bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and application of multifrequency acoustic techniques to the study of Antarctic krill distribution
Authors: Lawson Gareth L. , Wiebe Peter H. , Stanton Timothy K. , Ashjian Carin J.
Published: October 2013

Multifrequency acoustic techniques were refined and applied in a study of the distribution of Antarctic krill. Acoustic, video, and net data were collected in a continental shelf region west of the Antarctic Peninsula in the falls and winters of 2001 and 2002. Improved parametrization of a theoretical model of krill target strength was achieved through direct measurement of all model parameters. Krill visual acuity was used to determine a threshold level of volume backscattering strength for identifying krill aggregations. Differences in mean volume backscattering strength at 120 and 43 kHz further served to distinguish krill from other sources of scattering. Inversions were performed of mean volume backscattering strength (43, 120, 200, and 420 kHz) in these acoustically identified aggregations to estimate the weighted mean length and density of krill. Inversion results were comparable to net samples for estimated length, but acoustic estimates of krill density exceeded those from nets by one to two orders of magnitude, likely due to avoidance and differences in the volumes sampled by the two systems. Application of these methods to survey data demonstrated strong spatial and temporal variability in the horizontal and vertical distribution of krill aggregations, consistently associated with food availability, temperature, and predators.
Millisecond initiation of boiling by high-intensity focused ultrasound in tissue-mimicking phantoms
Authors: Canney Michael S. , Bailey Michael R. , Khokhlova Vera A. , Crum Lawrence A.
Published: October 2013

Nonlinear propagation effects leading to shock formation at the focus of high-intensity focused ultrasound (HIFU) treatments can accelerate heating and cause rapid boiling in tissue. Boiling can be utilized for targeting the treatment with B-mode ultrasound and should be taken into account when planning the treatment, because bubbles reflect ultrasound and thereby displace and distort the lesion shape. In these experiments, an HIFU transducer of 2-MHz frequency, 4-cm aperture, and 4.5-cm focal length was used to investigate heating effects from shock formation in tissue-mimicking phantoms. The time required to attain 100°C at the focus was calculated with weak shock theory from the peak amplitudes calculated with a KZK-type model, and time to boiling was measured by high-speed video and a 20–MHz passive cavitation detector (PCD) for different values of phantom absorption (both lower than tissue absorption) and HIFU power (100–200 W). Boiling was observed in 3 ms at the highest power level used by the observation of visible bubbles and by a significant change in the PCD time signal and spectrum. [Work supported by NIH DK43881, NSBRI SMS00402, and RFBR.]
Acoustic virtual laboratory: A modeling tool for high-intensity focused ultrasound applications
Authors: Curra Francesco P. , Kargl Steven G. , Crum Lawrence A.
Published: October 2013

The field of high-intensity focused ultrasound (HIFU) is emerging with strong potential and broad medical applications. Characterized by its ability to penetrate at depth inside the body without harming intervening tissue, therapeutic ultrasound has posed the basis for a new array of noninvasive therapies. However, the inherent complexity of biological media and the nonlinear nature of ultrasound propagation at HIFU regimes make optimization and control of the therapy still a challenging task. In this respect, an accurate modeling tool, the Acoustic Virtual Laboratory (AVL), will be presented for solving multidimensional HIFU problems in complex geometries that can greatly assists in predicting HIFU applications effects and, therefore, help in the optimization and control of the treatment. AVL consists of 2-D, 2.5-D (cylindrical symmetry), and 3-D coupled solutions for acoustic and elastic wave propagation in heterogeneous, lossy, bubbly, and porous media with the bioheat equation for temperature estimation. It includes linear and nonlinear wave propagation, arbitrary frequency power law for attenuation, and can account for multiple reflections and backscattered fields. Sample results for tumor ablation, acoustic hemostasis, and propagation through porous bones will be illustrated. [Work supported by US Army Medical Research Acquisition Activity and NIH NCRR Grant R21 RR 21472.]
Ultrasonic evaluation of blood coagulation from stroke patients
Authors: Li Ying , Paeng Dong-Guk , Anjaneya Reddy Guntur Sitaramanjaneya , Choi Min Joo , Kim Young Ree , Choi Jae-Chul
Published: October 2013

It is already known that the ultrasound speed and attenuation coefficient are increasing during the blood clotting process. A pulse echo system was set up to measure the sound speed and attenuation coefficient of human blood at 37 C. From ten healthy volunteers, the blood was taken to measure sound speed and attenuation coefficient during blood coagulation without and with heparin. For ten stroke patients, sound speed and attenuation were measured with aPTT or PT for comparison. The variation of sound speed and attenuation coefficient of blood after adding heparin was small. Sound speed of plasma from healthy volunteers was increased to 7 from 1535 m/s over 50 min without heparin, but to 1 m/s during the first 5 min for heparin-added blood. Sound speed of plasma from stroke patients was changed little compared to that from healthy volunteers without heparin. Attenuation coefficient was increased linearly during plasma coagulation for both volunteers and stroke patients, but its temporal slopes were much smaller for stroke patients. The blood samples from the stroke patients that investigated how heparin affects sound speed and attenuation as a function of time before and after taking the heparin and the results will be discussed.
Alias-free estimation of blood velocity using wideband pulse transmission
Authors: Tanaka Naohiko
Published: October 2013

Blood velocity information that is obtained from a pulsed Doppler system is applied to clinical diagnoses of the circulatory system. However, the conventional pulsed Doppler technique has a fundamental limitation on Doppler velocities: blood velocity is measured erroneously when it is greater than the Nyquist limit. This phenomenon is called aliasing. This study is aimed at expanding the range of measurable blood velocities while avoiding aliasing. A new technique proposed here is based on wideband pulse transmission and phase correction. A series of short pulses with a wide frequency band is transmitted in this technique. Received echoes are Fourier transformed and converted to the cross spectrum. The phase of the cross spectrum is proportional to the frequency and the blood velocity. When the blood velocity is greater than the Nyquist limit, a part of the phase of the cross spectrum is larger than ±π and is wrapped in ±π. The wrapped phase data are corrected using wideband echo information to avoid aliasing. Then the gradient of the corrected phase is estimated and converted to the blood velocity. Simulation results show that the proposed technique triples the velocity range.
Continuous delay estimation with polynomial splines
Authors: Pinton Gianmarco , Trahey Gregg
Published: October 2013

Delay estimation is used in biomedical ultrasonics to determine blood flow, phase aberration corrections, and elastographic images. The accuracy of the algorithms developed to determine these delays depends on noise, bandwidth, and delay range. Subsample delay resolution is required in most cases. Two new algorithms that use cubic polynomial splines to continuously represent the delay and the apply pattern matching functions are introduced. The continuous analytic expressions for the pattern matching functions are used to calculate the delay. Normalized cross correlation and the sum of the squared error are implemented. These algorithms are compared to conventional delay estimators, such as discrete normalized cross correlation, autocorrelation, and to another spline-based method. Simulations compare the performance across noise, delay, and bandwidth. The proposed algorithms perform better, in terms of bias and jitter. For example, the jitter at a 0.5 subsample shift is 2.3×10−3 subsample shifts for interpolated normalized cross correlation, and 3.5×10−4 and 4.0×10−4 for the two proposed algorithms. The computational requirements of the new algorithms are also considered and are shown to be competitive with the interpolated normalized cross correlation at low interpolation values and smaller at large interpolation values. [This work was supported by NIH grants R01-HL075485 and 1R01-CA114093-02.]
Lead zirconate titanate thick-film ultrasonic transducer for 1- to 50-MHz frequency bands fabricated by hydrothermal method
Authors: Ishikawa Mutsuo , Kurosawa Minoru , Hasegawa Tomohito , Kitsunai Hiroshi , Endoh Akito , Takeuchi Shinichi , Uchida Takeyoshi , Kikuchi Tsuneo
Published: October 2013

This prototype ultrasonic transducer had about a 30-μm thick hydrothermal PZT layer on a 50-μm thick titanium substrate. An active area of this transducer was 3.5 mm in diameter. Material constants of this hydrothermal PZT thick film were measured. Electromechanical coupling coefficient kt was over 0.25 and acoustic impedance was 6 Mrayl. A mechanical resonance frequency in the thickness mode of the prototype ultrasonic transducer was approximated by a mason’s equivalent circuit using the thickness and the material constants of the hydrothermal PZT film and the Ti substrate. The prototype ultrasonic transducer had a double broad peak spectrum of about 15 and 30 MHz in simulation. Also, these broad peaks were a half wavelength and a quarter wavelength resonance frequency in a combined structure of the hydrothermal PZT thick film and the Ti substrate. The prototype ultrasonic transducer transmitted ultrasound in water. Experimental results were the prototype ultrasonic transducer radiated ultrasound at the frequency range from 1 to 50 MHz as wideband using respective resonance frequency. A reason for the wideband characteristics radiation of ultrasound was the prototype ultrasonic transducer has low acoustic impedance and double broad peak.
Equivalent network representation for length-extensional vibration modes in a side-plated piezoelectric bar with a varying parameter
Authors: Yamada Ken
Published: October 2013

Equivalent network representation is derived for length-extensional vibration modes in a side-plated piezoelectric bar with varying parameters along it. In contrast to findings of a former report [Yamada et al., IEEE Trans. UFFC 48(2), 613–616 (2001)], which dealt with the longitudinal piezoelectric effect, the bar in this study is presumed to be excited through a transverse piezoelectric effect. The network comprises an electrical transmission line of length corresponding to the bar length and an electrical port with a capacitor that is linked to the line at both its ends via two ideal transformers. Frequency characteristics of the input electric admittance of the bar with a sinusoidally varying piezoelectric parameter, which shows the unique feature of the vibrator, is demonstrated using equivalent network analysis. The possibility of applying this network for modeling the interdigital transducer for excitation and detection of surface acoustic waves (SAWs) is discussed.
Let children experience speech science
Authors: Arai Takayuki
Published: October 2013

An education in acoustics is important for students of different ages: college, high school, middle school, and potentially even elementary school students, for whom such hands-on models are the most important. Because speech communication is a basic human activity, even for children, we expect that even the youngest students to be interested in speech science. With this in mind, we were motivated to develop intuitive and effective models for teaching speech science to all types of students. Our physical models of the human vocal tract [T. Arai, J. Phonetic Soc. Jpn., 5(2), 31–38 (2001)] have recently been installed in an exhibition in a museum in Japan. Children can watch, listen to, and touch the models. Our recent head-shaped and lung models [T. Arai, Acoust. Sci. Technol. 27(2), 111–113 (2006)] are also useful for educating students, because they are intuitive to produce a systematic and comprehensive education from the lungs to the head. Furthermore, we recently designed a sliding three-tube (S3T) model that has a simple mechanism for producing several different vowels [T. Arai, Acoust. Sci. Technol (to be published)]. This model is being used for an activity at a science workshop for children. [Work partially supported by JSPS.KAKENHI (17500603).]
Sonic boom perception: Live versus simulator playback
Authors: Hodgdon Kathleen , Gabrielson Tom , Atchley Anthony , Sullivan Brenda , Salamone Joe , Babcock Chris
Published: October 2013

A research team conducted a study at NASA Dryden Flight Research Center to compare the perception of real versus simulated booms. The field test included an assessment of noise measurement systems and a subjective jury trial on perception of sonic booms heard outdoors. Seventeen sonic booms were recorded under the flight path of four separate flights of three F-18s, using various microphones and recorders at multiple ground and ear level locations. Waveform analysis was conducted comparing the recordings as a function of location and measurement system. Eighteen subjects listened to live sonic booms, then rated the realism of the playback of a selection of those booms reproduced in the Gulfstream Supersonic Acoustic Signature Simulator II several hours later. The subjects also provided adjective descriptors of boom perceptions. The booms selected for the jury trial presented a variety of boom characteristics that included postboom noise. The subjects rated the playback as realistic, contributing to the validation of the simulator for use in future testing. Waveform comparisons and results from the field measurements and jury trial will be presented. [Work sponsored by FAA/NASA/TC PARTNER Center of Excellence.]
Umbo vibration in response to two-tone stimuli measured in human subjects
Authors: Turcanu Diana , Dalhoff Ernst , Gummer Anthony W.
Published: October 2013

The aim of these experiments was to noninvasively investigate cochlear mechanics near auditory threshold in human subjects by measuring the vibration response of the umbo. The vibration measurement setup consists of a custom-built laser Doppler vibrometer (LDV), employing a conventional heterodyne interferometer, for which all optical and electronic parts were tailored to the problem of measuring picometer-sized vibrations in the presence of large, extraneous movements in the order of 0.1 mm (e.g., heart beat, breathing, or swallowing). The cubic distortion product (DP) of the otoacoustic emissions (OAEs) in response to sound stimulation with two tones was measured as vibration on the umbo. For stimulus frequencies, f1 and f2, with f2/f1=1.2 and f2=4–9.5 kHz, and intensities L1 and L2, with L1=0.4L2+39 dB and L2=20–65 dB SPL, the vibration amplitudes were 1–8 pm in subjects (N=20) with hearing loss no more than 25 dB SPL. Application of this vibration technique to a recently proposed method [P. Boege and T. Janssen, J. Acoust. Soc. Am. 111, 1810–1818 (2002)] of objectively estimating hearing threshold by means of extrapolating DPOAE growth functions showed a standard deviation of the estimate of only 8.6 dB.
Neural correlates of psychometric functions for auditory detection
Authors: Dai Huanping
Published: October 2013

The psychometric function in a 2IFC task, which describes the relation between the percentage of correct responses (pc) and the signal strength (x), can be expressed using the Gaussian probability function (φ) with a threshold (α) and a slope (β) parameter, pc=φ[(x/α)β/21/2]. For auditory detection, the psychometric functions exhibited a wide range of slopes in different conditions, such as tone in noise [β≊1, D. M. Green, M. J. McKey, and J. C. R. Licklider, J. Acoust. Soc. Am. 31, 1446–1452 (1959)] and tone in quiet [β≊2, C. S. Watson, J. R. Franks, and D. C. Hood, J. Acoust. Soc. Am. 52, 633–643 (1972)] by listeners with acoustic hearing, and detection by listeners with electrical hearing [βmax≊10, G. S. Donaldson, N. F. Viemeister, and D. A. Nelson, J. Acoust. Soc. Am. 101, 3706–3721 (1997)]. To understand the mechanisms underlying the change in the slope of the psychometric function, the performance of a neural detector engaged in the same tasks as the listeners was analyzed, and the neural correlates of the psychometric function, the neurometric function, was derived. Under the assumption that the detection was based on spike counts of the neuron(s) tuned to the signal frequency, the derived neurometric function showed slope values in good agreement with those obtained from the listeners.
Determining the area of the sweet spot in a surround loudspeaker setup for various microphone techniques
Authors: Peters Nils , Braasch Jonas
Published: October 2013

Several types of microphone techniques exist to record music performances for surround-sound reproduction. Variations between different techniques are found in the distance and angle between the microphones, and the choice of directivity patterns. All the arrays are targeted to produce an accurate spatial impression at the sweet spot. The aim of this investigation is to determine how different microphone techniques affect the size of the sweet spot, the area in which the spatial cues are reproduced with sufficient accuracy. In particular, the common belief that spaced techniques lead to larger sweet-spot areas than coincidence and near-coincident techniques is investigated. For this purpose, impulse responses (IR) of different microphone arrays are measured in a concert hall. Afterwards, test sounds are convolved with the measured IRs and presented through a surround loudspeaker setup in a control room. A dummy head is used to record the reproduced sound fields at different positions inside the listening area. In a psychoacoustic experiment, listeners are asked to rate the different recordings according to the spatial impression provided by different recording techniques. The results of the listening test will be presented and compared to signal analyzes of a binaural model.
Predictors of auditory performance in hearing-aid users: The role of cognitive function and auditory lifestyle
Authors: Vestergaard Martin D.
Published: October 2013

Within clinical audiology, it is often observed that patients who are expected to perform the same differ in auditory performance. Hearing-aid users may be dissatisfied with their instruments while they score satisfactorily in objective tests, or they may be satisfied with their instruments while no objective benefit can be measured. It has been suggested that lack of agreement between various hearing-aid outcome components can be explained by individual differences in cognitive function and auditory lifestyle. We measured speech identification, self-report outcome, spectral and temporal resolution of hearing, cognitive skills, and auditory lifestyle in 25 new hearing-aid users. The purpose was to assess the predictive power of the nonauditory measures while looking at the relationships between measures from various auditory-performance domains. The results showed that only moderate correlation exists between objective and subjective hearing-aid outcome. Different self-report outcome measures showed a different amount of correlation with objective auditory performance. Cognitive skills were found to play a role in explaining speech performance and spectral and temporal abilities, and auditory lifestyle was correlated with self-report outcome. However, overall the predictive leverage of the various measures was moderate, with single predictors explaining only up to 19 percent of the variance in the auditory-performance measures. a)Now at CNBH, Department of Physiology, Development and Neuroscience, University of Cambridge, UK.
Spectrotemporal structure influences spatial release from informational masking in reverberant settings
Authors: Ozmeral Erol , Zutshi Priyanka , Best Virginia , Shinn-Cunningham Barbara
Published: October 2013

Spatial separation between target and masking sources improves target identification due to both changes in energy (acoustic benefit) and the ability to focus attention on the target (spatial benefit). Studies of speech intelligibility show that while acoustic benefits are reduced by reverberation, spatial benefits remain robust [Kidd et al., Acustica 114, 526–536 (2005)]. The current study extends a previous study of nonspeech communication calls [birdsong; Best et al., J. Acoust. Soc. Am 118, 3766–3773 (2005)] to explore whether, like speech, the spatial benefit for these signals is robust in reverberation. It was found, however, that reverberation decreased both acoustic and spatial benefits for birdsong identification. To examine whether the decrease in the spatial benefit was due to spectrotemporal differences between speech and birdsong, songs were slowed down to half the original rate (making them more similar to speech). For these songs, the spatial benefit was preserved in reverberation. These results suggest that spatial benefits in reverberation are less effective for rapidly fluctuating signals, presumably because reverberation smears their temporal structure, impairing segregation of competing syllables. Thus, the relatively slow fluctuations in speech may be important for its resilience to interference from other talkers in reverberant environments. [Work support by Grants AFOSR-FA9550-04-1-0260 and NIDCD (P30) DC04663.]
Effect of peripheral interference and attentional loss on divided listening to multiple simultaneous talkers
Authors: Kawashima Takayuki , Sato Takao
Published: October 2013

Effects of two factors, peripheral interference (masking) and attentional loss, that may impose restriction on divided listening were investigated using Japanese words. In each trial in the divided listening task, simultaneous multiple voices were presented first, then followed by a target voice produced by one speaker. Participants reported whether the target was included in the multiple voices or not. When the number of talkers (manipulated from one to six) was more than three, the estimated hit ratio was lower than unity, and decreased monotonically as the number of talkers increased. To investigate factors inducing the decrement, participants were also tested when the target was presented before the multiple voices. In this condition, decrement of the performance as a function of the number of talkers was gradual, compared to that in the divided listening condition. Decrement of the performance in the pretarget condition was thought to come mainly from peripheral interference, and the difference between the two tested conditions was interpreted as representing the cost in dividing attention. The result suggests that failure in divided listening to three or four talkers largely comes from the attentional factor, although the role of peripheral interference becomes larger when there are more talkers.
Factors influencing the auditory and cross-modal attentional blink
Authors: Bronkhorst Adelbert W. , van der Hoeven Marieke , Theeuwes Jan , van der Burg Erik , Koelewijn Thomas
Published: October 2013

When an observer has to report two targets (T1 and T2) embedded in a stream of distracters, an attentional blink can occur. This is the degradation in performance for T2 when T1 and T2 are presented sufficiently close in time (within about 500 ms). The attentional blink paradigm has been extensively used within the visual domain as a tool to study bottlenecks in the processing of sensory information. Several studies have shown that an attentional blink can also occur during auditory or cross-modal presentation. However, these blinks are smaller and more stimulus dependent than visual blinks. In our research we have found a robust blink when T1 and T2 are tones embedded in distracters tones, but no blink when T2 is replaced by a visually presented letter among different distractor letters. The cross-modal blink is also absent when both T1 and T2 are digits. We do find a clear cross-modal blink when a visual T1 with increased difficulty (three letters or a word) is combined with a T2 consisting of a spoken letter. Our results indicate that there are modality-specific as well as amodal bottlenecks and that the latter occur when stimuli are processed on a verbal or semantic level.
Effects of listening environment on speech recognition in noise
Authors: Thibodeau Linda , Keene Tina
Published: October 2013

The ability to recognize speech in noisy situations varies among individuals despite normal hearing. Although some of the variation may be related to physiological differences, some may be attributed to environmental experiences. The purpose of this investigation was to examine how everyday listening experiences were related to speech recognition in noise abilities. Using the Hearing in Noise Test, reception thresholds for speech were compared for listener groups who differed in their preferred listening levels for music and signal-to-noise ratios for daily communication. Results suggested that speech recognition in noise was related to listening levels. These results have implications for the use of assistive devices to improve the signal-to-noise ratio in adverse communication situations.
Improving the voice pitch discrimination threshold through cochlear implants
Authors: Hiki Shizuo , Shiroma Masae
Published: October 2013

Aiming at the maximum use of linguistic information conveyed by the periodicity pitch of speech sound through cochlear implants, the possibility of improving the voice pitch discrimination threshold was examined for cochlear implantees: three acquired deaf adults and four congenitally deaf children. Female and male adult speech samples of vowel /a/ were analyzed and resynthesized using the STRAIGHT computer program to shift the original voice pitch (c1 and c) one octave upward and downward with a half-step interval on the musical scale. By presenting those synthetic speech samples in pairs, the discrimination threshold of the voice pitch interval was observed. Association of the speech samples to the picture of a piano keyboard was helpful for conceptualizing the voice pitch change, especially for children. Preliminary observation results suggested that the discrimination threshold can be improved by less than one whole step by adults and two whole steps by children. Those figures were promising because, even for Japanese word accent and Chinese tones, which were conveyed by the precise changes in voice pitch, it was ascertained by acoustical analyses of both their production and perception that discrimination of a half-step difference was small enough to recognize their pitch patterns.
Infants’ attention to repeated speech and musical patterns
Authors: McRoberts Gerald W. , Dawson Colin
Published: October 2013

Previous investigations have shown that infants older than 5 months listen longer to speech with repeated utterances than to speech without utterance repetition. The present studies investigated whether infants also attend preferentially to repeated musical patterns. Musical phrases of four and five notes and ending with a rest were composed using several pitch contours and rhythmic patterns. Experiments 1 and 2 compared trials in which phrases were immediately repeated (AABBCC), to trials in which the same phrases occurred without repetition (ABCDE). In the first experiment, no listening preference for either trial type was found for 6- or 9-month-old infants. In experiment 2, silence was added after each phrase to assist infants in parsing the phrases. Infants again failed to show a listening preference. In experiment 3, trials of speech, half with repeated utterances and half without repeated utterances (from previous experiments), were interspersed with trials of repeated and nonrepeated music. Nine-month-olds demonstrated a preference for the repeated trials of both speech and music over nonrepeated trials of the same type. The fact that a preference for musical repetition is only obtained through induction (from verbal repetition) suggests that repeated speech may hold a special attentional status for infants. [Work was supported by Grants NIH—R15/DC005947 and NIH—R01/DC00403.]
Aussie, Aussie, Aussie, Oi-Oi-Oi: Infants love an Australian accent
Authors: Kitamura Christine , Panneton Robin , Notley Anna , Best Catherine
Published: October 2013

This study examines infant’s attention to dialect differences following Nazzi et al.’s [J. Mem. Lang., 43, 1–19 (2000)] finding that American 5-month-olds can discriminate British- and American-English. Using a serial preference task, 48 6-month-old Australian and American infants heard sentence sets spoken in Australian- and American-English. Results showed that at 6 months, American infants listen longer to Australian than American sentences, but Australian infants show no preference. By 8 months, American infants also show no preference. The developmental lag suggests Australian infants have more exposure to the American dialect (e.g., television programs) than American infants to the Australian dialect. Thus, it is predicted, with less linguistic experience, Australian 3-month-olds will show a dialect preference comparable to American 6-month-olds. Data from 14 3-month-olds support this hypothesis; moreover, they also listen longer to Australian than American sentences. Together the results imply that the ability to generalize across two dialects is a function of experience, and that, with age, infants filter out irrelevant phonetic information and cluster American and Australian dialects into the same group. Future directions of this study are discussed as are the reasons why Australian English is the dialect of preference for infants from both dialect environments.
Exploring and learning the consequences of vocalizations in early infancy
Authors: Lacerda Francisco , Gustavsson Lisa
Published: October 2013

The ability to discover and learn about the consequences of own vocalizations is currently being studied in three groups of infants, 3–5-, 6–8-, and 9–11-month olds, exploring a situation that resembles an audiovisual memory game. The infants are tested individually, in a quiet and dimmed studio. They sit in front of a black computer monitor connected to an eye-tracking system. At randomly selected intervals, a circle appears in the center of the screen and expands and shrinks rapidly to a bright circle to signal that an observation trial is in progress. If the infant vocalizes during the trial, an animated actor emerges after about 200-ms delay at screen coordinates that are contingent on spectral characteristics of the initial part of the infant’s vocalization. The actors brightness and time on display is controlled by the vocalizations overall intensity. By analyzing the changes in predictive looking behavior that probably occur during the session, we expect to gather valuable information on the infant’s capacity to learn about consequences of their vocalizations at different ages. [Work supported by grants from the Bank of Sweden Tercentenary Foundation (MILLE, K2003-0867) and EU NEST program (CONTACT, 5010).]
Evaluation of spatial impression of sound in horizontal and depth directions for the purpose of developing an advanced multichannel live sound reproduction system
Authors: Okubo Hiroyuki , Nishiguchi Toshiyuki , Okumura Reiko , Hamasaki Kimio
Published: October 2013

A prototype of an advanced multichannel live sound reproduction system was developed. In this system, multiple loudspeakers are arranged in the horizontal and depth directions in front of listeners to reproduce a sense of sound depth and width [K. Hamasaki et al., Proc. 119th AES Convention, (2005) p. 6559 ]. Using this prototype, a number of subjective tests were conducted to evaluate the listeners sense of sound depth and width. The results revealed that while the direct sound source was perceived near the predicted horizontal location, the sense of depth varied largely from subject to subject. Another listening test was conducted in which reflections from the upper-front of the listeners were reproduced. Simulated reflections of a virtual space were divided into 11 directional room impulse responses (RIRs). The RIRs were convoluted with individual sound sources (male vocals), and subjects compared their spatial impressions of the sound sources reproduced with and without such reflections. The results of this listening test revealed that the feeling of sound depth was one of the factors of spatial impressions and it increased when the reflections from the upper-frontal direction were reproduced.
Self-similar analysis of the room impulse response
Authors: Tang Yong , Shibayam Hideo , Tanaka Wakako , Itakura Tooru
Published: October 2013

Important information of the room acoustic characteristics is contained in the room impulse response. We analyze the time-space correlation of the impulse response by the self-similarity method. The room impulse response is divided into the frame of the length of the fixed time. Attractors are composed by affine transformation of each frame. The attractors that make the Hausdorff distance become the shortest between the standard frame and attractors are decided. The impulse response is reconstructed by using these attractors. In the self-similar analysis, the frame length is decided from the period of the Hausdorff distance between the initial sound and the reflection sound. We show results for the relation between the room acoustic characteristics and the attractors calculated from the self-similar analysis.
Effects of reproduction methods and audio coding on word intelligibility with competing talkers
Authors: Ozawa Kenji , Nakagai Junichi
Published: October 2013

Effects of reproduction methods and high-efficiency audio coding on word intelligibility were examined in a tele-collaboration system. Monaural, stereophonic, and binaural methods were studied. Transform domain weighted interleave vector quantization (TwinVQ) [Iwakami et al., Proc. ICASSP’95, pp. 937–940 (1995)] was used as the audio coding method. Intelligibility tests using word lists, in which word familiarity was controlled, were conducted under six conditions combining three reproduction methods with two conditions, i.e., with or without audio coding. In the experiments, three talkers pronounced different words simultaneously; a listener was then asked to selectively hear the word of a designated talker. Analyses of variance of the experimental results showed that intelligibility for the binaural method was higher than for the other two reproduction methods in both conditions with or without audio coding. Moreover, the benefit of the binaural method was demonstrated because intelligibility for the method with audio coding was higher than that for the stereophonic method without coding, whereas the amount of audio data in the former method was much smaller than in the latter, indicating that the binaural method with high-efficiency audio coding is useful for a tele-collaboration system. [Work supported by JSPS: KAKENHI (17560336) and RIEC, Tohoku Univ. (H18/A10).]
Applying broadband beam-based decomposition of the time reversal operator (BBDORT) to midfrequency active sonar systems
Authors: Fromm David M.
Published: October 2013

This paper reports on progress developing broadband beam-based decomposition of the time-reversal operator (BBDORT) for midfrequency hull-mounted active sonar systems. BBDORT combined with backpropagation has been previously demonstrated to localize a mid-water-column target in shallow water using a vertical source-receiver array [Fromm and Gaumond, J. Acous. Soc. Am. 118, 2039]. However, the array spanned the water column, and choosing an optimal beam set (to scan for targets in a short period of time) can make as much as 30-dB target improvement over nonoptimal beam sets. Current research efforts will address: source-receiver array configurations and tactical frequencies of Navy operational interest, evaluating performance in different environments, and determining efficient algorithms to optimize beam sets. [Work supported by the Office of Naval Research.]
Characterization and modeling of synthetic aperture sonar image statistics
Authors: Lyons Anthony P. , Johnson Shawn F. , Abraham Douglas A. , Williams Kevin L.
Published: October 2013

Interest in the application of synthetic aperture sonar (SAS) to seafloor mapping and object detection has been increasing in recent years. Because images of the seafloor obtained with SAS systems can sometimes exhibit large pixel-to-pixel fluctuations, robust seafloor segmentation or target detection still requires a thorough understanding of the SAS image statistics and their relation to seafloor parameters. As part of the SAX04 sediment acoustics experiment, acoustic data suitable for SAS processing were collected using a bottom-mounted rail system off the coast of Florida in the Gulf of Mexico in October, 2004. This unique data set has been used to explore several important aspects of SAS image statistics including their dependence on system resolution and on the correlation structure of SAS reverberation due to ripples that were present at the study site. Models of the reverberation envelope probability distribution function (pdf) based on the K-distribution have been found to well describe the reverberation environment for systems with lower resolutions than possible with broadband SAS systems. Characterization and modeling of SAS image statistics based on the K-distribution and using ground truth collected during SAX04 will be presented. [Work performed under ONR Grants N00014-04-1-0013 and N00014-06-1-0245.]
Using a dual-band synthetic aperture sonar for imaging various seafloor compositions
Authors: Stroud John S. , Brown Daniel , Cook Daniel , Fernandez Jose , Commander Kerry , Kolesar David , Montgomery Tom
Published: October 2013

The Small Synthetic Aperture Minehunter (SSAM) is a synthetic aperture sonar mounted aboard a 12.75-in. REMUS600 unmanned underwater vehicle transmitting both low (10–50 kHz) and high (105–135 kHz) frequency bands. The sonar and the vehicle are highly integrated, which allows precise pulse timing, attitude correction, and object geolocation. Operating simultaneously in both bands produces two independent images of each scene. The upper band is capable of 2.5- by 2.5-cm resolution that provides high-fidelity images of proud targets. The lower band, processed to 7.5- by 7.5-cm resolution, adds clutter reduction as well as capabilities against buried targets. The dual bands of this sonar have proved to be a robust solution for minehunting in the littorals. In the past 18 months, SSAM has been deployed nine times. In these tests, the system has operated against bottom types including mud, sand, rippled sand, layered mud and sand, posidonia, and coral. Imagery from sea tests showing all of these bottom types will be presented. [The authors would like to acknowledge support from the ONR, Code 32.]
Performance of a buried object scanning sonar against targets buried in sand at the SAX-04 (Sediment Acoustics Experiment 2004) site
Authors: Schock Steven
Published: October 2013

The performance of synthetic aperture processing for imaging buried targets in the band of 3 to 20 kHz is quantified by measuring the SNR of 3-D acoustic images of targets buried in sand at the SAX-04 site. A buried object scanning sonar consisting of an omnidirectional projector and a 40-channel hydrophone line array is towed within 10 m of the seabed at various horizontal offsets to buried targets to measure the SNR of target echoes as a function of grazing angle. Detections of the targets occurring at grazing angles smaller than the critical angle suggest that buried targets can be detected using the evanescent boundary wave thereby improving the range of the sonar for detecting shallow-buried targets. Acoustic images of buried targets also show that backscattering from sand ripples, sediment variability, and sediment layer interfaces limit the performance of the sonar for detecting and imaging buried objects.
Subcritical grazing angle detection of targets buried under a rippled sand interface
Authors: Lopes Joseph L. , Dowdy Carrie L. , Lim Raymond , Tang Dajun , Williams Kevin L. , Thorsos Eric I.
Published: October 2013

Controlled acoustic measurements were conducted to investigate subcritical detection of targets buried in sand having a rippled sediment-water interface. The measurements were performed in a freshwater test-pond with a 1.5-m layer of sand on the bottom. Bottom ripple was formed by scraping the sand with a machined rake. Broadband (10 to 50 kHz) transducers were placed onto an elevated rail that translated horizontally permitting data to be processed using synthetic aperture sonar (SAS) techniques. Targets included silicone oil-filled spheres and flat-endcapped, solid aluminum cylinders. Data were acquired for various ripple wavelengths, heights, and orientations. For each bottom configuration, the seabed roughness over the buried target was measured to verify the ripple parameters and to estimate the small-scale roughness spectrum. This information was used in models predicting backscatter signal levels from the target and bottom. Results for spherical targets have generally been good. However, when cylindrical targets were inspected, model agreement was variable for reasons not fully understood. Characteristics of the target return are found to depend sensitively on ripple height and wavelength, and bottom parameters. Results are discussed with an eye towards understanding previously unexplained field test detections of buried cylindrical targets. [Work supported by ONR and SERDP.]
Development of new sound insulators with perforated board and honeycomb layer systems
Authors: Toyoda Masahiro , Takahashi Daiji
Published: October 2013

Two newly developed types of sound insulators are introduced in this study. The first type is derived from an analytical model of a vibrating surface with an impedance facing. The model is investigated theoretically; the results indicate the possibility of reducing radiation from the vibrating surface by giving appropriate impedance. To realize this effect, a model using a perforated board with a subdivided air cavity is proposed. It is shown theoretically and experimentally that this insulator can achieve radiation reduction at an arbitrary frequency. The second type is proposed from the viewpoint of the subdivision strategy. It presents the possibility of improving insulation by restricting the air-particle motion at the interface between the vibrating surface and air. This method for noise control has an attractive simplicity and considerable practical benefit. The attenuation mechanism is discussed theoretically and experimentally. Results of this investigation show that the effect of this insulator is characterized by reduction of acoustic radiation at low frequencies near and below the critical frequency of coincidence. Wide use of these two insulators in many fields is anticipated.
Sound absorbing material made of polyester nonwovens
Authors: Koga Shin-ichi , Fujimoto Kazutoshi , Anai Ken
Published: October 2013

Polyester nonwovens (PW) comprise fine fibers, similarly to glass wool (GW). Therefore, PW is expected to have high sound-absorption capabilities. In recent years, application of PW, an entirely recyclable material, as an absorbent material has attracted much attention from the viewpoints of resource recycling and waste reduction. In some cases, manufactured PW has been used as an interior material in an actual acoustic laboratory. Reportedly, however, PW has slightly inferior sound absorption capabilities compared to GW. For wider use as a sound-absorbing material, PW must have better sound absorption. In this study, sound absorptions of PW were measured for various fiber compositions. Specifications that engender high sound absorption capabilities were examined. Results revealed PW specifications that provide similar sound absorption as GW with similar thickness and density. The PW presented in this paper has both high sound absorption and good environmental properties. Therefore, it is useful as a sound absorbing material not only for architectural use, but also in various other fields. Finally, two examples are introduced of an actual anechoic chamber that was finished using PW.
Propagation characteristics of airborne ultrasonic wave in porous materials
Authors: Aoki Kenichi , Kamakura Tomoo
Published: October 2013

The attenuation coefficient and propagation speed of airborne ultrasound are measured for highly porous open-cell polyurethane foams and fibers at frequencies of 1 kHz to 1.7 MHz. A theoretical model is proposed to explain the frequency responses of the transmission loss and speed of an air coupled wave physically in porous materials. The model is derived from Biot’s flow resistance and density [M. A. Biot, J. Acoust. Soc. Am. 28, 179–191 (1956)], Lambert’s bulk modulus of fluids in pores [R. F. Lambert, J. Acoust. Soc. Am. 72, 879–887 (1982)], and Zwikker and Kosten’s concept for compliance of the side holes with entrance resistance [Sound Absorbing Materials (Elsevier, Amsterdam, 1949)]. Using measured data of static flow resistance to determine the mean pore size and the proposed model, theoretical prediction is made for the transmission losses and sound speeds in porous materials. Good agreement of theory and results of experiments in the whole frequency range supports the usefulness of the present model. Additionally, the model provides some findings for the extra attenuation coefficient of a slow wave in cemented glass bead specimens and sandstone for high-frequency ranges [P. B. Nagy, J. Acoust. Soc. Am. 93, 3224–3234 (1993)].
Acoustical design of Sejong Performing Arts Center recital hall
Authors: Jeon Jin Yong , Kim Yong Hee
Published: October 2013

Acoustical design of a convention center into a recital hall of Sejong Performing Arts Center located in Seoul, Korea was carried out to renovate its function. The area of the convention space is about 612 m2 and it is mainly used for meetings, symposia, and so on. The volume of the existing hall is limited to 3100 m3, which causes lack of late reflections, due to its structural limitations. Therefore, the existing ceiling slab was designed to be pulled up so that a new ceiling can create extra volume of 1000 m3. A leaf-shaped floor plan and tilted side balconies within 16-m width between side walls were designed to adequately increase enough lateral reflection and spatial impression. The inclined side wall of 1:10 slope was proposed through the comparison with different angles of walls. The saw-tooth-shaped GFRC (glass fiber reinforced concrete) wall reflectors and center protruded stage rear wall are designed for sound diffusion. From the results of computer and scale modeling, it was predicted that the new space will have adequate reverberation time of 1.5 s and a uniform distribution of sound-pressure levels within 3 dB.