bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence against power amplification in the cochlea
Authors: van der Heijden Marcel , Versteegh Corstiaen
Published: May 2014

Sound-induced traveling waves in the mammalian inner ear peak at a frequency-dependent location. Some form of motility is widely believed to boost this peaking by injecting extra power into the wave. We determined the power carried by the wave from two-point recordings of basilar membrane motion in sensitive cochleae. Up to moderate intensities, the peak wave power was slightly less than the acoustic power entering the middle ear. At higher intensities, an increasingly smaller fraction of the acoustic power reached the peak region. Thus, cochlear dynamic compression stems from variable dissipation rather than saturating amplification. Additional measurements revealed that the peaking of the wave envelope is realized by focusing the acoustic power rather than amplifying it.
Effects of self-generated noise on estimates of detection threshold in quiet in school-age children and adults
Authors: Buss Emily , Porter Heather L. , Leibold Lori J. , Grose John H. , Hall Joseph W.
Published: May 2014

Detection in quiet develops earlier in childhood for high than low frequencies. The present study tested the hypothesis that self-generated noise could play a role in this finding. When adults listen for sounds near threshold, they tend to engage in behaviors that reduce physiologic noise (e.g., quiet breathing), which is predominantly low frequency. Children may not suppress self-generated noise to the same extent as adults. This possibility was evaluated by measuring sound levels in the ear canal simultaneous with adaptive threshold estimation for 250-, 1000-, and 4000-Hz pure tones. Stimuli were delivered and recordings were made using a single foam insert. Listeners were children (4.3–16.0 yr) or adults. Consistent with previous data, the effect of child age was robust at 250 Hz, whereas thresholds of even the youngest listeners were nearly adult-like at 4000 Hz. The spectral shape of self-generated noise was generally similar across listener age groups, although the magnitude was higher in younger listeners. Trial-by-trial data were evaluated to assess the relationship between noise and the accuracy of listener responses: there was an association for younger listeners. These results provide preliminary evidence that self-generated noise may play a role in the prolonged development of low-frequency detection in quiet.
Relative importance of individual spectral features for intraconic localization
Authors: Romigh Griffin D. , Simpson Brian D. , Thompson Eric R. , Iyer Nandini
Published: May 2014

Most researchers agree that physical features present in the monaural spectra act as the primary set of cues for sound source localization within a cone-of-confusion. Less consensus has been reached as to whether these localization judgments are based on the presence of simple spectral features, or whether a more broad spectrum pattern matching occurs in which information across many bands are utilized. The present work first describes a head-related transfer function decomposition technique by which spectral cues are separated into components utilized for lateral localization judgments (when combined binaurally) and those used for localization judgments within a cone-of-confusion. This decomposition allows us to modify individual spectral features of an arbitrary virtual stimulus while maintaining its naturalness and perceived lateral location, criteria that were not adhered to in previous studies. Using this technique, a set of virtual localization studies was conducted in which individual spectral features were removed to examine their relative importance to intraconic localization judgments. Results indicate that while both spectral peaks and notches contribute to localization judgments, spectral information appears to be integrated across multiple frequency bands.
A computational approach to flow noise
Authors: Cox Donald , Perez Daniel , Guarendi Andrew N.
Published: May 2014

The ability to calculate the noise internal to a structure due to external flow is a necessity for the optimal design of a low noise structure. Whether the structure is an automobile, an airplane or an acoustical array, the goal is the same: to in some way minimize the acoustic pressure/particle velocity resulting from flow excitation at a design location. The excitation is usually that due to wall pressure fluctuations resulting from turbulent boundary layer (TBL). There is a long history of modeling plate excitation due to TBL loads. In most cases, the existing work makes use of statistical, empirically based models for the TBL excitation. This work focuses on combining the capabilities of computational fluid dynamics with computational structural acoustics to enable the calculation of flow noise primarily for undersea vehicles. The work is limited to the non-coupled problem, where the flow calculations are made over a non-deforming boundary with the goal of calculating wall pressure fluctuations and using them as loads on a finite element structural acoustics model. The ultimate goal of this work is to develop the capability to calculate flow noise for three dimensional undersea structures for which analytical approaches are not possible.
Energy finite element formulation for unbound acoustic domains
Authors: Vlahopoulos Nickolas , Medyanik Sergey
Published: May 2014

The Energy Finite Element Analysis (EFEA) method has been developed for conducting structural-acoustics simulations for complex vehicles at mid-to-high frequencies where conventional finite element methods are no longer computationally efficient. In applications where exterior heavy fluid loading effects must be included in the model, these effects are currently accounted in the EFEA formulation through an added mass and a radiation damping approach. This is suitable when there is an interest in computing the vibration of the structure and the total radiated power emitted in the exterior fluid. A new formulation for modeling the exterior fluid explicitly with energy finite elements is presented. There are three main components in the new development: deriving the differential equation; solving it numerically using a finite element approach; and introducing infinite finite elements in order to represent the non-reflective conditions at the outer domain of a finite element model. In this presentation, the technical aspects associated with the main elements of the new EFEA formulation for exterior non-reverberant acoustic domains will be discussed. Comparisons with analytical closed form solutions for validating the new developments and their numerical implementation will be presented.
PraatR: An architecture for controlling the phonetics software “Praat” with the R programming language
Authors: Albin Aaron L.
Published: May 2014

An increasing number of researchers are using the R programming language (http://www.r-project.org/) for the visualization and statistical modeling of acoustic-phonetic data. However, R's digital signal processing capabilities are still limited compared to free-standing phonetics software such as Praat(http://www.fon.hum.uva.nl/praat/). As such, it is typical to extract the acoustic measurements in Praat, export the data to a textfile, and then import this file into R for analysis. This process of manually shuttling data from one program to the other slows down and complicates the analysis workflow. The present work reports on a software architecture ("PraatR") designed to overcome this inefficiency. Each of its R functions sends a shell command to the operating system that invokes the command-line form of Praat with an associated Praat script that imports a file, applies a Praatcommand to it, and then either brings the output directly into R or exports the output as a textfile. Since all arguments are passed from R to Praat, the full functionality of the original Praat command is available inside R, making it possible to conduct the entire analysis within a single environment. Moreover, with the combined power of these two programs, many new analyses become possible. Further information on PraatR can be found at the author's website.
The effect of contextual mismatches on lexical activation of phonetic variants
Authors: McGowan Kevin B. , Sumner Meghan
Published: May 2014

Listeners' everyday experience of speech is highly varied and much of this variation is richly informative. We routinely make accurate use of phonetic cues in fast speech, for example, that would be ambiguous if decontextualized. In an influential study, Andruski et al. (1994) showed that a word like “king” facilitates the recognition of a semantically-related target like “queen” better with a canonically long VOT on the initial [k] than when portions of this VOT are spliced out. These and similar findings are cited as evidence for idealized or canonical lexical representations–a surprising result given the rarity of these forms in listeners' experience. In a series of semantic priming experiments, we test the hypothesis that such findings are attributable not to a benefit for the canonical variant but to a mismatch between the manipulated variants and the contextual phonetic frame in which they are presented. The short VOT variants facilitate recognition equally robustly as their long VOT counterparts when each is presented in an appropriate phonetic frame. Our results make it difficult to argue for a canonical bias in perception but, instead, connect such findings to converging evidence from the coarticulation literature showing that coarticulation facilitates perception.
The generalized sinusoidal frequency modulated active sonar waveform ambiguity function: Theoretical and experimental results
Authors: Hague David A. , Buck John
Published: May 2014

The generalized sinusoidal FM (GSFM) waveform modifies the sinusoidal FM (SFM) waveform to use an instantaneous frequency (IF) function that resembles a FM chirp waveform and as a result of this the GSFM possesses a thumbtack ambiguity function (AF) [Hague, Buck, Asilomar (2012)]. This is a drastic improvement over the SFM, which suffers from poor range resolution as its AF contains many ambiguous peaks generated by the periodicity of the SFM's IF. Analyzing the Taylor Series expansion of the GSFM's AF near the origin proves that the GSFM achieves minimal range-Doppler coupling for single target measurements. This minimizes the error in jointly estimating target range and velocity. The GSFM's AF Peak Sidelobe Level (PSL) and Integrated Sidelobe Ratio (ISLR) are comparable to or better than that of other waveforms with a thumbtack AF. Consequently, the target masking effect experienced in multi-target environments is less severe for the GSFM than other thumbtack waveforms. Lastly, test tank experiments demonstrate that the GSFM's desirable AF properties are robust to the signal conditioning necessary for transmission on practical piezoelectric transducers. [Work supported by ONR and the SMART Scholarship Program.]
An effective Sine-Chirp signal for multi-parameter estimation of underwater acoustic channel
Authors: Yang Guang , Yin Wei J. , Li Ming , Pan Rong Z. , Zhou Ling H.
Published: May 2014

An effective Sine-Chirp signal is proposed for the multi-parameter estimation of underwater acoustic channel. The Sine-Chirp signal is made up of a sine signal and a Chirp signal with a fixed time interval. The sine part is adopted to estimate the multi-path number and its corresponding Doppler shift, while the Chirp part is used to estimate the multi-path delay. Furthermore, the Chirp-based decomposition character of the fractional Fourier transform (FRFT) is applied to analyze the Chirp part of the Sine-Chirp signal for the delay estimation, which greatly improves the process efficiency of the Sine-Chirp signal. The simulation results verify the effectiveness of the Sine-Chirp signal.
Uncertainty versus parameter in room acoustics. A case study
Authors: Arana Miguel , Arregui Abel , Machin Jorge , San Martin Ricardo
Published: May 2014

An exhaustive characterization of the auditorium of Baranain (Navarre, Spain) has been carried out. All acoustic parameters (both monaural and binaural) in many seats (96 for monaural and 48 for binaural) have been measured for three source positions on the stage. For acoustic characterization, a countless results can be obtained in accordance (in all cases) with the views of the ISO-3382 for the presentation of the results. The spatial dispersion for each source position and combinations thereof will be shown. Accuracy on the acoustic evaluation of the room will be discussed from a statistical point of view.
Echolocation strategy for multiple target-preys by foraging bats investigated by field measurement and mathematical modeling
Authors: Fujioka Emyo , Aihara Ikkyu , Watanabe Shotaro , Sumiya Miwa , Hiryu Shizuko , Watanabe Yoshiaki , Riquimaroux Hiroshi , Aihara Kazuyuki
Published: May 2014

Using a super microphone-array system, 3-D flight paths of echolocating Japanese house bats, Pipistrellus abramus, across whole foraging area were successfully measured in the field, together with the directional aim of their sonar beams. Sonar sounds were sometimes rapidly alternated between its direction and other one or two particular directions during search phase. Especially, when the bats consecutively captured multiple insect preys, their emissions were directed toward not only the current target prey and also the next target. These suggest that the bats process multiple echo streams by time-sharing manner and plan the flight path to efficiently capture multiple target preys. In order to examine whether the bats select the efficient flight path to consecutively capture multiple targets, the bats' 3-D flight behavior while approaching two target preys was then modeled. The modeling analysis suggested that the echolocating bats select their flight paths to easily direct their sonar beams toward both targets. [This research was supported by the Aihara Project, the FIRST program from JSPS, initiated by CSTP, a Grant-in-Aid for Young Scientists (A) of JSPS, and the Murata Science Foundation.]
Bats (Tadarida brasiliensis) jam conspecifics in food competition
Authors: Corcoran Aaron J. , Conner William E.
Published: May 2014

We here describe field experiments testing whether bats adaptively produce sounds to interfere with (“jam”) the echolocation of other bats. Visual observations, low-light videography, and ultrasound recording with microphone arrays allowing reconstruction of bat flight paths were used to document interactions between Mexican free-tailed bats (Tadarida brasiliensis) at two foraging locations in southern Arizona and New Mexico. We tested three sets of predictions based on the jamming hypothesis and two competing hypotheses—cooperative foraging and food patch defense. Bats produced putative jamming calls (termed sinFM calls) that overlapped temporally and spectrally with “feeding buzz” calls made by conspecifics when attacking insects. Bat capture success decreased by 400% when sinFM calls were present compared to when they were absent. Behavioral sequences consisted of two or more bats sequentially making feeding buzzes within a restricted area while another bats made sinFM calls. After making sinFM calls bats frequently turned toward where the other bat made its feeding buzz and then made a buzz of its own. Together, the results support the hypothesis that bats jam conspecifics in extended bouts of food competition. This is the first known case of echolocating animals adaptively jamming conspecifics.
Recent advancement in transcranial brain imaging using photoacoustic computed tomography
Authors: Anastasio Mark , Mitsuhashi Kenji , Huang Chao , Schoonover Robert , Maslov Konstantin , Garcia-Uribe Alejandro , Wang Lihong V.
Published: May 2014

Photoacoustic computed tomography (PACT) holds great promise for transcranial brain imaging. However, the strong reflection, scattering, and attenuation of acoustic waves by the skull present significant challenges for image reconstruction. In this talk, we will review our recent progress on transcranial PACT image reconstruction. Our contributions include the following: (1) development of a methodology to establish a discrete transcranial PACT image model by use of adjunct X-ray CT data; (2) development of image reconstruction methods that can compensate for speed-of-sound and density variations within the skull; and (3) a detailed investigation of the role of shear waves in transcranial PACT. Computer-simulated and experimental data are employed to demonstrate the feasibility of transcranial PACT.
A systems engineering approach to musical acoustics
Authors: Eyring Nicholas J.
Published: May 2014

Research in musical acoustics has benefited greatly from advances in technology; however, the ever increasing complexity of measurement systems may lend to inefficient experimental design and procedure. A systems engineering approach to experimentation can improve the process. Systems engineering involves the design of complex, many element, systems that maximize overall performance, considering all elements related in any way to the system, including human efficiency and the characteristics of each of the system's components. This paper explores how a background in the full product development lifecycle of a Raman spectroscopy based measurement instrument allowed for the rapid development of an automated directivity acquisition system (ADAS) used to measure a concert grand piano. Prior experience also assisted in adapting the ADAS to measure musicians when assessing elements like reliability, logistics, work-processes, and optimization methods. An account of how research in musical acoustics provides applicable experience for employment in a non-acoustics industry position will also be given.
Tribute to Kenneth McKechnie Eldred
Authors: Sutherland Louis C.
Published: May 2014

I first met Ken while at the Boeing Co and he was Vice President at the Western Electro-Acoustics Laboratory in Los Angeles. I met him again at Wright Patterson Air Force Base, Dayton, Ohio, where he was Chief of Physical Acoustics under Henning von Gierke. He recruited me to come to Huntsville, Alabama, to join the new branch of Wyle that Marshall Space Flight Center wanted for rocket noise programs supporting NASA's rocket noise programs. To augment this Wyle staff, Ken recruited several outstanding acoustical scientists from Southampton University in the UK, including the late Martin Lowson. More on this in Richard Potter's paper. Ken's Wyle staff worked with the Federal Aviation Administration, the Boeing Co. and Lockheed Aircraft in pursuing the environmentally failed development of the SST. Ken supported the U.S. Environmental Protection Agency Office of Noise Abatement and Control (ONAC) and guided Wyle in their preparation of key documents on Noise Policy. He left Wyle to join Bolt, Beranek and Newman (BBN) and later left BBN to form Ken Eldred Engineering. He was a Fellow of ASA, received the ASA Silver Medal in Noise in 1994, and was active on ASA Standards committees, the National Research Council, the Society of Automotive Engineers, and the National Academy of Sciences. The other speakers will discuss other aspects of Ken's many contributions, including those for the Institute of Noise Control Engineering (INCE).
Harvey H. Hubbard's contributions to aircraft noise control during his NACA-NASA career
Authors: Maglieri Domenic J.
Published: May 2014

Following his service in the US Army Air Corps during World War ll, Harvey accepted a position at the NACA Langley Memorial Aeronautical Laboratory in 1945. Propeller aircraft dominated the air transport system at that time and Harvey became one of the first to perform research on the noise associated with propellers. In the next decade jet engine powered aircraft made their appearance and they became the focus of a rapidly growing acoustics research program at Langley. Harvey's pioneering experimental noise studies on propellers and jet engines provided significant insight and understanding of these two concerns. Foreseeing that additional research efforts would be required to address the many new aircraft noise issues, including the sonic boom and airport-community noise concerns of the proposed U.S. supersonic transport, he played a key role in getting NASA to expand its acoustic efforts. As a result, Harvey became NASA's technical focal point for all major acoustical activities. This paper will show the acoustic activities that Harvey was involved in and present some highlights of his research on propeller noise, jet noise, and sonic boom.
Measurement of dispersion and attenuation in granular media using a filter-correlation method
Authors: O'Connor Caleb , Petculescu Andi
Published: May 2014

A wideband technique for measuring sound dispersion and frequency-dependent attenuation in granular media is presented. The measurements were done on a mono-disperse medium of 2-cm solid polypropylene balls, over the frequency range of 500 Hz–20 kHz, enough to cover both weak- and strong-scattering regimes. A horn driver was used to launch sound into a foam-lined bucket containing the granular medium. The latter was mechanically isolated from the driver so as to minimize direct-contact coupling. The foam isolation was not enough, especially at resonances of the bucket-granular system. To account for the mass loading of the bucket by the granulars, the response of the bucket wall was measured by laser Doppler vibrometry both without and with the granulars. The response of the granular medium itself was extracted from the overall response through successive measurements of the individual responses of the driver, driver + bucket, and driver + bucket + granular. The frequency-dependent wavenumber of the granular is obtained by a filter-correlation method, using the driver response as reference. After successive bandpass filtering, the phase speed and attenuation are obtained within each band, respectively, by signal alignment and amplitude log ratio.
Metal based acoustic metamaterials
Authors: Norris Andrew , Nagy Adam J. , Titovich Alexey S.
Published: May 2014

Two apparently distinct types of acoustic metamaterial are considered: a metallic phononic lattice structure and an array of metal shells in water. The unifying feature is that metal acts primarily as a stiffness, and by adding material one arrives at a desired effective density. The metal provides a reservoir of stiffness in the sense that a little bit goes a long way toward the effective stiffness of water, or properties close to water. We first describe the Metal Water structure proposed as a generic metamaterial for transformation acoustics, in both 2D and 3D. The structures have isotropic elastic properties with low shear modulus, hence mimicking water. While designed for long-wavelength effective properties the structures also display interesting finite frequency effects, such as negative index properties. The thin shell metamaterial elements achieve the bulk modulus of water at a specific thickness/radius ratio. Simultaneous matching of effective bulk modulus and density is obtained using an internal mass. By design, both types of metamaterials separate stiffness and density, allowing for simple lumped parameters modeling. The use of metal also has implications for optimal cloaking properties, which result from the fact the metallic structure is non-causal. [Work supported by ONR.]
Transparent acoustic metamaterials for broadband aqueous applications
Authors: Martin Theodore P. , Naify Christina J. , Layman Christopher N. , Rohde Charles A. , Thangawng Abel , Nicholas Michael , Calvo David C. , Orris Gregory J.
Published: May 2014

Matched impedance between different components is an integral part of many wave transport device applications. Achieving transparency in acoustics has typically been accomplished using bulk materials such as ρc rubbers or resonance phenomena over narrow bandwidths. This talk will focus on broadband acoustic metamaterials that are impedance matched to water and that offer a broad range of locally definable sound speeds. Experimental investigations of a number of device applications will be presented, including a transparent gradient index (GRIN) lens, an omnidirectional focusing coating, and elastic lattices that mimic the material properties of water. Impedance-matching over a wide range of sound speeds is achieved by changing the filling fraction of sub-wavelength acoustic scattering components that are individually impedance-matched to water. Both sonic crystals and pentamode trusses are explored as component lattices to produce fluid-like transport over a broad bandwidth in the homogenization limit of the lattices. Excellent agreement is obtained between predictions using fully elastic homogenization theory and the acoustic multistatic signatures measured in the vicinity of the as-realized devices. [Work supported by the Office of Naval Research.]
Pressure-invariant non-reflective and highly dissipative acoustic metamaterials
Authors: Amirkhizi Alireza , Nielsen Christian , Jia Zhanzhan , Nantasetphong Wiroj , Sadeghi Hossein , Holzworth Kristin , Srivastava Ankit , Nemat-Nasser Sia
Published: May 2014

Metamaterials have shown great potential to transform the design of acoustic components in many applications. Many composites with extreme properties have been envisioned, designed, fabricated, and experimentally verified. The next step involves testing such composites in realistic application environments. Oceans are one such environment in which the mechanical effects of water pressure and flow become important factors in any acoustic design, particularly for soft dissipative shells. We have designed a layered metamaterial composite that not only shows very high dissipation but also matches the acoustic impedance of water. Furthermore, we have experimentally verified that the relevant properties of the constituents of this layered design do not change under pressure levels that exist down to significant depths. We are in the process of fabricating this composite to test its acoustic properties under pressure. The metamaterial composites lend themselves naturally to multi-component designs, examples of which as well as gradient media will be presented. Some potential novel applications of gradient and layered components will be discussed.
Wave propagation in three dimensional crystalline foams
Authors: Spadoni Alessandro
Published: May 2014

Recent progress in manufacturing of crystalline foams has introduced cellular solids with very low relative density, the portion of volume occupied by the solid phase. For closed-cell configurations, this means thin films enclosing entrained fluid. While numerous mechanical models for the mechanical properties of 2D, open-cell configurations have been proposed, 3D closed-cell configurations are described by phenomenological models based on powers of the relative density due to their complexity. Elastic wave propagation in such media presents similar challenges and is described by Biot's theory, a model derived from a strain-energy functional defined at the macroscale, based on averaged microstructural quantities. Biot's theory requires equivalent mechanical properties for drained and undrained configurations which are often not available. Exploiting periodicity, we developed a detailed finite-element model to explicitly describe the coupling of fluid and solid. The entrained fluid is compressible, inviscid, and both convection and heat conduction are neglected. Three crystalline foams are considered: Kelvin, rhombic, and Weaire-Phelan configurations. In this talk, I will discuss frequency regimes with a single and two longitudinal pressure wavemodes, and super anisotropy. Dispersion depends on two key frequencies: film resonant frequency, and the natural frequency of a pore with deformable walls.
Acoustic metamaterial elements from tunable elastic shells
Authors: Titovich Alexey , Norris Andrew
Published: May 2014

Elastic shells are used as elements in novel acoustic metamaterials. Tuning the shells produces unnatural and favorable acoustic qualities in the quasi-static regime. This is achieved by internally stiffening the shell with an axisymmetric distribution of springs which connect the added central mass to the shell. The two parameters: stiffness and mass are carefully optimized for the desired effect. Flexural resonances of the shell dominate the frequency response, but are constrained in the quasi-static regime as shown by the analytical model. As an example of transparency, an aluminum shell of radius 1 cm is tuned to water with and acrylic internal oscillator exhibiting a near-zero scattering cross section up to ka = 0.6. Also, individually tuning each shell in a fluid saturated array is a means of creating devices based on transformation acoustics such as a cylindrical to plane wave lens. Investigations of favorable high frequency effects and active tuning are presented. Another method of changing the effective acoustic properties of a shell is to attach a second shell to the inside creating a composite structure. The thickness of each shell is optimized to yield desired effective medium properties. Tuning to water yields a broad frequency range of transparency.
Asymmetries in vowel perception: Do they arise from focalization, perceptual magnets, or both?
Authors: Masapollo Matthew , Polka Linda
Published: May 2014

While directional asymmetries are ubiquitous in cross-language studies of vowel perception, their underlying mechanisms have not been established. One hypothesis is that listeners display a universal perceptual bias favoring vowels with greater formant frequency convergence, or focalization (Polka and Bohn, 2011). A second, but not mutually exclusive, hypothesis is that listeners are biased toward prototypical vowel exemplars in their native language (Kuhl, 1993). In a test of these hypotheses, English listeners discriminated synthesized English /u/ and French /u/ vowels presented in pairs. While the French /u/ tokens exhibit greater formant convergence (between F1 and F2), English listeners have previously been shown to rate the English /u/ tokens as “better” instances of the category (Molnar, 2010). Preliminary results demonstrate that the degree of focalization affects vowel discrimination. When discriminating vowel changes presented in the direction going from the more focal (French) to less focal (English) /u/ vowels, English listeners' reaction times were slower, relative to the same changes presented in the reverse direction. These results suggest that listeners treat the more focal vowels as perceptual reference points. Additional data collection with French listeners is ongoing. The implications of these findings for theories of vowel perception will be discussed.
Perceived emotional valence in clear and conversational speech
Authors: Morgan Shae D. , Ferguson Sarah H.
Published: May 2014

In the laboratory, talkers asked to speak as though talking to an individual with hearing loss modify their speech from their everyday conversational style to a “clear” speaking style. In the real world, individuals with hearing loss sometimes complain that their frequent communication partners seem to be shouting at them, while the communication partners insist that they are just trying to speak more clearly. Acoustic analyses have contrasted angry speech with neutral speech and clear speech with conversational speech. A comparison of these analyses reveals that angry speech and clear speech share several acoustic modifications. For example, both clear speech and angry speech show increased energy at high frequencies. The present study will explore whether clear speech sounds angry to listeners. Young adult listeners with normal hearing will be presented with conversational and clear sentences from the Ferguson Clear Speech Database (Ferguson, 2004) and asked to assign an emotion category to each sentence (anger, sadness, happiness, fear, disgust, or no emotion). The resulting data will show whether clear speech is more likely to be judged as sounding angry than typical conversational speech.
Using the short-time speech transmission index to predict speech reception thresholds in fluctuating noise
Authors: Ferreira Matthew , Payton Karen
Published: May 2014

The Speech Transmission Index (STI) predicts the intelligibility of speech degraded by noise and reverberation. Recently, Payton and Shrestha [J. Acoust. Soc. Am. 134, 3818–3827 (2013)] reported on the ability of a short-time speech-based STI (ssSTI) to predict the intelligibility of speech in the presence of fluctuating noise using analysis windows shorter than 1 s. They found the ssSTI highly correlated with theoretical STI calculations using windows as short as 0.3 s. In the current work, extended versions of the ssSTI were investigated for their ability to improve speech intelligibility prediction in the presence of fluctuating noise; a condition for which the long-term STI incorrectly predicts the same intelligibility as for stationary noise. No STI metric predicts a normal-hearing listener's improved ability to perceive speech in the presence of fluctuating noise as compared to stationary noise at the same signal-to-noise ratio. The investigated technique used window lengths that varied with octave band, based on human auditory temporal resolution as in the Extended Speech Intelligibility Index [Rhebergen and Versfeld, J. Acoust. Soc. Am. 117, 2181–2192 (2005)]. An extended sSTI using speech-shaped noise instead of speech as a probe predicted published speech reception thresholds for a variety of conditions.
On the gradience in perceptibility of word-final voicing contrast in Russian
Authors: Matsui Mayuki
Published: May 2014

Russian is one of the languages in which the underlying voiced obstruents devoice in word-final position, resulting in voicing neutralization (e.g., /rok/ [rok] “fate” vs. /rog/ [rok] “horn”). However, recent studies have shown that word-finally devoiced (i.e., underlying voiced) obstruent and the underlying voiceless one are acoustically different (Chen 1970, Dmitrieva et al. 2010, among others). That is, word-final devoicing shows a case of incomplete neutralization. Also, those acoustic differences are in some degree perceptible for listeners (Matsui 2011, Kharlamov 2012). This paper presents a perceptual analysis of incompletely neutralized obstruents in Russian. Pseudo-nouns produced by the native speakers of Russian were presented to the listeners as auditory stimuli. Sixteen native listeners identified what they heard in a forced-choice identification task. The most striking result to be reported in this paper is that the listeners' sensitivity to the underlying voiced and voiceless stimuli is different between obstruent types: the underlying voicing contrast in stops is harder to perceive than that in fricatives for listeners. Other than obstruent type, the effects of the stimuli presentation type and of the magnitude of the acoustic difference will also be discussed.
Acoustic properties of multi-talker babble
Authors: Silbert Noah H. , de Jong Kenneth , Regier Kirsten , Albin Aaron , Hao Yen-Chen
Published: May 2014

Multi-talker babble can function as an excellent masker for speech stimuli in perception experiments. It has a higher degree of ecological validity than other maskers (e.g., white noise, speech-shaped noise), as it is a type of noise that many listeners encounter on a regular basis in everyday life. In addition, maskers constructed from speech have, by definition, acoustic properties similar to that of the signal. While multi-talker babble is used extensively in speech perception research, relatively little work has been done on the fine-grained acoustic properties of multi-talker babble. We present analyses of a number of acoustic properties of multi-talker babble generated by randomly combining phonetically balanced utterances (e.g., amplitude modulation depth, amplitude modulation frequencies, spectral properties, and spectro-temporal variability). In order to gain a fuller understanding of the nature of multi-talker babble, we analyze how the acoustic properties of babble vary as a function of the number (2–20), gender, and native language (English vs. Mandarin) of the speakers constituting the babble components. Future extensions of this work will (a) focus on how these acoustic variables affect speech perception, and (b) provide the foundation for a web-based system for generating customized samples of multi-talker babble noise for speech perception researchers.
Subcritical width rectangular bands of vocoded speech reveal the nature of envelope processing
Authors: Bashford James A. , Warren Richard M. , Lenz Peter W.
Published: May 2014

Bandwidth requirements for temporal envelope processing were examined using sentences that were reduced to arrays of sixteen rectangular bands (4800 dB/octave rolloff) having center frequencies ranging from 250 Hz to 8000 Hz, spaced at 1/3-octave intervals, and having subcritical bandwidths ranging from 4% to 0.5%. Envelopes extracted from the speech bands, without smoothing, were used to modulate white noise or tones centered at the speech band center frequencies. When the bandwidth of the modulated signals matched that of the speech, tone-vocoded arrays were more intelligible than noise-vocoded arrays and less intelligible than parent speech-band arrays. However, doubling the bandwidths of tone-vocoded arrays, which passed the upper and lower modulation sidebands fully, increased intelligibility to that of the parent speech array. Moreover, when the widths of modulated noise-band arrays were expanded to either an ERBn or 1/3-octave, their intelligibility equaled that of the speech for parent bandwidths of 4% and 2% and greatly exceeded speech array intelligibilities for parent bandwidths of 1% (58% vs. 25%) and 0.5% (28% vs. 3%). These and other findings indicate that optimal temporal envelope processing of speech requires that envelope cues stimulate a majority of fibers comprising critical bands. [Work supported by NIH.]
A phonetic basis for the sonority of [X]
Authors: Bakst Sarah , Katz Jonah
Published: May 2014

Although after voiceless stops French rhotics are realized as voiceless uvular fricatives [Х], they pattern phonologically as high-sonority liquids and are the only obstruent allowed between a consonant and a vowel. This poses a problem for the sonority hierarchy. This experiment tests whether [Х], which has apparent approximant-like formant structure (Yeou and Maeda, 1995) patterns like the fricative [f] or the approximant [l] in its ability to convey information in formant transitions from a preceding consonant. In an AX burst detection task, native English speakers heard syllables of the form ClV, CХV, and CfV (spoken by a native French speaker) with and without a burst. Pilot data (n = 8; 410 trials each) suggests participants are more likely to respond “same” for [Х] and [l] trials than for [f] trials (p < 0.001), suggesting that [Х] carries more redundant information from a preceding consonant than [f] does and thus behaves more like approximants than other fricatives do. This suggests that the sonority of [Х] is grounded in acoustics and perception, rendering an abstract account of sonority unnecessary. This result predicts that other fricatives with long front cavities should also be able to function as high-sonority segments.
Evaluation of web speech and lab speech for automatic classification of prosody
Authors: Howell Jonathan
Published: May 2014

This study evaluates the performance of two very different sources of speech data in prosodic classification tasks: naturally occurring speech collected from the web (e.g., podcasts) and speech elicited in a laboratory. Speech from the web contains useful variability from which to generalize, e.g., variations in speaker and context; however, this variation also includes much statistical “noise,” which may obscure the correct generalizations, e.g., different dialects or overlapping speech and other acoustic artifacts. We trained machine learning algorithms (support vector machines and linear discriminant analysis) to detect prosodic prominence in utterances of the comparative construction, e.g., “than I did.” From 217 web-harvested utterances and 394 lab-elicited utterances (16 items, 27 subjects), we extracted more than 300 acoustic values, including measures of duration, F0, F1, F2, intensity, amplitude, voice quality, and spectral tilt. Both the web and lab training sets yielded similarly high-accuracy classifiers. The best performing algorithm achieved 87.6% accuracy (p < 0.05) when trained on web data and tested on lab data and 90.6% accuracy (p < 0.05) when trained on lab data and tested on web data. Significance values were calculated using a permutation-achieved empirical distribution.
A scientific crossroad: Carey's influence in affecting shallow water acoustics research after the cold war
Authors: Badiey Mohsen , Knobles David P.
Published: May 2014

Before the end of cold war most of the U.S. Navy's underwater acoustics research was focused on deep water. However, in the late 1980s and early 1990s, a shift toward shallow water environments was emphasized. With a body of knowledge from Ewing, Worzel, and Pekeris to Weston, Bill Carey took it upon himself to test a set of realistic goals in understanding complicated shallow water acoustics problems. His major field experiments in 1988–1993 produced results directing the community to address the issue of bottom attenuation and array coherence in a much more serious manner. In addition, due to his work, the community also considered the important problem of the effects of the water column, such as those associated with internal waves, on the acoustic propagation in these regions. This paper presents a summary of Carey's research in shallow water acoustics in light of the broader picture of the community's progress and direction in this field.
Spatial variation of seabed acoustic bulk properties
Authors: Chotiros Nicholas P. , Isakson Marcia J. , Piper James N. , McNeese Andrew R.
Published: May 2014

The seabed is modeled as a poro-elastic medium with a rough interface. The spatial variation of bulk properties, along with the interface roughness, are important contributors to the acoustic scattering strength of the seabed. Their effects are often indistinguishable. While roughness may be measured directly, the variability in the bulk properties is more difficult to obtain. In a recent experiment over a sandy seabed off Panama City, FL, known as the target and reverberation experiment of 2013 (TREX13), the seabed roughness and the normal acoustic reflection loss were simultaneously measured using a laser profiler and a short range acoustic sounder deployed aboard a remotely operated vehicle (ROV). Using the measured roughness statistics, the fluctuations in acoustic reflection loss due to roughness were estimated. Subtracting the roughness contribution from the total measured reflection fluctuations, the component due to bulk property changes was estimated, from which the fluctuation in the bulk properties may be inverted. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]
A brief history of the modeling of sound propagation in bubbly liquids
Authors: Dolder Craig N. , Wilson Preston S. , Hamilton Mark F.
Published: May 2014

William M. Carey is well known for his interest in sound propagation through bubbly liquids. He was also a champion of re-attributing the low frequency effective medium model widely known as Wood's law to its original author Arnulph Mallock, who published a paper titled “The Damping of Sound by Frothy Liquids” in 1910. In the same spirit, this presentation will discuss the evolution of theories involving sound propagation through bubbly liquids over time from Mallock to modern day. Since bubble pulsations can exhibit strong nonlinearity, the presentation will conclude by reintroducing another often-overlooked modeling advance, at least in the western literature, that of Zabolotskya and Soluyan [Sov. Phys. Acoust. 13, 254–256 (1967)] describing the nonlinear propagation of sound in bubbly liquids. [Work supported by ONR.]
A dipole source in a free surface and its representation as a near-surface monopole
Authors: Evans Richard B.
Published: May 2014

A delta function impact on a free surface creates a dipole radiation pattern. This idealized source is of interest in the study of underwater ambient noise, in connection with noise caused by breaking waves, spray, and rain. The radiation pattern, due to the delta function impact, is derived and identified with the partial derivative of a fundamental monopole solution, or Green's function. Underwater acoustical models usually employ a monopole source. The representation of the surface dipole by a near-surface monopole is, therefore, a convenient approximation. The approximation of the dipole by a near surface monopole is an application of numerical differentiation. The reason for a distance of one quarter of a wavelength in the finite difference is described.
Uncertainties in speech transmission index measurements
Authors: Mapp Peter
Published: May 2014

A detailed study has been carried out into the uncertainties associated with Speech Transmission Index (STI) measurements. The uncertainties and measurement errors are shown to be either systematic or random in nature. Systematic errors were found to include limitations of the technique itself as well as uncertainties related to measurement hardware and software implementations. Systematic errors were found to be caused by a range of issues including measurement microphone properties, test signal generation and replay errors, talker loudspeaker directivity and frequency response variations, and measurement system algorithms. Some forms of digital signal processing are also shown to affect the measured result and were found to be highly dependent upon the nature of the test signal and its processing. Measurement uncertainties due to random errors were found to include out of band, high sound pressure level, low frequency modulations or overloading of the microphone preamplifier stages, the pseudo random nature of the STI test signal itself, and the sensitivity of some test signals, such as maximal length sequences, to short term environmental and acoustic changes. Changes and fluctuations in the background noise level during measurements were also found to be a significant cause of error and uncertainly.
Evaluation and improvement of a model to predict the measurement uncertainty due to the directivity of room acoustical sound sources
Authors: Witew Ingo B. , Mueller-Giebeler Mark , Vorlaender Michael
Published: May 2014

With the aim to reduce the necessary efforts to empirically determine the uncertainty in room acoustical measurements, in previous work, a model was developed that can predict the uncertainty a directivity of a sound source introduces to a measurement. As part of the validation extensive series of scale measurements have been conducted. In this contribution, the predicted uncertainty based on simulations and the empiric data is compared to each other. The results were used to improve the model. Concluding it will be discussed whether the model is suitable for a reasonable measurement uncertainty discussion.