bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modeling of seismogram envelopes in 2-D random media
Authors: Fehler Michael
Published: October 2013

Several portions of seismograms recorded from regional earthquakes cannot be easily explained as resulting from waves propagating along deterministic paths within the Earth. For example, seismic coda, which is the tail portion of the seismogram of an earthquake recorded at distances of less than 100 km, is considered as resulting from waves that are multiply scattered from random heterogeneities in the Earth’s lithosphere. At greater distances, observations that the duration of the initial arriving wave packet is much longer than the source–time duration is explained as being due to multiple forward scattering along the path between the source and the receiver. To investigate these phenomena, we use a finite difference method to numerically simulate 2-D scalar-waves that propagate through random media characterized by a von Karman autocorrelation function. Such media are considered to be appropriate models for the random component of the structure of the Earth’s lithosphere. We investigate the characteristics of the resulting wavefields and compare them with those of observed seismograms.
The coda of artificial shots on volcanos
Authors: Wegler Ulrich
Published: October 2013

The data of active seismic experiments at Merapi volcano and at Vesuvius volcano are used to analyze the scattering of elastic waves in the shallow structure of these volcanos. The seismograms from artificial explosions located on the volcanos are characterized by spindle-like envelopes, small or missing P-onsets, missing S-onsets, and long codas. These unusual shapes of the envelopes can be explained by strong multiple scattering in the shallow heterogeneous eruptive material and are modeled using the diffusion model. As a result diffusivities of d=0.05 km2/s in the case of Merapi and of d=0.1 km2/s in the case of Vesuvius are obtained independent of frequency between 2 to 20 Hz. Assuming the dominance of shear waves in the coda and a typical S-wave velocity of around 1.5 km/s for the shallow volcano this corresponds to a transport mean free path of only 100 m in the case of Merapi and of only 200 m in the case of Vesuvius. The corresponding length scales for intrinsic attenuation, on the contrary, depend on frequency and are at least one order of magnitude larger than the transport mean free path. These results show that multiple scattering is an important effect for the seismic wave propagation in volcanic environments.
Feasibility study of acoustic agglomeration of fly ash in shaped resonators
Authors: Lipkens Bart , Conrad Theodore J.
Published: October 2013

An interesting method for controlling fine particulate emission is acoustic agglomeration. Acoustic agglomeration is a process where fine particles coalesce and grow into bigger particles when they are subjected to a high intensity sound field. As a result the particle size distribution shifts to larger sizes. Acoustic agglomeration can thus be used as a preconditioner prior to a conventional filter and improve the overall capture rate of the filter. An experimental study was performed to evaluate the potential of a new high intensity acoustics technology, resonant macrosonic synthesis (RMS), to agglomerate fly ash. RMS allows the generation of very high amplitude shock-free acoustic standing waves within shaped resonators. Experiments were performed in a football shaped resonator at 570 Hz under varying fly ash loadings and sound pressure levels. Particle size measurements were obtained using a laser diffraction particle-sizing instrument. Reduction of fine particulate matter (diameter of particles less than 5 micron) of up to 50% has been achieved. [Work supported by Dominion Corp.]
Computing structural energy density and power flow using spectral elements
Authors: Arruda José Roberto F. , Ahmida Khaled M.
Published: October 2013

The large deterministic models obtained using numerical methods are frequently inadequate to deal with structural dynamics problems in the audio frequency range. An alternative approach that has been used for many years is the spectral approach. After transformation to the frequency domain, structural dynamics problems are described by partial differential equations that can be solved analytically in an exact way. In the case of one-dimensional waveguides, the spectral approach may be combined with a mobility approach yielding a spectral element methodology that, in many ways, resembles the finite element method. The major drawback of this approach is the difficulty in treating two- and three-dimensional waveguides. Exact solutions exist only for plates and shells with particular geometry and boundary conditions. An approximate method has been proposed for flat plates with arbitrary conditions, but the element assembling is still restricted to one dimension. In this paper, different formulations for flat-plate spectral elements are presented and their advantages and drawbacks are discussed. Expressions for the computation of energy densities and power flow in frame and plate spectral elements are derived and some examples are shown to illustrate the advantages of this approach in energy flow analysis applications.
Is the modal approach appropriate for analysis of energy flow?
Authors: Pavic Goran
Published: October 2013

Modal superposition is a most commonly used approach in a numerical analysis of vibration. However, the computation requirements of a typical analysis of energy flow limit the attractiveness of the modal approach because, as a rule, a very large number of modes have to be taken into account in order to produce realistic results. The reason for this particularity is that the energy analysis involves not only vibration displacements but also higher derivatives of these which are contributed by higher modes, the higher the derivative order. More careful analysis of structure-borne vibration shows that the modal truncation is not the only inconvenience where the modal approach is used. An equally important factor limiting its use is the representation of vibration dissipation by modal damping. The paper shows comparisons of computed energy flow in plates using modal and wave approaches. The differences between the two are noticeable, in particular where the vectorial functions of energy flow field, divergence and curl, are concerned. The wave approach to vibration analysis is shown to be more physically consistent than the modal approach.
Desirable characteristics in algorithms for measurements of features in pathological voices
Authors: Hernandez-Diaz Huici Maria E.
Published: October 2013

In this paper a critical review of some reported algorithms is made, regarding the objective measurement of features in pathologic speech. The discussion is grouped in the following topics: prosody, pith related measurements, hoarseness and vowel/consonant production. The prosody topic includes measurements of timing, stress, tempo and intonation. Pitch related measurements involve the algorithms based on pitch period, hoarseness groups measurements of noise and turbulence related to the pharyngeal functioning, while vowel/consonant production includes formant’s transitions, voice onset time and nasality perturbations. Every algorithm was analyzed taking into account the following aspects: Domain of analysis, sampling frequency, sample of speech or voice used, amount of patients and kind of disease, correlation with subjective evaluations. Limitations of analyzed algorithms are shown and the desired characteristics for each topic’s measures are proposed. (To be presented in Spanish.)
Ultrasonic sensor system to detect solids in a milk pasteurization process
Authors: Barroeta Z. Carlos , Sanchez M. Fernando L. , Fernando R. G. Moreno , Montes P. Laura
Published: October 2013

In the food industry, many products require a specific process. In the milk industry, the raw milk passes through several process stages before reaching the end user in a very qualitative and healthy way. One of the problems of the milk is that it can contain solids in suspension, result of contamination of the milk, or inherent to the pasteurization process itself. In order to control these solids, a solid detection system is being developed, which will detect the solids by the reflection and refraction of ultrasonic waves. The sensor must be set in the upper part of the milk containers, and with a grid array to allow the control system to prevent these solids from entering into the pipes of the processing plant. The sensing system may activate an acoustic alarm to indicate that a solid has been detected, and a visual one to indicate the affected part of the process. (To be presented in Spanish.)
Some constraints on the use of ABR in hearing studies: Investigation in dolphins
Authors: Popov Vladimir , Supin Alexander
Published: October 2013

The main difficulty in using ABR in frequency-tuning measurements arises from the fact that these responses are evoked only by transient acoustic stimuli. This limits their use as probes for measuring frequency selectivity. Even with a slowly rising and falling stimulus, only a shorter part of the stimulus may be effective to evoke the response, and the spectrum of this short part is broader than the spectrum of the whole burst. It was shown in tone–tone masking study in dolphins, that tuning curves at lower frequencies reflect not the real frequency tuning but broad spectral bandwidth of the probe’s effective part. In the bottlenose dolphin, this effective part is not longer than 0.5 ms, irrespective of the actual probe duration. Another problem in the use of the ABR technique is that it is not clear which spectral part of the wideband stimulus participates in ABR generation, and what is the contribution of various parts of the cochlear partition to ABR. ABR to clicks and noise bursts of various frequency bands were recorded in dolphins in order to find these contributions. ABR amplitude increased with increasing the stimulus frequency, thus indicating a higher contribution of basal cochlear parts.
Experience-dependent cortical processing of complex sounds by rats
Authors: Orduna Itzel , Gluck Mark A. , Mercado Eduardo , Linden Jennifer F. , Bao Shaowen , Merzenich Michael M. , Sahani Maneesh
Published: October 2013

Auditory cortex is thought to play a critical role in the processing of species-specific vocalizations and other acoustically complex sounds. Although evolutionary processes strongly constrain cortical sensitivities to sound, cortical processing is not fixed by biology, but rather is shaped by the auditory experiences of each individual. Auditory cortical neurons in adult rats respond selectively to spectrotemporal features of complex sounds. These selective responses are predictive of rats’ behaviorally measured perceptual sensitivities. With extensive training, the abilities of rats to discriminate frequency-modulated sounds improve. Recordings from cortical neurons in trained rats show increased sensitivities to features of the sounds used in training. These results demonstrate that discrimination training with biologically irrelevant complex sounds can change how cortical neurons process those sounds. Changes in cortical processing of complex sounds can also be induced by controlling activity in neuromodulatory neurons while a rat experiences the sounds. Pairing the presentation of complex sounds with electrical stimulation of basal forebrain neurons radically changes cortical sensitivities to spectrotemporal features of those sounds. These data suggest that auditory cortical representations of acoustic events can be flexibly adjusted throughout the lifespan of an individual rate. Presumably, similar or greater flexibility exists in animals with more sophisticated auditory systems.
Effect of the diameter and the sound speed of a kidney stone on the acoustic field induced by shock waves
Authors: Cleveland Robin , Tello Juan
Published: October 2013

A time domain finite difference solution to the acoustic wave equation was used to model the propagation of lithotripsy shock waves in kidney stones. The stones were modeled as cylindrical objects and the impact of stone sound speed, stone diameter, and the internal structure on the pressure field inside the stones was calculated. The sound speed was varied from 2500 to 3500 m/s and had a minimal effect on the peak pressures within the stone. However, reducing the stone diameter from 15 mm to 3 mm reduced the peak negative pressure by 67%. For cases where the sound speed of the stone was inhomogeneous (inner core different from outer ring), the amplitudes of the peak pressures varied slightly, however the spatial distribution of the peak negative pressure varied significantly. In particular configurations with a lower outer sound speed lead to the peak negative pressure occurring at the boundary between the layers. The results indicate that the pressure field in a kidney stone is very sensitive to the size and internal composition of a kidney stone. This effect could be partly responsible for the large variance in fragility observed in human stones. [Work supported by the Whitaker Foundation and NIH-DDK.]
Evidence of oxidative stress in both kidneys after shock-wave lithotripsy to one renal pole
Authors: Willis Lynn R. , Klaunig James E. , Xu Yong , Connors Bret A. , Evan Andrew P. , Lingeman James E.
Published: October 2013

Shock-wave lithotripsy (SWL) damages renal tissue and reduces renal perfusion. These studies asked whether SW-induced injury or reduced perfusion might cause oxidative stress. Two groups of 3 anesthetized pigs received 2000 shock waves (SWs) at 24 kV (Dornier HM3, 2 Hz) to one renal pole. Renal hemodynamics were measured 1 h before and 1 and 4 h after SWL. Samples of renal tissue from upper and lower poles of each kidney were analyzed for malonaldehyde (lipid peroxidation) and 8-OH-deoxyguanosine (OH8dG, DNA damage). SWL reduced perfusion in both kidneys, but injured only the shocked kidneys. Malonaldehyde levels were elevated in both poles of the shocked kidneys, but were not elevated in the contralateral unshocked kidneys. In contrast, OH8dG levels were elevated in the treated pole of the shocked kidneys, and in both poles of the contralateral unshocked kidneys. In conclusion, (1) The elevated levels of malonaldehyde seen in the shocked kidneys but not in the unshocked kidneys are consistent with lipid peroxidation occurring after SWL-induced tissue injury; (2) elevated OH8dG levels in contralateral unshocked kidneys denotes oxidative stress and may reflect reperfusion injury associated with SWL-induced renal vasoconstriction. [Work supported by a grant from NIH P01 DK43881.]
Attenuation of high-level acoustic impulses by hearing protectors
Authors: Zera Jan
Published: October 2013

Attenuation of acoustic impulses by hearing protectors was measured in peak level ranges of 115–135 dB and 145–170 dB. The impulses were generated by a loudspeaker system in the low range of levels and by a blast of air expanding from a cylinder in the high level range. Transmission loss method was used to determine the difference between the peak level under the earmuff and outside the earmuff for over 30 different types of earmuffs. The measurements confirm that attenuation of high-level impulses depends on their peak level. In the 115–135 dB range the difference between the peak level outside and under the earmuff is approximately constant. In the 145–170 dB range, as the impulse level is increased, the level under the earmuff increases to a lesser extent. The peak-to-peak level characteristics determined for the 115 to 170 dB level range substantially differ for various types of protectors and may be a useful indicator of the effectiveness of protectors for impulse noise. [Work supported by the State Committee for Scientific Research Grants Nos. III-7.03 and III-6.07.]
Diffusing acoustic wave spectroscopy
Authors: Page John H. , Cowan Michael L. , Weitz David A.
Published: October 2013

Diffusing Acoustic Wave Spectroscopy (DAWS) is an ultrasonic technique that has been developed to measure the dynamics of heterogeneous media from the temporal fluctuations of multiply scattered waves. This technique is similar to more recent developments in field fluctuation spectroscopy, called coda wave interferometry, that use variations in the seismic coda to infer changes in the medium with time. After reviewing the basic principles on which Diffusing Acoustic Wave Spectroscopy is based [M. L. Cowan, J. H. Page, and D. A. Weitz, Phys. Rev. Lett. 85, 453 (2000); Phys. Rev. E 65, 066605 (2002)], its potential as a sensitive method for probing the dynamics of strongly scattering materials will be illustrated with recent experiments on fluidized suspensions of particles. In this type of system, DAWS measures the local relative motion of the scatterers (or strain rate) on a length scale determined by the transport mean free path of the multiply scattered waves. When combined with the complementary technique of Dynamic Sound Scattering using singly scattered waves, DAWS can also determine the instantaneous velocity correlation length of the moving scatterers, thus giving a quite complete picture of the system dynamics over a wide range of length and time scales.
Conveying discourse structure in synthetic speech
Authors: Gordon Peter C. , Halpin Harry
Published: October 2013

A pre-processing system for assigning prosodic characteristics of speech was created in order to investigate how synthesized speech can capture the global characteristics of discourse structure. The system allows manipulation of a variety of prosodic characteristics that have been tied to the structure of discourse above the level of the sentence, in particular: pitch fluctuation, pitch range, speaking rate, and pauses. These characteristics can be used to highlight the onset of a discourse segment, defined as a group of utterances that contribute to a single discourse purpose. After highlighting the onset of the discourse segments, these speech characteristics are progressively modified to indicate the continuity of the discourse segment. The system was evaluated by comparing it to a corpus of natural speech, the Boston Directions Corpus. That corpus has been analyzed both in terms of the informational content of the discourse and the acoustic manifestations that appear in natural speech for conveying that content. Ways in which those acoustic manifestations can be realized in natural speech are discussed.
Dynamic constraints on the inverse problem in speech
Authors: Iskarous Khalil
Published: October 2013

The problem of determining the area function from the speech signal has long been known to be an ill-posed problem—there are many area functions that correspond to the same speech spectrum. To make the problem well-posed, the inversion process must be constrained. In this work, inversion is performed for a dynamic formant pattern of a CV or a VV transition as a whole, rather than for a single static pattern. The input to the process are formant values along with the first and second time derivatives of each formant for each frame of the formant pattern. This provides more information about the possible area function solutions, and thereby acts as a constraint. Also the area function change during the transition is constrained to be stationary at one location in the vocal tract, while maximal change occurs at only two other locations, with the area increasing at one of the locations and decreasing at the other. This constraint is derived from an empirical study of area function change. These constraints are implemented as constraints on a Riccati recursion for the reflection coeficients. Comparison with other work on dynamic constraints on speech inversion will be provided. [Work supported by NIH.]
Cross spectral measurement of head related speech transfer functions using speaker’s own voice
Authors: Nukina Masumi , Kawahara Hideki
Published: October 2013

A cross spectrum method is applied to measure sound pressure variations around the head using the speaker’s own speech sounds. The variations are represented as transfer functions from the mouth reference point to a set of measuring points. Preliminary tests indicated that there are systematic frequency response variations depending on vowel colors. This vowel color dependency was not replicated in the classical measurement of speech radiation characteristics by J. L. Flanagan. However, taking into account the large (sometimes exceeding 20 dB) amount of variations, it is not likely to be negligible. A set of calibration and normalization procedures were introduced to reduce artifacts due to background noise, room acoustics, zeros in the speech spectra. A series of M-sequence based transfer function measurements were also conducted using a head and torso simulator to evaluate intrinsic errors in the cross spectral measurements. It was found that the standard errors in the cross spectral measurements using recorded speech sounds are around 1 dB. Based on these reference data and confidence interval calculations based on coherence, it is safe to conclude that the vowel color dependency is significantly modifying the transfer functions. [Work supported by JSPS.]
Remote full control, by an Internet link, of an underwater acoustics laboratory
Authors: Ranz-Guerra Carlos , Cobo-Parra Pedro , Siguero-Guerra Manuel , Fernandez-Fernandez Alejandro
Published: October 2013

The Underwater Tank Laboratory located at the Instituto de Acustica, CSIC, Madrid, has been fully reshaped. Now, the two bridges (emission and reception) have full automatic motion control by the operator. These capabilities were complemented by a new management of signal generation, signal acquisition, processing and storing of data. This new framework makes many of the tasks to be performed in this kind of facility easier by putting at the hands of the operator specific friendly software programs that attend to the main aspects of the ongoing experiment. In one step forward, the remote control of all the functionalities was considered feasible. The potentialities of the Internet were thought to provide a new dimension to the laboratory by lowering the difficulties of taking over the full control of the installation, by any user around the world. Here is one real example of how this achievement can be carried out. The Underwater Acoustics Laboratory at the Instituto de Acustica, CSIC, is now ready to be run by any one interested. The main lines, over which this problem has been considered, are described in this paper. [Work supported by PN on Science and Technology and CSIC, Spain.]
Pressure and velocity fields produced by an underwater explosion
Authors: Hunter Kendall S. , Geers Thomas L.
Published: October 2013

A model for a moderately deep underwater explosion bubble has recently been developed that integrates the initial shock wave phase and the subsequent oscillation phase of the motion [T. L. Geers and K. S. Hunter, J. Acoust. Soc. Am. 111, 1584–1601 (2002)]. A hyperacoustic volume-acceleration model for the shock wave phase employs an empirical pressure-profile expression for the far field to determine bubble radius as a function of time, thereby providing initial conditions for the subsequent oscillation phase. The model for the oscillation phase yields bubble-response equations that incorporate first-order wave effects in both the external liquid and the internal gas. In this paper, a radiation model consistent with the bubble model is formulated and evaluated. The far-field pressure and velocity fields produced during the shock wave phase derive from the previously mentioned pressure-profile expression. Those produced during the oscillation phase derive from a matched-asymptotic-expansion solution for a translating acoustic source/dipole [F. G. Leppington and H. Levine, Proc. R. Soc. London, Ser. A 412, 199–221 (1987)]. Computed far-field pressure and velocity histories and snapshots are shown. Comparisons with existing data exhibit good agreement. [Research sponsored by ONR.]
The social effects of poor classroom acoustics on students and The District of Columbia Public Schools demonstration of support through mandating the ANSI Classroom Acoustics standard
Authors: Ellis Donna
Published: October 2013

The effects that poor acoustics have on students extend beyond the classroom. This paper is to discuss the immediate and long-term results that inadequate acoustical design in the educational setting has on academic and social development and how the District of Columbia Public Schools (DCPS) are contributing to the classroom acoustic movement. DCPS is taking a pro-active stance in educational acoustics by mandating the ANSI Draft S12.60-200X classroom acoustic standard in the transformation of ten schools a year for the next ten to fifteen years. Synthesizing the ANSI S12 standard with the DCPS Design Guidelines describes explanation of how to design for appropriate acoustics in all core-learning spaces. Examples of the existing conditions of the facilities and acoustical remediation for new and historical preservation projects will be demonstrated. In addition, experience will be shared on the International Building Code Council hearings for classroom acoustics.
A speech perception test for children in classrooms
Authors: Feijóo Sergio , Fernández Santiago , Álvarez José Manuel
Published: October 2013

The combined effects of excessive ambient noise and reverberation in classrooms interfere with speech recognition and tend to degrade the learning process of young children. This paper reports a detailed analysis of a speech recognition test carried out with two different children populations of ages 8–9 and 10–11. Unlike English, Spanish has few minimal pairs to be used for phoneme recognition in a closed set manner. The test consisted in a series of two-syllable nonsense words formed by the combination of all possible syllables in Spanish. The test was administered to the children as a dictation task in which they had to write down the words spoken by their female teacher. The test was administered in two blocks on different days, and later repeated to analyze its consistency. The rationale for this procedure was (a) the test should reproduce normal academic situations, (b) all phonological and lexical context effects should be avoided, (c) errors in both words and phonemes should be scored to unveil any possible acoustic base for them. Although word recognition scores were similar among age groups and repetitions, phoneme errors showed high variability questioning the validity of such a test for classroom assessment.
Ethnographic model of acoustic use of space in the southern Andes for an archaeo-musicological investigation
Authors: Perez de Arce Jose
Published: October 2013

Studies of ritual celebrations in central Chile conducted in the past 15 years show that the spatial component of sound is a crucial component of the whole. The sonic compositions of these rituals generate complex musical structures that the author has termed ‘‘multi-orchestral polyphonies.’’ Their origins have been documented from archaeological remains in a vast region of southern Andes (southern Peru, Bolivia, northern Argentina, north-central Chile). It consists of a combination of dance, space walk-through, spatial extension, multiple movements between listener and orchestra, and multiple relations between ritual and ambient sounds. The characteristics of these observables reveal a complex schematic relation between space and sound. This schema can be used as a valid hypothesis for the study of pre-Hispanic uses of acoustic ritual space. The acoustic features observed in this study are common in Andean ritual and, to some extent are seen in Mesoamerica as well.
Acoustic communication by ants
Authors: Hickling Robert , Brown Richard L.
Published: October 2013

Effective communication is essential in highly organized ant societies. Currently myrmecologists believe that pheromones play the central role in ant communication and that relatively little is accomplished with sound. However many ant species make sounds by stridulating, i.e., running a scraper over ridges on their abdomen. Hence, it seems likely that ants communicate using a combination of pheromones and sound. Because ants appear insensitive to airborne sound, myrmecologists have concluded that stridulatory signals are transmitted through the substrate. However, this conclusion is untenable for a number of reasons. How then can ants transmit signals through the air when apparently they are insensitive to airborne sound? The answer lies in the fact that ants are much smaller than the wavelength of the sound they generate, so there is a relatively significant near field surrounding a stridulating ant. The near field is characterized by a major increase in the particle velocity of sound, which can be detected by hair-like sensilla on the apical segments of the ants’ antennae. By sensing the relative difference in particle sound velocity between the antennae, an ant can detect stridulation signals from a nearby ant, yet appear deaf to extraneous airborne sound.
Gene transfection by echo contrast agent microbubbles
Authors: Tachibana Katsuro
Published: October 2013

In vitro and in vivo experiments have demonstrated that various echo contrast agent microbubbles can be intentionally ruptured by diagnostic and therapeutic ultrasound. Violent microstreaming are produced during microbubble collapse. Researchers have hypothesized that these microjets or microstreaming could be applied to promote diffusion of drugs into various tissues and lesions. The most exciting application of this method is probably delivery of genes into cells. As various genes are currently under investigation for the purpose of treating diseases, ultrasound and microbubbles may be used as a modality to promote better outcome for gene therapy. Recent studies have shown that different gases contained within the bubbles greatly influence the degree of gene transfection. Also, the outer layer of the microbubbles can be custom-made for binding to target tissue. Recent advance on this topic will be discussed.
Perspectives on anechoic chamber qualification
Authors: Cunefare Kenneth A. , Biesel Van B.
Published: October 2013

The qualification of a new anechoic chamber requires demonstration that the chamber produces a free-field environment within some tolerance bounds and over some acceptable volume. At the most basic level, qualification requires measurement of sound levels at increasing distances from a test source, and then comparing the levels to a theoretical free-field decay. While simple in concept, the actual performance of a qualification test is problematic in implementation, with troublesome issues relevant to the nature of the sound source, test signal (broadband or pure tone), spatial resolution of measurements (e.g., measurements at discrete locations or spatially continuous), and comparison of the data to a theoretical decay. This presentation will provide a brief historical perspective on chamber qualification and review current practice. It will demonstrate the inadequacy of broadband noise and widely spaced discrete measurements for qualification purposes. It will demonstrate that pure tone signals and spatially continuous measurements provide a rigorous test of a chambers performance.
Help! There are 60 screaming kids in my lab!
Authors: Darvennes Corinne
Published: October 2013

What do you do when you have a large noise control facility available and you want to introduce local children to science and engineering? You invite them in! This presentation will describe a day of hands-on activities for 60 fifth graders in the Acoustics and Vibrations Laboratory at TTU. This includes the logistics of having 60 kids in the lab and keeping their attention, a description of each activity, and the equipment used. Activities included learning about hearing and hearing loss, propagating and standing waves, ultrasound, vibrations, and resonance. Students used slinkies, sound level meters, a strobe light, Vernier LabPro data collection systems and sensors (ultrasonic motion detectors and microphones). They popped balloons in the reverberation chamber to listen to the sound decay. Their most memorable experience, however, was the screaming contest in the anechoic room!
Recent advances in active noise and vibration control at NASA Langley Research Center
Authors: Gibbs Gary P. , Cabell Randolph H. , Palumbo Daniel L. , Silcox Richard J. , Turner Travis L.
Published: October 2013

Over the past 15 years NASA has investigated the use of active control technology for aircraft interior noise. More recently this work has been supported through the Advanced Subsonic Technology Noise Reduction Program (1994–2001), High Speed Research Program (1994–1999), and through the Quiet Aircraft Technology Program (2000–present). The interior environment is recognized as an important element in flight safety, crew communications and fatigue, as well as passenger comfort. This presentation will overview research in active noise and vibration control relating to interior noise being investigated by NASA. The research to be presented includes: active control of aircraft fuselage sidewall transmission due to turbulent boundary layer or jet noise excitation, active control of interior tones due to propeller excitation of aircraft structures, and adaptive stiffening of structures for noise, vibration, and fatigue control. Work on actuator technology ranging from piezoelectrics, shape memory actuators, and fluidic actuators will be described including applications. Control system technology will be included that is experimentally based, real-time, and adaptive.
Perception of different speech registers in noise
Authors: Andruski Jean , Bessega Eileen
Published: October 2013

Infant-directed speech and adult-directed clear speech both exhibit acoustic characteristics (other than amplitude differences) which should make them easier to perceive against a background of noise than adult-directed conversational speech. For example, in adult-directed clear speech, vowels are typically acoustically more distinct. Infant-directed speech shows similar differences in vowel quality, and in addition typically shows larger pitch contours. This experiment examines listeners’ perception of these three speech registers (adult-directed conversational speech, adult-directed clear speech, and infant-directed speech) in noise. Effect of the different speech registers will be compared for easy words (frequent words with few frequent lexical neighbors) and hard words (infrequent words with numerous, frequent neighbors).
Auditory and visual clear speech effects measured during a simulated conversational intercation
Authors: Gagne Jean-Pierre , Charest Monique , Laplante-Levesque Ariane , Guilbert Olivia
Published: October 2013

Iterations of sentences were recorded audio-visually from talkers while they participated in a speech-tracking task. Six female talkers produced iterations of conversational and clear speech under two different experimental conditions: (a) while the talker was informed that only her visual–speech cues would be transmitted to the interlocutor and (b) while she was informed that only her auditory–speech cues would be transmitted to the interlocuter. In reality, both her auditory– and her visual–speech cues were recorded under each experimental condition. Target sentences were extracted for the recordings, edited, and presented in a random order to a group of 48 subjects. The subjects completed a speech-recognition task under two perceptual modalities: auditory-only and visual-only. The subjects’ mean speech-recognition scores were used to determine the speech intelligibility scores of individual talkers for each experimental condition. The results failed to reveal any differences between the speech intelligibility scores obtained while a talker intended to produce iterations of visual-clear speech and those obtained while she intended to produce iterations of auditory-clear speech. Hence, the findings failed to demonstrate that talkers modify their articulation patterns in order to compensate for the perceptual modality under which the interlocutor receives the speech information. [Work supported by a NSERC grant awarded to J-PG.]
Effects on performance of partial misalignments of spectral information in acoustic simulations of cochlear implants
Authors: Spahr Anthony , Dorman Michael , Loizou Philipos
Published: October 2013

Objective: To assess the effects on speech understanding of frequency misalignments in channel outputs for an acoustic model of a cochlear implant. Design: Consonants, vowels, and sentences were processed through a four-channel sine-wave simulation of a cochlear implant. In the five experimental conditions, channels 1 and 3 were always output at the correct frequency while channels 2 and 4 were output at frequencies varying from the correct frequency to frequencies 25%, 50%, and 75% lower than appropriate. In a fifth condition (2-of-4 condition), channels 2 and 4 were turned off. Results: Consonant recognition was reduced significantly with a 50% shift in channels 2 and 4. Vowel and sentence recognition were reduced significantly with a 75% shift in channels 2 and 4. For all material performance in the 75% shift condition was better than in the 2-of-4 condition. Conclusions: The perceiving system that underlies speech recognition is relatively tolerant of misplaced frequency information if other information is presented to the correct frequency location. This flexibility may account for some of the success of cochlear implants. [Research supported by a grant from NIDCD (No. RO1 00654-12) to the second author.]
Native-language influence on phonetic perception in Dutch–English bilinguals
Authors: Mondini Michele , van Alphen Petra M. , Miller Joanne L.
Published: October 2013

We examined how native-language experience influences processing a second language, focusing on how native Dutch listeners who learned English as a second language perceive the English voiceless consonant /p/. Previous research [J. E. Flege and W. Eefting, Speech Commun. 6, 185–202 (1987)] shows that the voiced–voiceless boundary for an (English-based) voice-onset-time (VOT) series is located at a shorter VOT for such bilingual listeners than for native English listeners, consistent with the fact that voiceless stops are produced with shorter VOTs in Dutch than in English. We asked whether such bilinguals also differ from native English listeners in which stimuli throughout the series are perceived as reasonable exemplars of /p/. Native English listeners and native Dutch listeners were tested on a three-choice identification task with an (English-based) extended VOT series that ranged from /ba/ to /pa/ to an ‘‘unnatural’’ exaggerated /pa/, labeled */pa/. Both the /b/-/p/ and /p/-*/p/ boundaries were located at shorter VOTs for the native Dutch than the native English listeners, indicating that Dutch native-language experience influenced the entire range of VOTs perceived as reasonable exemplars of the /p/ category. Thus native-language experience has a comprehensive influence on the mapping from acoustic signal to phonetic category. [Work supported by NIH/NIDCD.]
Audio-visual integration of speech with time-varying sine wave speech replicas
Authors: Tuomainen Jyrki , Andersen Tobias , Tiippana Kaisa , Sams Mikko
Published: October 2013

We tested whether listener’s knowledge about the nature of the auditory stimuli had an effect on audio-visual (AV) integration of speech. First, subjects were taught to categorize two sine-wave (sw) replicas of the real speech tokens /omso/ and /onso/ into two arbitrary nonspeech categories without knowledge of the speech-like nature of the sounds. A test with congruent and incongruent AV-stimulus condition (together with auditory-only presentations of the sw stimuli) demonstrated no AV integration, but instead close to perfect categorization of stimuli in the two arbitrary categories according to the auditory presentation channel. Then, the same subjects (of which most were still under the impression that the sw-stimuli were nonspeech sounds) were taught to categorize the sw stimuli as /omso/ and /onso/, and again tested with the same AV stimuli as used in the nonspeech sw condition. This time, subjects showed highly reliable AV integration similar to integration obtained with real speech stimuli in a separate test. We suggest that AV integration only occurs when subject are in a so-called ‘‘speech mode.’’
Audio-visual integration in listeners with normal hearing and hearing aid users
Authors: Marrone Nicole L. , Stockmann Ellen S. , Guenther Frank H. , Vick Jennell C. , Perkell Joseph S. , Lane Harlan
Published: October 2013

In listeners with normal hearing, the sight of a speaker’s face articulating a syllable can influence the auditory percept, most observably when the auditory and visual stimuli are different from one another. This study investigates differences in audio-visual (AV) integration (‘‘the McGurk effect’’) between adults with hearing loss who wear hearing aids (HA) and their normal-hearing (NH) counterparts. The following hypothesis is being tested: HA users will rely more on visual input and thus be biased more toward the visual stimulus in the mismatch condition. Audio-visual stimuli from three speakers are presented, pairing the consonants /b/, /d/, and /g/ with the vowels /a/, /i/, and /u/, in three conditions (auditory-only, visual-only, and AV) to the two subject groups, NH and HA. Participants label each stimulus according to the consonant perceived. Responses are coded into four categories: fusion, combination, auditory, or visual. Data analysis examines the relative strength of visual influences in the two groups. Pilot data show fusion and visual bias in an HA user. Further results will be presented. [Work supported by NIH.]
A comparison of East China Sea low frequency bottom scattering strength determinations
Authors: Cable P. G. , Gibson R. , Dorfman Y. , Knobles D. P. , Yudichak T. W. , Zhang R. , Peng Z. , Li F. , Li Z. , Dahl P. H. , Miller J. H. , Potty G. R.
Published: October 2013

Low frequency shallow water bottom scattering strength determinations conventionally involve accounting for the two-way transmission from source to scattering region to receiver and correcting for the size of the contributing bottom scattering area. Experiment uncertainties in transmission loss, bottom homogeneity and isotropy, contributions from volume, and ocean surface backscatter, can all contaminate the accuracy and robustness of such determinations. Bottom scattering strengths were determined in octave bands from 50–800 Hz reverberation data using Institute of Acoustics sources and the receiving array on Shi-Yan III and from transmission data obtained on the APL-UW/URI receiving array on R/V Melville during East China Sea ASIAEX in 2001. Seabed geoacoustic parameters were inferred from the forward data, which were then used to model transmission and extract scattering strength from the reverberation data. The ASIAEX scattering strengths were compared with other measurements of bottom scattering strength derived from previously obtained East China Sea broadband data sets. The separate bottom scattering strength determinations, though obtained at different times and East China Sea sites, and by different methods, are very close. The experimental sensitivity of these measurements will be described and implications regarding the robustness of the results to seasonal variability and geographic change discussed. [Work supported by ONR.]
Spatial coherence of signals forward scattered from the sea surface in the East China Sea
Authors: Dahl Peter H. , Eggen Christian J. , Light Russell D.
Published: October 2013

Measurements of sea surface forward scattering, wind speed, and directional wave spectra made in 100 m of water in the East China Sea are discussed. The experiment was part of the Asian Seas International Acoustics Experiment (ASIAEX) conducted in the spring of 2001. Signals were received at ranges near 500 m on 2 vertical line arrays that were co-located but separated in depth by 25 m. Estimates of the vertical spatial coherence along these arrays as a function of frequency, path geometry, and sea surface environmental conditions are compared with a model for spatial coherence. The model is based on identifying the probability density function that describes vertical angular spread at the receiver position. An alternative approach utilizing the van Cittert–Zernike theorem from statistical optics is shown to give equivalent results. Both approaches require computation of the sea surface bistatic cross section, done here with the small slope approximation. Forward scattering from the sea surface represents an important channel through which sound energy is transmitted, and spatial coherence determines in part the performance of imaging and communication systems that utilize the sea surface bounce path.
The songs of Tlaloc: Interference of ten ceramical duct flutes, Offering 89 of the Aztec Templo Mayor
Authors: Both M. A. Adje
Published: October 2013

Among the many preserved sound artefacts deposited in the offerings of the Aztec Templo Mayor are a set of ten tubular duct flutes made from clay, dating Late Postclassic Mesoamerica, 1350–1521 AD. The aerophones are completely painted in blue, and characterized by: (1) a short mouthpiece; (2) a framed aperture; (3) a tube with four fingerholes; and (4) an applicated mask with features of the Aztec rain god Tlaloc, basically three rings and a standardized relief structure of two clouds. While all measurements follow the same pattern, one particular organological distinction was made, as five flutes show an exit hole in the middle ring of the mask and five flutes are stopped. Thus, five instruments sound considerably higher, apart from the minimal pitch deviation of each specimen. Both the tonal capacity of each flute and the acoustics of several flutes played simultaneously were recorded and measured. A series of remarkable interference effects could be produced, which were strongly related to the ritual complex reflected in the offering. Taking in consideration the Aztec concept of music, it could be supposed that they were perceived as a principle of the song, or proper voice of Tlaloc.
Effect of absorption on nonlinear propagation of short ultrasound pulses generated by rectangular transducers
Authors: Khokhlova Vera A. , Ponomaryov Anatoly E. , Averkiou Michalakis A. , Crum Lawrence A.
Published: October 2013

A numerical solution of the KZK-type parabolic nonlinear evolution equation is presented for finite-amplitude sound beams radiated by rectangular sources. The initial acoustic waveform is a short tone burst, similar to those used in diagnostic ultrasound. The generation of higher harmonic components and their spatial structure are investigated for media similar to tissue with various frequency dependent absorption properties. Nonlinear propagation in a thermoviscous fluid with a quadratic frequency law of absorption is compared to that in tissue with a nearly linear frequency law of absorption. The algorithm is based on that originally developed by Lee and Hamilton [J. Acoust. Soc. Am. 97, 906–917 (1995)] to model circular sources. The algorithm is generalized for two-dimensional sources without axial symmetry. The diffraction integral is adapted in the time–domain for two dimensions with the implicit backward finite difference (IBFD) scheme in the nearfield and with the alternate direction implicit (ADI) method at longer distances. Arbitrary frequency dependence of absorption is included in this model and solved in the frequency–domain using the FFT technique. The results of simulation may be used to better understand the nonlinear beam structure for tissue harmonic imaging in modern medical diagnostic scanners. [Work supported by CRDF and RFBR.]