bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of amplitudes of acoustic normal modes from the reciprocity principle
Authors: Godin Oleg A.
Published: October 2013

Recently, J. D. Achenbach [J. Acoust. Soc. Am. 116, 1481–1487 (2004)] put forward, on heuristic grounds, an elegant technique to calculate amplitudes of guided waves generated by mechanical loading in a range-independent elastic medium. The technique is based on application of the reciprocity principle and allows one to solve the problem without use of integral transforms. In this paper, the technique is applied to acoustic waveguides in a layered fluid. By taking into account continuous spectrum of the field, which was disregarded by Achenbach, a mathematical justification of the technique is obtained. The technique is shown to be exact. It is further extended to enable calculation of excitation coefficients of modes of both discrete and continuous spectra by a given sound source. The results are shown to be identical to those derived with the traditional, more cumbersome methods that rely on integral transforms. [Work supported by ONR.]
Three different directions of sound propagation in the China South Sea
Authors: Li Ma
Published: October 2013

In June 2004 three directions of sound propagation experiments were done in the China South Sea. One direction is equally sea depth. The second direction is slope. The third direction is largest gradient in sea depth direction. In the mean time three temperature chains have been applied for measuring the internal wave. During each temperature chain their distances are about 1000 m. The experiment results show that the packet of solitary waves has been found and each direction of sound propagation has different transmission loss. In the equally sea depth direction the sound propagation has the smallest transmission loss. And in the largest sea depth direction the sound propagation has the largest transmission loss. By three temperature chains data the packet of solitary waves propagation velocity and direction may be measured. And through the packet of solitary waves propagation direction the packet of solitary waves may be induced by the West Sand Island. In the end the couple normal mode program has been used to simulate the sound propagation which is affected by the packet of solitary waves. The simulating results are compared to experimental data.
Long-range acoustic transmission in a deterministic range-dependent ocean: Contribution from interference of near-axial waves
Authors: Grigorieva Natalie S. , Fridman Gregory M.
Published: October 2013

The propagation of energy along the waveguide axis cannot be described in terms of geometrical acoustics because of the presence of cusped caustics repeatedly along the axis. In neighborhoods of these cusped caustics a very complicated interference pattern is observed. Neighborhoods of interference grow with range and at long ranges they overlap. For an arbitrary range-independent ocean, it was shown in [N. S. Grigorieva and G. M. Fridman, J. Comp. Acoust. 12, 127–147 (2004)] that the interference of wave fields corresponding to near-axial rays results in a diffractive (as opposed to geometrical acoustics) component of the field which can be viewed as distinct, ‘‘axial’’ wave and effectively calculated using its integral representation. In this paper the integral representations of the axial wave in the frequency and time domains are obtained for a range-dependent ocean. In the frequency domain this representation has the form of a linear superposition of the solutions of the Helmholtz equation that are concentrated in a neighborhood of the sound-channel axis. The weight function is selected in such a way that the localization principle holds. The axial wave is simulated for a deterministic model of a range-dependent ocean corresponding to AET experiment. [Work supported by ONR Global.]
Phase characterization of soundscapes
Authors: Gibiat Vincent , Padilla Abril , Emiya Valentin , Cros Lionel
Published: October 2013

Signal processing of soundscapes remains far from the auditive perception. It is particularly true when sounds recorded inside railway stations, are compared with the most accurate spectrographic representations. Such architectural realizations provide a soundscape between closed and opened spaces. As microphones used to discriminate sound sources as well as low level sounds use diffractions properties of radiation, as time discrimination between near sounds is efficient through time domain perception, as filtering often introduces phase distorsions, it has been decided to explore a new kind of signal representation based on the phase of the Short Time Fourier Transform. After a basic presentation of the numerical tool named SAFIR for Spectrography in Amplitude and Frequency, Instantaneous and Reallocated, examples will be given that first show the differences between closed and opened spaces, then the differences between the soundscape inside a train and inside a station. As this work has been realized with sounds recorded for a later musical realization that deals to reconstruct both a new realistic or imaginary coherent soundscape, it has been essential to extract the pertinent, coherent, details as magnification of time or space opposed with the incoherent urban noise. Finally SAFIR will be compared with the composer work.
How does hearing get into architectural design?
Authors: Bauer Juergen , Schulte-Fortkamp Brigitte
Published: October 2013

Serious soundscape research needs an interdisciplinary approach to architecture. The design and the perception of architecture are dominated by the visual senses. Architects developing a complex building may be advised by a specified acoustic engineer. However the support provided by the acoustic engineer focuses less on creating acoustic qualities than on minimizing acoustic problems and noise effects. How about the sense of hearing of the architect? Designing architects have learned to shape 3-D. They have a precise vision of space and proportion. They know about light and shadow, about fabric and color. This profound world of vision is the basis of their inspiration, and they would be grateful to get more consciously in touch with the world of hearing not in terms of creating extraordinary sound-effects but in terms of imaginative listening. The visual phenomena architects are dealing with offer an approach to the world of hearing or rather analogies from watching towards listening. Light, shadow, fabric and color are no more matters only of sight but subject to audiovisual awareness. What acoustic processes might be most relevant to designing architects? What acoustic events and impacts should be specified in the education of design?
Monitoring ecologically important fish sounds: The characteristics and diel trends of sounds produced by three species of Pomacentrids
Authors: Mooney T. Aran , Lammers Marc O. , Santos Pedro A. , Nachtigall Paul E.
Published: October 2013

Many fish species make sounds. These sounds can be recorded, characterized, identified to species, correlated with behavior, and then monitored for temporal and behavioral trends. We developed a two-part approach to accomplish these tasks. The first is a Portable Underwater Acoustic (PUA) device, composed of a two-hydrophone, handheld, digital recorder. This system is used to identify fish sounds that can then be correlated with specific behaviors. The second is a single-hydrophone, autonomous recording system that is placed on the seafloor to record the ambient sound field at set temporal intervals. This presentation describes both systems and how they are being applied in the field to study three species of fish: Abudefduf luridus, in the Azores, Portugal, and Dascyllus albisella, and Abudefduf sordidus, in Hawaii, USA. A. luridus sounds were usually produced in a doublet, 100 ms in duration, a peak frequency of 400–450 Hz, and associated with aggressive displays. Sounds produced by D. albisella were typically 2–4 s, with a peak frequency of 300–400 Hz and a bandwidth of up to 6 kHz. A. sordidus produced 100 ms broadband clicks, up to 5 kHz bandwidth, in aggressive chases. After identification, sounds were associated with behaviors and ecologically important events, and monitored for diel trends in their production.
Transmitting beam patterns of an echolocating bottlenose dolphin
Authors: Muir Thomas G. , Lemerande Tobias J. , Baker Steven R. , Ridgway Samuel H.
Published: October 2013

Measurements on a free-swimming subject, echlocating under a simple go paradigm, were conducted at SSC San Diego, with a linear array of seven simultaneously and individually processed wideband hydrophones (response to 400 kHz), arraigned either vertically or horizontally, and centered on a small underwater video camera, with the video output synchronized with the recording of acoustic data. The measurement apparatus itself served as the test target. Lowering it into the water provided the cue for the blindfolded subject to locate its position in the test pen, swim to the apparatus, and touch it with the tip of its rostrum; whereupon the trainer provided a bridge signal, indicating reward due. During this process, acoustic beampattern measurements were made on echolocation clicks, as a function of frequency, which support previous, non-simultaneous, statistical beampattern measurements. Early in the experiment, the subject emitted echolocation clicks that peaked at 78 kHz, with −3 dB beamwidths of 8 to 10 degrees; but also containing high frequency components (above 135 kHz), with beamwidths that narrowed with increasing frequency, ranging to only a few degrees around 300 kHz, far beyond the subjects hearing range. After several days, the task appeared to become easier and there was much less high frequency content, but the click repetition frequency increased. Wideband noise was then introduced into the test pen, at frequencies below 135 kHz; and as the task became more difficult, the subject resumed transmitting clicks with high frequency components, although the peak frequency remained at 78 kHz, and click rates again increased, to much higher values.
A juvenile salmon acoustic tracking system (JSATS) for the Columbia River estuary
Authors: McComas Lynn , Easton Alex
Published: October 2013

The Juvenile Salmon Acoustic Tracking System (JSATS) was developed as a means to estimate the downriver survivability of sub-yearling salmon in the Columbia River. The system consists of a bottom-mounted sonar array which detects signals from acoustic projectors that are surgically implanted in juvenile salmon. JSATS is the result of a development program which began in 2001 when Northwest Fisheries Science Center National Marine Fisheries Service (NMFS) and Science Applications International Corp. (SAIC) developed the top level, biology driven, requirements for the system. SAIC then conducted environmental surveys to characterize the physical and acoustic environments in which JSATS would operate. Battelle PNNL developed the acoustic projector used in JSATS. The signaling characteristics of this projector are driven by the requirement that it not affect the behavior of the 90 mm salmon in which it is implanted, and that it operate continuously for 30 days. SAIC developed the detection array portion of JSATS. The design was driven by the requirements that it be bottom mounted, cabled to shore, and successfully withstand high current and moving sand waves. NMFS and SAIC jointly developed the shore stations and the installation/recovery procedures. Installation of an array spanning the Estuary is planned for April 2005.
Estimation of the absorption coefficients of classroom surfaces by multiple regression
Authors: Scherebnyj Katrina , Hodgson Murray
Published: October 2013

The absorption coefficients of room surfaces are important parameters for predicting room sound fields. Of particular interest are classrooms, for which characteristics such as speech intelligibility are essential. Values obtained in laboratory settings may differ significantly from those measured in real-world situations. This study determined surface absorption coefficients in university classrooms and compared them with values given by manufacturers and published literature. Various surface categories were established, and the total area of each was measured in 104 UBC classrooms, along with the early decay times (EDT) in octave bands from 125 to 8000 Hz when the rooms were unoccupied. Average octave-band absorption coefficients for these surfaces were determined from the measured EDTs, using diffuse-field theory. Multiple-regression analysis was then applied, and the data was fit to estimate the average absorption coefficients of each surface category in each octave band. Absorption coefficients were established for seven types of surfaces commonly found in university classrooms; in general they tended to be significantly lower than commonly accepted values.
The influence of agent delivery mode on cardiomyocyte injury induced by myocardial contrast echocardiography in rats
Authors: Miller Douglas , Dou Chunyan , Armstrong William
Published: October 2013

Bioeffects induced in rat hearts by the interaction of ultrasound with contrast agent gas bodies depends on user controlled parameters. This study examined the influence of contrast agent delivery mode on cardiomyocyte injury. Hairless rats were anesthetized and mounted vertically in a water bath. Evans blue dye was injected as stain for cardiomyocyte injury. The contrast agent (Definity, Amersham Health Inc., Princeton NJ) was diluted in saline and injected IV at 20 or 80 μL/kg either as bolus or continuous infusion. Echocardiography was performed with a GE Vingmed System V in a short axis view with 1:4 or 1:16 ECG triggering at 1.5 MHz for 5 or 20 min. The peak rarefactional pressure amplitude (PRPA) was 2.0 MPa. Fluorescent stained cells were scored on frozen sections of heart samples obtained 24 hr after scanning. Five min infusion led to 3.4 times (P<0.01) more cardiomyocyte injury than bolus injection for the same 20 μL/kg dose. Contrast agent dose appeared to be a more important parameter than infusion rate and number of triggers. Contrast agent delivery mode, as well as dose and PRPA, has a significant influence on the bioeffects potential of myocardial contrast echocardiography. [Work supported by NIH grant EB00338.]
Tangible interactive interface using acoustic time reversal process
Authors: Ing Ros K. , Quieffin Nicolas , Catheline Stefan , Fink Mathias
Published: October 2013

Time reversal in acoustic is a very efficient solution to focus sound back to its source in a wide range of material including reverberating media. It expresses the following physical properties: a wave still have the memory of its source location. The concept presented in this paper consists in detecting the acoustic waves in solid objects generated by a simple human touch. In a second step, the information related to the source location are extracted from a virtual time reversal experiment in the computer. Then, an action (turn on the light or a CD player) is associated to each location. Thus, the whole system transforms solid objects into interactive interfaces. Compared to the existing acoustic techniques, it presents the great advantage to be simple and easily applicable on inhomogeneous objects with any shape. The number of possible touch locations at the surface of objects is shown to be directly related to the mean wavelength of the detected acoustic wave.
Localization of amplitude and frequency modulated sounds
Authors: Ericson Mark
Published: October 2013

Everyday sounds, such as speech, music, and environmental noises, vary in level and frequency. The dynamic cues of natural sounds help to identify and segregate multiple sources. Amplitude and frequency modulation of simple pure tone complexes were manipulated in several experiments to measure their effects on auditory localization. The tonal complexes had 500 Hz fundamental frequencies and 26 components, providing 13 kHz in bandwidth. The complexes were either amplitude modulated, frequency modulated, co-modulated in frequency and amplitude, or not modulated. In addition, phase of the carrier and modulation frequencies were randomized to aid in sound source segregtion. Three normal hearing subjects participated in the task of localizing and identifying up to four simultaneous sounds. Amplitude modulated sounds provided the best localization acuity and identification data. Comodulated, frequency modulated and no modulation were found to provide lower amounts of acuity performance in decreasing order.
Measuring the binaural temporal window
Authors: Kolarik Andrew J. , Culling John F.
Published: October 2013

Sensitivity to small ITDs in detection and discrimination tasks was measured. In experiment 1, four listeners performed 3 tasks. The first 2 were 4I- and 2I-2AFC adaptive detection tasks. The third was a 2I-2AFC adaptive discrimination task. All stimuli were 100 ms noise bursts. Reference stimuli were diotic, and target stimuli contained a probe duration of 64, 32, 16, 8, 4, or 2 ms, which carried an interaural time delay. These probes were temporally fringed with diotic noise. Thresholds for the discrimination task were significantly higher than for the detection tasks. In experiment 2, psychometric functions were obtained from 4 participants for the six probe durations using the same 2I-2AFC detection and discrimination tasks. Binaural temporal windows were fitted to the data using a variety of fitting functions. Fits to the detection task data demonstrated narrow tips but unmeasurably long skirts. In the discrimination task neither parameter could be accurately measured, suggesting that the overall stimulus duration was too short to encompass the window. A stimulus length of 500 ms and probe durations of 256, 128, 64, 32 and 16 ms allowed both parameters to be measured. The resulting equivalent rectangular duration was approximately 50 ms.
Multiple auditory steady-state response thresholds to bone-conduction stimuli using three oscillator placements in premature infants
Authors: Hatton Jennifer , Small Susan A. , Stapells David R.
Published: October 2013

Auditory Steady State Responses (ASSRs) are a promising technique for estimating the behavioral audiogram in infants. The current study investigates the effects of bone-oscillator placement on ASSR thresholds in premature infants (N=15, mean age: 35 weeks PCA). Using the MASTER research system, ASSR thresholds to multiple bone-conduction tones (0–50 dBHL re:mastoid; 77–101 Hz) presented to the (i) superior-posterior temporal bone, (ii) mastoid, and (iii) forehead were obtained. Results with no response at 50 dBHL were arbitrarily assigned a threshold of 60 dBHL. No differences in threshold were found between the temporal and mastoid placements. Thresholds averaged across these placements were 17, 15, 34, and 30 dBHL for 500, 1000, 2000, and 4000 Hz, respectively. However, on average, thresholds for the forehead placement were significantly higher by at least 14, 11, 18, and 14 dB at 500, 1000, 2000, and 4000 Hz, respectively, compared to the temporal and mastoid placements. These differences may be even greater because absent responses at the maximum intensity were seen more often with forehead placement compared to other placements. In conclusion, one may use either the temporal bone or mastoid for bone-oscillator placement, but the forehead should be avoided. [Work supported by CIHR and NSERC-Canada.]
Real-time implementation of a model auditory-nerve fiber
Authors: Iyengar Satish G. , Datta Jayant , Carney Laurel H.
Published: October 2013

A time-varying model auditory-nerve (AN) fiber based on Tan and Carney (2003) was developed on a digital signal processor (DSP) platform to simulate AN responses in real-time, using the Motorola DSP56367, a 150 MIPS audio processor. To understand the schemes employed by the brain for decoding different sound stimulus parameters, it is first essential to get an accurate representation of peripheral (external, middle, and inner ear) responses that in turn excite the higher levels along the auditory pathway. Though present computational models predict essential AN response properties, their use in testing mechanisms hypothesized to occur at higher levels of the auditory pathway is limited due to the large processing times that they require. This is because such nonlinear models require computational implementation in the time domain, with time-step-by-time-step changes in model parameters as the bandwidth and gain of the inner ear change with stimulus fluctuations. The DSP-based model presented here aims to speed up inquiries related to auditory signal processing strategies at higher levels by providing a real-time solution to AN fiber simulations. Details of the implementation and some prospective auditory-research utilities will be discussed. [Work supported by NIDCD R43-DC006591 (JD, SGI) and R01-DC001641 (LHC, SGI).]
Tuning phenomena of melodies and resonance frequencies (formants) in infants pre-speech utterances
Authors: Wermke Kathleen , Mende Werner , Manfredi Claudia , Bruscaglioni Pierro , Stellzig-Eisenhauer Angelika
Published: October 2013

In a former study [Wermke et al., Med. Eng. Phys. 24, 501–514 (2002)], an increasing tuning between laryngeal (melody) and pharyngeal (resonance frequencies) activity was demonstrated during pre-speech development. This tuning was observed unexpectedly early during development in mitigated cries and earliest non-cry utterances and prepares probably articulation in speech-like vocalizations of older infants. A new retrospective study supported this assumption by comparing tuning processes in cries and early non-cry utterances (N=2500) in two groups (low versus high word production performance at 18 months) of term-born healthy infants (N=20). Additionally, age-matched comparisons were made in 4 cleft-lip-palate-infants treated with a palatal plate. In order to demonstrate the interaction between melody and resonance control we designed a special graphical representation. The tracking function of the resonance frequencies is displayed synchronously to the melody and its harmonics. Resonance frequencies in pre-speech utterances are not yet identical to formant bands associated with speech sounds. The results support the existence of an early active tuning and its relation to later speech. This behavior seems to prepare formant tuning in later speech. Medical applications are seen for infants with disturbances of the vocal tract transfer function, e.g., infants with cleft-lip-palate. [Work supported by DFG.]
Perturbed palatal shape and North American English /r/ production
Authors: Tiede Mark K. , Gracco Vincent L. , Shiller Douglas M. , Espy-Wilson Carol , Boyce Suzanne E.
Published: October 2013

It is well established that the lowered F3 associated with the acoustic percept of American English /r/ can be achieved with different tongue shapes in production. Broadly speaking these shapes may be grouped into ‘‘bunched’’ and ‘‘retroflex’’ varieties. In this work the effects of somatosensory perturbation on /r/ production are examined. Subjects were fitted with a custom palatal prosthesis incorporating a 0.5 cm protrusion along the alveolar ridge, and tongue position during production of /r/ in vocalic contexts was observed using EMA under four conditions: before prosthesis placement; while wearing the prosthesis immediately following placement; still wearing the prosthesis following an unrecorded 20 min adaptation period; and immediately after prosthesis removal. Acoustic effects of the perturbation were minimal, especially after adaptation; production effects were most pronounced in the low vowel context. One subject showed an unperturbed preference for a retroflex configuration, but increased the degree of retroflexion with the palatal prosthesis in place. The remaining subjects preferred unperturbed bunched shapes, but under the perturbed conditions produced primarily retroflex configurations, which for one subject persisted after prosthesis removal. These results suggest that speaker preference for one shape over another may be determined by palatal morphology. [Work supported by NIH.]
Differential effects of speaking rate and phonemic vowel length on formant frequencies of Japanese vowels
Authors: Tsukada Kimiko , Hirata Yukari
Published: October 2013

This study examined the extent to which variation in speaking rate and phonemic vowel length affect the first two formant frequencies of Japanese vowels. If vowel duration is a factor that determines the degree of formant undershoot [Moon and Lindblom, J. Acout. Soc. Am. 96, 40–55 (1994)], formants of phonemic long vowels or vowels spoken at slower rates would occupy more peripheral areas in the F1/F2 vowel space than the short counterparts. Four male native speakers produced Japanese disyllabic non-words, /mVmV/, /mVVmV/, and /mVmVV/ (V=/i e a o u/, VV=/i: e: a: o: u:/) spoken in a carrier sentence at slow, normal, and fast rates. Effects of vowel length were clear for all five vowels: the long vowels occupied more peripheral areas of the vowel space than the short vowels. However, such a systematic effect was not found with speaking rate changes. ANOVAs performed on each vowel type indicated that, for non-high vowels /e(:) a(:) o(:)/, effects of vowel length and speaking rate interacted. The F2 of /e:/, for example, did not differ across rates, but the F2 of /e/ was significantly lower for faster rates. Implications are discussed in terms of Moon & Lindbloms formant undershoot model.
The effects of auditory-visual vowel and consonant training on speechreading performance
Authors: Richie Carolyn , Kewley-Port Diane
Published: October 2013

Recent work examined the effects of a novel approach to speechreading training using vowels, for normal-hearing listeners tested in masking noise [C. Richie and D. Kewley-Port, J. Acoust. Soc. Am. 114, 2337 (2003)]. That study showed significant improvements in sentence-level speechreading for listeners trained on vowels compared to untrained listeners. The present study examined the effects of combining vowel and consonant training on speechreading abilities. Normal-hearing adults were tested in auditory-visual conditions in noise designed to simulate a hearing loss. Using a monosyllable context, one group of listeners received training on consonants, and another group received training on consonants and vowels combined. A control group did not receive training. All listeners performed speechreading pre- and post-tests, on words and sentences. Comparison with the earlier study showed posttest sentence-level speechreading increased by 10 percentage points for participants in the vowel training program, 8 percentage points for participants in the consonant training program, and, unexpectedly, only 2 percentage points for participants in the combined training program. Results from these relatively short training programs suggest that vowels, previously unused in speechreading training, may provide gains in speechreading abilities and play an important role in rehabilitation of hearing-impaired persons. [Work supported by NIHDCD02229.]
Position and place effects in Russian word-initial and word-medial stop clusters
Authors: Kochetov Alexei , Goldstein Louis
Published: October 2013

Studies of inter-gestural timing have shown that (i) word-initial obstruent clusters tend to exhibit less gestural overlap than word-medial or word-boundary clusters, and (ii) the degree of overlap is further affected by the place of articulation of the obstruents (Byrd, 1996; Chitoran, Goldstein, and Byrd, 2002). Both findings have been attributed to perceptual recoverability considerations. This paper presents results of a magnetic articulometer (EMMA) study of Russian word-initial and word-medial stop clusters (e.g., [pt]ashka little bird versus la[pt]a bat). Data collected from 3 native speakers of Russian show that clusters with coronals and dorsals as C1 ([tk], [kt], [kp], [tjm]/[djb]) exhibit less overlap word-initially than word-medially, while the cluster with the labial as C1 ([pt]) does not exhibit the same timing pattern. The findings are interpreted as providing additional support for the role of perceptual recoverability in intergestural timing. First, less overlap in word-initial clusters, compared to word-medial clusters, ensures better place recoverability of C1 (cf. Chitoran et al., 2002). Second, unreleased labials are more perceptually robust than unreleased coronals (Byrd, 1992; Surprenant and Goldstein 1998) and dorsals (Wright, 2001; Kochetov and So, 2005), and thus do not require the same degree of overlap. [Work supported by SSHRC.]
Voice onset time in Mandarin esophageal speech
Authors: Ng Manwa , Liu Hanjun
Published: October 2013

As an important perceptual cue for voicing and aspiration of stops, voice onset time (VOT) is mainly determined by the aerodynamic interaction between the intraoral and subglottal regions. However, since the PE segment serves as a new vibratory source in esophageal phonation, aerodynamic events are very different from laryngeal phonation. VOT associated with esophageal speech of English has been reported previously. However, few studies have reported VOT characteristics of esophageal speech of tone languages. The present study will investigate the possible VOT difference between esophageal and normal laryngeal speakers of Mandarin Chinese. Seven superior esophageal speakers and 7 normal laryngeal speakers will participate in the present investigation. They will be native male speakers of Mandarin Chinese. The participants will produce the syllable /ta/ embedded in a carrier phrase at a comfortable loudness level for three times. VOT values will be measured from a time domain waveform. With reference to a wide-band (300 Hz) spectrogram, VOT will be defined as the release of stop and the first identifiable period of the vocalic portion. An independent sample t-test will be used to determine if VOT values of esophageal and normal laryngeal speakers were significantly different.
The role of attention in infant phonetic perception
Authors: Molnar Monika , Polka Linda , Rvachew Susan
Published: October 2013

Attention is an important factor underlying phonetic perception that is not well understood. In this study we examined the role of auditory attention in infant phonetic perception using a distraction masker paradigm. We tested infant discrimination of /bu/ vs /gu/ with a habituation procedure and three natural productions of each syllable. For the quiet condition each token was copied into a separate sound file. For the distractor condition, a high frequency noise was added to each sound file so that it gated on and off with the onset and offset of the syllable. The distractor noise was a recording of bird and cricket songs whose frequencies did NOT overlap with the test syllables. Thus, the noise did not change the audibility of the syllable, but it could distract infants if they do not focus their attention well. Infants (6- to 8-month-olds) were tested in each condition. Infants tested in quiet performed significantly better than infants tested in the distractor condition; discrimination scores showed little overlap between the two groups. These findings indicate that in young infants, attention to subtle phonetic differences is easily disrupted. The implications for developmental models of speech perception will be discussed.
Experimental study on passive/active hybrid isolation
Authors: Zhang Zi Jun , Chang Woo Suk , Nyang Koon Meng , Chan Yew Wing
Published: October 2013

This paper discusses the control of a high stroke low stiffness non-linear actuator which formed the key element of a smart engine mount system that provides strong support for the engine while at the same time absorbing the engine vibration energy. The actuator is made of a stacked PZT embedded in an elliptical shaped metal frame, in the horizontal direction. Due to the geometry of the frame, the displacement generated by the PZT stacks is amplified up to about 5 times in the vertical direction. However, due to the geometry of the actuator, the vertical and horizontal motions are non-linear and excite motions at multiples of the driving frequency. Feedback controllers cannot be used since the high frequency motion causes spillover problem and control becomes unstable. The filtered-X adaptive controller with sufficient high sampling rate is tested and found to be a useful and reliable controller for the actuator for suppressing the vibration to almost ambient noise level. This actuator requires relatively lower driving voltage level and delivers larger stroke range. This would be more suitable for vibration isolation application where the actuator is serially connected with passive dampers.
Lateralization of high-frequency transposed stimuli under conditions of binaural interference
Authors: Bernstein Leslie R. , Trahiotis Constantine
Published: October 2013

The purpose of this study was to determine whether binaural interference would occur if ITD-based extents of laterality were measured using high-frequency transposed stimuli as targets. The results of an earlier study [L. R. Bernstein and C. Trahiotis, J. Acoust. Soc. Am. 116, 3062–3069 (2004)], which focused on threshold-ITDs rather than extents of laterality, suggested that high-frequency transposed stimuli might be immune to binaural interference effects resulting from the addition of a spectrally-remote, low-frequency interferer. In contrast to the earlier findings, the data from this study indicate that high-frequency transposed targets can, indeed, be susceptible to binaural interference. High-frequency transposed targets, even when presented along with an interferer, yielded greater extents of ITD-based laterality than did Gaussian noise targets presented in isolation. That is, the enhanced potency of ITDs conveyed by transposed stimuli persisted even in the presence of a low-frequency interferer. Predictions made using an extension of the model of Heller and Trahiotis [L. M. Heller and C. Trahiotis, J. Acoust. Soc. Am. 99, 3632–3637 (1996)] accounted well for binaural interference obtained with conventional Gaussian noise targets but generally over-predicted the amounts of interference found with the transposed targets.
Bottlenose dolphins audiogram dependence on azimuth: Evoked potential study
Authors: Popov Vladimir
Published: October 2013

ABR thresholds to tonal pips were measured in two bottlenose dolphins at different azimuthal positions of the sound source. The tested frequency range was from 8 to 128 kHz. Azimuth varied within a limit of 90 degree relative to the animals’ longitudinal axis. This experimental paradigm allowed us to obtain ABR audiograms at different locations of the sound source. The zero-azimuth audiogram, at the sound source position in front of the animal, was of a standard appearance (minimum thresholds at frequencies of 38 90 kHz, steep threshold increase at higher frequencies, and shallower increase at lower frequencies). The audiograms at lateralized sound-source positions looked in a different manner. With the azimuth increase, high-frequency thresholds rose much higher than low-frequency ones, so at azimuths of 6090, the threshold versus frequency function was almost monotonous: the lowest threshold was observed at the lowest frequency (8 kHz) and the highest threshold at the highest frequency (128 kHz). With monaural ABR recording, audiograms contralateral to the sound source featured higher thresholds and steeper threshold increase with frequency as compared to the ipsilateral ones. [Work supported by the Russian Foundation for Basic Research.]
Effects of damping materials on heavy-weight impact noise in reinforced concrete floor
Authors: Jeon Jin Yong , Jeong Young , Yoo Seung Yup
Published: October 2013

Damping materials for reducing heavy-weight floor impact noise in reinforced concrete structures were tested in apartment buildings. The effect of damping materials and an impact isolator were compared in an on-site experiment conducted in a high-rise apartment building. The results showed that the resonance frequency increased and vibration acceleration level decreased when the damping materials were used. Heavy-weight impact sound levels of the structure decreased substantially at 63 Hz, whereas the sound levels of the structure with the impact isolator increased. Subjective evaluation of the perceptual effects of the damping material and the impact isolator were also conducted in the laboratory.
A technique for monitoring and controlling cavitation activity during high intensity focused ultrasound application
Authors: Thomas Charles R. , Farny Caleb H. , Roy Ronald A. , Holt R. Glynn
Published: October 2013

It has been reported that cavitation can lead to enhanced heating in the focal region of a HIFU source. In order to exploit this heating for in vivo use, it is essential that the cavitation only occur in the focal region. Thus, the onset and evolution of inertial cavitation activity must be monitored and controlled during HIFU therapy. One candidate sensor is a confocally-aligned passive cavitation detector; however this would add complexity to a clinical HIFU applicator. Instead we propose that the HIFU source itself can serve as a monitoring device. The combination of broadband acoustic emissions (inertial cavitation) and backscatter (stable cavities) emanating from the HIFU focus manifests itself as fluctuations of the otherwise constant driving voltage amplitude, providing a convenient means for sensing cavitation activity. We will present results of experiments assessing the feasibility of using the variance in the amplitude of the HIFU drive voltage as a feedback control signal. Success is determined by the shape of the lesion created using supplemental control compared to the shape obtained otherwise. Two independent control parameters were used: the amplitude and the duty cycle of the HIFU. [Work supported by the Department of the Army award DAMD17-02-2-0014.]
Onsets, autocorrelation functions and spikes for direction-based sound source separation
Authors: Smith Leslie S. , Fraser Dagmar S.
Published: October 2013

The aim of this work is separation of foreground speech from background sound sources using selective remixing of bandpass filtered channels. Clearly, the remixing parameters must be dynamic since the speech and noise spectra are highly non-stationary. Remixing parameters are recomputed at onsets, detected using biologically motivated techniques [L. S. Smith and D. S. Fraser, IEEE TNNS 15, 1125–1134 (2004)]. However, onsets may originate from the foreground or the background. To select appropriate onsets from the foreground source (whose direction is known) a two microphone system is used, selecting onsets for which the estimated direction in that channel corresponds to the foreground direction. Two different techniques for direction estimation are used: a channel by channel short-term autocorrelation technique, and a channel by channel spike based phase synchronous system (SBPSS), computing ITDs [L. S. Smith, in Artificial Neural Networks, Proc ICANN 2001, LNCS 2130, pp. 1103–1108 (Springer, 2001)] and IIDs [L. S. Smith, in From Animals to Animats, Vol. 7, pp. 60–61 (MIT Press, 2002)]. Results comparing the performance of autocorrelation and SBPSS on single source and source plus noise signals in an office environment are presented. [Work supported by UK EPSRC.]
An acoustic window for sustainable buildings
Authors: Kang Jian , Brocklesby Martin , Li Zhemin , Oldham David J.
Published: October 2013

Encouraging the use of natural ventilation is an important tendency in the green building movement, but opening windows can often cause noise problems. This research develops a window system which allows natural ventilation while reducing noise transmission. The core idea is to create a ventilation path by staggering two layers of glass and using micro-perforated absorbers (MPA) along the path created to reduce noise. The MPA are made from transparent materials so that daylighting is relatively unaffected. Starting with a brief introduction of the MPA theory and its application in ducts, the paper presents a series of numerical simulations using finite element method based software FEMLAB, and experiment results measured between a semi-anechoic chamber and a reverberation chamber. Performance in acoustics, ventilation and daylighting are all taken into account. A basic window configuration is first considered, studying the effectiveness of various window parameters. A number of strategic designs are then examined, including external hoods and louvers in the sound path. There is generally a good agreement between simulation and measurement, and the noise reduction can be as good as a single glazing, with air movement to achieve occupant comfort, rather than just for minimum air exchange. [Work supported by EPSRC.]
Modeling the influence of the cochlear nonlinearity on estimates of psychophysical tuning
Authors: Zhang Xuedong , J. Oxenham Andrew
Published: October 2013

Most behavioral measures of human frequency selectivity have been made with simultaneous masking and the notched-noise technique. The resulting filter shapes may be influenced by the effects of cochlear nonlinearity, such as suppression. Forward masking may provide a measure that is more comparable to neural tuning curves, because it does not involve stimuli that interact with each other along the basilar membrane. This study investigated the extent to which cochlear nonlinearities can account for differences in results between forward and simultaneous masking. The model was constructed using a nonlinear auditory filter, a sliding temporal integrator, a logarithmic transform and a template mechanism. The effects of compression and suppression on psychophysical performance were simulated by varying the relevant parameters of the model auditory filter. The psychophysical results were simulated for both forward and simultaneous masking, using the same parameters and tracking procedure as in the behavioral studies. The results provide a detailed evaluation of the role of compression and suppression in the models predictions of psychophysical tuning and assist in the development of the refined nonlinear cochlear models for human. [Work supported by the ASA Hunt Fellowship and NIH R01DC03909.]
An impedance modeling technique of a fluid-loaded structure
Authors: Cheng Chih-Chun , Wang Pi-Wen
Published: October 2013

A methodology of modeling the fluid-loaded structures using the impedance technique is proposed. The structural response and the fluid loading effect are expressed in terms of structural impedance and the acoustic wave impedance. Then a formulation that assembles the acoustic impedance and the structural impedance is derived and can be used to determine the response of a fluid-loaded structure. The advantage is simply that the impedance can be obtained either experimentally or analytically and then the response of the fluid-loaded structure can be found using the proposed impedance coupling formula without deriving the equation of motion which usually encounters difficulties when the structure is in an irregular shape or the associated boundary conditions are complicated. Two numerical examples are presented. The first is to validate that the fluid loading calculated using the proposed methodology is the same as that from the traditional Fourier Transformation method. The second is to demonstrate the potential of this proposed method applied in analyzing an active material system which is commonly used in the vibro-acoustic control. [Work supported by NSC of Taiwan.]
Effect of changes of complex surface impedance for acoustic scattering from a wedge
Authors: Hughes Ron G. , Niemiec Jan M. , Überall Herbert
Published: October 2013

A code written earlier for the calculation of acoustic scattering from a submerged wedge has been employed in order to study the dependence of the scattering amplitude on various assumed surface impedances of the wedge. Typical wedge opening angles are 10°. Plane waves are assumed incident with source and observation points coinciding in the far field along the bisector of the wedge. The target strength for an impedance-coated wedge is found to lie in between those of a rigid and a pressure release wedge. A frequency region up to 20 kHz was considered. Various numerical impedances and angles of incidence are assumed.
Tone and prosodic organization in Cherokee nouns
Authors: Johnson Keith , Haag Marcia
Published: October 2013

Preliminary observations in the speech of one speaker of Cherokee led us to postulate three factors affecting tone in Cherokee. (1) Tone may be lexically specified with distinctive low, low fall, low rise, and high tones. (2) There is a metrically determined high fall pattern which may be distributed over not more than 2 syllables from the right edge of a prosodic domain. (3) Intonational domains may be associated with discourse functions, marked by high fall, or by pitch range upstep. This paper tests these observations in recordings of word lists and sentences produced by five additional speakers. The analysis we give, positing both lexical tone and metrical prosodic accent, is not unique in descriptions of language, but is different from the usual description of Cherokee. [Work supported by NSF.]
Numerical simulation of acoustic tomography of the atmosphere
Authors: Ostashev Vladimir E. , Vecherin Sergey N. , Goedecke George H. , Wilson D. Keith , Voronovich Alexander G. , Patton Edward G.
Published: October 2013

A state-of-the-art array for acoustic travel time tomography of the atmosphere is under construction by several organizations in the U.S. The array will allow the estimation of the temperature and wind velocity fields within a tomographic volume located a few meters above the ground with a horizontal size of about 80 m. This paper is devoted to numerical simulation of acoustic travel time tomography of the atmosphere. The temperature and velocity fields within the tomographic volume are modeled with the use of quasi-wavelets and Large Eddy Simulation. Then, the travel times of sound propagation between different pairs of sources and receivers of the tomography array are calculated. Given these travel times, three algorithms for reconstruction of the temperature and velocity fields are employed: the cell approach, basis function approach, and stochastic approach. It is shown that the first of these approaches allows us to reliably estimate the mean temperature and velocity vector within the tomographic volume, while the other two give a good reconstruction of fluctuations in the temperature and velocity with respect to their mean values. [Work supported by ARO, Grants DAAD19-03-1-0104 and DAAD19-03-1-0341.]
Scattering of sound and infrasound waves by internal gravity waves in the atmosphere
Authors: Ostashev Vladimir E. , Chunchuzov Igor P. , Wilson D. Keith
Published: October 2013

Internal gravity waves (IGW) propagating in the atmosphere produce highly anisotropic fluctuations in temperature and wind velocity that are stretched in a horizontal direction. These fluctuations can significantly affect sound propagation in a night-time boundary layer and infrasound propagation in the stratosphere. In this paper, 3-D spectra of temperature and wind velocity fluctuations due to IGW, recently derived in the literature for the limiting case of large wave numbers, are generalized to account for small wave numbers. The generalized 3-D spectra are then used for development of a theory of sound propagation through and scattering by IGW. First, the sound scattering cross-section due to IGW is calculated. It is shown that the dependence of this scattering cross-section on parameters of the problem (the scattering angle, sound frequency, etc.) is qualitatively different from that for the case of sound scattering by isotropic turbulence. Second, the mean sound field and the transverse coherence function of a plane sound wave propagating in the atmosphere with IGW are calculated and compared with those for sound propagating through isotropic turbulence. [Work supported by ARO, Grant DAAD19-01-1-0640, and RFBR, Grant 03-05-04001.]