bluuebunny/crossref_metadata_2025 huggingface dataset:
Japanese language learners’ production of short/long vowel and single/geminate consonant contrasts: A longitudinal development.
Authors: Hirata Yukari , McNally Ian C.
Published: March 2010

This longitudinal study examined the development of native English speakers’ production ability to distinguish between single/geminate consonant and short/long vowel pairs in Japanese over 4 months abroad in Japan. Seven participants, who had formal Japanese language classes for 2 years in the US, recorded rika(a) and ka(k)ko pairs in a carrier sentence three times each, at three speaking rates, before and after the study abroad (pre-/post-Japan). Seven measures, including the duration of contrasting segments, words, and sentences, were taken and various ratios were also calculated. Of the native Japanese speaker criteria used to evaluate participants’ data, the vowel-to-word and closure-to-word duration ratios of 0.38 and 0.35 were used as boundary ratios between short and long segments [Hirata (2004); Hirata and Whiton (2005)]. Using these criteria, participants’ data were classified at 66% accuracy at pre-Japan but improved to 85% at post-Japan for vowel distinction. In contrast, they improved from 73% to 74% accuracy for consonant distinction. Analyses of other durational measures also supported that participants made significant improvements in vowel distinction, but not in consonant distinction. These results support the claims of Toda (1997) and Han (1992) and extend to include intermediate language learners into their respective studies.
Utilization of the pressure gradient along a sparse vertical line array to determine vertical arrival angle from partial reflections from a layered seabed.
Authors: Dall'Osto David R. , Dahl Peter H.
Published: March 2010

Pressure signals measured by two four-element vertical line arrays, centered at depths 25 and 50 m, during an experiment off the New Jersey coast in Summer 2006 (SW06, depth 80 m) are combined to determine the pressure gradient of the received signal. The pressure gradient is converted to an estimate of vertical particle velocity, which combined with an estimate of the mean-squared pressure, and the plane wave impedance establishes a non-dimensional quantity. This quantity is inverted to determine arrival angle estimates from separate multipath arrivals of the transmitted signals (1 kHz). A geoacoustic model for the seabed [Choi et al., J. Acoust. Soc. Am. 124 EL128–EL134 (2008)] includes a prominent sub-bottom reflector at depth 20 m below water sediment interface, which produces an energetic arrival time separated from the bottom arrival. The arrival angle estimates are examined as the source moves out in range from 50 to 300 m, and results are compared to arrival angle estimates derived from PE simulations. The performance of this gradient-based estimator is evaluated for various types of noise sources and levels, utilizing both real and PE-simulated time series. [Work supported by ONR.]
Three dimensional sound source localization and sound mapping using a p-u sensor array.
Authors: Wind Jelmer
Published: March 2010

An acoustic sensor array, which consists of pressure and particle velocity sensors, is an attractive alternative to phased pressure array because knowledge of the three dimensional (3-D) particle velocity directly characterizes the direction of the source. Hence, it is possible to localize sources in the low-frequency range, where the phase difference between pressure sensors is small, and in the high-frequency range, where aliasing occurs with pressure sensors. This article applies advanced source localization techniques from aeroacoustics to acoustic vector sensors. Several methods are simulated and tested with several configurations and validated using measurement data from an anechoic chamber. The setup to test the algorithms consists of 24 sources that are distributed in 3-D around the set ups in the anechoic chamber. The sources are uncorrelated driven with white noise. Conventional beamforming methods have been compared with acoustic vector based deconvolution methods and MUSIC algorithms. Four configurations are tested: (1) a planar array of sound pressure microphones, (2) a planar array of pu probes (pu probes are collocated sound pressure and particle velocity probes); the velocity probes where the velocity probes are oriented in randomly, (3) a velocity gradient array, (4) a quad array of three dimensional velocity probes plus collocated sound pressure. The different methods and algorithms
Similarities in the echolocation beam pattern of vespertilionid bats.
Authors: Jakobsen Lasse , Surlykke Annemarie
Published: March 2010

Echolocating bats can navigate and fourage by sound, emitting short high-frequency sound pulses and listening to echoes reflected from obstacles and prey. Small insectivorous bats typically emit higher frequencies than larger bats. This correlation has been explained as an acoustic constraint by prey size since small bats feed on small prey and small objects only reflect echoes efficiently at short wavelengths, i.e., high frequencies. However, very small bats use higher frequencies than what is needed for effective reflection from their prey. Thus, we propose an alternative or supplementary hypothesis: Small bats emit high frequencies to obtain highly directional biosonar sound beams. Directionality increases with the size of the sound emitter relative to the wavelength. Hence small bats can counteract the decrease in directionality caused by their small size by increasing their emitted frequency. Echolocation calls were recorded from five species of echolocating bats of different sizes flying in the laboratory using a multimicrophone array and their beam pattern was calculated. The results show high similarity in beam patterns across species, indicating that directionality is indeed a constraint on echolocation frequency. [Funded by the Oticon Foundation.]
Echolocation in a fresh water lake.
Authors: vonMuggenthaler Elizabeth , Gregory Joseph , Mardis Scott H.
Published: March 2010

Lake Champlain is host to myriad interesting geological peculiarities, including the oldest Middle Ordovician reef bed in the world containing coral. Autogenic succession suggests animals adapt to modifications in climate. Eleven thousand year old Beluga whale skeletons have been found in Vermont and Beluga whales currently survive in the St. Lawrence Seaway. In 2003, 2005 and 2009 sites on Lake Champlain were explored using computers with National Instruments Polynesia real-time sound analysis, NI PCMCIA 6062-E cards, DAT recorders, GPS, amplifiers, three vector sensors, two hydrophones, and a Nagra IV-S5. ECHO Aquarium in Vermont facilitated recording of known lake inhabitants and non-biological signals studied formed the basis for the control. Neither recordings nor literature indicate that the known native creatures echolocate. Combining wavelet applications, aiding in reduction in ambient noise in this opposing environment along with conventional analysis, the experiments have been able to conduct far reaching, low-noise sound measurements and were capable of detecting signals the nature of which suggests the presence of some interesting and unexpected phenomena within the ranges and inherent structure of Beluga whale, killer whale, and dolphin echolocation. To protect Lake Champlain, further investigations into this acoustic anomaly is encouraged. [Work supported by the Radius Foundation.]
Aerial audiograms of Steller and California sea lions measured using auditory steady-state response methods.
Authors: Mulsow Jason , Reichmuth Colleen , Gulland Frances , Rosen David A. S. , Finneran James J.
Published: March 2010

Detection of aerial vocal signals by conspecifics is important in the reproductive behavior of the otariid pinnipeds. However, aerial hearing sensitivity measurements have only been obtained for a few otariid individuals that were trained to participate in behavioral experiments. In order to expand upon this small data set, auditory steady-state response (ASSR) methods were used to examine the aerial hearing sensitivity of Steller and California sea lions. Although ASSR thresholds were elevated relative to behavioral thresholds reported for otariids, the ASSR audiograms of the majority of individuals were similar to each other and to behavioral audiograms in terms of relative sensitivity. A marked reduction in sensitivity with increasing frequency regularly occurred between 16 and 32 kHz, indicating a consistent high-frequency cutoff. The reliability of the ASSR audiograms for both species suggests that behavioral aerial audiograms that exist for a few Steller and California sea lion individuals can be appropriately extrapolated to larger populations. The similarity of the ASSR audiograms among the Steller and California sea lions supports the notion that the otariid pinnipeds form a functional hearing group, with similar aerial hearing in terms of sensitivity and frequency range of hearing. [Work supported by ONR and NOAA Ocean Acoustics Program.]
Distance perception by non-territorial zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus).
Authors: Radziwon Kelly E. , Dent Micheal L.
Published: March 2010

Birds use long-range acoustic signals to defend territories, attract mates, and locate conspecifics. However, long-range acoustic signals progressively degrade during their transmission from the signaler to the receiver. This degradation makes perceiving these signals more difficult, but receivers can use such information to estimate the signaler’s distance. The perception of auditory distance cues (overall amplitude, frequency-dependent attenuation, and reverberation) has typically been studied in the field with territorial birds. The present study examined auditory distance perception in a non-territorial songbird, the zebra finch, and in a non-songbird, the budgerigar in a controlled laboratory setting. Three zebra finches and three budgerigars were trained to identify 1-m (undegraded) and 75-m (degraded) recordings of three budgerigar contact calls, one male zebra finch song, and one female zebra finch call. Test stimuli were then introduced on 20% of the total number of trials. These stimuli were created manually by manipulating the naturally recorded 1-m calls. By editing these calls, we could manipulate each distance cue separately to determine which cue was the most salient for the birds. Our results suggest that amplitude was the most important cue for these birds, similar to humans and other animals.
Phase synchronization and collective instability in oscillating bubble clouds.
Authors: Sinden D. , Stride E. , Saffari N.
Published: March 2010

The effect of bubble interactions within a bubble cloud under ultrasonic forcing is investigated. Under certain conditions, phase synchronization is found, revealing parameter regimes where the dynamics of the bubble system are primarily determined by the interactions of the bubbles, rather than the applied ultrasonic acoustic field. Due to the Bjerknes interaction, the stability thresholds for critical pressure and size leading to unpredictable oscillations for bubble clouds are lower than the stability thresholds for single bubbles. Interestingly, numerical simulations confirm that in the regimes where bubbles exhibit chaotic oscillations, the dynamics are determined by a complicated geometric object called a low-dimensional strange attractor which is qualitatively the same as that for the chaotic oscillations of a single bubble. Thus an averaged equation may also be low-dimensional. The effects of synchronization on Landau damping are discussed. The effect of delays between the interactions is also investigated. The implications for applications in high-intensity focused ultrasound, harmonic imaging, and targeted drug delivery will be discussed.
The banjo: Developing a plausible model from first principles.
Authors: Dickey Joe
Published: March 2010

The banjo is one of the few musical instruments which is amenable to analytical modeling. It is fundamentally two connected canonical wave bearing systems, and as such, it can be solved. Furthermore, the requisite computer code runs quickly, making it practical to examine the instrument’s response as functions of a variety of parameters. The parameters are the things banjo players tweek in their attempt to get the sound they want; things like head tension, bridge mass, and string gauge. This tutorial will start with first principles in both the physics and the mathematics and end with movies of the calculated head response and radiated sound as functions of time and frequency. Numerical models can never be exact. Real systems, and particularly musical instruments, are just too complex for this, but models can provide useful guidance by illuminating what might happen as parameters are changed.
Effects of building mechanical system noise on worker performance and perception.
Authors: Wang Lily M.
Published: March 2010

This paper presents results from a number of studies that investigated the effects of noise from building mechanical systems on human task performance and perception. Three phases of research were conducted, each of which utilized a different set of noise signals produced by building mechanical systems: (1) broad-band noise at different levels and spectral qualities, (2) tonal noise conditions, and (3) noise conditions with time-varying fluctuations. In each phase, six different noise signals (many based on in-situ measurements) were reproduced in an office-like setting. Thirty participants completed tasks (e.g., typing, grammatical reasoning, and math) plus subjective questionnaires, while exposed to each noise condition for up to 1 h. In general, no statistically significant differences were found in task performance across the various noise signals tested. However, higher annoyance/distraction responses from the test subjects were often significantly correlated with reduced typing performance. These higher annoyance/distraction responses were also closely correlated to higher subjective ratings of loudness, followed by roar, rumble, and tones or fluctuations. Of particular interest is that a greater perception of low-frequency rumble was significantly linked to reduced performance on both the routine and cognitively demanding tasks. [Work supported by the American Society of Heating, Refrigeration and Air-Conditioning Engineers.]
A control suite to reduce roof bolting machine drilling noise.
Authors: Lowe M. Jenae , Peterson J. Shawn , Alcorn Lynn , Yantek David
Published: March 2010

Among underground coal miners, hearing loss remains one of the most common occupational illnesses. In response, the National Institute for Occupational Safety and Health (NIOSH) conducts research to reduce the noise emission of various underground coal mining equipment, an example of which is a roof bolting machine. Field studies support the premise that, on average, drilling noise is the loudest noise that a roof bolting machine operator would be exposed to and contributes significantly to the operators’ noise exposure. NIOSH has determined that the drill steel radiates a significant amount of noise during drilling. NIOSH in collaboration with Corry Rubber Corporation has developed a suite of controls to reduce drilling noise which consists of a bit isolator, chuck isolator, and a Collabsible Drill Steel Enclosure. This control suite effectively reduces the noise radiated by the drill steel. Laboratory testing confirms that the control suite reduces sound pressure levels generated during drilling by 13 dB(A) at the operator’s location. As a result of this reduction in drilling noise, the noise exposure of the roof bolting machine operator is reduced.
Evaluation of stiffeners for reducing noise from horizontal vibrating screens.
Authors: Yantek David , Catlin Shawn
Published: March 2010

Sound levels around vibrating screens in coal preparation plants often exceed 90 dB(A). The National Institute for Occupational Safety and Health (NIOSH) is developing noise controls to reduce noise generated by horizontal vibrating screens. NIOSH determined the vibration mechanism housings and the screen body to be the dominant noise sources on a horizontal vibrating screen. Researchers used beamforming, experimental modal analysis, and operating deflection shape analysis to examine noise radiated by the screen body. Based on these results, finite element analysis and a NIOSH-written program were used to estimate the sound power level reduction resulting from adding rib stiffeners to key locations on the screen sides. Rib stiffeners made from two sizes of steel channel and two different cross-sections, C and T, were evaluated. In addition, the effects of orienting the stiffeners horizontally and vertically were examined. Finally, the stiffeners were evaluated with the ends welded to the existing ribs on the screen sides and with the ends free. The results indicate that for a broadband input, the smaller T cross-section oriented vertically with the ends welded to the existing ribs was the best option. This configuration reduced the predicted A-weighted sound power level by 7 dB.
Deep dynamic compaction vibrations impacts on neighboring structures.
Authors: Yazdanniyaz Amir , Bui Sen
Published: March 2010

This paper describes results from vibration study conducted for a construction of proposed building structures on a covered landfill site. Construction site is surrounded by various land uses, including mobile homes, single dwelling units, and infrastructures. Deep dynamic compaction (DDC) method is utilized to provide soil compactions necessary for the construction of the buildings and parking lot foundations. Concern with the potential structural damage and the human perceptions of the ground vibration exist because of close proximity of the existing structures (i.e., mobile homes, single homes, roadways, and bridges) to the compaction area. DDC induced ground-vibrations level were modeled using actual vibration measurements “pilot tests” and the site’s soil dynamic characteristics. Vibration mitigation plan were developed to minimize the impacts.
Modeling ground response functions in rock: A comparison of multiple methods.
Authors: Glickman Gary , Carman Richard
Published: March 2010

Rail transit operations often produce groundborne vibration with energy that extends into the audible frequency range. It is often necessary to predict potential ground/structure-borne vibration and noise transmission in the design of new buildings in close proximity to existing rail lines or for new rail facilities/alignments. In a detailed analysis, key factors include source vibration characteristics (spectral force input to soil and/or track structure), ground vibration propagation characteristics (spreading and material damping losses), building foundation type (soil/structure interaction and coupling losses), and structural design of upper floors (floor and wall resonances and attenuation through the building). This paper focuses on methods for obtaining vibration propagation characteristics in rock which is an efficient transmitter of vibration at audible frequencies. Three methods for obtaining one-third octave band response functions are compared: empirical methods, finite element analysis, and seismic modeling.
Hearing loss mitigation through applied acoustics.
Authors: Yankaskas Kurt
Published: March 2010

Hearing loss in the Navy and Marine Corps has been accelerating for decades, reducing combat effectiveness and creating hazardous conditions. This paper will discuss applied acoustics in current and future programs and its related challenges. Source noise reduction limits the amount of energy transmitted to the structure or into the environment. Acoustic modeling, insulation/isolation, and personal hearing protection are vital tools in this process, but often adding weight and complexity. Source noise solutions such as isotropic superfinishing treatment of gears increases transmitted power and reduces fuel consumption and lubricant temperatures while increasing gear life and maintenance intervals. Great strides are also currently being made in the arena of personal hearing protection to reduce hearing loss rates in environments where reducing source noise is not a viable option, such as the aircraft carrier flight deck. Technological advances in insulation and isolation and possible operational changes will also be discussed, adding to the tools required to approach this issue from an integrated systems approach. In conclusion, a systems integration approach to incorporating noise reduction into the design of vessels, vehicles, and platforms from the start of the design process will reduce life cycle costs, benefiting the Navy and Marine Corps.
Experiments on the directivity of sound emission from firearms.
Authors: Huseby Morten , Fykse Haakon
Published: March 2010

Personnel firing weapons will be exposed to noise created by the expanding gunpowder gas escaping from the muzzle. The noise from a rifle is directive, up to 20 dB louder in the shooting direction than behind the weapon. Usually personnel firing a weapon is taking advantage of the lower noise level behind the weapon. However, today firearms will be used by soldiers in complex scenarios where the head of one soldier might be directly to the side or even slightly in front of the muzzle of another soldier’s weapon. Most countries training regulations have not been updated to include all effects of the directivity of firearms in complex scenarios. Unexpected results were obtained from previous measurements on weapons with flash suppressors attached to the end of the barrel. The noise may be considerably larger in front of the weapon with flash suppressor fitted. The angular resolution of previous experimental data was not high enough to provide an explanation. This motivated us to design an experimental setup where the pressure wave from the weapon is measured, at 80 cm from the muzzle, in 180 directions relative to the firing direction. The measurements are done with and without a flash suppressor mounted.
Need for standardization of psychoacoustics.
Authors: Genuit Klaus
Published: March 2010

In the last decades, psychoacoustic parameters gained more and more importance in the context of sound perception and assessment in various applications. In particular, loudness was introduced as a better parameter than A-weighted level, because it shows a much better correspondence with the subjective impression of “volume” (loudness). This parameter was the object of standardization in the last years and few loudness standards were established (DIN 45631/A1, ISO 532, ANSI S3.4). The calculation of sharpness is also standardized (DIN 45692) and the standardization of roughness is recently under consideration by the DIN. These efforts have led to a global acceptance and a widespread use of psychoacoustic parameters in the automotive and IT-field. However, since the human signal processing is complex and the development of valid calculation models difficult, psychoacoustic phenomena must further be studied. Moreover, the validity, accuracy, and applicability of psychoacoustic parameters to specific noises must be determined. Especially, in the context of the description and classification of environmental noise, the potential of psychoacoustics has not been fully used so far. This paper will show the current status of standardization of psychoacoustics and will discuss the needs for the future.
Sonic boom research in NASA’s supersonic fundamental aeronautics project.
Authors: Coen Peter G.
Published: March 2010

The Supersonics Project of NASA’s Fundamental Aeronautics Program is a broad based effort designed to address the technical challenges associated with flight in the supersonic speed regime. One of the key environmental challenges that must be overcome for successful commercial supersonic flight is sonic boom. The NASA Supersonics Project has chosen this challenge as a focus for its research activity over the next several years. In cooperation with the FAA and the ICAO Committee on Aviation Environmental Protection (CAEP) NASA has initiated the development of a roadmap for research into the community response to sonic booms with noise levels significantly less than those of the Concorde and current supersonic aircraft. The purpose of the roadmap is to define the key research that should be accomplished in order to provide a firm technical basis for future noise-based standards for sonic boom acceptability. This presentation will discuss the elements of this roadmap and outline some of the recent research contributions made by the NASA Supersonics Project.
Damping in auxetic materials and structures.
Authors: Scarpa Fabrizio
Published: March 2010

Negative Poisson’s ratio (NPR) (otherwise called auxetics) materials and structures feature enhanced energy absorption under cyclic loading both at low- and high-frequency excitations. We show in this paper experimental and simulation results related to open cell PU-PE foams, honeycombs, and composites, all exhibiting a negative Poisson’s ratio value. The open cell auxetic foams provide a significant damping capacity at low frequency and high preload as well as under broadband excitation compared to the conventional foams from which they are derived. We show also that the acoustic absorption properties of the auxetic foams are significantly enhanced compared to conventional PU-PE under 500 Hz, and their loss factor increased using their specific shape memory property. We describe also the vibration damping properties of NPR honeycombs with different unit cell topologies and the damping capacity of NPR carbon fiber composites under flexural cyclic loading.
Damping mechanism concepts in ocean wave energy conversion: A simplified model of the Pelamis converter.
Authors: Thiam Amadou G. , Pierce Allan D.
Published: March 2010

The conversion of mechanical energy to another energy form is often built into a structural acoustics model by adding some damping mechanism to the model. Also, in ocean wave energy conversion, one damping mechanism, which is occasionally of great importance in the determination of the limiting upper efficiency of a device, is the re-radiation of wave energy back into the ocean. Present paper focuses on a simplified model of the Pelamis wave energy converter, with the model consisting of a modified Euler–Bernoulli beam oriented head-on to incoming ocean waves and with energy conversion accounted for by a damping term, where the additional bending moment is proportional to the time derivative of the beam curvature. The wave energy converted is ideally equal to the energy dissipated by this term. The beam is taken as having circular cross-section with a mass density that is one-half that of water. An incident wave causes a transverse force along the bottom of the beam so that it heaves up and down in a snake-like fashion, and this heaving causes ocean waves to be re-radiated back into the ocean, causing an additional apparent damping. Consideration is limited to a linear analysis and to a deep-water ocean.
Acoustic changes in the vocal signals of grasshopper sparrows, Ammodramus savannarum, during early development.
Authors: Lohr Bernard , Laudick Lacey
Published: March 2010

Grasshopper sparrows produce unusually high-pitched vocalizations for birds, with fundamental frequencies of species typical songs in the range of 7–9 kHz. The characteristics of vocalizations produced early in life, however, are relatively understudied in this and related species. In this study, the development of vocal signal structure and vocal behavior in grasshopper sparrows was investigated in the field immediately after birds hatched. Acoustic characteristics of nestling begging calls were measured throughout the course of the 8–9-day nestling period. Starting at day 6 post-hatch, nestling calls changed qualitatively, incorporating frequency-modulated elements that resembled some parts of the adult vocalizations. With increased nestling age, there was also an increase in the average duration, average acoustic frequency (pitch), and average amplitude of nestling calls. Overall, our results showed that the complexity of nestling vocal signals increased during early development, with vocalizations exhibiting some adult-like properties by the end of the nestling period.
Speech intelligibility of air conducted and bone conducted speech over radio transmission.
Authors: Tran Phuong , Letowski Thomas
Published: March 2010

Personal radio-communication devices are traditionally used with built-in or external air conduction microphones. Recently, there have been some efforts to use bone conduction microphones mounted on the operator’s head as a replacement for external air microphones. The goal of this study was to compare the intelligibility of speech transmitted through a boom-type noise-cancelling air microphone and a bone microphone using Thales multiband inter-intra-team radios. Eight participants were divided into four pairs with each participant serving as both a talker and a listener. The Callsign Acquisition Test was used to collect speech intelligibility data with the talker in quiet and in 100 dB(A) noise. The listener was always located in a quiet environment. Both types of microphones resulted in speech intelligibility scores ranging from 100% to 94% in quiet and from 100% to 90% in noise condition. There was no statistically significant difference in speech intelligibility between the two types of microphones. The advantages and disadvantages of using bone microphones under various civilian and military conditions are discussed.
Relationships between the modified rhyme test and objective metrics of speech intelligibility.
Authors: Yu Gongqiang , Brammer Anthony J. , Swan Kara , Tufts Jennifer B. , Cherniack Martin G. , Peterson Donald R.
Published: March 2010

Relationships between the modified rhyme test (MRT) and the speech transmission index (STI), and MRT and the speech intelligibility index (SII), have been obtained for additive stationary noise and nonlinear distortion of the speech signal. The former was speech-spectrum shaped noise, white noise, or −3-dB/octave noise presented at speech signal-to-noise ratios ranging from −25 to +10 dB. The speech distortions were peak clipping or center clipping, with clipping thresholds from 2% to 98% of the cumulative magnitude histogram. Subjects (4 male, 4 female) with normal hearing were seated in an anechoic chamber. Speech was reproduced by a small, high-fidelity loudspeaker located 2.4 m to the center-of-head and the inter-aural axis. Noise was reproduced by four-loudspeaker systems and processed to simulate a diffuse field at the ear in the horizontal plane. The revised STI was computed using the standardized test signal [IEC 60268-16 (2003)] and the speech signal. The SII was calculated using coherence to estimate the effects of distortion. Results will be discussed in terms of the ability of each objective metric to predict intelligibility and adjustments to the metrics to improve performance. [Work supported by NIOSH Grant R01OH008669.]
The perceptual organization of noise-vocoded speech under competitive conditions.
Authors: Roberts Brian , Summers Robert J. , Bailey Peter J.
Published: March 2010

Research using sine-wave speech suggests that across-formant grouping depends critically on modulation of the frequency but not the amplitude contours of the formants. The generality of this finding was explored using noise-vocoded sentences. Sentences were filtered into six frequency bands, and the amplitude envelope of each band was used to modulate a matched noise-band carrier (N). Bands were paired, corresponding to F1 (=N1+N2), F2 (=N3+N4), and the higher formants (F3′=N5+N6), so that the frequency contour of a formant was implied by variation in the relative amplitudes of the corresponding pair of bands. Perceptual organization was probed by presenting stimuli dichotically (F1+F2C; F2+F3′), where F2C is a competitor for F2 that listeners must resist to optimize intelligibility. F2Cs were derived from F2 by time reversing the envelopes of N3+N4. Implied frequency variation in F2C was manipulated by varying the AM depth in the constituent bands (100%-0% of original depth) or by comodulating both bands with the same envelope (from N3, N4, or N3+N4). Competitor efficacy declined with AM depth. Comodulated competitors were less efficacious than their 100% modulated counterpart. The findings are consistent with the proposal that it is the time-varying frequency contours of formants that govern their grouping. [Work supported by EPSRC.]
Word perception, intelligibility, and simultaneous task performance.
Authors: Srinivasan Nirmal Kumar , Carrell Thomas D.
Published: March 2010

The relationship between speech intelligibility and simultaneous task performance was investigated in the present experiments. Specifically, the following indicators were measured: intelligibility, reaction time for word repetition, visual-motor performance, cognitive load, and visual word recall. These relationships were measured using natural, synthetic, and cell phone speech. It is clear from other reports that different patterns of results may be expected from different types of speech signals [Pisoni et al. (1985)]. Intelligibility was based on participant’s accuracy in repeating the final word of a sentence. Visual-motor performance was measured as the average speed of rotation in adaptive pursuit rotor task [Srinivasan and Carrell (2007)]. Task load was measured using the NASA-TLX instrument [Hart and Staveland (1988)]. TLX was highly correlated with the simultaneous pursuit rotor task in the cell phone listening condition (r = 0.41, p < 0.0001). However, the pursuit rotor measure consistently demonstrated much lower variability than the TLX score. Perception was also measured in two attention conditions, consistent-mapping and variable-mapping [Schneider and Schiffrin (1977)]. In the consistent-mapping condition, cell-phone speech led to better performance at the pursuit rotor task than natural speech, whereas in the variable-mapping condition, the natural speech led to better performance.
Production of sibilant fricatives by children with cochlear implants.
Authors: Todd Ann E. , Edwards Jan R. , Litovsky Ruth Y. , Li Fangfang
Published: March 2010

Children who use cochlear implants (CIs) are likely to show differences in speech production relative to children with normal hearing (NH) due to the suboptimal auditory input provided by CIs. The present study compared word-initial /s/ and /S/ produced by children with bilateral CIs and two comparison groups of children with NH (children matched for hearing age and children matched for chronological age). The first spectral moment (i.e., centroid), a measure which describes the mean frequency differences in the spectra of sibilant fricatives, was calculated at the midpoint of the fricative noise for /s/ and /S/. Results showed that the children with CIs produced less differentiation between /s/ and /S/, had lower centroid frequencies for /s/, and less variability for /s/ than both groups of children with NH. These results may be explained by the perceptual limitations of CIs; /s/ is a sound produced with more energy at higher frequencies, and CIs provide poor frequency resolution for higher frequencies. Currently the amount of coarticulation in productions of /s/ and /S/ with the following vowel is being examined to determine whether the groups show a difference. [Work supported by NIH Grant Nos. R01DC008365 to R.Y.L. and R01DC02932 to J.R.E.]
Shallow water channel tracking using gradient-based mixed norm optimization techniques.
Authors: Sen Gupta Ananya , Preisig James
Published: March 2010

The underwater acoustic channel is challenging to estimate and track due to channel dynamism, the ill-conditioned nature of the estimation problem, as well as the need to optimize over a complex field. An extension of previous work is presented where the sparse channel coefficients in the delay and delay-Doppler spread domains are estimated using mixed norm convex optimization. The estimation algorithm is extended to track the time-varying channel using a gradient descent approach, trading off optimality for tracking efficiency. A computationally inexpensive approximation of the dynamic gradient is used rather than re-computing the precise gradient every time. Results presented are based on field data collected over 15-m depth and a range of wave heights and distances using the normalized prediction error as the performance metric. Comparison of performance between tracking the delay-only and delay-Doppler coefficients is presented for different weightings on the mixed norm between L1 and L2 measures and over different lags. Performance and computational efficiency of the proposed tracking algorithm are compared to conventional sparse estimation techniques. [Work supported in part by ONR Grants N00014-05-10085 and N00014-07-10184 and in part by Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by the Doherty Foundation.]
Convex hull method of acoustic field interpolation.
Authors: La Cour Brian R.
Published: March 2010

Empirical knowledge of the local acoustic field typically comes in the form of time samples at discrete points in space corresponding to the locations of, say, omnidirectional microphones or hydrophones on an underwater array. To determine the acoustic field at an arbitrary point in space requires either propagation modeling, signal interpolation, or some combination of the two. In this paper, a method of field interpolation is presented which estimates the acoustic field at any point within the convex hull of all sample points. This method is compared against more traditional inverse beamforming methods using both simulated and measured data.
Compressive sensing in underwater acoustics.
Authors: Edelmann Geoffrey F. , Gaumond Charles F.
Published: March 2010

The performance of compressive sensing for determining frequency tonals is shown for several cases. The sampling requirements for infinite signal-to-noise ratio (SNR) is shown first. A detection threshold is developed for the case of additive noise with known noise level. The number of samples needed per tonal is shown as a function of SNR. The effects of temporal variability in the form of fading due to motion through an oceanic waveguide is discussed. [Work supported by the Office of Naval Research.]
Compressive matched field processing.
Authors: Maetzel William , Romberg Justin , Sabra Karim G. , Kuperman William
Published: March 2010

Sound source localization in shallow water environment is commonly done using matched field processing (MFP). MFP is usually implemented by systematically placing a test point source at each point of a search grid, computing the acoustic field (replicas) at all the elements of the array and then correlating this modeled field with the data from the real point source whose localization is unknown to determine the best-fit location. However, a direct implementation of MFP (i.e., brute force search) over a large grid space—or search area—is computationally demanding especially in the presence of complex propagation environments. We formulated instead the localization problem of a few acoustic sources as the sparse approximation of the measured signals in a specific dictionary of atoms obtained from discretization of this sparse search space. Spatial random projections are performed to efficiently span the search space. This compressive MFP approach allows for significant computation time savings with a computational cost increasing with the number of random projections instead of the number of search grid points. The performance of this approach will be illustrated using numerical and experimental data in a shallow water waveguide.
How musical instruments make sounds: An exploration of standing waves and resonance frequencies.
Authors: Neilsen Tracianne B.
Published: March 2010

A basic understanding of the production of sound waves can be obtained by studying standing waves and resonance frequencies. A vibrating string will settle into a steady, standing wave pattern when it is driven at one of its resonance frequencies. The resonance frequencies depend on the string length and the tension applied to the string. Similarly the resonance frequencies of tubes are determined by the tube length and whether the ends are open or closed. In a series of hands-on demos, we will explore the factors that influence the creation of standing waves by exciting the resonances of strings, tubes, rods, a metal plate, slinky, and a wine glass. These simple models provide insight into how musical instruments produce sound.
Chlandi pattern demonstration.
Authors: Isakson Marcia J.
Published: March 2010

Chlandi patterns will be demonstrated using sand on a plate and an air acoustic source. As the source frequency is changed, different nodal patterns will become evident on the plate. In this manner, the different vibrational modes of the plate can be qualitatively determined.
Fourier synthesis.
Authors: Nagao Kyoko
Published: March 2010

When two or more simple sound waves that differ in frequency and amplitude are added together, a complex wave is generated. This is called Fourier synthesis, named after a French mathematician Joseph Fourier. Many sounds we hear every day are complex waves. For example, the sound wave produced by the vowel “ah” is a complex wave. By combining simple waves with appropriate values, we can generate speech with a computer. In this experiment, you will synthesize a complex sound wave by adding two or more pure tones using a computer program. The ultimate goal here is to create a complex tone that sounds like the vowel ah. You will learn important acoustic components used in speech sounds.
Phonation: Mickey Mouse and Darth Vader.
Authors: Bent Tessa
Published: March 2010

During voicing, the vocal folds are brought together and then caused to vibrate by air being pushed out of the lungs. In order to illustrate several phenomena regarding phonation, three demonstrations will be provided. First, an experiment with balloons will demonstrate how people can change the pitch of their voice by stretching their vocal folds. Second, the aerodynamic forces involved in phonation will be demonstrated with the use of soda cans and a straw. Last, high-speed videos of the vocal folds in action will be shown.
Seelos Theater: A case study for a renovated multipurpose room with multiple loudspeaker systems.
Authors: Moore Matthew J. , Bagnall Alexander G. , Farbo Aaron M.
Published: March 2010

The Seelos Theater at Holy Cross College has been renovated twice since starting out as a bowling alley in the main student center on campus. This most recent renovation provided an opportunity for the school and design team to update and modernize this heavily used lecture hall and cinema. The authors will show how two different loudspeaker systems and AV systems were integrated with the architectural acoustics design built for reproduced sound. The authors found that the resultant performance of the systems performed better than was expected in computer modeling. Existing mechanical system noise mitigation, integration of existing film equipment, short construction timelines, and serving the needs of different audience types will be discussed. The authors used lessons learned with this project to help with the design of spaces for future projects.
Mixing studio isolation.
Authors: Hoover Anthony K.
Published: March 2010

A new suite of mixing and teaching studios had been discussed for many years at Berkley College of Music in Boston. The authorization to proceed with design and construction of the studios finally came with a new Dean of the Music Technologies Department, who, without benefit of much of the background and previous discussions, contacted an old colleague for the final studio design, and then contracted with a reputable full-service contractor for construction services. Some unusual problems developed during construction, which sensitized the client to subsequent situations, in turn requiring acoustical consulting services. This paper will review some of the project history, outline the problems, and discuss solutions and recommendations, and will address some of the concerns with the specialized construction and unusual complications.
Obtaining a frequency independent reverberation time in listening rooms.
Authors: Adelman-Larsen Niels Werner , Jeong Cheol-Ho , Liu Jiazi
Published: March 2010

High-frequency sound emitted from loudspeakers is very directive and can be easily aimed at the listeners. Investigations show that even a few people decrease the mid-/high-frequency reverberation time of a room significantly both due to actual absorption but also due to the scattering of the sound that they introduce which makes the placement of absorptive material important. People absorb approximately one-sixth of the sound at low frequencies than at high frequencies, but still much reproduced music contains very loud levels of bass frequency sound. In order to avoid loud, reverberant bass sounds masking the direct mid-/high-frequent sound, the room needs to be designed with quite large amounts of bass absorption in order to properly serve its purpose. Helmholtz and porous type absorbers need a large cavity in order to also achieve bass absorptive qualities and this is a challenge in many smaller rooms. Membrane absorbers require less space and due to the omni-directional behavior of bass sound their placement is not so critical. This paper will present new measurements of absorption coefficients of standing persons as well as a new type of modular bass absorber system: 2.6 in. deep, absorption coefficient of 0.6 from 50–125 Hz, and designed to readily incorporate into the architectural design.
The Festival Hill concert hall.
Authors: Boner Richard , Harght Pamela
Published: March 2010

The Festival Institute at Round Top, TX, was established in 1971, and began with ten pianists performing on an open stage, under the stars. Following the dream of the founder, Concert Pianist James Dick, Festival Hill has grown to be a premier summer venue for classical music, with over 30 concerts performed each June and July. The August-to-April Series, the International Guitar Festival, the Theatre Forum, The Poetry Forum, and the Herbal Forum bring the total number of year-round events to more than 50. This paper focuses on the excellent and visually unique 1000 seat concert hall, which was built in stages over a 26-year period from 1981–2007. Also discussed are the renovated 19th-century homes which have been moved to Festival Hill, serving as housing and practice spaces for musicians.
Whispering arches as intimate soundscapes.
Authors: Everbach E. Carr , Lubman David
Published: March 2010

Whispering archways are whispering galleries. They are sometimes found around smooth arches, doorways, and even bridges. Persons positioned on opposite sides of a whispering arch communicate privately by whispering into the arch. In that way they function as private and even intimate soundscapes. Some whispering arches that have stood for centuries have inspired local folk legends. Such acoustical architecture can help to establish a sense of place and strengthen emotional ties. It is said that a whispering arch at the entrance to a 10th c. Gothic cathedral at the historic monastic site of Clonmacnoise in the Irish midlands figured in local courtship for centuries. There, shy young lovers are said to have uttered vows of love and proposals of marriage. The arch was also used by lepers to give confession without infecting the priest. Whispering arches were almost certainly unintended in the past but can also be created intentionally as an intimate form of public art. Recent measurements on a whispering archway at West Chester University show that high background noise levels from traffic or air handlers can ruin an otherwise intimate space; however, so modern architects should plan the entire soundscape carefully.