations at both segmental and suprasegmental level. However, it is unclear what matters more to the listener: the deficits at the segmental or suprasegmental level. In this study, reading samples were collected from subjects with any of the three types of dysarthria: scanning speech of ataxic dysarthria, spastic dysarthria, and hypokinetic dysarthria. All had slow speaking rate, monopitch, and monoloudness. Acoustic analyses were used to examine changes at both segmental and suprasegmental level. At the segmental level, parameters obtained include word and syllable per minute, vowel F1 and F2, syllable, word, sentence, and pause duration, mean F0 and vF0 at sentence and paragraph level. Peak F0 and vowel duration of stressed and unstressed vowels were also obtained. Perception experiment was conducted. Pitch contours were extracted and tested separately from those un-manipulated stimuli. Listeners made forced choice for rate and speech naturalness for the former and for overall speech intelligibility, speech rate, and speech naturalness for the latter. Effective size was used to determine the contributions of parameters at the segmental and suprasegmental level.
Perceptual evaluation of the functional and aesthetic degradation of speech by wind noise during recording
Authors: Jackson Iain R. , Kendrick Paul , Cox Trevor J. , Fazenda Bruno M. , Li Francis F.
Published: May 2013

This paper will present results from a systematic investigation into functional and aesthetic audio quality of speech recordings degraded by wind noise. The major source of wind noise tested comes from velocity fluctuations interacting with the transducer, generating pressure fluctuations at the microphone diaphragm. To better understand the effect of this type of noise, a perceptual experiment was designed to assess task performance and perceptions of quality when speech and simulated wind noise are presented together. A wind noise simulator was developed, which produces realistic audio from anemometer data, to allow the noise to be isolated from other ambient sounds, and also enable salient parameters to be controlled. Two key components of wind noise in recordings were evaluated, the average level and its temporal variance or “gustiness.” Eight levels of wind noise were factorially combined with three levels of gustiness. Each of these permutations was then presented with one of 24 randomly assigned, grammatically correct, nonsense sentences. Participants were asked to type the sentence they heard, rate the difficulty of the task, and indicate overall quality of the clip. Each sentence contained four keywords—correct identification of which was used for scoring performance.
Measurements of the aero-acoustic properties of the vocal folds and vocal tract by broad and narrow band probes during phonation into controlled acoustic loads
Authors: Hanna Noel N. , Smith John , Wolfe Joe
Published: May 2013

The aeroacoustic properties of the vocal folds and tract are difficult to measure directly. Here, they were measured using broad- and narrow-band excitation at the mouth during phonation into various acoustic loads, including a non-resonant load provided by an acoustically infinite waveguide with cross section comparable with that of the tract. The tract is treated as a duct terminated by the larynx. Mechanical properties of the walls and terminations were determined using a microphone array [Dickens et al. (2007)]. The vocal fold response was monitored with an electroglottograph and wall motion was measured electromechanically. The impedance spectra show negative resistance bands at frequencies near those of phonation, consistent with regeneration at the folds. The walls give inertances consistent with thicknesses of order 1 cm and compliances consistent with distributed stiffnesses of about 100 kN/m3 [Hanna et al. (2012)]. The duct resonant properties are consistent with losses several times higher than the viscothermal losses at smooth rigid walls. Dickens et al., J. Acoust. Soc. Am. 121, 1471–1481 (2007). Hanna et al., in Proceedings of the Australian Acoustical Society Conference (2012).
Flow development in the uniform glottis and viscosity effects
Authors: Fulcher Lewis , Scherer Ronald
Published: May 2013

Thirty-two pressure distributions at minimal diameters of d = 0.005, 0.0075, 0.01, 0.02, 0.04, 0.08, and 0.16 cm have been measured at a number of transglottal pressures of interest for phonation. Care is taken to identify those portions of the pressure distributions within the glottis that include substantial regions of uniform decrease with axial distance. These portions are further examined to identify their components that have a linear dependence on the volume velocity and those that have a quadratic dependence on the volume velocity. An analysis based on the Navier Stokes equation creates a natural framework for investigating corrections to the parabolic profile of fully developed flow, which leads to the Poiseuille formula. For glottal diameters between 0.0075 and 0.02 cm the Poiseuille formula is a good approximation. Overall, an inverse 2.59 power law to describe the diameter dependence of the linear coefficients is found to be superior to the inverse cube dependence of the Poiseuille formula. Glottal flow resistance is used as a means of comparing the accuracy of the two power laws.
Circular harmonics beamforming with spheroidal baffles
Authors: Holmes Stewart
Published: May 2013

Circular microphone arrays have been well studied when mounted on cylindrical and spherical baffles. In this paper, the oblate and prolate spheroids are explored as a baffle for a microphone array system. It is shown that the prevailing methods for analysis of circular arrays may be easily adapted to this class of baffle, and that the use of these baffles represent a continuously variable geometry with edge cases that are the cylindrical and spherical baffles, and the array in empty space with no baffle. The performance—in the form of directivity index, maximum side-lobe level and main beam resolution—of spheroidally baffled arrays is analyzed with respect to errors created by transducer noise, positioning error, and modal aliasing, for both delay-and-sum and eigenbeamforming arrays. It is shown that the noise and position errors depend strongly on the spheroidal eccentricity while the aliasing error is fairly independent of baffle shape. Simulations of example arrays are used to show that while the prolate spheroidal baffle is of little advantage compared to current systems, the oblate spheroidal baffle can be used to create a significantly smaller array with only a relatively minor performance degradation.
Lattice theory models for space-time sampling of acoustic signals
Authors: Adhikari Kaushallya , Buck John R.
Published: May 2013

The space-time sampling of underwater acoustic signals by both fixed and towed arrays of sensors can be modeled by lattice theory. The sampling schedule of a fixed array produces a rectangular space-time lattice while the sampling schedule of an array towed at a uniform velocity produces a trapezoidal lattice. Changing the velocity of a towed array corresponds to changing the skewness of a trapezoidal lattice. Willis and Bresler [IEEE Info. Theory (1997)] established an upper bound on the space-time-bandwidth product of a signal that can be sampled time sequentially by a lattice without aliasing. This upper bound provides a valuable perspective on the tradeoff among the temporal intersample interval, the interelement spacing of sensors, the velocity of the towed array, and the spectral support of signal that can be sampled without aliasing. A towed array with the same interelement spacing and temporal intersample interval can sample signals with broader spectral support than a fixed array. Alternately, a towed array can sample a signal with the same spectral support at a slower rate than an equivalent fixed array decreasing load on the data processing system. [Work supported by ONR.]
Least squares versus non-linear cost functions for a virtual artificial head
Authors: Rasumow Eugen , Blau Matthias , Doclo Simon , Hansen Martin , van de Par Steven , Püschel Dirk , Mellert Volker
Published: May 2013

In order to take into account spatial information into binaural recordings, it is common practice to use so-called artificial heads. Disadvantageously artificial heads are inherently non-individual and bulky devices. Alternatively, the individual frequency-dependent directivity pattern of human head related transfer functions (HRTFs) can also be approximated by a microphone array with appropriate filters [Rasumow et al. (2011)]. Such a setup may be referred to as a virtual artificial head (vah). The filters for the application of the vah can be derived by minimizing a narrow band cost function including regularization constraints. As a first approach, it is appropriate to apply a least-squares cost function. The major advantage is its closed form solution [cf. Rasumow et al. (2011)], whereas from a psychoacoustically point of view, it seems more reasonable to minimize the dB-error instead. The latter cost function must, however, be minimized iteratively. We propose a minimization procedure for and present first results regarding the subjective appraisal of binaural filters derived using both cost functions. Future work includes the extension of this work to binaural cost functions.
Data-based sensitivity kernel in a highly reverberating cavity
Authors: Yildiz Selda , Marandet Christian , Rakotonarivo Sandrine T. , Roux Philippe , Kuperman W. A.
Published: May 2013

Our goal is to acoustically localize medium inhomogeneities, (i.e., scatterers) in a very complex medium without having to resort to constructing an accurate propagation model. Instead, we use a data-based sensitivity kernel approach to characterize medium changes in this complex medium which, in this study, is a highly reverberating cavity. The efficacy of the method is confirmed in an experiment with a moving aggregate of ping-pong balls inside a fish tank of 5.6 m diameter and water depth of 1.05 m in the ~10 kHz frequency regime; acoustic sources and receivers are on the periphery of the tank. Using a sensitivity kernel constructed from field data for scatterers at a sparse set of known positions, we demonstrate that we can localize other scatterers at unknown positions.
Three-dimensional localization of multiple sources in an uncertain ocean environment
Authors: Tollefsen Dag , Dosso Stan E.
Published: May 2013

This paper develops a Bayesian focalization approach to simultaneous three-dimensional localization of multiple sources in shallow water with uncertain environmental properties, for application to horizontal line array (HLA) data. The algorithm maximizes the posterior probability density over unknown environmental (seabed and water column) and source parameters (includes source-bearing) using an adaptive hybrid optimization algorithm. Maximum-likelihood expressions for source strengths and noise variance are used that allows these parameters to be sampled implicitly rather than explicitly. An extension to the algorithm that optimizes for a priori unknown number of sources, based on minimizing the Bayes information criterion, is developed and presented. The algorithm is applied to simulated multi-frequency data in a continental shelf environment, and to data recorded on a HLA deployed on the seafloor in an experiment conducted in the Barents Sea.
Small boat localization using adaptive three-dimensional beamforming on a tetrahedral and vertical line array
Authors: Gebbie John , Siderius Martin , Nielsen Peter , Miller James H. , Crocker Steven , Giard Jennifer
Published: May 2013

Passive acoustic detection and localization of small surface craft has a number of practical applications, such as monitoring and protecting sensitive marine habitats. Moored passive equipment can be cumbersome to deploy and communicate with, so AUV-mounted devices are being investigated as an alternative. The GLASS’12 experiment was designed to assess the feasibility of using a hybrid autonomous underwater vehicle outfitted with a compact volumetric nose array as a data collection platform. The array consisted of five vertical elements and 4 in a tetrahedral arrangement, and the hybrid underwater vehicle had the capability operating in either glider or propeller-driven modes. The rigid design of the array minimized element location mismatch and enabled the use of aggressive adaptive beamforming in 3-D. This facilitated isolation of broadband multipath arrivals originating from the motor of a small rubber boat. Cross-correlation of beams enabled the time-lag between the arrivals to be measured, which, in turn yielded information about the target range. The underlying formulation bears similarity to the passive fathometer [J. Acoust. Soc. Am. 120(3) (2006)], which exploits surface wave noise rather than ship noise. This presentation will focus on the array beamforming and potential applications for localization and environmental sensing.
Measured scattering of a first-order vortex beam by a sphere: Cross-helicity and helicity-neutral near-forward scattering and helicity modulation
Authors: Bollen Viktor , Zartman David J. , Marston Timothy M. , Marston Philip L.
Published: May 2013

The wavefield of a traveling wave acoustic vortex beam has an axial null and an angular phase ramp. An appropriately phased four-element transducer array can be used to generate a first order vortex beam [Hefner and Marston, J. Acoust. Soc. Am. 106, 3313–3316 (1999)]. The direction of the phase ramp determines the helicity of the beam. Superposition of signals from an appropriately positioned four-element receiver array gives a helicity selective detector and commutation of diagonal source elements can be used to reverse the source helicity [Marston and Marston, J. Acoust. Soc. Am. 127, 1856 (2010)]. These techniques were used to investigate the near forward scattering by a small sphere placed on or near a beam’s axis. The forward scattering vanishes in the on-axis case [Marston, J. Acoust. Soc. Am. 124, 2905–2910 (2008)]. As the sphere is moved off axis the scattering to a helicity neutral receiver is found to increase linearly in the displacement with a first order phase swirl as a function of the sphere coordinates. For cross-helicity detection (detection opposite the beam’s helicity) as required by symmetry, the signal is approximately quadratic in the displacement with a second-order phase swirl. [Work supported by ONR.]
Inversion of a room acoustics model for the determination of acoustical surface properties in enclosed spaces
Authors: Pelzer Soenke , Vorlaender Michael
Published: May 2013

Acoustic consultants are often in charge of treating spaces to fix problems or improve their room acoustics. To assess the situation and to find a solution, it is common practice to perform computer simulations. This technique is well established, cheap and effective. But it requires a CAD model of the room as well as properties of its boundaries, such as absorption and scattering coefficients. The CAD model is usually easy to obtain by asking the architect or measuring yourself, but quantifying the absorption and scattering coefficients of every single wall is a challenging task. This contribution presents a method that automatically matches absorption coefficients for every single wall by applying an inverse room acoustics model which bases on geometrical acoustics. The inversion is done numerically using a non-linear least-squares optimization process in MATLAB. The independent variables are all absorption coefficients and the goal is to minimize the error between measured and simulated impulse responses at all measured positions in the room. In addition to the acquisition of absorption and scattering coefficients, the goal after the optimization process is to perform interactive binaural auralizations that have a high perceptual congruence with the existing space.
Speech intelligibility prediction in very large sacral venues
Authors: Ahnert Wolfgang , Behrens Tobias
Published: May 2013

In very large sacral venues like cathedrals or mosques the intelligibility of spoken words is very important especially during praying. For such venues with volumes of up to more than one million m3 special routines are needed for simulation to obtain predicted STI values by using of up to more than 1000 sound sources. Special cloud computing has been developed which allow to do the calculation by providing the needed memory size and by cutting the calculation time from days or weeks to hours. Here also modern binaural or ambisonic B-format impulse responses are derived. Additionally the absorption behavior of typical floor materials in such venues has to be known like worshipers in church pews or sitting or kneeing on carpets in mosques. This absorption is often the only one in sacral venues to reduce the reverberation time. For mosque projects the measurement of absorption coefficients of persons in typical postures and arrangements has been done according to the reverberation room method. Persons have been tested on a carpet as a 10 m<+>2<+> sample within a surrounding reflective barrier while standing, kneeing on carpet or being in Muslim specific praying posture.
The effect of edge caused diffusion on the reverberation time - A semi analytical approach
Authors: Drechsler Stefan , Stephenson Uwe
Published: May 2013

The basic numerical model here is the Anisotropic Reverberation Model (ARM). This geometrical/energetic model assumes a homogeneous but anisotropic sound field in room acoustics. Its system of linear differential equations describes the redistribution of sound energy to different directional ranges by wall reflections, which may be specular or diffuse, where the diffuse reflections are caused also by the edges (edge effect). The reverberation times result from eigenvalues and eigenvectors of the differential equation system. Recently, an analytical formula has been found, that calculates the diffracted, angle dependent sound field, averaged over the octave band even for arbitrarily shaped polygons. The reverberation times calculated with the ARM extended by that edge diffraction are presented. So, first time, not only for the typical shoe-box room with an absorbing floor and reflecting walls realistic reverberation times can be calculated, taking the edge effect into account.
Three-dimensional point-cloud room model in room acoustics simulations
Authors: Markovic Milos , Olesen So/ren K. , Hammersho/i Dorte
Published: May 2013

Telepresence applications require communication with the feeling of being together and sharing the same environment. One important task in these applications is to render the acoustics of the distant room for the telepresence system user. This paper presents a fast method for the room geometry acquisition and its representation with a 3D point-cloud model, as well as utilization of such a model for the room acoustics simulations. A room is scanned with a commercially available input device (Kinect for Xbox360) in two different ways; the first one involves the device placed in the middle of the room and rotated around the vertical axis while for the second one the device is moved within the room. Benefits of both approaches were analyzed. The device's depth sensor provides a set of points in a three-dimensional coordinate system which represents scanned surfaces of the room interior. These data are used to build a 3D point-cloud model of the room. Several models are created to meet requirements of different room acoustics simulation algorithms: plane fitting and uniform voxel grid for geometric methods and triangulation mesh for the numerical methods. Advantages of the proposed method over the traditional approaches are discussed.