bluuebunny/crossref_metadata_2025 huggingface dataset:
Rule-based and information-integration categorization during an incidental learning task
Authors: Roark Casey L. , Holt Lori L.
Published: May 2015

Research in visual category learning supports the existence of dual category-learning systems with distinct neurobiological substrates. Rule-based category learning is engaged by category input distributions that vary orthogonally in perceptual space whereas information integration learning is engaged when categories are defined across multiple input dimensions. Investigators have recently begun to explore these dual systems in audition, including phonetic category learning. However, investigations of dual category learning systems have tended to use category training tasks in which participants actively search for category-relevant dimensions, make overt category labeling decisions, and receive explicit feedback about the correctness of their responses. Recent neuroimaging research highlights the fact that overt category training tasks like this engage learning systems that differ from those engaged by more incidental category learning. Since most natural category learning occurs under more incidental conditions, it is important to understand how training tasks interact with category learning systems. The aim of the present research is to investigate the interaction of input distribution and task. We examine nonspeech auditory category learning across the same perceptual input space for rule-based and information-integration categories in incidental and overt training tasks to characterize how training task interacts with input category distributions.
Listeners’ sensitivity to nasal coarticulation and its interactions with lexical neighborhood density
Authors: Nielsen Kuniko , Scarborough Rebecca
Published: May 2015

Previous research has shown that words from dense phonological neighborhoods, thus subject to greater lexical competition, are hyperarticulated (Wright, 2004; Munson and Solomon, 2004) and produced with a greater degree of coarticulation (Scarborough, 2013). The current study investigates listeners’ sensitivity to lexically conditioned degree of nasal coarticulation. If the basis of attested Neighborhood Density (ND) effects is listener-oriented (as suggested by Wright), listeners’ sensitivity to different degrees of coarticulation may be influenced by ND patterns as well. Forty-three native speakers of American English participated in a forced-choice discrimination task. The stimuli consisted of 32 monosyllabic words with nasal codas, and the degree of vowel nasality was natural or artificially increased or decreased. A Generalized Linear Mixed Effects regression was performed on Correct Response with Direction of Manipulation and ND as fixed factors. The model revealed a significant interaction of Direction and ND (p<0.001), where increased nasality was discriminated more correctly among high ND words while decreased nasality was discriminated more correctly among low ND words. This result shows that listeners are indeed sensitive to differences in degree of nasal coarticulation, and in ways that reflect neighborhood conditioned patterns.
Role of adaptive beamforming with random and irregular arrays
Authors: Hursky Paul
Published: May 2015

When we design an array to accommodate as many as 4–5 octaves of bandwidth, the design must provide a variety of apertures and element spacings. Further, the concept of operations may be such that no structure is available for maintaining a regular array structure (even if we actually wanted one). One example of this is an array of freely drifting sonobuoys. Clearly, with a limited number of elements (far fewer than would be needed to provide half wavelength spacing for the highest frequency over the aperture needed at the lowest frequency), compromises must be made. Solutions include combinations of nested apertures, geometrically increasing spacings, and random spacings to varying degrees—in short irregular and random arrays. Such designs have very poor conventional beam response patterns, with very high sidelobes, compared to the fully populated arrays spaced at half wavelength. However, these objections are a red herring. We will show that adaptive beamforming produces beam responses with very low sidelobes. We will also show that irregular and random arrays indeed outperform regular arrays (of equivalent cost), if a wide bandwidth and range of interference directions are considered. We will also briefly review requirements for array calibration for adaptive beamforming.
The role of water column variability on three-dimensional sound propagation in shallow water
Authors: Badiey Mohsen
Published: May 2015

Simultaneous measurements of sound field and the sound speed profile perturbed by passage of internal waves in shallow water and the resulting modal evolution in space-time domain is reported. The waveguide modal behavior for broadband signals centered at 100, 200, and 300 Hz with the bandwidth of 60 Hz during the Shallow Water 2006 (SW06) experiment is studied using an L-shaped hydrophone array. Several cases are considered where the angle of the internal wave front with the acoustic track ranges from −8 to + 83 degrees. Mode filtering obtained from the vertical array and tracking the filtered mode along the horizontal array reveals that individual modes propagating between the source and receiver arrive at different angles. Using the method of vertical modes and horizontal rays the phase of the acoustic field is calculated and the change in the angle of arriving ray at the L-shaped array, that is the horizontal angle of refraction, is obtained. A 3D PE model is used for comparison between the calculations and the experimental data. [Work supported by ONR 322OA.]
Evaluation of a three-way omnidirectional sound source for room impulse response measurements
Authors: Dick David A. , Neal Matthew T. , Tadros Carol S. , Vigeant Michelle C.
Published: May 2015

Commercially available omnidirectional loudspeakers, which are used to measure room impulse responses, typically have a limited bandwidth and are only omnidirectional below approximately 1kHz. To extend the operating bandwidth, a three-way omnidirectional source was built consisting of a subwoofer, a mid-frequency dodecahedron, and a high-frequency dodecahedron. The subwoofer contains two 10 in. drivers in a sealed box. The mid-frequency dodecahedron uses 12 4 in. mid-bass drivers. The high frequency dodecahedron was made with 12 closely spaced 3/4 in. dome tweeters, providing omnidirectional behavior up to approximately 5 kHz. The directivities of the dodecahedrons were validated by taking measurements in an anechoic chamber. The performance of the sources in a realistic setting was assessed using measurements taken in Eisenhower Auditorium, located at Penn State. Measurements were made with the three sources placed individually on the stage in the same location and compared to measurements made with the sources stacked one on top of the other. The stacked configuration yielded significantly different results than the individual configuration. Additionally, measurements were made rotating the individual sources on the stage to evaluate the effect of angular orientation on measured parameters. Parameter differences were found to be small up to the 4 kHz octave band. [Work supported by NSF Grant 1302741.]
Quantifying response in vocal behavior of fin whales to local shipping in the Southern California
Authors: Joseph John E. , Margolina Tetyana
Published: May 2015

Analysis of a year-long passive acoustic dataset collected at Thirtymile Bank from December 2012 to December 2013 revealed two main types of response, if any, in the vocalization behavior of fin whales to passing ships. The whales ceased calling or reduced the vocalization intensity and then resumed it after the ship passes, or the vocalization intensity increased during the passage and remained elevated for a short period of time afterward. While the response has been primarily observed in 20 Hz calls, several cases have been observed when the call pattern changed with 40 Hz calls recorded after the ship passed. Our study quantifies observed response in terms of both vocalization intensity and call rates. The latter is made possible by applying an image-based detection algorithm allowing for extraction of individual calls. Intensity variations and call rate changes related to ship sounds are statistically estimated, as well as the type and strength of the response to ship sound amplitude, frequency content and relative position of the whales to the passing ships. The received level of the ship sounds presumably heard by whales is modeled using an acoustic propagation model and a Monte Carlo approach to estimate the unknown whale location.
Numerical investigation of the nonlinear attenuation and dissipation of acoustic waves in a medium containing ultrasound contrast agents
Authors: Jafari Sojahrood Amin , Karshafian Raffi , Kolios Michael C.
Published: May 2015

The presence of microbubble ultrasound contrast agents (UCAs) in path of an ultrasound beam increases the attenuation of the medium. A detailed knowledge about the medium attenuation in the presence of UCAs is critical for optimizing ultrasound applications. In this study, a model incorporating the nonlinear attenuation of microbubbles is developed by deriving the complex and real part of the wave number from the Calfish model. Results showed that when UCAs are sonicated by their linear resonance frequency (fr), the effective attenuation of the medium can potentially decrease as the pressure increases, in agreement with experimental observations of the attenuation of monodisperse microbubbles. When sonicated with their pressure dependent resonance frequency (fs), the effective attenuation of the medium is smaller than the case of sonication with fr, but only below a pressure threshold (Ps). Above Ps, the effective attenuation increases abruptly (e.g. ~3 fold) and becomes significantly more than the attenuation during sonication with fr. The attenuation in the subharmonic (SH) regimes of oscillations (sonication with n*fr where n = 2, 3.) are considerably smaller compared to the cases of sonication with fr and fs (~10 times). The attenuation undergoes a sharp increase concomitant with the generation of SH oscillations.
An equivalent source model for simulating high intensity focused ultrasound fields using a nonlinear parabolic equation
Authors: Khokhlova Vera A. , Yuldashev Petr V. , Rosnitskiy Pavel B. , Kreider Wayne , Maxwell Adam D. , Bailey Michael R. , Sapozhnikov Oleg A.
Published: May 2015

The nonlinear parabolic Khokhlov-Zabolotskaya (KZ) equation is commonly used for simulation of nonlinear focused fields generated by medical ultrasound transducers. Axially symmetric codes can be easily implemented on personal computers with simulation times on the order of tens of minutes even for the most extensive simulations of shock formation conditions. However, model accuracy can be limited for high intensity focused ultrasound sources with large convergence angles. In previous studies, it was shown that nonlinear parabolic modeling can provide good matching with measurements and full diffraction modeling in the focal region for both single element piston sources and multi-element arrays. Boundary conditions for the modeling were adjusted by varying the aperture of an equivalent planar source with a uniform pressure magnitude and a phase distribution for parabolic focusing. With this approach, there were slight discrepancies in the lateral pressure distributions in the focal plane. Here, it is proposed that an additional variation in the position of the equivalent source enables matching both axial and lateral distributions of the real HIFU sources with higher accuracy. Several examples are presented to compare modeling and measurements of the fields generated by laboratory and clinical HIFU transducers. [Work supported by RSF 14-12-00974 and NIH EB007643.]
Designing ultrasound fields to control the morphology of engineered microvessel networks
Authors: Comeau Eric S. , Hocking Denise C. , Dalecki Diane
Published: May 2015

Spatial patterning of endothelial cells using ultrasound standing wave fields (USWF) can promote extensive microvessel network formation throughout the volume of three-dimensional collagen hydrogels. The goal of this study was to identify acoustic exposure parameters that generate specific initial spatial patterns of cells, in order to control resultant microvessel morphology. Endothelial cells were suspended in soluble collagen and exposed to a 1-MHz continuous wave USWF for 15 min during collagen gel polymerization. Samples were exposed to peak USWF pressures of 0, 0.1, 0.2, or 0.3 MPa. Samples were either imaged immediately post-exposure using high frequency ultrasound or cultured for ten days. Analysis of B-mode ultrasound images confirmed differences in initial cell band spacing and cell band density between the four exposure pressures tested. After ten days in culture, USWF-induced cell patterning resulted in three distinct microvessel morphologies. Specifically, 0.1 MPa exposure resulted in capillary-like networks, 0.2 MPa exposure resulted in non-branching vessel structures, and 0.3 MPa exposure resulted in hierarchical branching microvessel networks. Spatial characteristics of initial cell bands were then correlated with resulting microvessel network morphology. Results of these investigations allow for the capability to predictively, reproducibly, and rapidly form microvessel networks of known morphology within 3D engineered hydrogels.
PT-symmetric acoustics
Authors: Zhu Xuefeng , Ramezani Hamidreza , Shi Chengzhi , Zhu Jie , Zhang Xiang
Published: May 2015

The concept of acoustic parity-time (PT) symmetry is introduced and used for the study of extraordinary scattering behavior in acoustic PT-symmetric media consist of loss and gain units. The analytical study of acoustic PT-symmetric media shows that these media can be designed to achieve unidirectional transparency at specific frequencies named exceptional points (EPs). This unidirectional transparency occurs at the EPs is due to the asymmetrical arrangement of the periodic loss and gain units that results in different Bragg scatterings on the two sides of the PT-symmetric media. A close look at the phases of the reflections on both sides reveals a sudden jump of the reflection phase on one side at the EPs. This step-function like behavior causes an infinite delay time of the reflected wave on that side, and hence the media become reflectionless in that direction. Combining the concept of acoustic PT-symmetry with transformation acoustics, we design a two-dimensional acoustic cloak that is invisible in a prescribed direction. This kind of directional cloak is important especially for military use since a target object is hidden from the enemy in front can still be identified by friendly at the back. Other useful applications such as directional acoustic imaging, noise cancellation, architectural acoustics, acoustic amplification, etc., can also be developed.
Identification of fractures in carbonates using sonic imaging logs Example from the central of East European plain
Authors: Che Xiaohua , Qiao Wenxiao , Liu Peng , Ju Xiaodong , Lu Junqiang
Published: May 2015

Compared with sandstone, the structure of carbonate rocks is much more complex for its heterogeneity and anisotropy. The Republic of Tatarstan of Russia lies in the central of East European Plain, where oil-gas resource is very rich, and formations are mainly carbonates. In order to detect the underground geology of the region, array acoustic logging tool, micro-electrical scanning tool, and conventional logging tools were applied. We processed and analyzed the array acoustic logging data. The results demonstrated that monopole shear wave attenuation, Stoneley wave attenuation and monopole variable-density waveforms were all sensitive to the boundary where wave impedance contrast was high. The boundary may be a fracture, or a bed interface between shale and limestone in the region. In the micro-electrical scanning images, both the low-angle fracture and the bed interface showed one sine curve. The sine curve of the low-angle fracture was relative rough and the curve width changed with different azimuth, compared with that of the bed interface. The direction of fracture and stress can be obtained by processing cross-dipole waveforms of array acoustic logging data. Micro-electrical scanning tool provided three caliper curves of different azimuth that can determine borehole expanding direction, further getting the stress direction.
The validation of SSWs forecasts in atmospheric global circulation models
Authors: Assink Jelle D. , Smets Pieter , Evers Läslo , Le Pichon Alexis
Published: May 2015

While the influence of the troposphere on the stratosphere is well known, recent observational and modeling studies have demonstrated that the stratosphere has an impact on the troposphere as well. The dynamical coupling between stratosphere and troposphere is particularly strong during sudden stratospheric warming (SSW) events. The correct forecasting of the onset and duration of SSW events is therefore important and is a current challenge for weather forecasting centers. As there is a lack of observations in the upper stratosphere with good temporal and spatial coverage, additional techniques may be helpful to constrain SSWs. This is illustrated using volcanic infrasound measurements. The observations are compared with nowcast and forecast models up to 10 days. While a general agreement is found during the summer period, larger discrepancies are found during the equinox and major SSW of January 2013.
Effect of cueing on stability of behavioral measurements of basilar membrane responses with a precursor
Authors: Necciari Thibaud , Laback Bernhard
Published: May 2015

Stimulation of the olivocochlear efferent system can reduce the gain of the basilar membrane (BM) response to a sound. This gain reduction may be accompanied by a reduction in BM compression, although behavioral data are inconclusive. In this study, the effect of efferent stimulation on compression is assessed using fixed-duration masking curves (FDMCs) with a precursor. In a pilot experiment, presenting a broadband noise precursor before the masker resulted in large within-listener variability for the shortest target durations, although a three-interval forced-choice task was used. To reduce possible confusion effects and increase the dynamic range of BM response measurement, a contra-lateral broadband cue signal, gated simultaneously with the precursor and masker, was added. FDMCs with a 150-ms precursor were measured with and without cue for target durations of 3, 9, and 15 ms. The total masker-target duration was fixed at 25 ms. Listeners were trained at least 2 h, then each condition was measured three times. In contrast to the literature, the presence of the cue neither reduced within-listener variability nor increased sensitivity. Alternative methods are thus required to improve the stability and dynamic range of behavioral measurements of BM responses with a precursor. [Work supported by the FWF project I-1362-N30.]
Comparing human middle-ear motion and pressure gain across idealized and progressively more realistic three-dimensional finite-element models
Authors: O'Connor Kevin N. , Cai Hongxue , Gottlieb Peter K. , Steele Charles R. , Puria Sunil
Published: May 2015

The mammalian tympanic membrane (TM) is linked to the cochlea via a flexible and circuitous three-bone ossicular chain for which much of the mass is concentrated away from the entry axis to the cochlea. As the TM area (ATM) is much larger than that of the stapes footplate (AFP) and the length of the malleus (LM) is somewhat longer than the incus (LI), the middle ear is considered to function as a pressure transformer to optimize the flow of vibrations from low-density air to high-density cochlear fluid, with an ideal pressure gain defined as (ATM/AFP)*(LM/LI). Even so, the reasons for this complex ossicular arrangement, as opposed to the more straightforward case of a columella directly connecting the TM to the cochlea, are not entirely clear. We explore the effects of middle-ear anatomy and material properties on ossicular motion and pressure gain by comparing the behavior of a series of 3D finite-element models ranging from idealized simple axisymmetric cases of a flat-circular or conic TM connected to a columella, all the way to an anatomically accurate three-ossicle human middle-ear model based on a micro-CT scan of a temporal bone. In doing this, we will test whether the complex 3D anatomy of the human middle ear can be shown to offer any concrete advantages in terms of pressure gain over a simpler columella design, or whether other possible reasons for this complex design are more likely. [Work supported by R01 DC05960 from the NIDCD of the NIH.]
The southern vowel shift in women from Mississippi
Authors: Knight Whitney , Herd Wendy
Published: May 2015

Though previous research has documented the Southern Vowel Shift (SVS) in Alabama and Tennessee, no research has focused on the SVS in Mississippi. The majority of SVS research has also focused on European-Americans and assumed that African-Americans do not participate in the shift. The SVS consists of three stages: /aɪ/ monophthongization; lowering and centralizing of /e/ toward /ɛ/ and raising and peripheralizing of /ɛ/ toward /e/; and lowering and centalizing of /i/ toward /ɪ/ and raising and peripheralizing of /ɪ/ toward /i/. In this study, data were collected from women from northern (N = 11) and central (N = 23) Mississippi, with central residents evenly recruited from urban and rural areas. Of these, 15 were European-American and 19 were African-American. Participants read a list of words including the target vowels in bt and bd frames, and then F1 and F2 were measured at five equidistant points. F1, F2, and trajectory length were analyzed to determine to what extent participants exhibited the SVS. There were effects of Region, Rurality, and Race such that central residents shifted more than northern residents, rural residents shifted more than urban residents, and African-American residents shifted more than European-American residents. These results suggest that African-Americans do participate in the SVS.
Human recognition of familiar voices
Authors: Wenndt Stanley
Published: May 2015

Recognizing familiar voices such as friends and co-workers is something we do every day. In typical environments such as an office or home, it is usually easy to identify who is speaking. In noisier environments, this can become a difficult task. This research examines how robust listeners are at identifying familiar voices in noisy, changing environments and what factors may affect their recognition rates. While there is previous research addressing familiar speaker recognition, it is a difficult topic to research since the focus is on familiar voices. The data being used for this research was collected in such a fashion to mimic conversation, free-flow dialog, but in a way to eliminate many variables such as word choice, intonation or non-verbal cues. This data provides some of the most realistic test scenario to-date for familiar speaker identification. A pure-tone hearing test was used to separate speakers into normal hearing and hearing impaired groups. It is hypothesized that the results of the Normal Hearing Group will be statistically better than then results of the Hearing Impaired Group. Additionally, a new aspect of familiar speaker recognition is addressed by having each listener rate his or her familiarity with each speaker.
Phonetic convergence during conversational interaction and speech shadowing
Authors: Pardo Jennifer , Urmanche Adelya , Wilman Sherilyn , Wiener Jaclyn , Gash Hannah , Parker Sara , Francis Keagan , Decker Alexa
Published: May 2015

Phonetic convergence has been studied in both speech shadowing tasks and in conversational interaction. In both settings, phonetic convergence has been found to be highly variable, with higher convergence measures usually found in studies that used speech shadowing. In order to examine whether phonetic convergence in both settings arises from similar mechanisms, the current study compared phonetic convergence in both speech shadowing and in paired conversational interaction in the same set of talkers. A set of 96 talkers (48 female) provided shadowed recordings and participated in a paired conversational map task. Moreover, the pairs were constructed to permit comparisons of same- and mixed-sex pairings. Phonetic convergence was assessed in both tasks using AXB perceptual listening tests with naïve listeners. Overall, phonetic convergence was highly variable across pairings in both shadowing and conversational tasks, with interesting effects of talker and pair sex.
Three-dimensional underwater acoustic scattering from ocean boundaries: Proposed benchmark problems
Authors: Isakson Marcia J. , Chotiros Nicholas P. , Lin Ying-Tsong
Published: May 2015

Acoustic scattering from ocean boundaries is a major component of both the signal for mapping sonars and the noise for imaging sonars. However, models of scattering are often reliant on boundary methods such as the evaluation of the Helmholtz-Kirchhoff integral and its approximations. These methods do not account for sub-surface scattering from layers or inclusions although additional approximations are often used. Often, these approximations are employed with only a cursory knowledge of their realm of validity with respect to such parameters as interface roughness conditions, sediment types and layering structure. We propose a series of benchmark problems to begin to establish the regions of validity for extant scattering models. The problems include 3D scattering from an air/water interface, scattering from a layered ocean sediment and scattering from a simple target buried beneath a rough ocean floor. By comparing the results from a variety of benchmark models, it may be possible to establish a better range of validity for the current suite of modeling tools. [Work supported by ONR, Ocean Acoustics.]
Links between acoustic field statistics, baroclinic wave geometry, and bathymetry computed with time-stepped three-dimensional acoustic simulations
Authors: Duda Timothy F. , Newhall Arthur E. , Lin Ying-Tsong
Published: May 2015

Simulations of sound propagation in a canyon region and in an area populated with internal-wave packets have been performed. Time dependence was introduced into the three-dimensional water-column environments using dynamical ocean models. In the canyon simulation, time-dependence is limited to waves with hydrostatic pressure generated by tidal transports prescribed at the dynamical model boundaries. The wave-packet simulation includes both hydrostatic and nonhydrostatic waves. For the canyon, propagation of 300-Hz sound from shallow to deep water is simulated. For wave packets, 200-Hz sound is simulated. For each situation, statistics related to horizontal correlation are estimated at synthetic “arrays” inserted into the domain. Correlation properties are estimated from single field snapshots and from time-series analysis of the output, and the two are compared. Array performance evaluations from the two methods are also compared. Covariance matrix properties for the time-series output, including principal component behavior, are analyzed to examine the interference effects and fluctuation mechanisms that are responsible for the spatially patchy array performance results.
Empirical mode decomposition-discrete Hilbert transform based solution to detect decompression-induced gas bubble from Doppler ultrasound signal
Authors: Khan Md Iqbal Aziz , Nakai Takayoshi
Published: May 2015

This paper concerns the detection of decompression-induced gas bubble from underwater construction workers Doppler ultrasound signal based on empirical mode decomposition (EMD), discrete Hilbert transform (DHT), and some parameters, which could be useful to detect gas bubble. EMD in combination with DHT is used to generate time-frequency-energy distribution and systolic phase is detected from that distribution. The properly detection of the systolic phase is the most important task to the detection of gas bubble. Time-varying mean frequency (TMF) is determined from instantaneous amplitude and instantaneous frequency. An algorithm is applied to extract some specific segments from TMF. Then the segments are considered as gas bubble on the basis of some parameters such as spreading in frequency, ratio of the gas bubble signal to the background signal, ratio of the gas bubble signal’s total energy to the background signal, and rising rate.
Three-dimensional pulsation of rat carotid artery bifurcation observed using a high-resolution ultrasound imaging system
Authors: Jin Changzhu , Nam Kweon-Ho , Paeng Dong-Guk
Published: May 2015

The arterial structure experiences cyclic pulsation in three-dimension (3-D) by pulsatile blood flow. Here we reconstruct the 3-D carotid artery bifurcation (CAB) geometry from three rats to observe the pulsatile variation of the carotid artery geometry by a high-resolution ultrasound imaging system (Vevo 770, VisualSonics, Canada). Two experienced observers manually segmented the cross-sectional ultrasound images to outline the arterial lumen. From the constructed geometry of three subjects, we observed that the CAB geometry favorably expanded to anterior/ posterior direction which parallel to sagittal plane. Furthermore, an in vitro blood flow experiment using an anthropomorphic flow phantom was implemented to more clearly understand the asymmetric pulsation phenomenon. Finally we confirmed the elastic bifurcation geometry favorably expands in a direction of bifurcation, both in vivo and in vitro measurements, which derived by bifurcated flow. This finding, the asymmetrical pulsation phenomenon of carotid bifurcation in 3-D, may be useful in understanding hemodynamic etiology of cardiovascular diseases and also provide more realistic input data for computer simulation of hemodynamics. [This work was supported by MSIP Korea, under the C-ITRC support program (NIPA-2014-H0401-14-1002) supervised by the NIPA and also supported by the Richard Merkin Visiting Fellowship Program of the Focused Ultrasound Foundation.]
“Good acoustics” is culturally determined: Evidence that prehistoric performance space selection was based on different world views
Authors: Waller Steven J.
Published: May 2015

“Ideal” performance spaces are in the ear of the listener. Cases will be presented to argue that the response to a particular set of acoustic characteristics of a space is a function of the world view of the audience/performers. For example, in today's modern society that values speech intelligibility and appreciation of polyphonic classical and contemporary music, a distinct echo in a performance space is considered an unforgivable fault. However, in the ancient past when wave characteristics of sound were not understood, virtual sound effects arising from complex sound wave interactions (echoes, reverberations, interference patterns, etc.) were misinterpreted as invisible beings (echo spirits, thunder gods, sound absorbing bodies, etc.) as described in ancient myths around the world. Some of these myths contain accounts of purposeful searches for the best echoes, which were worshiped. Scientifically conducted experiments involving blindfolded participants show how various ambiguous sounds can be interpreted in more than one way (like optical illusions). Sound level measurements demonstrate that cave paintings and canyon petroglyphs were placed in locations with the strongest echoes. Prehistoric flutes have been found in reverberating caves. These experiments thus can help in understanding our ancestors’ perceptions and reactions to sounds they considered supernatural (https://sites.google.com/site/rockartacoustics/).
Affective prosody production in autistic and typically developed adult males
Authors: Hubbard Daniel J. , Faso Daniel J. , Sasson Noah J. , Assmann Peter F.
Published: May 2015

This study examined differences in production of affective prosody in adult males with autism spectrum disorder (ASD) and typically developed (TD) controls. Previous studies of children with ASD have reported increased variability in fundamental frequency (f0) in spontaneous and semi-spontaneous speech compared to TD children. A controlled set of expressive speech recordings was collected from 30 talkers (15 ASD) to measure differences between the two groups using the same lexical content. Isolated vowels, vowel-consonant-vowel (VCV) syllables, words and short phrases were elicited in five emotion contexts: angry, happy, interested, sad, and neutral. The recordings were obtained using evoked and portrayed elicitation techniques: talkers were asked to recall past emotional episodes (evoked) and role-play scripted scenarios (portrayed) specific to each emotion context. Consistent with previous work and extending the findings to adults producing the same lexical content, talkers with ASD showed increased f0 variability in each emotion context except for neutral. In addition, systematic group differences were found in acoustic properties other than f0 used to convey affective prosody—including harmonics-to-noise ratio and intensity—which were higher in each emotion context for talkers with ASD compared to TD talkers.
Production of contrastive focus in children with autistic spectrum disorder
Authors: Rapin lucile , Trudeau-Fisette Paméla , Bellavance-Courtemanche Marie , Ménard Lucie
Published: May 2015

Contrastive focus serves to emphasize the importance of a semantic unit in the language string. Children with autistic spectrum disorder (ASD) appear to show difficulties in producing this prosodic marker. This study aimed to identify acoustic correlates related to contrastive focus in children with ASD. Nine francophone children with ASD and nine francophone typically developing (TYP) children produced simple four-word sentences (for example, «C’est une chaise.»: «it is a chair.») in a neutral condition and then in a contrastive focus condition. Ninety-six speech productions were recorded using a system that synchronized acoustic signals with lingual and labial movements. Maximum pitch, mean pitch, and pitch range, as well as maximum and mean sound intensity and duration were investigated. Values for pitch range, maximum and mean sound intensity, and duration were greater in the focus condition than in the neutral condition. Moreover, the differences were significantly greater in TYP children than in ASD children, who did not have increased speech values when switching to the focus mode. This suggests that pitch range, and intensity and duration of sound correlate most with contrastive focus marking in both groups. Yet, it appears that ASD children show less contrastive focus marking than TYP children.
Fundamental frequency of speech directed to children who have hearing loss
Authors: VanDam Mark , De Palma Paul , Strong William E.
Published: May 2015

Studies of child-directed speech (CDS) have shown that when talking to children, parents systematically use (among other strategies) increased fundamental frequency (F0). Lombard effects such as increased F0 have also been documented when addressing a listener who is hard-of-hearing (HH). Here, we examine F0 of mothers and fathers in families with HH versus typically developing (TD) children in CDS and adult-directed speech (ADS) contexts. Whole-day audio recordings were collected by a child-worn audio recorder and analyzed by automatic speech recognition (ASR) software to identify segments of vocal activity by children and their parents (LENA Research Foundation, Boulder, CO). Custom software extracted F0 values in all conditions. We found that (1) mothers are much more systematic in their use of CDS than fathers, (2) parents do not appear to be sensitive to the hearing status of their children, and (3) parents of HH children may have higher overall F0 irrespective of CDS or ADS. Results suggest that mothers and fathers do not use F0 with their children in the same way, and parents of children with hearing loss may have certain global F0 characteristics not shared by parents of TD children.
A comparative study of variability in landmark sequences and implications for dysphonic speech analysis
Authors: Ishikawa Keiko , Rao Marepalli B. , Boyce Suzanne
Published: May 2015

Dysphonia negatively affects speech intelligibility especially in the presence of background noise. This may be because dysphonic speech often contains a higher proportion of noise and/or a lower proportion of harmonic power, leading to reduced information in the speech signal. Landmark (LM) analysis was designed to identify patterns of information in the speech signal that are particularly salient for the auditory system. Consequently, it describes speech as a sequence of LMs. Past studies successfully differentiated disordered speech from normal speech based on the number of times each LM occurs. While the count was a sufficient measure for their purposes, transitional patterns in LM sequences may yield more descriptive information on underlying mechanism of the intelligibility deficits. Shannon’s Entropy and Markov chain model were used to evaluate the difference in LM sequences between normal and dysphonic speech. Landmarks were obtained from the first sentence of the Rainbow Passage for 33 normal speakers and 36 dysphonic speakers using SpeechMarkTM software package. The variability in the transitional patterns of LM was significantly less in dysphonic speech compared to normal speech. This suggests intelligibility deficits may be due to the greater acoustical constraints inherent to dysphonic speech.
Effects of reading ability on lexically-informed perceptual learning
Authors: Thompson Emily , Graham Stephen , Bohner Alexandra T. , Drouin Julia R. , Theodore Rachel M.
Published: May 2015

Research on perceptual learning for speech shows that lexical information can be used to modify phonological representations. Moreover, lexically informed perceptual learning is domain general in that it also influences the mapping to phonology from printed text. Given phonological processing deficits in adults with reading impairment, we hypothesized that reading ability would meditate how lexical information is used to dynamically adjust perceptual representations. Adult participants were identified as either good or poor readers based on standardized assessments of reading and reading sub-skills. All completed a lexical decision training phase followed by a test phase. Stimuli in both phases consisted of printed text. During training, readers viewed an ambiguous grapheme midway between “N” and “H.” Lexical information was used to bias perception of the grapheme as either “N” or “H.” At test, all readers categorized tokens along an “N” to “H” continuum. The results to date indicate that both groups of readers used lexical information to modify letter perception; however, the learning effect was more robust in the good readers compared to the poor readers. These results suggest that the degree to which lexical information is used to modify the mapping to sound structure is related to phonological ability.
Elevated depressive symptoms associate with an emotion-general deficit in speech perception at a cocktail party
Authors: Xie Zilong , Maddox W. Todd , Chandrasekaran Bharath
Published: May 2015

Individuals with major depressive disorder demonstrate significant deficits in social communication. While the majority of work on individuals with elevated depressive symptoms focuses on speech production, much less is known about speech perception in individuals with elevated depressive symptoms. Here, we examine speech perception in the presence of different types of distractions. Two forms of distraction are hypothesized to interfere with speech perception in such listening conditions: energetic masking (EM) and information masking (IM). Relative to EM, IM places greater demands on executive function. A recent study showed that individuals with elevated depressive symptoms exhibit a selective deficit in perception of neutral speech during primarily IM conditions, likely due to their impairments in executive function. Here, we examined whether this selective deficit extends to emotional speech that portrays anger, fear, happiness, or sadness. Results showed that during IM conditions, individuals with elevated depressive symptoms exhibited poorer performance for neutral as well as for the four emotion categories, compared with those without elevated depression symptoms. However, both groups performed comparably during EM conditions. These findings suggest that elevated depressive symptoms are associated with an emotion-general deficit in speech perception in noise conditions that place demands on executive function.
An investigation into how the acoustics of different sized open plan classrooms affects speech perception in Kindergarten children
Authors: Mealings Kiri T. , Demuth Katherine , Buchholz Jörg , Dillon Harvey
Published: May 2015

Open plan classrooms, where several classes share the same space, have recently re-emerged in Australian primary schools. This paper examined how the acoustics of four Kindergarten classrooms (an enclosed classroom (25 students), a double classroom (44 students), a linear fully open plan triple classroom (91 students), and a semi-open plan K-6 classroom (205 students)) affect speech perception. Twenty-two to 23 children in each classroom participated in an online four-picture choice speech perception task while adjacent classes engaged in quiet versus noisy activities. The noise levels recorded during the task were higher in the larger open plan classrooms compared to the smaller classrooms for both the quiet and noisy conditions. A linear mixed effects model revealed that children’s performance accuracy decreased as noise level increased. Additionally, children’s speech perception abilities decreased the further away they were seated from the loudspeaker, and this effect was stronger the higher the noise level. Children’s response time was also slower in the noisiest compared to quietest classroom. These results suggest that open plan classrooms may not be appropriate learning environments for didactic-style teaching with young children due to their high intrusive noise levels which negatively impact speech perception.
Vocal comfort and effort in speech: Accommodation to different room acoustic conditions
Authors: Graetzer Simone , Hunter Eric J. , Bottalico Pasquale
Published: May 2015

Background: Vocal effort is a physiological entity that accounts for variation in voice production as loading increases, measured as sound pressure level (SPL). A number of studies have investigated vocal effort and load, but few have considered the role of acoustic clarity (C50), the early to late arriving sound ratio. Method: 20 subjects performed vocal tasks in various room acoustic conditions. Tasks were performed in three styles: soft style, comfortable conversational style, and loud classroom style. C50 in the position of the talker was changed by means of two reflective panels. Two noise levels were used: background noise, and artificial child babble noise. After each task, the subject answered questions addressing their perception of vocal comfort, control and fatigue. SPL and Fundamental Frequency (F0) were measured. Results: When panels were present, talkers perceived the room as being more comfortable to speak in. In particular, in the babble condition and in loud speech, comfort and control tended to increase. Vocal effort (SPL) tended to decrease when panels were present. An assessment of F0 is also reported. The results indicate that even while keeping reverberation time constant, reflective surfaces may be optimized to increase voice comfort and reduce vocal effort.
Vowel and sibilant sound production in noise
Authors: Reilly Kevin J.
Published: May 2015

The present study investigated speech production in noise and whether speakers modulate the spectral contrasts of vowel and sibilant sounds depending on the frequency characteristics of the background noise signal. Twelve speakers participated in the present study. Speakers were presented with three-word sequences one word at a time on a computer monitor and, after a variable delay, produced the three words in the order they were presented. Word sequences were comprised of CVC words containing either or both of the vowels, /a/ and /ae/, and either or both of the sibilants, /s/ and /ʃ/, in word-initial position. During the presentation and production of each sequence, speakers were exposed to one of four possible noise conditions: (1) silence; (2) vowel masking; (3) sibilant masking; and (4) speech-shaped noise. The sibilant masker contained energy at frequencies associated with a speaker’s productions of /s/ and /ʃ/ and the vowel masker at frequencies associated with their productions of /a/ and /ae/. These masking signals were generated prior to the experiment based on practice productions of the stimulus words by each speaker. Spectral contrast distances are based on vowel formant frequencies and sibilant spectral moments (1–4). Noise condition effects on spectral contrast distances are being evaluated to determine whether speakers selectively alter their production of those sounds masked by background noise.
Cutaneous vibration enhances the Lombard Effect
Authors: Brajot François-Xavier , Gracco Vincent L.
Published: May 2015

The Lombard Effect is traditionally defined as a compensatory vocal response to noise at the ear. Somatosensory feedback is also relevant to speech, however, and may be expected to play a role in the Lombard response and perceived vocal effort. The effect of masking both auditory and laryngeal vibrotactile feedback was assessed in adults without speech or hearing disorders. Autophonic loudness, speech intensity, fundamental frequency, and formant frequencies were measured in each of three conditions: unmasked, auditory masking, and mixed auditory plus somatosensory masking. Neither the slope of the autophonic loudness curve nor the shape of the oral reading intensity contour changed as a function of masking condition. However, the intercept of the autophonic loudness curve and the offset of the intensity contour were greater in the mixed masking as compared to the auditory masking condition, indicating that vibrotactile masking effectively enhanced the Lombard Effect. These findings support the hypothesis that both auditory and somatosensory feedback function to adjust speech gain, without affecting relative production intensity or autophonic loudness perception. As such, the Lombard Effect is proposed to result from a general sensorimotor process rather than from a specific audio-vocal mechanism.
Informational masking of monaural speech by a single contralateral formant
Authors: Roberts Brian , Summers Robert J.
Published: May 2015

Recent research suggests that the ability of an extraneous formant to impair intelligibility depends on the variation of its frequency contour. This idea was explored using a method that ensures interference occurs only through informational masking. Three-formant analogues of sentences were synthesized using a monotonous periodic source (F0 = 140 Hz). Target formants were presented monaurally; the target ear was assigned randomly on each trial. A competitor for F2 (F2C) was presented contralaterally; listeners must reject F2C to optimize recognition. In experiment 1, F2Cs with various frequency and amplitude contours were used. F2Cs with time-varying frequency contours were effective competitors; constant-frequency F2Cs had far less impact. Amplitude contour also influenced competitor impact; this effect was additive. In experiment 2, F2Cs were created by inverting the F2 frequency contour about its geometric mean and varying its depth of variation over a range from constant to twice the original (0–200%). The impact on intelligibility was least for constant F2Cs and increased up to ~100% depth, but little thereafter. The effect of an extraneous formant depends primarily on its frequency contour; interference increases as the depth of variation is increased until the range exceeds that typical for F2 in natural speech. [Work supported by ESRC.]