bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing acoustic measures of the spontaneous phonetic imitation of vowels.
Authors: Babel Molly E. , Munson Benjamin
Published: March 2010

It is well established that people imitate fine phonetic detail of another talker in shadowing tasks [Goldinger, Psych. Rev. 105, 251–279 (1998)] and in interactive conversation [Pardo, J. Acoust. Soc. Am. 119, 2382–2393 (2006)]. That is, the acoustic characteristics of a model talker’s production (MTP) are more similar to a participant’s shadowed production (PSP) than they are to that participant’s baseline production (PBP), typically elicited in a reading task. This presentation compares two methods of assessing the acoustic distance between the vowels in PSP and PBP monosyllabic words taken from two previous studies [Babel, thesis, University of California (2009); Kaiser & Munson, (unpublished)]. One of these measures is the F1/F2 Euclidean distance between PSP and PBP vowels. This measure does not take into account the direction of the difference. The other [adapted from Titze, Principles of Voice Production (1994)] compares the distance and direction of the F1 and F2 values in the PSP and PBP vowels relative to those of the MTP. The merits of each of these methods are assessed by comparing them to measures of listener judgments of the similarity of PSPs and PBPs to the MTPs in AXB perception tasks.
An acoustic study of front rounded vowels in Shetland dialect.
Authors: Gao Man , Sundkvist Peter
Published: March 2010

This paper presents an acoustic analysis of front rounded vowels (FRVs) in the dialect spoken in the Shetland Islands, the northernmost locality of the British Isles. FRVs are typologically marked and estimated to occur in only 6.6% of the world’s languages [I. Maddieson, in Haspelmath et al. The World Atlas of Language Structures (2005)]. Their occurrence in the Shetland dialect is, at least partly, attributable to a Scandinavian substratum language. There is significant variation across the archipelago regarding several aspects such as (1) the number of lexically contrastive FRVs, (2) phonetic quality (close to half-close), (3) contrastive length, and (4) lexical distribution and support. This paper presents an investigation of three speakers from one locality in which FRVs have retained firm lexical support. The issues addressed concern the dialect’s overall acoustic vowel space (based on F1, F2, and F3), the position of FRVs within the acoustic space, and what the contrasts among FRVs and other adjacent vowels appear to rest on acoustically. Special focus is directed to phonetic contexts that support the greatest number of vowel contrasts and display the most crowded acoustic vowels spaces.
A new non-linear regression model for formant trajectories in English monosyllables incorporating dual targets for vowels.
Authors: Nearey Terrance M.
Published: March 2010

A new non-linear regression model is proposed to characterize the formant trajectories of the vocalic portion of English CVC syllables in the data described by Hillenbrand et al. [J. Acoust. Soc. Am. 109, 748–763 (2001)]. The modeling framework builds on work of Broad and Clermont [J. Acoust. Soc. Ame. 81, 155–165 (1987)], wherein formant trajectories were modeled via three additive components: (1) a single vowel target, (2) an exponential approach (in time from onset) toward the vowel target from an initial consonant onset value, and (3) an exponential approach (in time from offset) toward the vowel target from a final consonant offset value. The new model extends this to allow for a dual specification (nucleus + offglide) of the vowel targets [T. Nearey and P. Assmann, J. Acoust. Soc. Am. 80, 1297–1308 (1986)]. Initial results suggests that inclusion of a second vowel target provides substantial reduction (about 40%, 23% and 7% respectively for F1, F2, and F3) of error variance on trajectories averaged across 12 speakers. More detailed statistical analyses of variants of the new model are underway and will be reported for both the data described above and that reported on by Assmann et al. [this meeting].
Effects of ambient pressure and gas mixture on a numerical model of subglottal acoustics and vowel spectra.
Authors: Lulich Steven M.
Published: March 2010

Divers’ speech in hyperbaric heliox environments becomes significantly distorted, making communication between divers and with surface-based personnel difficult. Previous research identified two basic mechanisms underlying this distortion. First, the speed of sound increases significantly in heliox, causing a linear increase in the second and higher formant frequencies. Second, in hyperbaric conditions the specific impedance of air in the vocal tract approaches that of the vocal tract walls, leading to a nonlinear increase in the first formant frequency. Effects of ambient pressure and gas mixture on subglottal acoustics and subglottal-vocal tract coupling in vowel spectra have not been sufficiently investigated. In this paper, such an investigation is carried out using a numerical model of subglottal and vowel acoustics. It is shown that subglottal resonance frequencies increase linearly as the speed of sound increases, and the corresponding subglottal pole-zero pairs in vowel spectra become disproportionately prominent as ambient pressure increases. Increased acoustic coupling between the subglottal system and the vocal tract in hyperbaric heliox therefore constitutes a third significant source of speech distortion. The results have implications for understanding subglottal coupling in vowels and for heliox speech unscrambling techniques. [This work was supported in part by NSF Grant No. 0905250.]
Developing vowel mappings for an interactive voice synthesis system controlled by hand motions.
Authors: Nordstrom Karl I. , Fels Sidney , Hassall Cameron D. , Pritchard Bob
Published: March 2010

This study investigates vowel mappings for a voice synthesizer controlled by hand gestures for artistic performance. The vowel targets are on a horizontal plane navigated by the movement of the right hand in front of the performer. Two vowel mappings were explored. In one mapping, the vowels were evenly distributed in a circle to make the vowel targets easier for the performer to find. In the other mapping, the vowels were arranged according to the F2 versus F1 space. Linear hand motions were then made through the vowel space while plotting the formant trajectories. The evenly distributed mapping resulted in formant trajectories that were not monotonic; the F1 and F2 pitch contours varied up and down as the hand carried out the linear motions. This had the unintended result of producing multiple diphthongs. In contrast, the F2 versus F1 mapping enabled the performer to create monotonic formant trajectories and the perception of a single diphthong. The performer found it easier to speak and sing through the system when a single linear hand motion resulted in a single diphthong. [This project was supported by Canada Council for the Arts, Natural Sciences and Engineering Council of Canada, and Media and Graphics Interdisciplinary Centre.]
Psychometric functions for rough voice quality.
Authors: Eddins David A. , Shrivastav Rahul
Published: March 2010

Dysphonic voices arising from laryngeal lesions are generally believed to vary across three perceptual dimensions—breathiness, roughness, and strain. This experiment sought to evaluate the psychometric functions for roughness and to determine the acoustic cues for its perception. Ten normal-hearing listeners, all native speakers of American English, were recruited for this experiment. The perception of roughness in dysphonic voices was evaluated for 34 voices from the Kay Elemetrics Disordered Voice Database (Kay-Pentax, Inc., Lincoln, NJ). Listeners compared the roughness of these test stimuli against that for a sawtooth wave with a 40-Hz squared-cosine amplitude modulation (AM). The modulation depth of the sawtooth wave was varied from low to high in a paired comparison task. Psychometric functions for roughness were derived by plotting the listener response for each stimulus pair against the modulation depth of AM sawtooth wave. The data for each stimulus were fitted with a logistic function, and various parameters (threshold, slope, and saturation point) were computed. These parameters were then compared to various acoustic measures obtained from each voice to determine candidate acoustic cues for roughness.
Effects of asymmetric vocal fold activation on phonation.
Authors: Chhetri Dinesh K. , Neubauer Juergen
Published: March 2010

The effects of asymmetric vocal fold activation on phonation were studied using an in vivo canine model and graded neuromuscular stimulation of the recurrent laryngeal nerve (RLN). One RLN was stimulated at 21 levels of graded stimulation, from threshold activity to maximal contraction, at three levels of contralateral vocal fold contraction (low, medium, and high). Phonation onset pressure (Pth) was recorded at each condition. The effects of airflow and cricothyroid (CT) muscle activation were studied by varying airflow and CT activation levels. Pth remained relatively constant over nearly all conditions while the level of graded stimulation needed to reach Pth varied. Increasing airflow and higher level of contralateral vocal fold activation allowed Pth to be reached at lower levels of graded stimulation, while activation of CT muscles had the opposite effect. At maximal CT activation, Pth was reached only at high levels of contralateral vocal fold activation but Pth was doubled. Results show that in vocal fold paresis/paralysis, phonation onset can be achieved by increasing either airflow or activation level of the normal vocal fold, and that CT activation increases the phonatory effort. These results provide further insights into the compensatory mechanisms required for phonation in these common laryngeal pathologies.
An acoustic and electroglottographic study of phonation contrast in Yi.
Authors: Kuang Jianjing
Published: March 2010

This study examines the phonation contrast of Yi, a Tibeto-Burman language of Southwestern China with phonation as a phonemic dimension (traditionally described as tense versus lax contrast). The language has seven monophthongs as well as three tones (high, mid, and low). Tense versus lax phonation contrast can apply to all the vowels and two tones (mid and low) in the language. In this study, both acoustic and electroglottographic data were collected with minimal pairs for all combinations of tones and vowels. Extensive acoustic measures were done by VOICESAUCE, including F0, H1, H2, H1-H2, H2-H4, H1-A1, H1-A2, F1, F2, and cepstral peak prominence (CPP); EGG measures were closed quotient (CQ) and peak-velocity (PV). Preliminary data suggest that H1-H2, CPP, CQ, and PV measures can exclusively distinguish the two phonation types. Moreover, EGG data also suggest voice quality interacts with tones, but the patterns vary among speakers. This might due to the different strategies used by speakers to produce the tense versus lax contrast. In addition, formant frequency measures also show salient differences between tense and lax vowels; tense vowels generally have higher F1 than the lax counterparts. All of the facts suggest that phonation contrasts in Yi are realized across different phonetic dimensions.
Acoustic analysis of phonation and tone interactions in Mazatec.
Authors: Garellek Marc
Published: March 2010

Jalapa de Diaz Mazatec is unusual in contrasting three phonation types (breathy, modal, and laryngealized) and three tone heights: low, mid, and high, including tone contours. Using the acoustic measures H1-H2, H1-A2, and cepstral peak prominence (CPP), previous research has shown that the three phonation types on mid tones are best distinguished at the beginning of the vowel, with each phonation gradually tending toward breathiness [Blankenship (2002)]. The present study extends previous findings by investigating tone and phonation interactions in over 650 Mazatec words and for a large range of acoustic measures. The speech samples, from the UCLA Phonetics Archive, were produced by six female and eight male speakers and vary across the three phonation types and two tonal groups (non-low and low). Using the voice analysis program VOICESAUCE [Shue et al. (2009)], acoustic measures such as harmonic amplitudes, F0, energy, CPP, formants, and bandwidths were extracted. The results generally support previous findings. Several measures also show effects of tone on phonation. In addition, how the phonation types and tone groups differ in timing and the effect of preceding consonants on phonation were investigated. Results show that preceding aspiration changes the timing and degree of phonation. [Work supported by NSF.]
A spectral-slope compensated scale for measuring perception of vocal aperiodicity.
Authors: Gerratt Bruce R. , Kreiman Jody
Published: March 2010

The influence of sound intensity on listeners’ perception of pitch and of sound frequency on the perception of loudness are well known. Similar interaction effects occur in voice quality perception, but are not well understood. Previous studies suggest that listeners’ sensitivity to noise levels in voice depends on the shape of the harmonic spectrum: As the amount of high-frequency harmonic energy present in the voice spectrum increases, listeners require a corresponding increase in noise energy to perceive a constant noise level. These results indicate that perceptually meaningful measurement of spectral noise in voice requires derivation of a spectral-slope-compensated noise scale (similar to equal loudness curves). Based on 12 natural voices, series of stimuli will be created by modifying (1) the noise-to-harmonics ratio (NHR) for different source spectral slopes and (2) the source spectral slope for different NHR values. Just-noticeable differences for each parameter will be plotted as a function of the other, to create a set of equal noise contours reflecting the perceptual interactions of these two acoustic attributes. [Work supported by NIH.]
Voice quality as a cue to location in a speaker’s fundamental frequency f0 range: A perceptual study of English and Mandarin.
Authors: Bishop Jason B.
Published: March 2010

Recent research shows that listeners can locate a specific f0 within a speaker’s individual range without prior experience with the speaker’s voice [Honorof and Whalen, J. Acoust. Soc. Am. 117, 2193–2200 (2005)], suggesting that perhaps some acoustic parameters co-vary with f0 range and are available to listeners. Here we tested Honorof and Whalen’s hypothesis that this information lies in voice quality. English- and Mandarin-speaking listeners heard brief, steady-state /ɑ/ tokens from various locations throughout the f0 ranges of ten English and ten Mandarin voices and were asked to identify where in the speaker’s pitch range a given token came from. To test for listeners’ use of voice quality in the task, we compared mixed effect linear models of responses that included three acoustic measures of the stimuli associated with voice quality: H1-H2, H2-H4, and cepstral peak prominence. Preliminary findings show (1) each of the voice quality measures contributed significantly to the models, although they accounted for only a small portion of the variance in responses compared to f0 and (2) models improved significantly when the language of the voice, but not of the listener, was included; this variable represents further language-specific properties of the voices still to be explored.
Online monitoring of auditory feedback is sensitive to language experience.
Authors: Chen Zhaocong , Liu Peng , Wang Emily Q. , Larson Charles R. , Liu Hanjun
Published: March 2010

It has been demonstrated that vocal responses to pitch perturbations vary as a function of stimulus parameter and can be modulated according to the specific demands of vocal task. The purpose of this cross-language study was to examine whether the online monitoring of auditory feedback is sensitive to language experience during vowel phonation. Native speakers of Cantonese and Mandarin participated in the experiments. They were asked to vocalize a vowel sound /u/ at their conversational pitch, during which their voice pitch feedback was unexpectedly shifted (±50, ±100, ±200, or ±500 cents, 200 ms duration) and fed back to them over headphones. The results showed that, as compared to previous findings in English speakers [Chen et al. (2007)], both Mandarin and Cantonese speakers produced smaller but faster responses to pitch perturbations. In addition, Mandarin speakers produced larger response magnitudes than Cantonese speakers, and the modulation of response magnitudes as a function of stimulus magnitude was observed in Cantonese but not in Mandarin speakers. These findings demonstrate that voice F0 control is language dependent. Further, the different patterns of vocal responses between Mandarin and Cantonese speakers indicate that this highly automatic feedback mechanism works within the specific tonal system of each language.
Effects of tone on the three-way laryngeal distinction in Korean: An acoustic and aerodynamic comparison of the Seoul and South Kyungsang dialects.
Authors: Lee Hyunjung , Jongman Allard
Published: March 2010

The three-way laryngeal distinction among voiceless Korean stops has been well documented for the Seoul dialect. The present study compares the acoustic and aerodynamic properties of this stop series between two dialects, non-tonal Seoul and tonal South Kyungsang Korean. Sixteen male Korean speakers (eight from Seoul and eight from Kyungsang) participated. Measures collected included VOT, f0 at vowel onset and midpoint, H1-H2, and air pressure and airflow. The presence versus absence of tone affects both the acoustic and aerodynamic properties. First, Seoul speakers primarily use f0 to distinguish the three laryngeal gestures of Korean stops, while Kyungsang speakers mainly use VOT. Second, the high versus low tonal contrast for Kyungsang speakers makes f0 an unreliable acoustic cue for the three Korean stops. Third, dialectal differences in VOT to mark the three-way distinction support the notion of a diachronic transition whereby VOT differences between the lenis and aspirated stops in Seoul Korean have been decreasing over the past 50 years. Finally, the aerodynamic results make it possible to postulate the articulatory state of the glottis. Based on the acoustic and aerodynamic results, different phonological representations for the tonal and non-tonal dialects are suggested.
Identification of prominence and discrimination of pitch patterns by Japanese and American listeners.
Authors: Shport Irina A. , Guion-Anderson Susan
Published: March 2010

This study examines how native language shapes the perception of prominence in three-syllable nonce words nenema with F0 patterns varying in F0 peak alignment and F0 fall. F0 is the fundamental cue to perception of pitch accent in Japanese, in which the accent location and accent type (accented versus unaccented phrases) are mainly defined by the relationship between the F0 peak, which is associated with the accented syllable, and the F0 fall, which follows the peak. In English, F0 fall is not considered to be a cue to stress. In two experiments, the alignment of the F0 peak (eight locations) and the F0 fall (no fall, moderate fall, steep fall) were manipulated. In the identification task, participants were asked to decide whether the first or the second syllable sounded more prominent to them. In the discrimination task, participants decided whether the pitch patterns of two words were the same or different. Japanese listeners were expected to be more sensitive to the F0 fall than American listeners for all F0 peak locations. Difference in the perception of peak location between the groups was also predicted, as a reflection of peak delay typical to the native language.
Statistical pattern classification: A review and some current problems/paradigms.
Authors: Miller David J.
Published: March 2010

Unsupervised clustering is the ability to automatically partition a set of data patterns into meaningful groups without prior knowledge of the groups or their number. Supervised classification is the ability to automatically recognize a data pattern as an instance from one of a known set of classes. These problems are fundamental to a variety of application domains, including scientific (e.g., bioinformatics), engineering (e.g., speech recognition), business (e.g., marketing and document clustering), and military (target detection). In this talk, we first review the basic supervised and unsupervised classification problems, standard solution methodologies, and how to characterize their performance. We then discuss some recent problem variants and associated paradigms, including semisupervised learning, unsupervised clustering in high-dimensional feature spaces, and decision fusion techniques.
Target/clutter discrimination using Bayesian active/passive data fusion.
Authors: La Cour Brian R. , Aughenbaugh Jason M. , Yocom Bryan A. , Yudichak Thomas W.
Published: March 2010

Discriminating targets of interest from background clutter is a key challenge in undersea active sonar. This is particularly true in littoral areas, where scattering from the bottom, motion in the water column, and activity on the surface all contribute to produce echoes which are difficult to distinguish from targets of interest. Statistically, these effects manifest themselves in non-Rayleigh, heavy-tailed amplitude distributions. An approach to target/clutter discrimination is described which uses the complementary information from both active and passive acoustic sensors to facilitate this task. The method uses an efficient, grid-based Bayesian track-before-detect scheme to combine data from the two types of sensors by carefully modeling the effects of array processing, replica correlation, normalization, and clutter statistics. Representing measurements and uncertainty in terms of likelihood functions then provides a common framework for fusion. In this manner, active returns with coincident and appropriate passive signals are given more credence, while the presence of only one or the other, while perhaps suggestive, is not as compelling. The presentation will give a general overview of the approach, and an example will be used to illustrate the potential power of using passive data to mitigate active clutter. [Work supported by the Office of Naval Research.]
Moments in history.
Authors: Cohen Leon
Published: March 2010

We discuss how moments and functions of moments have been historically used to characterize and classify distributions, as well as to construct distributions. Among the methods that have been devised are the Gram-Charlier and Edgeworth series, which are methods used to improve on the Gaussian distribution when the moments deviate from Gaussian. We show how these series can be generalized and how any two distributions can be transformed into each other by systematically changing the moments. In this manner, one can develop families of distributions. We illustrate the methods by applying them to pulse propagation in a dispersive medium where the moments can be deterministic or stochastic. [Work supported by the Office of Naval Research.]
Computationally enabled alternatives to Gaussian classification and tracking—A survey.
Authors: Sacha John R.
Published: March 2010

The normal distribution is a good model of physical phenomena in numerous situations where central limit theorem effects come into play. It has a prominent place historically because the many special properties of the Gaussian PDF often yield mathematically elegant closed-form solutions to problems. This role was especially important when numeric calculation was expensive. Normality is not a valid assumption in many applications of modern acoustical signal processing, perhaps especially involving classification and tracking. For pattern recognition, Gaussian classifiers are a straightforward methodology requiring mean and covariance estimates of the class distributions. However, in many cases, feature PDFs themselves are not multivariate-Gaussian; even if they are, estimating parameters in large feature spaces with limited data is difficult. In tracking, the Kalman filter is the canonical formulation, but it requires normally distributed process noise and measurement errors. The advent of cheap computation power has made practical a host of alternative models. In classification, this includes empirical PDF estimation via binning, fuzzy logic, neural nets, support vector machines, featureless classification, Bayesian belief nets, and decision trees. For tracking, particle filters are used to model densities as clouds of point estimates; although computationally expensive, they admit arbitrary densities and are amenable to parallel implementation. [Portions of this work were sponsored by ONR.]
Estimation of densities and information measures: An overview and some recent results.
Authors: Kulkarni Sanjeev R.
Published: March 2010

A fundamental problem that arises in many applications is to estimate an unknown probability distribution from a set of observations drawn according to this distribution. Of particular interest is the case of non-parametric estimation in which little or nothing is known about the underlying distribution. Surprisingly, consistent estimators can be obtained even in this case and the resulting methods are called universal. A related problem is to estimate various information measures based on observations drawn one or two unknown distributions. This talk provides an overview of universal density estimation and the problem of estimating information measures. Some recent results and applications are also described.
Classification of non-Gaussian reverberation as a mixture.
Authors: Chotiros Nicholas P.
Published: March 2010

There are a few different ways to obtain non-Gaussian statistics, one of which is through the heterogeneity of the seafloor. It is often the case that the seafloor is a patchwork of different bottom types. Measurements of seafloor reverberation, using omni-directional sources and receivers, often show Gaussian statistics, because it is the result of the superposition of a large number of random contributions, satisfying the central limit theorem. For sonar systems that have the spatial resolution to resolve the patches, the statistics of the reverberation will change from one resolution cell to the next. Due to positional inaccuracies associated with most sonar systems, it is often not possible or feasible to separate the reverberation from each bottom type. When taken as a whole, the reverberation will have non-Gaussian statistics. The statistical properties will be explored. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]
Characterization of non-Gaussian, bistatic, acoustic clutter on the Malta Plateau.
Authors: Preston John R.
Published: March 2010

Sonar clutter is one of the primary limitations to active ASW. This work focuses on statistical analysis of clutter from some bistatic measurements. Non-Gaussian characterizations of bistatic clutter from a mud volcano field, a shipwreck and a high clutter patch of the Malta Plateau are presented. The received data are taken from the five octave research array (FORA) that has been used to collect extensive monostatic and bistatic data in two recent sea trials on the Malta Plateau off Sicily called Clutter 07 and BASE 07. This work uses data from the above mentioned sea trials to characterize non-Gaussian behavior of bistatic clutter from pulsed sources in the 8009576;3500-Hz band and to compare bistatic clutter with monostatic clutter. K-distributions with their shape and scale parameters are used to describe non-Gaussian behavior together with the models of Abraham and Lyons to infer scatterer densities. The ability to geo-reference key statistical measures of clutter can allow CFAR processors to adaptively set thresholds and reduce false alarms. Examples are shown to demonstrate this. Also included are presentations of the shape parameter vs bistatic aspect angle where appropriate. [Work supported by ONR Code 321US].
Active sonar clutter classification using higher order moments.
Authors: Gelb James M. , Oldag Andrew W.
Published: March 2010

The statistics of normalized matched-filter echoes from an active sonar system operating in a myriad of oceanic environments has been studied extensively for three broad clutter classes including using low-order cumulants to classify subregions of the data [Gelb et al., Proceedings of the ISURC (2008) and references therein]. That work compared empirical distributions to parametric models (e.g., the K distribution and the generalized Pareto distribution). A report on extensions of this work is presented including studies of the accuracy of analytic parameter estimation methods and the efficacy of using higher order moments in the classification process. For each class, with increasingly heavy non-Rayleigh distributed tails, comparisons are made of brute force parameter estimation with the use of analytic estimators. Additionally, comparisons of higher order moments (including skew and kurtosis) computed from the data are made with analytic fits to the data. Using a feature-based classifier, the gains of using increasingly higher order moments are assessed. [Work sponsored by the Office of Naval Research (ONR).]
Sonar waveform design for detection of elastic objects.
Authors: Hamschin Brandon , Loughlin Patrick
Published: March 2010

Animals that navigate and hunt by echolocation, such as some bats and marine mammals, have been observed to change their sonar pulse depending on the environment, as well as during hunting. It has become of interest to incorporate these strategies into man-made sonar waveform and receiver design. We examine the benefits of optimal waveform design versus transmitting a linear FM waveform for detecting elastic objects. Performance loss suffered by assuming a point target is also examined. Our approach utilizes a method recently proposed by Kay to design the optimal power spectrum of the transmit waveform. Because there is an unlimited number of waveforms with the same power spectrum, we further impose a time domain constraint, in terms of the signal duration, to obtain a unique optimal waveform. [Work supported by ONR 321US.]
Error bounds for classifying targets in non-Rayleigh clutter.
Authors: Abraham Douglas A.
Published: March 2010

False alarms in active sonar systems are often represented statistically as having a probability density function (PDF) with tails heavier than the traditionally assumed Rayleigh PDF. Distributions such as the Weibull, K, and Poisson–Rayleigh have been used to represent such non-Rayleigh clutter and to derive the associated probabilities of false alarm and detection, the latter for standard target models (e.g., nonfluctuating and fluctuating). In this presentation, the probability of at least one misclassification per ping (Pc) is evaluated when classifying the standard target types against non-Rayleigh clutter having equal average power. The Bhattacharyya bound is used as an upper bound for the Bayesian error probability (Pe) of a classifier operating on a single cluster and combined with the average number of clusters per ping (Nc) to form Pc. As expected, Pc increases as the clutter becomes more non-Rayleigh. Clutter statistics are seen to affect Pc through both Pe and Nc. However, the effect of clutter statistics on Nc is significantly greater than on Pe. Increasing bandwidth reduces Pc (and therefore Pe) when its impact is modeled as an increase in the number of independent samples available for classification. [Work sponsored by the Office of Naval Research under Contract No. N00014-09-C-0318.]
Comparison of two just-noticeable-difference test methods for clarity index (C80).
Authors: Giacomoni Clothilde B. , Jasinski Christopher M. , Celmer Robert D. , Vigeant Michelle C.
Published: March 2010

The just noticeable difference (JND) or smallest detectable increment of clarity index (C80) has been investigated due to the lack of consensus in the existing literature. The purpose of this study was to determine how the JND of C80 varies as a function of the test procedure. Test signals, with varying amounts of clarity, were generated and combined with short anechoic recordings of orchestral music. The testing took place in the University of Hartford’s anechoic chamber, and the signals were played back over eight spatially arranged loudspeakers. Two testing methods were compared, which both consisted of the subject hearing two signals, A and B, and deciding if the signals were the same or different in terms of clarity. For Test Method 1, the subjects were required to listen to all of signal A and then all of signal B before selecting their response. For Test Method 2, the subjects were allowed to switch between signals A and B in real-time. The difference in the JND of C80 for the two test methods, along with a comparison to previously published results, will be discussed. [Work is supported by the Paul S. Veneklasen Research Foundation.]
The effect of motif length in reverberation-time listening tests using the double-blind testing method ABX.
Authors: Edwards Scott S. , Ignatiuk Daniel A. , Celmer Robert D. , Vigeant Michelle C.
Published: March 2010

Subjective listening tests are often conducted to determine the relationship between an objective parameter and human perception. These tests can consist of auralizing measured or predicted room impulse responses (RIRs) that have been convolved with anechoic recordings. However, no previous research exists that provide guidelines in terms of how auditory memory affects the chosen length of the musical motif convolved with the RIR. Research in the field of auditory memory suggests that there is both short auditory memory of approximately 200 ms and long auditory memory lasting several seconds [Cowan, Psychol. Bull. 96, 341–370 (1984)]. A study was carried out using two motifs with three different lengths: 5, 7, and 10 s, where the successively longer motifs contained the same passages as the shorter ones. A relatively straightforward parameter of reverberation time was the independent variable, and signals were created with reverberation times between 1.0–1.5 s. The subjects were presented three signals, A, B, and X, where the difference in reverberation time ranged between 0.3–0.5 s. The subjects were required to identify which signal A or B matched the test signal X. The effect of motif length on the percent correct will be discussed. [Work is supported by the Paul S. Veneklasen Research Foundation.]
Modeling specular reflection in enclosures with energy-intensity boundary elements and an iterative relaxation method.
Authors: Michalis Krista A. , Bliss Donald B. , Franzoni Linda P.
Published: March 2010

Steady-state sound fields in enclosures with specular reflection boundaries are modeled by an energy-intensity boundary element method using uncorrelated broadband directional sources. The specular reflection case is solved using an iterative relaxation method extended from a three dimensional (3-D) diffuse reflection solution. When chosen properly, few directivity harmonics are required. Starting with a diffuse calculation, higher harmonics are estimated by post-processing, and the original diffuse influence matrix is refined accordingly and converges in few relaxation steps. The method is higher-order accurate and similar to the diffuse case in that it includes strict enforcement of energy conservation. The method is computationally efficient, making it useful for the design of acoustic spaces. This new 3-D energy-intensity boundary element method utilizes an absorption scaling theory, allowing for direct solution of the element power distribution that describes the primary spatial variation caused by the effects of specular reflection, the absorption dependence on incidence angle, and the non-uniform spatial distribution of absorption and input power in the enclosure. Sample results show that differences between diffuse and specular solutions are often fairly small. The iterative relaxation method, with a limited number of specular harmonics, appears to provide a reasonable approach in practice. [Sponsored by NSF.]
Architectural impacts on speech intelligibility in atrium spaces: Two case studies.
Authors: Fischer Julie E.
Published: March 2010

Case study reviewing the speech transmission index and voice intelligibility design and implementation of two atrium spaces where dedicated public address systems were implemented. The architectural design and selection of finishes has a great impact on the capability of any public address loudspeaker system distinct from any system performance characteristics. The presentation will review the design process, acoustical modeling, and testing results outlining the issues associated with meeting the NFPA 72 Common Intelligibility Score suggested goals. Architectural design requirements such as day-lighting and views are increasing large areas of glass in atrium spaces. These designs are making intelligibility increasingly difficult and the electronic systems and loudspeaker designs can only accomplish so much without architectural acoustical finishes as part of the design.
Characterization of classroom noise and noise control techniques and their effect on speech comprehension while learning.
Authors: SanSouci Sooch , Guerra Line , Campbell Dick
Published: March 2010

Classrooms have been shown to be prone to elevated occupied noise levels that reduce speech comprehension and inhibit learning. This presentation discusses a current study that includes three parts: (1) the characterization of masking invoked by noise commonly found in today’s classrooms, (2) the formulation of a metric that intends to associate masking risk to noise features, and (3) the attempt to quantify any increase in speech comprehension resulting from interior acoustic designs that aspire to reduce noise in occupied classrooms. Calibrated recordings made during classroom activities in 9 schools are post processed to allow noise characteristics to be rated based on attributes related to the noise source or type, duration, rate of recurrence, spectra, level, envelope, and peak energy. Binaural and monaural recordings are compared. Speech to noise ratios are statistically weighted over various time frames and activities in an attempt to refine reproducibility among different activities. All recordings were made in occupied rooms both before and after the various treatments were integrated. The results suggest that there are misconceptions in the literature in terms of today’s classroom design trends and a few novel principles emerged as being highly effective.
The role of innate and attentional mechanisms in parsing complex acoustic scenes: A neural and behavioral study.
Authors: Elhilali Mounya
Published: March 2010

The mechanisms by which a complex auditory scene is parsed into coherent objects depend on poorly understood interactions between task-driven and stimulus-driven attentional processes. We use a simultaneous psychophysical-neurophysiological experimental paradigm to manipulate human listeners attention to different features of auditory scenes. In a series of experiments, our findings reveal a role of attention in enhancing the sustained neural representation of the foreground. This enhancement, in both power and phase coherence, originates in auditory cortex, occurs exclusively at the frequency of the target rhythm, and is only revealed when contrasting two attentional states that direct subjects focus to different features of the acoustic scene. It also interacts with innate processes of the auditory system, particularly its differential sensitivity to temporal dynamics of sounds. These results have substantial implications for models of foreground/background organization and mechanisms mediating auditory object formation.
Intention and attention: Top-down influences on the representation of task-relevant sounds.
Authors: Fritz Jonathan B. , David Stephen V. , Winkowski Daniel , Yin Pingbo , Elhilali Mounya , Shamma Shihab A.
Published: March 2010

To explore the role of top-down projections from frontal cortex (FC) to auditory cortex (AC), which may play a role in adaptive reshaping of A1 receptive fields to attended acoustic stimuli during behavior, simultaneous recordings were made from single neurons in FC and AC in behaving ferrets, trained on multiple auditory detection and discrimination tasks in positive and negative reinforcement paradigms. Performance required selective attention to different salient spectral frequency and/or temporal cues. Previous observations revealed task-specific transformations in receptive fields in AC [Fritz et al. (2003); (2005); (2007); (2009); Atiani et al. (2009)]. In contrast, FC neurons showed recognition responses, which categorically distinguished between acoustic foreground and background stimuli. FC responses to targets were often independent of the acoustic properties of the target and thus encoded an abstract representation of the class of target stimuli [Fritz et al. (2009)]. Stimulation of FC, paired with tones, lead to receptive field transformations similar to those observed in behavior. These results emphasize the importance of interactions between multiple areas during selective attention, and the tight coupling of target recognition and auditory attention that enhances auditory cortical filters for attended acoustic stimuli, thus creating a functional representation of task-salient sounds during behavior. [This work was supported by grants from NIDCD, NIH.]
Top-down vocal feedback control in active hearing.
Authors: Wang Xiaoqin
Published: March 2010

Speaking is a sensory-motor process that involves constant self-monitoring to ensure accurate vocal production. This monitoring of vocal feedback allows a speaker to quickly adjust speech production to correct perceived errors between intended and actually produced vocal sounds. The self-monitoring in speaking is crucial for learning to speak native as well as foreign languages. An important behavior in vocal feedback control for both human speech and animal vocalizations is the compensatory change in speech or vocalizations (e.g., pitch, frequency, and intensity) when there is a mismatch between intended and perceived vocal sounds. Such a behavior requires mechanisms for continuously monitoring auditory feedback during vocal production. We have found that disruption of auditory feedback during vocalization alters coding properties of auditory cortex neurons in marmosets (a highly vocal primate species). Furthermore, when marmosets compensate for changes in vocal feedback, there are corresponding changes in their cortical neural activity. These findings suggest that the neural network underlying self-monitoring of vocal production likely consists of both sensory processing and top-down modulations via higher-cortical areas involving planning and memory.
Production and perception of sequential patterns in budgerigar (Melopsittacus undulatus) warble: Evidence for a magic number.
Authors: Tu Hsiao-Wei , Dooling Robert J.
Published: March 2010

The warble song of budgerigars (Melopsittacus undulatus) is composed of a large number of elements uttered in streams lasting from a few seconds to a few minutes without obvious repetition of particular patterns. Previous work showed that warble elements can be classified into eight acoustic categories for which budgerigars have corresponding perceptual categories. Here, we analyzed long sequences of natural warble to determine the proportion of these categories in warble as well as any sequential patterns of these categories in warble. Results showed that elements were not randomly arranged and that warble has at least a fifth-order Markovian structure. This suggests that budgerigars may have a motor control of approximately five elements during the production of warble. Investigations of the budgerigars’ ability to perceive warble sequences of various lengths showed convergent evidence that budgerigars are able to master a novel sequence between four and seven elements in length. In other words, budgerigars may have an attention span of about five elements which may be a limit of their capacity of neural processing. Through gradual training with chunking (about five elements), birds are able to learn sequences up to 50 elements. [Work supported by NIH/NIDCD R01DC000198 to R.J.D.]
Perception of alterations in natural budgerigar (Melopsittacus undulatus) warble: Implications of animal “syntactical capability.”
Authors: Tu Hsiao-Wei , Dooling Robert J.
Published: March 2010

The warble song of male budgerigars (Melopsittacus undulatus) is an extraordinarily complex, multisyllabic, learned vocalization that is produced continuously often for minutes at a time. Previous work has shown that warble elements form acoustic and perceptual categories for budgerigars and these birds can detect ordering changes in artificial sequences of warble elements. Using operant conditioning and a psychophysical paradigm, we examined the sensitivity of budgerigars for detecting different types of insertions (e.g., targets) in a running background of warble up 1000 elements in length. When the inserted targets are warble calls taken directly from the background, budgerigars show a species-specific ability to detect them solely based on sequence violations in the natural ordering of warble elements. Moreover, budgerigars, but not other species, are especially sensitive to temporally reversed warble elements inserted in natural warble sequences, indicating that the acoustic details of warble elements are also perceptually significant to budgerigars besides sequential cues. Although it is still unclear whether budgerigars perceive their warble as a rule-govern sequence or a pattern-based vocalization, the findings here open the door to studies of serial order learning in a natural, non-human communication system. [Work supported by NIH/NIDCD R01DC000198 to R.J.D.]
Bioacoustic and behavioral correlates of spatial memory in echolocating bats.
Authors: Barchi Jonathan R. , Gaudette Jason E. , Knowles Jeffrey M. , Simmons James A.
Published: March 2010

Echolocating bats face a unique orientation problem due to their reliance on echolocation over visual orientation. Each observation (sonar vocalization) only contains information about objects in front of and within at most 5–10 m of the animal. Because their behavior extends over much larger distances, spatial memory might be particularly important during foraging activity and free flight to integrate the shorter views provided by sonar. To investigate memory for object locations, Eptesicus fuscus were allowed to fly freely in an instrumented flight room populated with sparse obstacles (hanging chains). Bat position and vocalization were monitored with a stereo-registered pair of thermal cameras and an array of ultrasonic microphones synchronized to the video. Data were analyzed for correlates of spatial memory-flight path dynamics, head aim, and temporal structure of echolocation signals. Data recorded from bats free-flying in the chain array are consistent with memory of obstacle locations and high-level planning of a flight path through the entire space. These data reflect the behavior of bats flying in natural conditions. [Work supported by ONR and NSF.]