bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound speed and attenuation measurements of sandy sediments in reverberation chamber
Authors: Li Qi , Yu Qi S. , Huang Wang Y.
Published: May 2014

Sound speed and attenuation in sandy sediments are important acoustic parameters. But the uncertainties of current in-situ measurements at low-frequency are very large and the data are not sufficient to be used to test theory predictions. As an alternative, measurements in a water filled isolated reverberation chamber were attempted in laboratory, which preserves lower frequency limitation and smaller scale requirement of water tank. In order to know the feasibility of the method, a type of fine sand sediments was measured. Spatial averaged reflection and transmission coefficients of the sand layer and attenuation were calculated over the frequency range of 90–170 kHz. And sound speed was inverted with these measured parameters. After then measurements at low-frequency till to 2 kHz were tried in the same tank.
Comparison of computational predictions of broadband interior sound fields with experimental measurements
Authors: Michalis Krista A. , Bliss Donald B.
Published: May 2014

Predictions of broadband interior noise using an energy-intensity boundary element method (EIBEM) are compared to experimental measurements. Steady-state sound fields with reflection boundaries are modeled with the EIBEM method. The specular reflection field is represented using uncorrelated broadband directional sources, expressed as spherical harmonics. For each boundary element, the amplitudes of the harmonics are determined from the incident field from all other elements and sources, and are subject to energy conservation using a Lagrange multiplier integral constraint. The computational solution utilizes a relaxation method starting with 3-D diffuse reflection. Earlier EIBEM results were compared to exact analytical solutions obtained from modal analysis, and to a broadband image method. For the experimental study, 1/3-octave band measurements were made within a full-scale steel-walled enclosure with different absorption levels, distributions, and source locations. Measurements were made along three 10-microphone linear arrays spanning the enclosure, and by microphones at other selected locations. Source power was measured independently, and random incidence absorption was inferred from both reverberation times and from steady state processing using multiple microphone locations. Predicted and measured spatial variation of the steady-state fields were in good agreement. The sensitivities of the predictions to various assumptions, geometric, anomalies, and experimental uncertainties are discussed.
The position of the sound source in churches
Authors: Berardi Umberto , Martellotta Francesco
Published: May 2014

The position of the sound source is an aspect rarely considered in room acoustics because the shape of the space and its internal organization generally make clear where the sound source should be. However, this may not be the case in some buildings, such as churches. In these buildings, the source is not located in one position, but it moves from choir to the altar or the pulpit. This makes problematic the analysis of church acoustics. In particular, if the reverberation time is almost constant whenever the source may be, other acoustic parameters strongly depend on the position of the sound source. This paper focuses on the effect of the position of the sound source over the early lateral fraction and the center time. First, the results of computer simulations allow discussing the influence of some locations of the organ: above the entrance, in the middle of the room, between the altar and the worshipers, and behind the altar. Then, the values of the acoustic parameters for different sound sources are evaluated. In particular, the effect of speaking from the pulpit or from the altar are compared. Finally, suggestions to evaluate several positions of different sound sources in churches are reported.
Spectral resolution and its effects on temporal analysis in cochlear-implant perception
Authors: Oxenham Andrew J.
Published: May 2014

Sid Bacon's contributions to auditory science span a wide range of topics but two areas were constant themes throughout his career: temporal modulation perception, and peripheral processing and frequency selectivity. In this study, speech understanding in noise was measured, with a focus on the role of inherent temporal fluctuations in noise maskers. Tonal maskers, presented to cochlear-implant users, were placed at the center frequencies of each frequency channel of the implant, thereby producing the same masker energy as a noise masker in each frequency channel, but without the inherent fluctuations. In contrast to the results from normal-hearing subjects listening through a tone-excited envelope vocoder, cochlear-implant users gained no benefit from eliminating the inherent fluctuations from the maskers. Further experiments suggested that the poor spectral resolution of cochlear implants resulted in a smoothing of the temporal envelope of the noise maskers. The results indicate an important, and potentially overlooked, effect of spectral resolution on the temporal representations of speech and noise in cochlear implants. The results also suggest a new interpretation for why cochlear-implant users, and perhaps hearing-impaired listeners, generally show reduced masking release when additional temporal modulations are imposed on noise maskers. [Work supported by NIH grant R01DC012262.]
Tapered labyrinthine acoustic metamaterials for coherent controlling of acoustic wave
Authors: Xie Yangbo , Konneker Adam , Popa Bogdan-Ioan , Cummer Steven A.
Published: May 2014

Acoustic metamaterials with their exotic material properties enable unprecedented control over acoustic wave propagation and reflection. Besides utilizing locally resonating structures or non-resonant composite effective media, non-locally resonating spatial coiling structures have recently been adopted to design negative or high positive refractive index metamaterials. We have in the past experimentally demonstrated the unit cell characteristics of one kind of labyrinthine metamterial (Xie et al. PRL 2013) and its impedance matching improved versions (Xie et al. APL 2013). In this work, we present several coherent modulation devices based on our recently proposed tapered labyrinthine metamaterials. With thickness of only one or two metamaterial cell layers, we can create an acoustic blazed diffraction grating, a phase conjugation lens, or a flat lens that can perform plane wave-cylindrical wave conversion. The design process and experimental demonstrations will be presented. The coherent controlling devices feature precise phase modulation, high-energy throughput, broad operating bandwidth, and sub-wavelength thickness. Our work demonstrates that labyrinthine metamaterials can be the unit cells of choice for functional coherent acoustic modulation devices.
Ultrasonic subwavelength focusing above periodic membrane arrays in immersion
Authors: Lani Shane , Sabra Karim G. , Degertekin F. Levent
Published: May 2014

Subwavelength focusing and imaging has been a long sought after goal and one that metamaterials can possibly achieve. In 2011, Lemoult et al. used time reversal techniques to focus sound to as small as λ/25 in air by using the evanescent wave field above a gird of soda cans acting as Helmholtz resonators [Lemoult et al. Phys. Rev. Lett. 107, 064301, (2011)]. This paper will demonstrate subwavelength focusing in immersion in the 11–0 MHz frequency range with capacitive micromachined ultrasonic transducer (CMUT) arrays. CMUTs are microscale (10–100 μm wide) membrane arrays, which support evanescent surface waves that derive their dispersive properties not only from the periodic structure of the array, but also from the membrane resonance. Furthermore, CMUTs have embedded electrodes for electrostatic excitation and detection of acoustic waves which allow implementation of time reversal techniques to focus the dispersive evanescent surface waves using only the CMUTs on the same substrate as sources and receivers. Using a finite boundary element method simulation, we demonstrate subwavelength focusing at points in the near-field above a 2D CMUT array in immersion.
Error analysis and modifications to the short-time speech transmission index
Authors: Payton Karen , Ferreira Matthew
Published: May 2014

The Speech Transmission Index (STI) predicts the intelligibility of speech degraded by noise and reverberation. Recently, Payton and Shrestha [J. Acoust. Soc. Am. 134, 3818–3827 (2013)] reported on a short-time speech-based STI (ssSTI) to predict time-varying intelligibility of speech using analysis windows shorter than 1 s. While the ssSTI generally tracked a theoretical STI calculated using octave-band signal-to-noise ratios, it deviated from the theoretical calculation for windows shorter than 0.3 s. The current work analyzes and improves the performance of the ssSTI for speech degraded by stationary speech-shaped noise. Using a cluster analysis, the time-varying standard deviation was determined to be inversely proportional to window length, octave band and speech envelope variance. Two ssSTI modifications are proposed to reduce the 0.3 s window limitation: A silence detection algorithm eliminates non-zero ssSTI values that occur during silence and a modified envelope extraction scheme reduces the standard deviation by increasing envelope bandwidth. Using the 0.3 s window as a performance benchmark, new octave-band specific window limitations, ranging from 151 ms to 21 ms, were established. The modified ssSTI also works with common octave-band window lengths as short as 30 ms when full envelope bandwidths are used in combination with the silence detector.
Effects of linguistic structure on perceptual attention given to different speech units
Authors: Kang Shinae , Johnson Keith
Published: May 2014

Listeners can shift their attention to different sizes of speech during speech perception. This study extends this claim and investigates if linguistic structure affects this attention. Since English has a larger syllable inventory than Korean and Japanese, each phoneme plays a larger functional role. Also, listeners have different levels of phonological awareness due to the differences in the orthography. We focus on the effect of perceptual attention on the perceptibility of intervocalic consonant clusters (VCCV) and whether it varies cross-linguistically by these structural factors. We first recorded eight talkers saying VC- and CV-syllables and spliced the syllables to create non-overlapping VC.CV-stimuli. Listeners in three language groups (English/Korean/Japanese) participated in a 9-Alternative-Forced-Choice perception task. They identified the CC as one of 9 alternatives (“pt”, “pk”, “pp”, etc.) and in an attention-manipulated condition did the same task while also monitoring for target talkers. The preliminary result shows that Korean listeners showed less perceptual sensitivity to clusters than English listeners. Also, the English listeners showed better perception of syllable coda when prompted to focus on coda only. The result indicates that the linguistic structure of a language can potentially affect the level of perceptual attention that its users give to a linguistic unit.
Perception of dialectal prosody in Taiwan Mandarin
Authors: Chen Mao-Hsu
Published: May 2014

This pilot study aims at answering whether prosodic cues alone can account for the differences among three regional dialects in Taiwan Mandarin, Northern, Central, and Southern, which all belong to Mandarin Chinese. Assumed that prosodic cues alone can be used for distinguishing among different Taiwan Mandarin dialects, a perception experiment was conducted. The Northern dialect was best recognized while the identification rates of the Central and the Southern dialects were slightly below chance level. Results showed the tendency that it was easier for listener to identify his or her own dialect than it was to detect other regional dialects. Gender effect was observed to play a role in the recognition of the three dialects, which led to the following-up production experiment intended for exploring the acoustic differences among these three dialects. Preliminary results examined the descriptive tonal patterns of all four lexical tones in three Taiwan Mandarin dialects. The tonal registers produced by the Northern dialect speakers were more prominent than those of the Central and the Southern dialects in that they had the highest normalized F0 values for T1 tokens and greater pitch range, or steepest slope, for the other three contour tones, compatible with the result of the perception experiment.
The perception of postvocalic English stops in diphthongs and monophthongs using gating experiment
Authors: Lerdpaisalwong Siriporn
Published: May 2014

There have been many studies on the acoustic cues in the preceding vowels for the perception of the final consonants (Hillenbrand et al., 1983; Warren and Marslen-Wilson, 1988). Yet, none of the studies has been conducted to see whether there are any differences in listener perception of a final consonant in areas of diphthongs versus monophthongs. Since the average duration of diphthongs /eɪ/ and /oʊ/ is longer than that of monophthongs /i/ and /u/ (Hillenbrand et al., 1995), this study investigates whether a listener perceives postvocalic English stops /p, t, k/ in monophthongs /i/ and /u/ faster than in diphthongs /eɪ/ and /oʊ/ using the gating paradigm. Fifteen American English speakers participated in this study (6F, 9M; 18–44 y.). The stimuli consist of 24 CVC words and noncewords with final /p, t, k/. Vowels of 24 words were chopped into ten gates each. The results show that the listeners perceived the final stops at about the same gates (areas) in both diphthongs and monophthongs in both word types. The results also show no significant difference among the perception of three stops, except between /p/and /k/ in the real words with monophthongs.
Discriminability and perceptual saliency of acoustic cues for final consonant voicing in simulations of cochlear-implant and electric-acoustic stimulation
Authors: Kong Ying-Yee , Mullangi Ala , Winn Matthew , Donaldson Gail
Published: May 2014

Multiple redundant acoustic cues can contribute to the perception of a single class of speech sounds. This study investigates the effect of spectral degradation on the discriminability and perceptual saliency of acoustic cues for phonetic identification of word-final fricative voicing in “loss” versus “laws,” and possible changes that occur when low-frequency acoustic cues are restored. Three acoustic cues that contribute to the word-final /s/-/z/ contrast (first formant frequency [F1] offset, vowel-consonant duration ratio, and consonant voicing duration) were systematically varied in modified natural speech syllables. The first experiment measured listeners' ability to discriminate differences among stimuli within a single cue dimension. The second experiment examined the extent to which listeners make use of a given cue to label a syllable as “loss” versus “laws” when multiple cues are available. Normal-hearing listeners were presented with stimuli that were either unprocessed, processed with 8-channel noise-band vocoder to approximate CI spectral degradation, or low-pass (LP) filtered to simulate low-frequency residual hearing. They were tested in four listening conditions: unprocessed, vocoder alone, LP alone, and vocoder + LP where low-frequency fine-structure cues could enhance F1 perception and voicing cues. The impact of listening condition on discriminability and weighting of different acoustic cues will be discussed.
Sentence intelligibility during segmental interruption and masking by speech-modulated noise
Authors: Fogerty Daniel , Ahlstrom Jayne B. , Bologna William J. , Dubno Judy R.
Published: May 2014

Amplitude modulation from a competing talker can interfere with a listener's ability to process informative speech cues. The current study investigated how noise modulated by the wideband temporal envelope of a single competing talker impacts the contribution of consonants and vowels to the intelligibility of the target sentence. High variability speech materials were used, including talkers from different dialect regions. Young normal-hearing, older normal-hearing, and older hearing-impaired listeners completed speech recognition tests. All listeners received spectrally shaped speech matched to their individual audiometric thresholds to ensure sufficient audibility. Preliminary results demonstrated similar performance among the listener groups. When the modulated masker was interrupted, performance in consonant and vowel conditions was similar. However, sentence intelligibility in continuous single-talker-modulated noise was higher when vowels in the target sentence were preserved, as compared to consonants. Thus, masker continuity may facilitate source segregation for vowels more than for consonants. A second experiment that varied masker modulation rate for younger adults with normal hearing showed that modulation rate had more effect on processing cues conveyed by consonants than by vowels. Implications for hearing-impaired and older adults will be discussed. [Work supported by grants from NIH/NIDCD and ASHA.]
The relationship between fluency, intelligibility, and acceptability of non-native spoken English
Authors: Lin Mengxi , Francis Alexander L.
Published: May 2014

Non-native accented speech is typically less intelligible and less fluent than native speech, but it is unclear how these factors interact to influence perceived speech quality. To investigate this question, the speech of 20 non-native speakers of English varying in proficiency and native language was evaluated. Subjective measures of speech quality (listening effort, acceptability, and intelligibility) were compared to objective measures of word recognition by native listeners, and to acoustic measures of fluency and of segmental and suprasegmental properties related to intelligibility. Results showed that subjective quality measures were highly related to one another and to word recognition and were most strongly predicted by measures of fluency. Segmental and suprasegmental measures did not predict word recognition or subjective speech quality. There was also an interaction between the effects of proficiency and speaker's native language on word recognition, but this did not extend to subjective measures. Finally, listeners who first heard high-proficiency speakers gave overall lower subjective quality ratings but there was no interaction between proficiency and presentation order. Multivariate analyses suggest that factors related to speaking rate, including pause duration, have the greatest effect on measures of acceptability, intelligibility, and listening effort. [Work supported by Purdue Linguistics and Purdue Research Foundation.]
Sizing down the competition: Speaking style and word recognition
Authors: Van Engen Kristin
Published: May 2014

Identifying words with many phonological neighbors is more challenging for older adults than for younger adults. This difference has been attributed to reductions in inhibitory control associated with aging, which impair older adults' ability to cope with competition from similar-sounding words (Sommers and Danielson, 1999). Many difficulties in speech identification can be alleviated, however, when speech is produced clearly (i.e., the style adopted naturally by speakers when they perceive that their interlocutors are having difficulty understanding them). The current study investigates whether the acoustic-phonetic enhancements of clear speech can also reduce the inhibitory challenge of word recognition. If so, it is predicted that listeners will receive a greater benefit from clear speech when identifying lexically difficult words (i.e., words with many neighbors) vs. lexically easy words (i.e., words with fewer neighbors). Younger and older adults performed a word-recognition task in noise. Results to date show that the clear speech benefit is indeed greater for lexically difficult words than for lexically easy words for both groups of listeners. This pattern of results suggests that clear speech reduces the inhibitory demands associated with word recognition by increasing the perceptual difference between phonological neighbors.
What explains perceptual weighting strategies of children with CIs: Auditory sensitivity or language experience?
Authors: Nittrouer Susan , Caldwell-Tarr Amanda , Lowenstein Joanna H.
Published: May 2014

Cochlear implants (CIs) have tremendously improved speech perception for deaf children, but problems remain. To examine why, this study compared weighting strategies of children with CIs and children with normal hearing (NH), and asked if these strategies are explained solely by the degraded spectral representations they receive through their implants, or if diminished opportunity to hear the ambient language accounts for some of the effect, as well. One hundred 8-year-olds (49 with NH and 51 with CIs) were tested on four measures: (1) labeling of a final-voicing contrast with one duration and one formant-transition cue; (2) labeling of a fricative-place contrast with one stable spectral and one formant-transition cue; (3) duration discrimination; and (4) glide discrimination. Children with NH and CIs weighted the duration cue similarly, suggesting children with CIs have sufficient experience to acquire language-appropriate strategies when cues are salient. Differences in weighting of spectral cues (both stable and time-varying) were found, but were not entirely explained by auditory sensitivity. The conclusion was that more salient cues facilitate stronger weighting, but individuals differ in how salient cues need to be to capture perceptual attention. Stimulus familiarity (speech or non-speech) affects how reliably children attend to acoustic cues, as well.
A listener-based account for dispersion effects in sound change
Authors: Denby Thomas , McGuire Grant , Padgett Jaye
Published: May 2014

Phonetic dispersion has been proposed as the driving force behind a number of closely related sound-change phenomena. Listener-based accounts of dispersion (Labov, 1994, 587; Wedel, 2006; Denby, 2013) posit that phonetically unambiguous productions influence future productions of the listener more than ambiguous productions. The mechanism that drives this is a filter by which ambiguous productions are not stored, and thus do not update the phonemic categories of the listener. In turn, they are not reflected in that listener's future productions. In a new experiment, subjects heard words in noise and were asked to identify them by responding using a keyboard, following Goldinger (1996). Stimuli were from monosyllabic stop-initial minimal pairs differing in initial voicing, e.g., pat/bat. Half of these pairs were unambiguous productions, while the stop-initial VOT of the other half were manipulated to be somewhat ambiguous. If subjects store ambiguous words normally, their accuracy should improve with every exposure. If however, they do not store ambiguous productions, their accuracy should improve less than it does for unambiguous productions. Using d' scores, a repeated-measures ANOVA confirmed differences in improvement for unambiguous and ambiguous conditions were significant. A follow-up study is being implemented to test and expand these results.
Bill Carey and Bob Urick
Authors: Bradley David
Published: May 2014

Principles of Underwater Sound, written by Robert J. Urick, and last published in 1983, has been a staple on everyone's bookshelf. Bill Carey took on the job of updating that book, with the premise of not changing what was written, but simply updating each chapter with new information obtained over the succeeding three decades. One of the primary reasons the text was so popular is its ease in reading and grasping the import of the data and simplified ideas presented and their respective use(s) in the sonar equation. Work continues with Bill's firm imprint on the next edition, which is the focus of this discussion.
Environmental factors in shallow water active sonar design
Authors: Cable Peter
Published: May 2014

In 1991, when William Carey was at DARPA, he initiated an effort under the Adverse Environments Program to both establish and define the limits of low frequency active sonar performance in shallow water and littoral regions, and to demonstrate a system concept that could achieve limiting performance. In support of that objective sea tests were conducted in the West Florida Shelf (Gulf of Mexico), Northeast U.S. Continental Shelf and Korea Strait (Area Characterization Tests I, II, and III), each in ~100m deep water with sand-silt bottoms under downward refracting sound conditions. The design, conduct and subsequent analyses of those tests, including consideration of broadband sound transmission (100 Hz–1 kHz), signal dispersion and coherence, reverberation, bottom scattering strength, and clutter, will be traced with particular emphasis on Bill's leadership role in the endeavor. The key results of the program were sufficiently robust to guide the design of tactically significant shallow water active sonar, which they ultimately did.
From Wood to Carey to Mallock: A review of Bill Carey's work associated with the Mallock-Wood equation and the acoustics of bubbly liquids and gas-bearing sediments
Authors: Wilson Preston S. , Dolder Craig N. , Roy Ronald A. , Pierce Allan D.
Published: May 2014

One of Bill Carey's many scientific interests throughout his career was the acoustics of bubbly liquids. Many underwater acousticians know of Carey's work associated with bubble clouds and more recently, gas-bearing sediments, but Bill got his start with the subject earlier in his career, studying flow in a boiling water reactor while employed at Argonne National Laboratory. Here, the acoustic velocity of bubbly liquid is of interest because of the possibility of supersonic flow, at comparatively low flow rates, in the high-void-fraction mixture within the reactor's piping system. In this talk, an overview of Bill's work with the acoustics of bubbly liquids will be presented, including scattering from bubble clouds, and sound propagation within bubbly liquid and gas-bearing sediments. Finally, Bill's campaign to rename a famous equation (Wood's Equation) in honor of its forgotten originator (Mallock) will be reviewed. [Work supported by ONR.]
The development and analysis of a large variable acoustics space
Authors: Bliefnick Jay , Hulva Andrew , Cheenne Dominique
Published: May 2014

A new, large-scale variable acoustics space has recently been added to the Audio Arts & Acoustics department at Columbia College Chicago. Built within the current Motion Capture studio, this facility will provide students and faculty the ability to perform tests in an acoustically controlled environment, without the influence of small-room effects. The construction involved the creation of nearly 300 2 in. x 2 in. reversible boxes: one side diffusive and the other absorptive. These line three full walls of the space at a height of 10 in., totaling ~1200 ft2 of acoustically adjustable surface area. This allows the room to convert from a very absorptive space, to one that is much more acoustically active. Multiple specular reflector panels are also available for the creation of “hot spots,” allowing for even more diverse applications. This study focused on the construction and initial testing of this innovative new space. To analyze the effectiveness of the additions, frequency, time, and reverberation responses for the entire room were sampled in a variety of configurations: fully absorptive, fully diffusive, empty, etc. These objective metrics were then analyzed against perceptual data to determine the correlation between what could be measured and what could be heard.
Vocal diversity and taxonomy of white-cheeked crested gibbons
Authors: Ruppell Julia
Published: May 2014

Previous research suggests that gibbon song repertoire is genetically determined and song characteristics are useful for assessing systematic relationships. The taxonomy and distribution of crested gibbons (genus Nomascus) had not been studied previously. In addition, crested gibbons face several threats to extinction such as habitat loss, the pet trade, the domestic and international trade of wildlife, and unsustainable harvest of wildlife for subsistence consumption. Additionally, rice field expansion and poaching pose significant threats to gibbons and their habitats, especially because most populations are very small. I studied vocal diversity among different wild populations of Nomascus in Vietnam and Laos to assess their taxonomic relationships and to examine whether their vocal patterns correspond to forms previously described. Linear discriminant analysis, classification trees, and multidimensional scaling revealed distinct populations based on song characteristics and species (or subspecies) boundary locations were recognized. In addition, population sizes in different areas were estimated based on vocal analysis. The recognition of previously unknown diversity within Nomascus and ability to locate potential species boundaries aided in implementation and adaptation of gibbon conservation strategies and the development of gibbon management plans for protected areas. In addition, this project improved the monitoring of a poorly known and understudied ape, by working with provincial staff and local people.
Behavioral and phylogenetic differentiation in a potential cryptic species complex, the canyon treefrog
Authors: Klymus Katy , Gerhardt Carl , Humfeld Sarah
Published: May 2014

Detection of genetic and behavioral diversity within morphologically similar species has led to the discovery of cryptic species complexes. We tested the hypothesis that the canyon treefrog (Hyla arenicolor) may consist of cryptic species by examining mate-attraction signals among highly divergent lineages defined by mitochondrial DNA (mtDNA). Unexpectedly, calls exhibited little variation among the three U.S. lineages despite large mtDNA sequence divergences. We re-analyzed intraspecific and interspecific phylogenetic relationships by sequencing both mitochondrial and nuclear genetic markers among populations and a closely related, but morphologically and behaviorally different species, the Arizona treefrog (H. wrightorum). Discordance between mitochondrial and nuclear datasets suggests multiple instances of introgression of H. wrightorum's mitochondrial genome into populations of H. arenicolor. Furthermore, intraspecific population structure based on nuclear markers shows better congruence with patterns of call variation than population structure based on the mitochondrial dataset. Although the U.S. lineages do not appear to represent cryptic species, Mexican lineages do show biologically relevant call differences as assessed through female preference tests. Our results suggest that call variation can indicate genetic structure of populations; however, a multilocus approach should be used in defining genetic structure, as using only mtDNA may lead to erroneous conclusions.
Western and central North Atlantic fin whale (Balaenoptera physalus) stock structure assessed using geographic song variations
Authors: Delarue Julien , Dziak Robert , Mellinger David , Lawson Jack , Moors-Murphy Hilary , Simard Yvan , Stafford Kathleen
Published: May 2014

Variations in calls or songs between areas are increasingly acknowledged as a way to assess stock structure. We present the results of an analysis of 163 fin whale (FW) songs recorded in seven areas of the North Atlantic (NA): Irminger Sea, Davis Strait, Grand Banks of Newfoundland, Southern Newfoundland, Gulf of St. Lawrence, eastern Scotian Shelf, and the waters off Delaware Bay. Song measurements included inter-note intervals (INI), notes' peak frequency and bandwidth and note type (classic, backbeat, and high-frequency) proportion. Seasonal patterns of classic-classic INI provided the highest level of differentiation between areas and revealed the existence of six acoustic stocks. Classification trees revealed that other parameters distinguished between regions over larger spatial scales, grouping some of the recording areas together. These results suggest that (1) there are four distinct stocks in the western NA; (2) the range of a presumed central NA stock includes southwestern Iceland, both sides of Greenland and appears to extend south along the Mid-Atlantic Ridge, at least in recent years; (3) two stocks are present off West Greenland. These results bring new information on potential FW stock delineations in the NA. The latter will be compared to those derived using other stock assessment metrics.
Do spectral features of Risso's dolphin echolocation clicks vary geographically?
Authors: Soldevilla Melissa , Garrison Lance , Baumann-Pickering Simone , Cholewiak Danielle , Van Parijs Sofie , Hodge Lynne , Read Andrew , Oleson Erin , Rankin Shannon
Published: May 2014

The ability to classify odontocetes to species and population from acoustic recordings leads to improvements in stock identification, abundance and density estimation, and habitat-based density modeling, which are crucial for conservation and management. Risso's dolphins off Southern California have distinctive peaks and valleys in their echolocation clicks, which allow researchers to easily distinguish them from other species in passive acoustic recordings. However, Risso's dolphin echolocation clicks from other geographic areas have not been described and it remains unknown whether they have similarly distinctive click spectra and whether stocks are acoustically distinct. We investigate the potential for using acoustics to identify populations by quantifying the acoustic structure of Risso's dolphin echolocation clicks recorded over wide-ranging geographic regions including the U.S. waters of the North Atlantic Ocean (north and south of Cape Hatteras), Gulf of Mexico, and North Pacific Ocean (Eastern Tropical Pacific and Southern California). Several distinctive peak and valley patterns are found and we evaluate these in light of variability within individuals, groups, and regions as these acoustic differences may indicate differences in age, sex, or stock composition, foraging behavior, or ambient noise environment of the dolphin schools.
Small-scale soundscapes over coral reef ecosystems: Latitudinal variation in the Northwestern Hawaiian Islands
Authors: Freeman Simon E. , Freeman Lauren A. , Lammers Marc O. , Buckingham Michael J.
Published: May 2014

Two-dimensional seafloor “maps” of near-field ambient sound produced by biological sources in a coral reef environment were obtained from four spur-and-groove shallow water reef environments along a latitudinal gradient in the Papahanaumokuakea Marine National Monument, Northwestern Hawaiian Islands. Acoustic data were collected in conjunction with SCUBA based ecological surveys in an effort to establish correlation between components of the acoustic field and the ecological state of each field site. Simultaneous acoustic measurements and remote underwater photographs taken during the day and at night allowed for comparisons of biological activity with recordings over time. Using a bottom-mounted L-shaped array of hydrophones, the spatial distribution, frequency, and temporal characteristics of sounds produced by small-scale biological processes were estimated within a 40 m by 40 m region around the array. A fast cross-correlation guidance technique lessened the computational burden imposed by conventional and white noise constrained adaptive focusing (curved-wavefront beamforming). Likely sources of biological sound and variation of the acoustic field within and between the sample sites will be discussed. The variation of sound field properties over latitude and correlation with ecological information obtained at each site may be useful in underwater biological surveys that utilize passive acoustic recording.
Statistical properties of random arrays
Authors: Au Jenny , Thompson Charles , Mudasiru Ololade
Published: May 2014

In this work, the statistical properties of the randomly placed linear arrays is considered. The performance of random, random-bin and nearest-neighbor constraint placement of transducer elements is considered. Transducer placement locations drawn from the transducer density function satisfying the van der Maas objective function is of particular interest. It is shown that the variance in the response of the sidelobe region decays asymptotically as 1/N, where N is the number of transducers.
An experimental and computational study of beam-steering of parametric array
Authors: Been Kyunghun , Je Yub , Moon Wonkyu
Published: May 2014

A parametric array is a nonlinear conversion process that can generate a highly directional sound beam with a small aperture. It is expected that electrical beam steering of directional sound beams generated by the parametric array may be useful in many applications such as ultrasonic raging sensors or directional loudspeakers in air. One of the major issues of beam steering of the parametric array is to precisely predict the steered difference frequency wave field in the medium. In this study, beam steering of the parametric array is computed by using a time-domain numerical code that solves the Khokhlov-Zabolotskaya-Kuznetsov equation. Since it is impossible to compute the exact difference wave field due to a complex primary source distribution in the medium, a simplified numerical model is proposed. The computed result is compared with the experimental result. For experimental study, 16-channel piezoelectric micromachined ultrasonic transducer array, which consists of two resonant type unit drivers to generate bi-frequency primary waves (f1 = 100 kHz and f2 = 140 kHz), was designed, fabricated, and tested. The beam patterns of the primary and difference frequency waves were measured and compared with the computed result while applying complex weighting to each channel. [Work supported by ADD (UD130007DD).]
A piezoelectric micro-cantilever acoustic vector sensor
Authors: Moon Wonkyu , Yang Sungkwan , Cheeyoung Joh , Kim Kyungsub
Published: May 2014

An acoustic vector sensor measures the direction of wave propagation as well as the acoustic pressure. We investigate feasibility of using a piezoelectric micro-cantilever (PEMC) as an acoustic vector sensor in water at the frequencies range below 500 Hz. In order to measure the propagation direction, we try to devise the properties of a PEMC so that its deflection is proportional to the particle velocity due to acoustic waves. We found that the desired property can be obtained with PEMC if it is designed to be flexible enough. Under the assumption that the PEMC affects little on the wave propagation, we have developed a simple lumped parameter model to predict the relationship between the acoustic pressure of a progressive wave and the deflection of PEMC. The developed model shows that the deflection of PEMC is dependent on the magnitude and direction of the incoming progressive wave. In addition, the frequency of the wave is also found to affect the responses of PEMC. Based on the developed simple lumped parameter model, a PEMC acoustic vector sensor was designed with PEMC of 400 μm long 200 μm wide 5.25 μm thick for operating around 200 Hz. The designed PEMC acoustic vector sensor was fabricated by micro-machining and packaged inside cater-oil-filled rubber housing so that it can be tested in the water. The expected dependence of the fabricated PEMC on the direction and acoustic pressure can be observed in the experiments at the target frequency range.
The influence of the shallot shape on the sound of Trompete reed pipes
Authors: Angster Judit , Dolde Kai , Peter Rucz , Miklos Andras
Published: May 2014

The focus of investigations was the influence of certain shallot parameters on the sound of reed pipes. Since the dimensioning of organ pipes is mainly based on the experience of organ builders at present, the aim is to provide scientific data for organ builders explaining the influence of various shallot parameters on the sound. Due to this knowledge, it would be possible to realize the desired ideas of sound of organ pipes by targeted adjustment of these parameters during the dimensioning of the pipes. The investigated Trompete shallots differ in the termination angle of the shallot. To analyze the parameter of the shallot termination, angle measurements were carried out at a simple shallot model, which provide findings on the dependence of the reflection properties on various termination angles. The results show that the findings due to the model comply with the analyses of the sound spectra of the Trompete shallot.
Effect of generators and resonators on musical timbre in coupled systems
Authors: Braasch Jonas
Published: May 2014

The majority of Organ pipes are typical tone-generator/resonator systems, where the tone is either produced by an air jet or reed. My previous work on free reeds in pipe organs has raised my interest in how different sound generators affect timbre in terms of spectral balance and attack phase. Most recently, I have started to explore different tone generators with the soprano saxophone using custom adapters, including a brass mouthpiece from a cornetto, a bassoon reed and a free reed from the Chinese Bawu. Since the resonator remains the same, the role of the sound generator can be easily determined using a fast Fourier transformation and onset analysis of partial tones. With the brass mouthpiece, the soprano saxophone becomes an outward striking mechanism instead of a reed-based, inward striking mechanism. As a consequence, the instrument vibrates above the natural frequency of the conical resonator, and the B-flat instrument becomes a B instrument. It is important not to underestimate the range of the embouchure. In the case of the cornetto mouthpiece, it took some practice to attain the higher harmonics. Naturally, the spectrum with the cornetto mouthpiece is very similar to that of a regular soprano saxophone. [Work supported by NSF #1002851.]
Sound production in the reed organ and harmonium
Authors: Cottingham James P.
Published: May 2014

The free reed instruments of European origin, which originated around 1800 and were developed over the next 50–75 years, include the reed organ and the harmonium. These keyboard instruments enjoyed a period of great popularity beginning around 1840 and lasting until the early 20th century. They were widely used in homes and churches, and appeared in a variety of instrumental ensembles, including the salon orchestra. They are close relatives of the harmonica and the accordion-concertina family, but unlike these instruments they are not in wide use today. This paper discusses the fundamental mechanisms of sound production in the instruments as well as means used to alter the tone quality, which include the design of the wind system, effects of the chambers in which the reeds are mounted, and details of the reed tongue design. The presentation will include audio examples of the reed organ and the harmonium employed in various musical contexts.
Bach with sampled sounds
Authors: Hansen Uwe J. , Pickering Norman C.
Published: May 2014

A number of years ago Norman used a digital recorder to record sound samples from a Casavant organ with two manuals plus pedals, with a total of 13 stops in 16 ranks of 882 pipes. He did this by recording all pipes for every other key. He included the initial transient for each sample. Additional organ stops were synthesized from multiple oscillators of various waveforms, based on FFT analysis of actual organ stops. All these sounds were mapped onto the appropriate keys of two synthesizer keyboards. Using these sampled sounds, Norman recorded nearly the entire Bach Orgelbuechlein and several other major works including six Schuebler Chorales, a concerto, BWV 594, and a Prelude and Fugue, BWV 552. We will listen to a brief excerpt from “Wachet auf” to hear the effect of the initial transients. A portion of the Prelude of BWV 552 will give an impression of the full organ.
Noise control for an impact pile driver in an urban environment
Authors: Lilly Jerry G.
Published: May 2014

Soil conditions at a construction site for a new seven-story office building in downtown Seattle, Washington, dictated the use of an impact pile driver to set 50 to 60-ft long concrete piles into the ground, many less than 200 ft from existing offices. Exterior and interior noise measurements revealed that the pile driving activity exceeded the city's noise ordinance. A portable acoustic shield was designed, constructed, and implemented to reduce noise levels below the legal limits. Measured sound levels before and after will be presented along with details and photos of the shield in action.
Preparation, execution, and documentation of construction site visits
Authors: Shade Neil T.
Published: May 2014

Construction site visits, referred to as “work observation” by the American Institute of Architects, are a critical factor in project delivery. The unique nature of acoustic detailing requires visual and sometimes field testing to verify correct installation of products and construction assemblies. Preparation for site visits begins during the Construction Documents design phase. A list of site inspections, keyed to project milestones, should be issued to the Contractor at the start of the Construction Administration phase. Site visit objectives should be planned and the Contractor notified prior to arriving on site. When on site it is necessary to conduct inspections in a methodical manner, document potential deviations from design intent, and debrief the Contractor. Checklists can improve efficiency and avoid overlooking key objectives. Work observation reports become part of the project record and are important for tracking corrective measures by the Contractor. Acoustic measurements may be part of inspections to check quality of work or determine compliance with Specifications. Well-planned and executed site visits contribute to project success and boost our profession's esteem with the building construction industry.
Direct and flanking airborne sound transmission for hotel guestrooms; results and comments regarding three field tests
Authors: Borzym Jim X.
Published: May 2014

A “four-and-a-half star” hotel was constructed within an existing historic structure. Among the design/build team there were differences of opinion of what was needed for peace and privacy for hotel guests. Hotel guidelines suggested a moderately high airborne sound transmission class rating for the primary wall partition. Three field tests were conducted during an early phase of construction. A strong flanking transmission path in a corridor wall assembly was discovered during the first test. An error in preparation for this test caused an important opportunity for valuable field test data development to be lost regarding a flanking path via a common ceiling, which points to the kinds of difficulties encountered in conducting field tests. The second test showed improvement in results due to rectification of the corridor wall flanking path. The third test gave information about flanking transmission via the common floor. Comments will be made regarding field testing and flanking sound transmission.
Harnessing geometric and material nonlinearities to design tunable phononic crystals
Authors: Bertoldi Katia , Wang Pai , Shan Sicong , Babaee Sahab
Published: May 2014

We investigate numerically and experimentally the effects of geometric and material nonlinearities introduced by deformation on the linear dynamic response of two-dimensional phononic crystals. Our results not only show that deformation can be effectively used to tune the band gaps and the directionality of the propagating waves, but also reveal how geometric and material nonlinearities contribute to the tunable response of phononic crystals. Our study provides a better understanding of the tunable response of phononic crystals and opens avenues for the design of systems with optimized properties and enhanced tunability.