bluuebunny/crossref_metadata_2025 huggingface dataset:
A study on the influence of geometrical characters to the acoustical performance in vineyard terraced concert halls
Authors: Chen Yi-run , Chiang Wei-hwa
Published: October 2013

There are two distinctive features defining vineyard terraced concert hall: audiences surrounding the stage and vineyardlike seating arrangement. Besides that, people may find more differences than similarities within those limited built cases. This paper investigated the influence of geometrical characters to acoustical performance in vineyard halls using computer simulation. Through case studies of nine vineyard terraced halls, some geometrical characters were selected as research variables, namely volume, overall proportion, dimensions of key elements, seating capacity, arrangement of vineyard terraces, terraced side box shaping, and ceiling shaping. Acoustical parameters EDT, LF, C80, and G were analyzed by varying architectural features of a prototype developed based on the main geometrical characters of the nine halls. It has been found that raising terraced side boxes would help increase G and LF. For a constant room volume, increasing the number of terraces with sufficient height would raise the LF value in the nearby area mostly. Changing ceiling shape only had influence on the rear part of the front terrace.
Detection of objects in complex environments by echolocating big brown bats
Authors: DeLong Caroline M. , Stamper Sarah A. , Simmons James A.
Published: October 2013

In previous psychophysical experiments, big brown bats detected or discriminated objects (monopole and dipole targets comprised of 15 mm diameter cylinders) presented standing on smooth surfaces with little clutter. Performance was determined by mutual masking of echoes from the targets themselves. In new experiments, bats did two-alternative (left/right) forced choice tasks to detect a two-cylinder dipole target in complex, cluttered environments. In experiment 1, the targets were set inside 14-mm-deep, 20-mm-diam holes in a layer of foam 25 mm thick. Cylinders of different heights protruded 13, 5, or 2 mm above the surface of the foam, or were recessed 1 mm below the surface. The bats performance varied as a function of protruding height. In experiment 2, the dipole target was embedded within arrays of distractor objects that varied in shape, size, orientation, and material. Both experiments explore how bats isolate the echoes from the dipole target from the mixture of echoes returning from the clutter—whether distractor objects or echoes from the sides of the holes. Big brown bats must engage in this acoustic scene analysis when catching insects, such as beetles, against a backdrop of foliage.
Spatial release from masking of aerial tones in a California sea lion (Zalophys californianus)
Authors: Holt Marla M. , Schusterman Ronald J.
Published: October 2013

Spatial release from masking (SRM) occurs when a signal and masker are spatially separated, resulting in improvement of signal detection relative to when they are spatially co-located. Sea lions forage in the water, breed on land, produce airborne vocalizations that are associated with social and reproductive activities, and possess highly reduced pinnae. In this study, SRM was measured at 1, 8, and 16 kHz in a California sea lion who had to detect an aerial tone in the presence of an octave band of white noise centered at the tone frequency. Testing was conducted in a hemi-anechoic chamber. While the masker always occurred in front of the subject (0 deg), the tone occurred at 0, 45, or 90 deg in the horizontal plane. Absolute thresholds were also measured at these angles to account for differences in hearing sensitivity based on source azimuth. Masked thresholds were lower by as much as 12 dB at 1 kHz when the signal and masker were separated by 90 deg. These results were compared with those of a harbor seal who, like all true seals, naturally lacks pinnae. Performance differences between the two subjects at the highest frequency likely reflect variations in pinna anatomy.
Celebration of Floyd Dunn: Some remarks about his life, career, and accomplishments
Authors: O’Brien William D.
Published: October 2013

No celebration of Floyd Dunn would be complete without some remarks about the life, career, and accomplishments of this remarkable scientist/engineer. Floyd had made significant scholarly contributions in six general themes, and you will hear about their impact to our welfare during the celebration. The six ultrasonic biophysics themes include absorptive processes, nonlinear phenomena, application in living systems, toxicity, measurement techniques, and ultrasonic microscopy. Floyd has been recognized for his accomplishments by being the recipient of most of the important national and international awards including National Academy of Sciences, National Academy of Engineering, ASA’s Gold Medal and Silver Medal in Bioresponse to Vibration, Acoustical Society of Japan’s Medal of Special Merit, IEEE’s Edison Medal, and election to Fellowship in six professional societies.
Native and non-native identification of acoustically modified Mandarin tones
Authors: Lee Chao-Yang , Tao Liang , Bond Zinny S.
Published: October 2013

Lexical tones have been known to be one of the most difficult aspects of tone languages to master for non-native learners. Extending upon Gottfried and Suiter’s study [J. Phonetics 25, 207–231 (1997)] of tone identification in silent center syllables, four experiments examined how well Mandarin tones can be identified with partial acoustic information and whether native and non-native listeners show differences in the use of the limited acoustic information. Twelve minimal tone pairs including all six tonal contrasts in Mandarin were digitally processed to generate four types of stimuli: silent-center, center-only, onset-only, and intact syllables. The stimuli were presented in the original carrier phrase, excised from the carrier phrase, or excised and pasted onto another carrier phrase. Participants included 40 non-native speakers with 1–3 years of Mandarin instruction at Ohio University and 40 native speakers. Both learners and native speakers could identify the tones under all modification conditions at better than chance levels. For both groups, the onset-only syllables were the most difficult. Tone 2 received the fewest correct identifications and longest response times, being confused with tone 3.
A design of array-microphone system using pressure-gradient microphones and two-dimensional finite impulse response filters
Authors: Naono Hiroyuki , Nishikawa Kiyoshi
Published: October 2013

Delay-and-sum array microphones consisting of a linear array of microphones can achieve sharp directivity at high frequencies. A disadvantage is that the directivity is frequencydependent. An array microphone using a fan filter is proposed to resolve that problem. However, it is necessary to increase the filter order to form a sharp beam at a low frequency. This paper is reported improvement of the array microphone directivity, realizing a narrow beam with a low order of the filter using a two-dimensional frequency domain design. Using four microphones, a second-order pressure-gradient microphone is formed. The spacing of the microphones is set for high sensitivity and broad bandwidth in the operating frequency range. These microphone units are placed along a line and are cascaded to a two-dimensional fan filter so that the load is distributed. In the proposed configuration, the second-order pressure-gradient microphone is cascaded with an axially symmetric fan filter. The configuration thereby forms a single broadside beam. Consequently, the directional characteristics of the pressure-gradient microphone are reflected in the array microphone and a sharp directivity, which is frequencyindependent, is obtained over a wide frequency range.
The propagation of acoustic field uncertainty in an ocean waveguide having finite correlation length sound speed variations
Authors: Finette Steven
Published: October 2013

While the physical laws governing wave propagation in ocean waveguides are well understood, the appropriate wave equations typically depend on parameters, fields, boundary, and initial conditions that are, at best, only partially known in any given environment. Incomplete environmental knowledge concerning these quantities is a form of uncertainty that should be characterized and quantified in any simulation-based prediction scheme involving the acoustic field. This talk focuses on the quantification of uncertainty in ocean waveguide propagation using a probabilistic formulation in which both the sound speed and acoustic fields are represented by stochastic basis expansions. An example is discussed for the case of an ocean waveguide with separable depth and range correlation functions describing the sound speed field. The relationship between this example and the propagation of acoustic field uncertainty in an internal wave field is discussed. [Work supported by ONR.]
Acoustical development of the human baby cry: Anatomical and social factors
Authors: Nonaka Yulri , Kudo Noriko , Okanoya Kazuo , Kudo Noriko , Okanoya Kazuo , Kudo Noriko , Okanoya Kazuo
Published: October 2013

We investigated the acoustical development of the human baby cry based on our two-stage hypothesis, which holds that two distinct factors affect the development of the baby cry. First, humans possess the cortico-bulbar pathway connecting the face motor cortex and the medullary respiratory and vocal centers. This pathway is absent in nonhuman primates and other mammals. We postulate that the myelinization of this pathway would change the acoustic characteristics of the baby cry. Second, after neuroanatomical maturation enabled variable cry patterns, the social relationships with caregivers should differentiate the acoustical patterns of the baby cry. This should lead to family-specific cry patterns. To test the two-stage hypothesis, we recorded ten newborn babies until they were 1 year old. In all babies, the cry pattern was very simple up to 2 weeks, while after 1 month, the pattern became temporally and spectrally complex, suggesting neuroanatomical changes. At three months, we asked the mothers to classify the cries of their own babies into three categories: sleepy, hungry, and wet diaper. There were no acoustic patterns common to their classifications, suggesting that baby cry semantics are family-specific. These results support our two-stage hypothesis of cry development. [Work supported by JST and JSPS.]
Measuring emotional arousal in the voiced sounds of two mammals, the rhesus monkey and African elephant
Authors: Soltis Joseph , Wesolek Christina , Savage Anne , Leong Kirsten , Newman John
Published: October 2013

Emotional arousal is expressed in the voiced sounds of primates and other mammals, but there are no consistent acoustic measures used and few comparative analyses. We apply a representative suite of source and filter measurements to rhesus macaque (Macaca mulatta) coo calls on Cayo Santiago, Puerto Rico, and African elephant (Loxodonta africana) rumble calls at Disney’s Animal Kingdom, Florida, U.S.A. Based on social context, calls were classified into high and low arousal categories. In both species, MANOVA showed that the 15 measures taken together separated calls across arousal categories. In rhesus macaques, high arousal was associated with increased and more variable fundamental frequencies, increased amplitudes in the lower frequencies, and a shift in formant locations. In African elephants, increased arousal was associated with a shift of energy from lower to higher frequencies. In addition, low ranking females expressed a greater magnitude of acoustic change compared to high ranking females. The suite of acoustic features used here may successfully characterize arousal state in a variety of mammals, but the specific acoustic features that reflect arousal and the specific pattern of acoustic response may vary by species and individual. [Work supported by Grant Nos. NIH CM-5-P40RR003640-13 and NSF-IIS-0326395.]
Commonality in the vocalizations of order Perissodactyla
Authors: Browning David G. , Scheifele Peter M.
Published: October 2013

As a follow-on to the human genome project, it has been suggested that the next major gene sequencing program may be for the horse as a representative of the relatively small order Perrissodactyla. This order consists of three families; Equidae (equines), Tapiridae (tapirs), and Rhinocerotidae (rhinos), for a total of 17 species. Both sensual ability and environmental conditions (open plains to dense jungles) vary greatly among this small group; for example, horses have excellent eyesight, tapirs do not. Vocalizations of the various species are compared to determine any common characteristics that might serve as a basis for future association with specific genes. The universal quality appears to be the ability to vary pitch during the vocalization. Other subsets such as braying or whinnying exist among a limited number of species, which suggests that there may be evolutionary trends within the order.
Application of the source-filter theory to the study of loud-calling in male deer
Authors: Reby David
Published: October 2013

I will review recent studies of roaring in red deer males, which illustrate how source-filter theory can be successfully applied to studying mammal vocal signals. Combining anatomical analyses of the vocal apparatus, acoustical analyses, and playback experiments using resynthesized calls, we have shown that (i) red deer and fallow deer males have a descended and mobile larynx, an anatomical innovation that was previously believed to be uniquely human and that enables callers to modulate their formants during vocalising; (ii) minimum formant frequencies provide an honest indication of body size in red deer roars, (iii) stags use rivals’ minimum formant frequencies in assessment during male-male contests, and adjust the formants of their own replies in relation to what they hear; and (iv) hinds perceive size-related variation in formant frequencies, and pay more attention to roars in which formant spacing indicates larger males, independently of fundamental frequency. I will then compare the acoustic structure of sexual loud calls in related subspecies (Corsican deer, Wapiti) and species (fallow deer, pere Davids deer), highlighting the variability of source- and filter-related acoustic features in this group. To conclude I will suggest directions for future research in this area.
Can operating room nurses accurately classify noise exposures?
Authors: Stringer Bernadette , Haines Ted
Published: October 2013

Worker’s qualitative chemical exposure estimates when compared to estimates made by experts or with monitoring devices have been found to be accurate. But almost no research exists on worker’s ability to classify noise exposure. This investigation took place within a multi-hospital intervention study in which OR nurses completed a questionnaire at the end of each surgery and answered, ‘‘During this surgery could you easily hear: quiet talking, normal talking, or loud talking?’’ In 255 surgeries, noise was measured using a sound level meter, for a minimum of 15 min, while in 68 surgeries noise was measured for >70% of the surgery. In the 255 surgeries in which noise was measured for 15 min or >, it was found that nurses who heard quiet talking were exposed to 62.8 dB(A) and that nurses who heard normal or loud talking were exposed to 65.1 dB(A), a difference that was statistically significant (p=0.019). In the 68 surgeries where noise measurements lasted more than 70% of the surgery, nurses who heard quiet talking were exposed to 64.0 dB(A), while nurses who heard normal or loud talking were exposed to 67.3 dB(A), a difference that was borderline significant (p=0.07). Nurses can distinguish between noise that interferes with quiet talking during surgery and noise that does not. [Work funded by Ontarios Workplace Safety Insurance Board.]
Noise in Canadian hospital operating rooms
Authors: Haines Ted , Stringer Bernadette
Published: October 2013

Noise levels in hospital operating rooms have not been well characterized. Therefore, noise levels were measured using a sound level meter in a sample of surgeries included in a multihospital intervention study, assessing the effectiveness of a recommended work practice to decrease occupational exposure to blood during surgery. The duration of the measurements ranged from 15 min to several hours. Among types of surgery for which at least four measurements were done, the Leq for orthopedic surgery was the highest at 70.1 dB(A) (range 60.8–75.1), followed by 63.7 dB(A) for neurosurgery (range 57.4–68.1), and 62.8 dB(A) (range 58.5–70.3), for general surgery. Gynecological surgery had the lowest Leq, 60.8 dB(A) (range 56.5–62.5). Peak levels were found to be as high as 132.8 and 132.6 dB(A), in general and orthopedic surgery, respectively, and lowest in neurosurgery at 102.6 dB(A). These noise levels are consistent with those from a comprehensive U.S. study, and substantially exceed EPAs recommended level of 45 dB(A) for hospitals. [Work funded by Ontarios Workplace Safety Insurance Board.]
Speech and noise levels in classrooms—signal, noise, reverberation levels as a metric for acoustic design for learning
Authors: Guerra Line , Teichner Nicolas , San Souci Sooch , Campbell Dick
Published: October 2013

This study attempts to investigate the variance of speech levels in occupied classrooms during learning activities and their relationship to the total noise component (occupied, ambient, and reverberant). The methodology for the construction of a valid data base is presented, which would apply to criteria such as SNR (signal-to-noise ratio) and correlate to the term SNRL (signal, noise, reverberation levels). The interrelationship of speech and noise in any learning environment requires that the common variables associated with a stated speech level value should be stated along with the speech level value. The significance of the influences on the global value and in some cases the spectra of speech is discussed relative to variables such as the activity, the total occupancy and comportment of the audience, the volume of the room, total occupied noise in proximity to the speaker, speech directivity, effects of head diffraction among seated audience, and the distance from the source. Results from measurements taken in this study in actual classrooms are presented with an emphasis on specificity. This research has produced a strategy for the mapping of the speech-noise environment that significantly supports the use of a modeled SNR value as a goal for design.
Fully nonlinear model for spherical bubble oscillations between rigid parallel plates
Authors: Cui Jianying , Wilson Preston S.
Published: October 2013

Many medical ultrasound applications involve the interaction of intense acoustic waves with bubbles confined by blood vessels or tissue. As a step toward understanding such systems, a bubble confined between two parallel rigid plates was modeled using the image method. The model equation is of Rayleigh-Plesset form, including compressibility of the liquid and accounting for boundary conditions imposed by the plates [Cui et al., Proc. 17th ISNA, edited by Atchley et al. (AIP, New York, 2006), pp. 229–232]. An analytical solution for the second harmonic, and fully nonlinear solutions in the quadratic approximation, were reported previously. Here, a hybrid time-frequency algorithm is presented for solving the complete nonlinear model equation. In particular, the effect of the plates is most conveniently dealt with in the frequency domain, whereas the nonlinearity due to the gas law is best handled in the time domain. The procedure was verified for moderate drive amplitudes by comparison with a spectral algorithm for solving the model equation in the quadratic approximation [Cui et al., J. Acoust. Soc. Am. 118, 1942 (2005)]. Results obtained from the hybrid algorithm will be presented that illustrate the effect of plate separation for different amplitudes and frequencies of acoustic excitation.
Correlation of field measurements for footstep force pulse with finite element analysis model for determining vibration response of a building floor
Authors: Carman Richard , Phillips James
Published: October 2013

An idealized force pulse that simulates footsteps was developed by Galbraith and Barton. Their proposed forcing function was determined from direct force measurements using walkers of different weights walking at various speeds. Unger and White used this idealized footstep pulse to determine the maximum dynamic deflection of a floor for the purpose of building design calculations. These basic concepts were used to revisit the characteristics of the idealized forcing function. During the design phase of an academic research facility, extensive vibration measurements were obtained using an exemplar floor similar in design to that proposed for the new research building. The exemplar floor was modeled using FEA. Its modal characteristics were compared to the field test results and found to be in reasonable agreement. Upon having established confidence in the basic FEA model, the field measurement results of two walkers on the exemplar floor were compared with the FEA results predicted using the Galbraith-Barton footstep pulse. The shape and magnitude of the footstep pulse were iteratively adjusted until the measurement results and FEA results were in good agreement. The results of the FEA analysis and the measurement program behind the model will be presented.
Influence of lightweight structural design of office buildings on vibration levels due to people walking and operation of mechanical equipment
Authors: Pettyjohn Steven D.
Published: October 2013

West coast buildings typically use lightweight structural designs, even for Class A office building. This means the best floors use lightweight concrete on fluted decks with beam and column spacings of 30 to 35 ft. with open web joists at 10 ft. on center. Class B office building may use columns at 28 and 35 ft. with only two-layers of plywood on wood open web joists at 24 in. on center. The resulting floor/ceiling assemblies are structurally sound but dynamically very live. Some structural damping would be expected from the introduction of partitions, but with the use of large open areas and partial height partitions, damping is limited. These assemblies have relatively low resonance frequencies and are very susceptible to any sinusoidal input force such as people walking or operation of mechanical equipment. Vibration measurements, made on four buildings after complaints were received, show the source of some of these problems. The results are compared with predictions by Murray et al. and Ungar et al. The lack of composite action between the beams and joists/purlins and the floor appears to be the source of many of the problems. Solutions to the problems in these existing and occupied buildings are discussed.
Case history building structural vibration isolation for 500 Atlantic Avenue
Authors: Tocci Gregory , Wilson George , Phillips James , Unger Gladys , Moore James
Published: October 2013

Vent Building 3 of the new Central Artery Tunnel located at 500 Atlantic Avenue in Boston, Massachusetts is a heavy poured in place concrete structure with its roof situated about 3 ft. below grade. The vent building contains 23 100+-in.-diameter double-width centrifugal fans that, for a number of reasons, are not vibration isolated. The fans exhaust into a cluster of reinforced concrete shafts that rises up to about 250 ft. above grade. The tall stacks have been embedded in a luxury hotel/residential condominium complex that Extell Development Company is currently constructing. The stacks provide both vertical support and seismic support for the building. This paper summarizes the history of work on the project, and compares predicted and measured sound and vibration levels in representative building spaces. [We wish to acknowledge the support of Extell Development Company, Boston, MA for their support of this work.]
Perception and production of long and short vowels in Japanese by children
Authors: Arai Takayuki , Iitaka Kyoko , Ohki Eriko
Published: October 2013

Studies have shown that acquisition of reading depends on such phonological processes as verbal short-term memory and temporal processing of speech. An inability to encode phonological representations orthographically may cause reading disabilities, such as dyslexia. Categorical perception is known to be closely associated with phonological encoding. Thus, studies examining the temporal processing of speech sound categorization may be useful in differential diagnoses of reading development and disabilities. The first study examines the perception of long and short Japanese vowels by a group of seven normal six-year-old children and two with delayed phonological development. Subjects were asked to identify vowel length in sets of words. The first vowel in each stimulus word was made to vary with respect to length. Perception by normal and delayed children differed in ways similar to what had been reported in previous English studies. In the second study, the relation between perception and reading of long/short vowels was examined by a group of 125 children ages 4 to 8. Similar settings were used for the second experiment. The results showed that (1) a large developmental change of perception was observed in ages 6–8 and (2) a positive correlation was obtained between perception and reading tasks.
Effects of microphone and loudspeaker directivity on accuracy of synthesized wave fronts in sound field reproduction based on wave field synthesis
Authors: Kimura Toshiyuki , Ito Sadanori , Nakagawa Masaki , Kakehi Kazuhiko
Published: October 2013

Sound field reproduction based on wave field synthesis proposed by Camras [M. Camras, J. Acoust. Soc. Am. 43, 1425–1431 (1968)] is a technique that synthesizes wave fronts of a control area at a listening area using directional microphones and loudspeakers placed at the boundary of those areas. This study evaluates the effects of the directivity of microphones and loudspeakers on the accuracy of synthesized wave fronts. Microphones and loudspeakers were placed at the boundary of both areas that have two cases (a circle with a radius of 2 m and a square 4 m on a side). The number of microphones and loudspeakers were 630 (circle) and 801 (square). The interval of microphones and loudspeakers was less than 2 cm. Therefore, spatial aliasing does not occur if the frequency is less than 8 kHz. Three directional patterns (omnidirectional, unidirectional, and shotgun) were designed as directivity conditions of microphones and loudspeakers. Computer simulation results showed that there is no effect of directivity of loudspeakers and that accurate wave fronts can be reproduced when a unidirectional or shotgun microphone is applied. [Work supported by special grant for education and research of Tokyo Univ. of Agriculture and Technol.]
Frequency scaling reduces individual differences in external-ear transfer functions in developing cats
Authors: Tollin Daniel J.
Published: October 2013

There are three cues to sound location: Interaural differences in time and level and monaural spectral shape cues. The ultimate magnitudes of these cues depend largely on the linear dimensions of head and pinnae. During development, the increasing interaural distance associated with a growing head and pinnae result in cues that change substantially and continuously until maturation is complete. These experiments examined whether the intersubject differences in the directional transfer functions (DTFs), the directional components of the head-related transfer functions, of cats during development could be reduced by scaling one set of DTFs on a log-frequency axis. Measurements were made of both the physical dimensions of the head and pinnae and the DTFs of cats aged 4 weeks to adulthood. For each pair of subjects, an optimal frequency scaling factor was computed that minimized the differences in the DTFs. In many cases, the optimal factors for pairs of subjects were proportional to the ratios of the measured physical dimensions of the head and pinnae in those subjects. Although there were still considerable differences in the DTFs even after scaling, these data support frequency scaling as a potential method of modeling the development of the DTFs in cats. [Work supported by NIH Grant DC006865.]
Software-centered implementation of 128-channel loudspeaker array with stock PC and its application
Authors: Mizoguchi Hiroshi , Nakamura Takafumi , Takemura Hiroshi , Kagami Satoshi
Published: October 2013

A huge speaker array system of 128 loudspeakers was constructed and experimented. It was implemented as ‘‘software-centered’’ style, utilizing stock loudspeakers and a PC. No dedicated hardware nor DSP was utilized. Spot forming, instead of beam forming, could be realized by 32 by 4 square layout of the array. Spot means small area of higher sound pressure level. Number of the spot was not limited to one. In the experiment, within 3 m by 3 m area, four spots of different sounds could be simultaneously formed. This spot forming was confirmed by actually measuring spatial distribution of sound pressure level. The effect of the spot was also confirmed auditorily. Since the system was software centered, it was dynamic. By simply changing software parameters, the location of the spot can be easily moved even while the system is running. This movability of the spot was intended to be the basis for visual steering. To realize the system, a simultaneous 128-channel 14-bit DA converter PCI board was developed. The 44.1-KHz sampling rate was achieved by a 2.4-GHz Intel Xeon based PC utilizing the DA board and a real-time OS, named ART-Linux. Approximately 23-μs loop could be realized by the software. It was the world’s fastest software loop.
The acoustic information extraction of the indoor impulse response by multiresolution analysis
Authors: Tanaka Wakako , Tang Yong , Itakura Toru , Shibayama Hideo
Published: October 2013

The impulse response is divided into approximation and detail components by the multiresolution analysis. The correlations between the early sound and reflected sounds are estimated respectively for the impulse response and the approximate signal. The approximate signal was calculated as a function of level of the multiresolution analysis. The correlation coefficient of these correlations is over 0.7 under level three. We evaluate the differences of these correlations from the listening test.
A fundamental investigation of the small microphone array system and its applications
Authors: Nawa Akira , Watanabe Yoku , Hamada Hareo
Published: October 2013

A purpose of this research is to construct a 3-D sound recording and reproduction system that has a high presence by performing a spatially controlled sound field synthesis technique. For this purpose, it will be required to examine and choose the most suitable sound recording system, since a conventional sound recording system samples only original signal itself, and does not include enough spatial information. In other words, it will be required to examine the system to record the information of the three-dimensional spaces, such as the direction and the distance, and to transform the configuration to become effective to the reproduction system. This paper will deal with a basic examination to construct the microphone array placed in proximity and the recording system, which is able to control the directivities in the three-dimensional spaces, using algorithm based on LMS by FIR filter networks from signals to each microphone.
Blind source separation of musical signals applied to selectable-listening-point audio reconstruction
Authors: Niwa Kenta , Nishino Takanori , Miyajima Chiyomi , Takeda Kazuya
Published: October 2013

An audio reproduction system is being developed to generate binaural signals at user-selected listening positions from audio signals of multiple sound sources recorded with multiple microphones. The system consists of a sound decomposer based on blind source separation (BSS) and a sound recomposer using head-related transfer functions (HRTFs). In this work, musical signals of multiple instruments are separated into the original independent signals of the respective instruments using BSS based on frequency-domain independent component analysis (FD-ICA). HRTFs are then convoluted to the separated sound sources to reconstruct the music sounds of the selected listening point. Preliminary experiments are conducted using two or three sound sources of instruments: flute, violin, and piano generated by a synthesizer. The synthesizer sounds are played through small directional loudspeakers or spherical omnidirectional loudspeakers in a low-reverberant sound-proof room or moderately reverberant lecture room and recorded with multiple microphones. Live music played on real instruments including flute, violin, and trumpet are also recorded in the same rooms. Audio signals of respective instruments obtained by BSS are available on our web site.
Analysis and modeling of interaction of auditory-visual information
Authors: Asada Takahumi , Watanabe Yuko , Shibata Tatsuya
Published: October 2013

We analyze and model the interaction of movement of the synchronized auditory-visual information. We construct the relationship of movement between virtually sound source and object. We suppose that cubic local contrast model (CLCM) we propose and the optical flow method are useful for analyzing moving image. CLCM is a method that describes the movement of objects from temporal and spatial difference of local contrast between pixels in moving image, and we found CLCM can measure the orientation of camera motion and the moving direction of an object in a moving image. We use the feature of head-related transfer function (HRTF) as the feature of sound movement. We have done two experiments: experiment 1 is that we analyze the data of the interaural amplitude difference (IAD) and interaural phase difference (IPD) between right and left HRTFs of a sphere by local contrast model (LCM); experiment 2 is that we analyze the relationship between the movement of an object in a moving image and a virtual sound source. We discuss the interactive features between auditory and visual information.
A biologically inspired pitch determination algorithm
Authors: Camacho Arturo , Harris John G.
Published: October 2013

A biologically inspired pitch determination algorithm is presented. This algorithm combines existing models of the cochlea and inner-hair-cell based spike generation [Lopez et al., J. Acoust. Soc. Am. 110, 3107 (2001); Sumner et al., ibid. 113, 893–901 (2003)] to model spike trains in the auditory nerve. The pitch and its salience are then estimated using a method proposed by Cariani [Cariani et al., J. Neurophysiol. 76, 1698–1716], which computes a summary autocorrelation function over the spike trains. Unlike Cariani’s work, where spike trains are obtained experimentally, we simulate the spike trains from biologically inspired models. The main contribution of our approach is to combine models of the auditory system and a pitch estimation method based on neural spike trains. The proposed algorithm was tested using standard synthesized sounds, speech, and singing voices. Results show that this algorithm better matches human performance as compared to traditional pitch detection algorithms used in automatic speech processing.
Estimation of a talker and listener’s positions in a car using binaural signals
Authors: Takimoto Madoka , Nishino Takanori , Takeda Kazuya
Published: October 2013

The problem of estimating the location of a sound source is described which is based on signals observed at the entrances of the two ears. The purpose is to specify the talker’s and listener’s positions within a car using the binaural signal. The talker and the listener sit in two of the four car seats. In this experiment, two kinds of head and torso simulators are used as a talker and a listener. Given information includes the acoustic transfer functions for all positional patterns. Eight patterns of acoustic transfer functions are measured, involving those that have the same positional pattern, but in which the talker faces a different direction. A Gaussian mixture model for each positional pattern is generated. The parameters we used are interaural information such as the envelope of an interaural level difference. The models are evaluated by specifying the positional pattern. Results show that we can specify positions with up to 97% (35/36) accuracy using the binaural signals of two men. Then the input signal was expanded to one with background noise that resembles a real situation, and a model that involves motion of the talker’s head was also considered.
On the accuracy of speech source direction identification on the horizontal plane using 3-D audio displays
Authors: Terada Hirotoshi , Kondo Kazuhiro , Nakagawa Kiyoshi
Published: October 2013

This paper describes initial results of speech source direction identification experiments on the horizontal plane. This is an initial study for the sound localization required in order to separate the individual speech source location to increase the intelligibility in remote conference systems. Our focus here was to determine the effect of sound source characteristics on the source direction identification accuracy. Sound sources were located on three target locations (forward, right, and left) and five (45 deg in both right and left added) on the horizontal plane using a real-time virtual acoustic environment rendering system (NASA SLAB). SLAB integrates HRTFs to render the source localization. The sound sources used were conversation speech, white noise, and conversation speech mixed with noise at an SNR of 0 dB. The observers were asked to identify the direction of the rendered sound presented over a headphone. The results showed that the direction identification accuracy of conversational speech is approximately 20% higher than that of white noise in all directions tested. However, the accuracy of mixed conversation and white noise was about the same as the accuracy with white noise only, suggesting that the high-frequency components may be degrading the perceived accuracy.
On the numerical simulation of sound wave propagation using field programmable gate array device
Authors: Tsuchiya Takao , Sugawara Eiko , Inoguchi Yasusi
Published: October 2013

Numerical simulation of sound wave propagation using field programmable gate array (FPGA) device is proposed. The two-dimensional digital Huygensf model (DHM) or the transmission line matrix (TLM) model is configured in FPGA device as digital circuits. DHM is a numerical model in which the propagation and scattering of waves are simulated as the sequences of impulses scattering on the transmission line network as Huygens’ principle states. The digital equivalent circuit can be easily developed based on DHM because the formulation of DHM is very simple compared with the finite difference time domain (FDTD) method. In this paper, number of logic cells of the FPGA device required for a DHM element is estimated. To configure DHM elements in the FPGA device as much as possible, the fixed-point operations are applied to the DHM calculations. Numerical precision of DHM using the fixed-point operations is then discussed. The data length required for acoustic field simulation in practical precision is estimated. The capability of the FPGA simulator for room acoustics is discussed.
Decomposition of the time reversal operator (DORT) for extended objects
Authors: Robert Jean-Luc , Fink Mathias
Published: October 2013

The decomposition of the time reversal operator, known by the French acronym DORT, is widely used to detect, locate, and focus on scatterers in various domains such as underwater acoustics, medical ultrasound, or nondestructive evaluation. In the case of point scatterers, the theory is well understood: the number of nonzero eigenvalues is equal to the number of scatterers, and the eigenvectors correspond to the scatterers’ Green function. In the case of extended objects, however, the formalism is not as simple. We show that, in the Fresnel approximation, analytical solutions can be found, and that the solutions are functions called prolate spheroidal wavefunctions. These functions have been studied in optics and information theory as a basis of band-limited and time-limited signals. The theoretical solutions are compared to simulation results and previous experimental results Most importantly, we justify the intuition that for an extended object, the number of nonzero eigenvalues is proportional to the number of resolution cells in the object. The case of 3-D objects imaged by a 2-D array will also be described.
Measurements of temporal coherence of sound transmissions through shallow water
Authors: Yang T. C.
Published: October 2013

Temporal coherence of acoustic signals propagating through fluctuating oceans has received much attention in the literature as the rate of signal coherence loss impacts the sonar performance. This paper presents the measurement results of temporal coherence of acoustic signals propagating through shallow water using data from three experiments in three different parts of the world. The data are broadband signals covering three frequency bands: low frequencies below 1.2 kHz, mid frequencies between 2 and 5 kHz, and high frequencies between 18 and 22 kHz. The source-receiver range covers 3, 5, 10, and 42 km. Measurement issues and environmental impact on the temporal coherence are discussed. The signal coherence time, defined by the time that the signal becomes decorrelated, is deduced from the data. The signal coherence time varies with the source-receiver range and the signal frequency and is significantly influenced by the medium fluctuations. The data can be fit with a simple power law dependence on the range, frequency, and sound speed standard deviations. [This work is supported by the U.S. Office of Naval Research.]
Estimation for velocity dispersion of normal modes in a laboratory waveguide
Authors: Zhengliang Cao , Suping Wang , Shihong Zhou
Published: October 2013

As one character of normal modes, velocity dispersion defined as velocity dependent on frequency is related to the environment of a fluid and seabed in a shallow water waveguide. It is important to inverse geo-acoustic parameters or analyze normal mode propagation in the waveguide. With waveforms measured by a line array in a laboratory waveguide, velocity dispersion of normal modes is estimated by Prony’s method. Because of the influence of the sum of many modes in a frequency, the estimated dispersions are disordered and discontinued. While a number of modes fewer than that, in fact, are previously selected, the results can be improved on velocity dispersion curves. On the other hand, clear curves can be obtained for the components of waveforms intercepted by an adaptive time window. These results are consistent with that of synthetic waveforms simulated by a normal mode program. Comparing the dispersions estimated from data in different depths, there are abundant high-order modes in this case. [Work supported by SKLF.]
High-order wave decomposition using a dual-radius spherical microphone array
Authors: Rafaely Boaz , Balmages Ilya , Eger Limor
Published: October 2013

The acoustic performance of an auditorium is influenced by the manner in which sound propagates from the stage into the seating areas. In particular, the spatial and temporal distribution of early reflections is considered important for sound perception in the auditorium. Previous studies presented measurement and analysis methods based on spherical microphone arrays and plane-wave decomposition that could provide information on the direction and time of arrival of early reflections. This paper presents recent results of room acoustics analysis based on a spherical microphone array, which employs high spherical harmonics order for improved spatial resolution, and a dual-radius spherical measurement array to avoid ill-conditioning at the null frequencies of the spherical Bessel function. Spatial-temporal analysis is performed to produce directional impulse responses, while time-windowed space-frequency analysis is employed to detect direction of arrival of individual reflections. Experimental results of sound-field analysis in a real auditorium will also be presented.
Anechoic measurements of particle-velocity probes compared to pressure gradient and pressure microphones
Authors: Woszczyk Wieslaw , Iwaki Masakazu , Sugimoto Takehiro , Ono Kazuho , de Bree Hans-Elias
Published: October 2013

Microflown probes are true figure-of-eight-pattern velocity microphones having extended response down to below the lowest audible frequencies, low noise, and high output. Unlike pressure-gradient microphones, velocity probes do not measure acoustic pressure at two points to derive a pressure gradient. When particle velocity is present, acoustical particle velocity sensors measure the temperature difference of the two closely spaced and heated platinum wire resistors, and quantify particle velocity from the temperature measurement. Microflown probes do not require a membrane and the associated mechanical vibration system. A number of anechoic measurements of velocity probes are compared to measurements of pressure-gradient and pressure microphones made under identical acoustical conditions at varying distances from a point source having a wide frequency response. Detailed measurements show specific response changes affected by the distance to the source, and focus on the importance of transducer calibration with respect to distance. Examples are given from field work using microflown probes to record acoustic response of rooms to test signals. The probe’s cosine directional selectivity can be used to change the ratio between early reflections and the diffuse sound since only the 1/3 of the power in the diffuse sound field is measured with the particle velocity probe.
Soundscape in the old town of Naples: Signs of cultural identity
Authors: Brambilla Giovanni , Maffei Luigi , De Gregorio Leda , Masullo Massimiliano
Published: October 2013

Like all cities in Magna Grecia, the ancient Neapolis was built along three main parallel, tight, and straight streets called decumani. Since then and during the following centuries, commercial and handicraft activities, as well as social life, have been developed along these streets. The narrow ground rooms forced shopkeepers to occupy the main street to show their merchandise using vocal appeals to magnify their product, and handicrafts to work directly on the street (hammering, sawing, etc.). Music artists had their performance on the streets too. The soundscape in the area was a strong symbol of the Neapolitan cultural identity. Nowadays decumani have kept the main features of the past but some of these are overrun by road traffic. To investigate in which way the traffic noise has modified the soundscape perception and cultural identity, sound walks were registered during day and night time. A number of residents were interviewed and laboratory listening tests were carried out. Despite the congested urban environment and high sound levels, preliminary results have shown that part of the residential population is still able to identify the soundscape more related to Neapolitan historical identity.