bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of spatially correlated acoustic–tactile information on judgments of auditory circular direction
Authors: Cohen Annabel J. , Lamothe M. J. Reina , Toms Ian D. , Fleming Richard A. G.
Published: October 2013

Cohen, Lamothe, Fleming, MacIsaac, and Lamoureux [J. Acoust. Soc. Am. 109, 2460 (2001)] reported that proximity governed circular direction judgments (clockwise/counterclockwise) of two successive tones emanating from all pairs of 12 speakers located at 30-degree intervals around a listeners’ head (cranium). Many listeners appeared to experience systematic front–back confusion. Diametrically opposed locations (180-degrees—theoretically ambiguous direction) produced a direction bias pattern resembling Deutsch’s tritone paradox [Deutsch, Kuyper, and Fisher, Music Percept. 5, 7992 (1987)]. In Experiment 1 of the present study, the circular direction task was conducted in the tactile domain using 12 circumcranial points of vibration. For all 5 participants, proximity governed direction (without front–back confusion) and a simple clockwise bias was shown for 180-degree pairs. Experiment 2 tested 9 new participants in one unimodal auditory condition and two bimodal auditory–tactile conditions (spatially-correlated/spatially-uncorrelated). Correlated auditory–tactile information eliminated front–back confusion for 8 participants and replaced the ‘‘paradoxical’’ bias for 180-degree pairs with the clockwise bias. Thus, spatially correlated audio–tactile location information improves the veridical representation of 360-degree acoustic space, and modality-specific principles are implicated by the unique circular direction bias patterns for 180-degree pairs in the separate auditory and tactile modalities. [Work supported by NSERC.]
Trajectory perception in the free field
Authors: Miele Joshua A. , Hafter Ervin R.
Published: October 2013

Using virtual sound sources in an echo-attenuated chamber, the sensitivity of subjects to the direction of linear auditory motion was evaluated. Four sighted and four blind subjects participated. Subjects reported the perceived trajectory by orienting a freely rotating pointer. Subjects fell into two distinct categories: those who performed well at the task, and those who did not, with blind subjects tending to be in the first category and sighted subjects the second. Those subjects performing well at the task also showed improved performance with increasing linear velocity. Because the only stimulus parameter associated with increased linear velocity was frequency envelope, it can be concluded that frequency changes resulting from the Doppler effect can improve the accuracy of auditory trajectory perception. The same subjects performed discrimination tasks measuring sensitivity to changes in azimuthal acceleration, as well as to changes in amplitude and frequency envelopes. Two models of trajectory perception are considered: A Psychoacoustical Parameters Model uses a weighted combination of specific perceptual abilities such as sensitivity to azimuthal acceleration, and to changes in amplitude and frequency envelopes. An Informational Masking Model is considered as a possible explanation for those subjects demonstrating poor performance in the trajectory perception task.
On the perceptual and behavioral significance of saccular acoustic sensitivity
Authors: Todd Neil P. M.
Published: October 2013

Evidence accumulated over the last few decades supports the case that the sacculus has conserved an acoustic sensitivity throughout vertebrate phylogeny [N. P. Todd, J. Acoust. Soc. Am. 110, 380–390 (2001)]. In humans saccular acoustic sensitivity may be demonstrated by means of myogenic vestibular evoked potentials (MVEP) but the question remains whether saccular acoustic sensitivity in humans has any perceptual or behavioral significance. It has been shown that MVEP have the following properties: (1) MVEP can be obtained to natural acoustic stimuli above about 90 dB SPL; (2) MVEP have a frequency tuning property with a best frequency between 300 Hz–350 Hz; (3) MVEP exhibit adaptation, characteristic or normal sensory processing; and (4) there is a change of the quality of sensation above the MVEP threshold, indicative that saccular acoustic sensitivity may play a role in the perception of loud sound. In this paper new evidence is discussed which indicates that both myogenic and neurogenic vestibular evoked potentials (NVEP), particularly those obtainable from prefrontal cortex, may be linked to subjective and behavioral responses to loud sound. These responses may in turn be related to individual differences in the functioning of the mesolimbic dopamine system, including prefrontal cortex.
Filter asymmetry for short-duration signals as a function of signal delay from masker onset
Authors: Pimentel Veronica , Strickland Elizabeth A.
Published: October 2013

In a previous study, filter shapes were measured for short-duration tones at the onset or in the center of a longer-duration, notched-noise masker. The filter shapes sharpened with signal delay, with the amount of sharpening depending on the level of the signal. The pattern of results was interpreted in terms of a model incorporating published physiological data on nonlinear basilar-membrane input–output functions. The results suggested that these functions might become more linear as the signal is delayed from masker onset. The present study extends this approach to asymmetric notches. This was motivated by previous research suggesting that frequencies above the signal frequency might produce more of a temporal effect than those below the signal frequency, and by physiological data showing that basilar-membrane input–output functions differ for tones above and below the characteristic frequency. The signal was a 10-ms, 4-kHz sinusoid, fixed at levels from 40 to 70 dB SPL, and presented at the onset or in the center of a notched-noise masker. Notches were placed symmetrically or asymmetrically about the signal. The results will be discussed in terms of basilar-membrane input–output functions.
Cut-back frozen noise characterization of auditory sensory memory
Authors: Boemio Anthony , Poeppel David
Published: October 2013

Frozen noise stimuli were comprised of repeated concatenated segments of random noise, with the segment duration determining the periodicity or stimulus onset asynchrony (SOA). Seven conditions were constructed with SOAs ranging from 100–1000 ms. For each of the seven conditions, a fraction of the repeated segments were ‘‘cut-back’’ with nonrepeated noise. Subjects were presented with either a frozen noise stimulus or a nonrepeated noise stimulus of equal duration, and told to indicate if they detected periodicity. The thresholds for this two-alternative forced-choice infrapitch periodicity detection task were obtained by an adaptive tracking procedure. The results show that classification performance varies linearly with SOA over the entire 100–1000 ms. range. When normalized by SOA, it becomes evident that detection is characterized by a signal-to-noise ratio (SNR) where the repeated noise is the signal and the nonrepeated noise, the noise. The SNR for all seven conditions was approximately 0.7. It is proposed that cut-back frozen noise stimuli may be used to establish the upper storage limit of auditory sensory memory by extending this technique to SOAs greater than 1000 ms and looking for deviation from linearity in the plot of repeated noise segment vs SOA. [Work supported by NIDCD Grant No. DC 0463801.]
Perception of duration of ramped and damped sounds with exponential and raised cosine ramps
Authors: Grassi Massimo , Darwin Christopher J.
Published: October 2013

In the first experiment listeners were asked to adjust the duration of a steady-level sound in order to match the duration of 250-, 500-, 750-, or 1000-ms targets. Targets could be either steady in level, increasing in level with either a raised-cosine or an exponential ramp (ramped sounds), or the ramped sounds reversed in time (damped sounds). The results extended to longer durations than those reported by Schlauch et al. [J. Acoust. Soc. Am. 109, 2880–2887 (2001)]: damped sounds were matched as much shorter (∼35% for exponential ramps, ∼30% for raised-cosine ramps) and ramped sounds as slightly shorter (∼10%) than steady-level sounds. In the second experiment, the subjective duration of all targets used in the first experiment was measured as the difference between reaction times to their onsets and their offsets. Although delays in reaction times to onsets of ramped targets could explain their slight underestimation, anticipations to offsets of damped targets were too small to explain their underestimation. The results of the research contradict the predictions of the AIM model [R. D. Patterson and T. Irino, J. Acoust. Soc. Am. 104, 2967–2979 (1998)], where ramped and damped sounds longer than 200 ms should be perceived as possessing similar subjective durations.
The acquisition of L2 phonetic categories: Single-, two-, and multiple-category assimilation in Dutch learners of Spanish
Authors: Escudero Paola , Boersma Paul
Published: October 2013

The perceptual acquisition of Spanish vowel categories by Dutch speakers is examined. One might think that these learners have few problems because Dutch has as many as 12 monophthongs in its vowel inventory, and Spanish has only 5. However, a perception experiment shows that Dutch learners make quite a few mistakes when identifying Spanish vowels. It was predicted that these errors exemplify three well-attested patterns in the initial state of L2 acquisition: single-, two-, and multiple-category assimilation. These patterns may be found in the categorization of Spanish /i/–/e/, /e/–/a/, and /u/–/o/, respectively. The strategies that the learners follow to solve the problems associated with these patterns are presented, as well as the development of phonetic categorization in the three scenarios. Ninety-six listeners were tested with a three-way experiment design. The stimuli were Spanish CVCs embedded in Dutch or Spanish carrier sentences. The first two experiments were designed to find out to what degree learners perceive L2 sounds differently from L1 sounds. The third experiment tested the development of the learners’ L2 categorization accuracy. The combined results of the three experiments show that the learners indeed manifest the three different assimilation patterns, each of which is solved by a different strategy.
Perception of English final stops by native Spanish and Russian listeners
Authors: Argodale Paul , Strange Winifred
Published: October 2013

Spanish and Russian speakers perception of word-final stops was investigated in an identification task. Natural stimulus triads (sue-suit-sued, see-seat seed) were produced and presented in two conditions: (1) Final consonants released and CV in the utterance final position; (2) final consonants unreleased and CV produced before a word beginning with a voiceless stop. Russian listeners, whose first language has final voiceless stops, correctly identified English final stops better than Spanish listeners, whose first language does not have final stops (72% vs 60% correct overall). Spanish listeners were more likely than Russian listeners to identify words with final stops as open syllables (31% vs 2% errors). A significant effect of release condition was also found: Spanish listeners were much better at identifying released stops than unreleased stops (90% vs 29% correct). Russian listeners also showed a slightly higher correct rate of identification for released stops (91% vs 42%). Both groups identified voiceless final stops more accurately than voiced stops: Russians (80% vs 65% correct); Spanish (65% vs 54% correct). These results replicate and extend earlier work by Flege and colleagues. [Work supported by a grant from the Professional Staff Congress of the City University of New York.]
Perception of cross-language vowel differences: A longitudinal study of native Spanish learners of English
Authors: Imai Satomi , Flege James , Wayland Ratree
Published: October 2013

The study evaluated the ability of native Spanish speakers to perceive phonetic differences between Spanish vowels (/i e a o u/) and English vowels (/ieIɑoʊu/). Eighteen adult native speakers of Spanish who were learning English as a second language (L2) in Birmingham. AL were tested at 6-month intervals over a 3.5-year period (T1–T7). Five tokens of each Spanish and English vowel were randomly presented for classification in terms of one of the five vowels of Spanish, and were rated for goodness of fit on a 6-point scale (where 0 indicated ‘‘not Spanish’’ and 5 indicated a ‘‘good example’’ of a Spanish vowel). At both T1 and T7, English /i/, /eI/, /ɑ/, /oʊ/ and /u/ were usually classified as Spanish /i/, /e/, /a/, /o/ and /u/, respectively. A group analysis revealed that significantly higher ratings were given to the Spanish than English member of the /o/-/oʊ/, /u/-/u/, /e/-/eI/ and /a/-/ɑ/ pairs but not the /i/-/i/ pair. However, the number of individual L2 learners who gave significantly higher ratings to a Spanish vowel than to the corresponding English vowel differed substantially (/o/-/oʊ/ n=18, /u/-/u/ n=8, /e/-/eI/ n=5, /a/−/ɑ/ n=1, /i/-/i/n=1). Possible explanations for these between-pair differences —acoustic and perceptual—will be discussed. [Work supported by NIH.]
Factors affecting the duration of native and second-language sentences produced in unspeeded and speeded conditions
Authors: Flege James E. , MacKay Ian R. A.
Published: October 2013

The aim of this study was to provide insight into why non-natives generally produce longer second-language (L2) sentences than native speakers do. Four groups of 16 Italian–English bilinguals were recruited in Ottawa based on orthogonal differences in age of arrival (AOA) to Canada from Italy (early versus late) and self-reported percentage Italian use (low-L1 use versus high-L1 use). The bilinguals repeated duration-matched English and Italian sentences presented via a loudspeaker in an ‘‘unspeeded’’ condition, then as rapidly as possible (the ‘‘speeded’’ condition). The same effect of AOA was obtained in both conditions despite a 20% reduction in sentence duration in the speeded condition. That is, the early bilinguals produced significantly shorter English than Italian sentences, whereas the late bilinguals produced significantly longer English than Italian sentences. Different L1 use effects were obtained in the two conditions, however. In the unspeeded condition, the low-L1-use bilinguals produced shorter English than Italian sentences, with a nonsignificant effect of language for high-L1-use bilinguals. In the speeded condition, high-L1-use bilinguals produced shorter Italian than English sentences, with no language effect for the low-L1-use bilinguals. The underlying bases of AOA and L1 use effects on L2 sentence production will be discussed. [Work supported by NIH.]
Broadband DORT applied to bistatic active sonar
Authors: Fromm David M. , Gaumond Charles F.
Published: October 2013

The decomposition of the time reversal operator (DORT) is a single frequency method of spatially isolating scatterers with a multiple-source/multiple-receiver system [C. Prada et al., J. Acoust. Soc. Am. 99, 2067–2076 (1996)]. The DORT technique applied to the active sonar problem has demonstrated the ability to isolate scatterers at various depths and ranges from distributed bottom reverberation for a set of monostatic or vertically bistatic source/receiver geometries. The sound channel propagation has several consequences for DORT analysis: (1) frequency fading prevents the source and receiving steering vectors for the first singular value from isolating the scatterer across the entire bandwidth of the signal; and (2) dispersion causes space–time spreading of the analysis window and complicates the back-propagation procedure. These effects become more pronounced as the technique is extended to fully bistatic source–receiver geometries and range-dependent environments. This paper presents the extension of the DORT technique to the full broadband, bistatic, active sonar problem, including refinements to the range-resolution/time-windowing and back-propagation techniques, and enhancement to detection and classification by exploiting the response for several singular values across the entire bandwidth of the signal. [Work supported by ONR.]
Singular value spectra of transmission mode acoustic time reversal imaging
Authors: Lehman Sean K. , Devaney Anthony J.
Published: October 2013

We have formalized the theory of transmission mode time reversal imaging for arbitrary transducer geometry. Although it is not possible to implement such a system in practice, we have shown that transmission mode time reversal imaging is achievable a posteriori from the scattered field time series as measured at the receivers. We apply this theory to studying the singular value spectra of objects buried in the ground. We provide simulated finite-difference time-domain (FDTD) examples designed to model the case of geophysical vertical seismic profiling in which a series of sources are excited on the surface and the scattered fields are measured on a chain of receivers in a bore hole. A single, non-point scatterer can have multiple singular values dependent upon the scatterer’s physical properties. We study the relationship between the singular value spectra and these physical properties.
Near-bottom hydrophone measurements of ambient noise and sperm whale vocalizations in the northern Gulf of Mexico
Authors: Newcomb Joal , Fisher Robert , Field Robert , Turgut Altan , Ioup George , Ioup Juliette , Rayborn Grayson , Kuczaj Stan , Caruthers Jerald , Goodman Ralph , Sidorovskaia Natalia
Published: October 2013

Three bottom-moored hydrophones, 50 m above the bottom, were placed on a downslope line, ending at the largest concentration of sperm whale sightings in the northern Gulf of Mexico, in 600 m, 800 m, and 1000 m water depths. These depths were chosen after upslope propagation modeling, using historical databases, showed transmission losses greater than 110 dB at hydrophones near the bottom in water shallower than 600 m for a 500 m deep source at the 1000 m contour. These autonomously recording hydrophones were environmental acoustic recording system (EARS) buoys obtained from the Naval Oceanographic Office. They were capable of recording signals up to 5500 Hz continuously for 36 days and were deployed from July 17 through August 21. During this period a major marine mammal exercise was being conducted at the surface by the Minerals Management Service and the National Marine Fisheries Service, with other government and university scientists, in which temporary acoustic recording devices were attached to the whales and the whales were monitored by a surface towed array. Our near-bottom measurements of ambient noise and sperm whale vocalizations are discussed and compared to those surface and on-whale measurements. [Research supported by ONR.]
Full field spatial correlation of range dependent surface generated noise in a stratified ocean with application to hurricane sensing
Authors: Wilson Joshua D. , Makris Nicholas C.
Published: October 2013

Much of the ambient noise in the ocean is generated by wind at the ocean surface. In the case of a hurricane, the wind speed, and therefore the source level, is not constant over the ocean surface. The wind speed in a hurricane can range from 0 knots at the eye to 140 knots at the eye wall where the eye and the eye wall are typically separated by only 10 kilometers. A spectral model for the spatial correlation of range dependent surface generated noise based on wave number integration is developed. This model accurately represents the acoustic field directly beneath the hurricane and at arbitrarily long ranges. It is used to illustrate the dramatic variation in the noise field caused by range dependent features like the eye and eye wall. Results of this model are shown for hurricanes in shallow and deep water environments, including Bay of Bengal and Mid-Atlantic regions. This model is also compared with a previous normal mode model [Perkins et al., J. Acoust. Soc. Am. 93, 739–752 (1993)]. This comparison shows that at long range the two models agree but at close range the wave number integration model is necessary to accurately represent the field.
From time domain simulation of diatonic harmonica, proposal of a minimal free reed model
Authors: Laurent Millot , Daniel Ambroise
Published: October 2013

Chromatical playing on diatonic harmonica can be explained and reproduced using a temporal model. This model features a nonlinear vocal track, two free reeds and interaction of these three elements. The agreement between numerical simulations and experiment will be illustrated. From these results, and considering the sinusoidal reed motion during normal playing, a minimal description of free reed will be proposed. The equivalent reed oscillator will be derived from comparisons between quasistatic and modal description of the reed displacement; it will be shown that the modal description is a good choice. Then, a sufficient description of the flow through each reed will be built. Waveforms and related sounds will be presented for each tested assumption and will illustrate the fact that this flow must rely on the local reed displacement. Application of this model will be discussed in the case of other free reed instruments.
Recruitment-of-loudness effects of attenuative noise reduction algorithms
Authors: Whitmal Nathaniel , Vosoughi Azadeh
Published: October 2013

Hearing-impaired listeners have greater difficulty understanding speech in noise than normal-hearing listeners do. As a result, hearing aid users are often challenged by the inability of their hearing aids to improve intelligibility in noise. Several investigators have addressed this problem by using well-known signal processing methods (e.g., spectral subtraction, Wiener filtering) to enhance noise-corrupted speech. Unfortunately, these methods have failed to provide significant improvements in intelligibility. One possible explanation is the level-dependent nature of the attenuation that the algorithms impose on the speech. In the cases described above, this attenuation resembles the piecewise-linear input–output characteristic observed in certain recruitment-of-loudness simulators. The purpose of this study was to compare the intelligibility of processed speech with that expected for recruitment-of-loudness simulation. Trials of the CUNY Nonsense Syllable Test were conducted with 12 normal-hearing listeners, using syllables that were mixed with additive noise at SNRs of 6, 12, and 18 dB. Input–output characteristics for the signals were measured and used to determine the effective threshold shift imposed by the algorithms. Comparisons of measured intelligibility scores with articulation index-based intelligibility predictions indicate that the behavior of such noise reduction algorithms can be successfully modeled as a form of mild sensorineural hearing loss.
Statistical analysis of pyroshock data
Authors: Hughes William O.
Published: October 2013

The sample size of aerospace pyroshock test data is typically small. This often forces the engineer to make assumptions on its population distribution and to use conservative margins or methodologies in determining shock specifications. For example, the maximum expected environment is often derived by adding 3–6 dB to the maximum envelope of a limited amount of shock data. The recent availability of a large amount of pyroshock test data has allowed a rare statistical analysis to be performed. Findings and procedures from this analysis will be explained, including information on population distributions, procedures to properly combine families of test data, and methods of deriving appropriate shock specifications for a multipoint shock source.
Pyroshock testing—electrodynamic shakers
Authors: Smallwood David O.
Published: October 2013

Far field pyroshock (accelerations less than a few hundred grams, and bandwidths less than a few kHz) can be simulated on electrodynamic shakers. Typically, the specification is in terms of the shock response spectrum (SRS). Wave forms are synthesized which will match the required SRS. The process is not unique, as many wave forms can have essentially the same SRS. Sometimes additional restrictions are placed on the synthesized wave form. Most common are restrictions on the duration of the wave form. The process of synthesizing wave forms, which will match an SRS and conform to the limitations of electrodynamic shakers, will be described. The methods used to reproduce these wave forms on the shaker will then be discussed.
On the flexibility of phonetic categories
Authors: Francis Alexander L. , Nusbaum Howard C.
Published: October 2013

Research on phonetic category acquisition suggests that over the course of development children shift the relative weight given to various acoustic cues to particular phonetic categories [S. Nittrouer, J. Phon. 20, 1–32 (1992)]. Adults also show flexibility in acquiring second language categories and learning to recognize synthetic speech. In both cases listeners must shift attention among some acoustic cues and change the weighting and mapping of others. Recent research demonstrated that category-level feedback can induce adult listeners to shift attention between conflicting cues to native stop-consonant categories. Subsequent research showed that adult listeners also reorganize the distribution of their attention to acoustic cues in learning to better understand synthetic speech. Moreover, research on learning foreign phonetic contrasts suggests that listeners can learn to direct attention to unfamiliar acoustic cues. These results suggest that phonetic categories are flexible in terms of the nature and quality of the acoustic cues that define them. We argue that this flexibility is a consequence of the basic nature of the general mechanism that mediates speech perception: In order to resolve the problem of context-conditioned variability, listeners must dynamically modify attention to the acoustic signal in a context-dependent manner.
The interaction of short-term and long-term memory in phonetic category formation
Authors: Harnsberger James D.
Published: October 2013

This study examined the role that short-term memory capacity plays in the relationship between novel stimuli (e.g., non-native speech sounds, native nonsense words) and phonetic categories in long-term memory. Thirty native speakers of American English were administered five tests: categorial AXB discrimination using nasal consonants from Malayalam; categorial identification, also using Malayalam nasals, which measured the influence of phonetic categories in long-term memory; digit span; nonword span, a short-term memory measure mediated by phonetic categories in long-term memory; and paired-associate word learning (word–word and word–nonword pairs). The results showed that almost all measures were significantly correlated with one another. The strongest predictor for the discrimination and word–nonword learning results was nonword (r=+0.62) and digit span (r=+0.51), respectively. When the identification test results were partialed out, only nonword span significantly correlated with discrimination. The results show a strong influence of short-term memory capacity on the encoding of phonetic detail within phonetic categories and suggest that long-term memory representations regulate the capacity of short-term memory to preserve information for subsequent encoding. The results of this study will also be discussed with regards to resolving the tension between episodic and abstract models of phonetic category structure.
Performance of conventional and fluctuation-based signal detection applied to atmospheric acoustics in the presence of transients
Authors: Null Thomas , Clark Chris , Wagstaff R. A.
Published: October 2013

One problem encountered in atmospherics acoustics is the detection of steady signals in the presence of loud transient noise. The ability to discriminate against loud transients is an attractive feature of fluctuation-based beamforming. A fluctuation-based beamformer was developed and there was a need to evaluate its performance for acoustic environments that have frequently occurring transients. Synthetic noise fields, which included loud transient noise, were created. Subsequently, receiver operating characteristic (ROC) curves could be produced in a Monte Carlo fashion. In order to provide a benchmark, the results of a conventional beamformer were similarly tested via ROC curves. These ROC curves allowed for comparison of the two beamformers under specific signal and noise conditions. In this presentation, the effects of transients on the outputs of both the conventional beamformer and the fluctuation-based beamformer are discussed. Particular interest is focused on the amplitude distribution of the outputs.
Using cross-frequency cost functions for broadband source localization and environmental inversion
Authors: Honda Ethan P.
Published: October 2013

Cost functions that are constructed by coherently summing (model-to-data) correlations over hydrophone pairs and frequency have been used successfully for source localization [E. K. Westwood, J. Acoust. Soc. Am. 91, 2777–2789 (1992)] as well as source localization and environmental inversion [Neilsen, J. Acoust. Soc. Am. (to be published)]. Although the coherent sum is usually taken over the same frequency for both data and model, it is shown that summing over other regions of the fdata⊗fmodel space is also useful and may facilitate more efficient source localization. It is shown that lines of constant fdata/fmodel correspond to different source bearings. Although looking along lines of constant fdata/fmodel can be used as a crude form of spatial filtering, a new non-plane-wave spatial filter is also constructed that helps localize sources in the presence of multiple interferers. The spatial filter employed uses the environmental model to construct its set of basis functions and is therefore theoretically capable of spatially filtering in full 3-D as opposed to just bearing, as is done in adaptive beamforming.
A two-way coupled mode simulation of sound propagation in a shallow water wedge
Authors: Yudichak T. W. , Knobles D. P. , Koch R. A.
Published: October 2013

Near a shoreline an acoustic waveguide can be modeled by a wedge-shaped geometry with a penetrable bottom. The propagation of sound in such a waveguide was studied in a tank experiment conducted by Tindle et al. [J. Acoust. Soc. Am. 81, 275–286 (1987); 81, 287–294 (1987)]. An analysis of the time series data measured in this experiment was carried out by Royal et al. (unpublished), in which time series were simulated using a broadband, one-way, coupled normal mode approach. This analysis is extended using a two-way propagation approach that solves the integral equation form of the coupled mode equation. Also, the modal continuum is treated more realistically through the employment of a leaky mode decomposition. In particular, the importance of backscattering and coupling to the continuum is gauged by comparing the experimental data with the results of the two approaches.
Effect of model detail level on room acoustic computer simulations
Authors: Bradley David T. , Wang Lily M.
Published: October 2013

Computer modeling of room acoustics is limited due to approximations regarding wavelength to surface size ratios and diffraction. In fact, it is suggested that a model with high geometrical fidelity may actually lead to less accurate predictions. This project seeks to clarify how the level of model detail affects the accuracy of these simulations. Three models of the University of Nebraska’s Strauss Recital Hall have been generated at varying levels of detail; low (a rough model of the essential architectural dimensions), medium (a more accurate representation of the space), and high (a complete rendering of the surfaces within the space). The room acoustics modeling program Odeon is used to calculate objective measures (i.e., reverberation time and clarity) and create auralizations for each model. Meanwhile, the actual acoustical properties of Strauss Hall have been measured. The objective measure results are compared between the models and against measured data. Additionally, subjective tests are run with auralizations from all three models and the original space to determine if the difference in level detail can be perceived psychoacoustically. Quantitative results from these comparisons are presented to help users of room acoustic simulation software understand how the level of model detail will produce maximum accuracy.
Uses and limitations of statistical and geometrical modeling of nonexponential decay curves in performance spaces
Authors: Summers Jason E. , Torres Rendell R. , Shimizu Yasushi , Jaffe J. Christopher
Published: October 2013

The conditions under which the high-frequency, diffuse-field model of coupled rooms is a valid approximation to geometrical acoustics have been examined by comparison with ray-tracing predictions of decay curves in two and three room systems. Results particular to coupled rooms were noted. Because nonexponential decay shape is sensitive to both decay rates and relative energy densities, corrections to these parameters meaningfully improved the diffuse-field model. Variations in the free-path distribution of each subroom, introduced by coupling, complicated the use of improved decay models. Also, the expected decrease in energy density with distance from the source was found to result in spatial dependence of decay shape for certain coupling geometries. Insights from this study were used in the construction of diffuse-field and geometrical computer models of Bass Hall, a 2056 seat multipurpose auditorium with an acoustically coupled stage house. Preliminary results indicate that high-frequency decay curves in each of the subrooms predicted by geometrical acoustics are well matched to the predictions of diffuse-field models. The use of both models as prediction and design tools is assessed by comparison at high frequencies with measurements made during occupied and unoccupied conditions. [Research supported by the Bass Foundation.]
Identifying bird species from bird song using frequency component analysis
Authors: Mallett Jacky , Pepperberg Irene
Published: October 2013

The species-distinctive and highly stereotyped nature of bird vocalizations makes birdsong an obvious candidate for computational analysis. By using techniques from previous work in automatic music recognition and auditory analysis, a database of the detailed auditory characteristics of a selection of songs from over 150 different birds from the North Eastern region of the United States of America has been created. Examination of this database has allowed a picture to be built up of species-distinctive characteristics, and provides a more general picture of bird vocalizations than has previously been available. From this work it appears that frequency use by birds is of some significance, with evidence that the presence of a particular set of dominant frequencies in a bird’s song can be used as a distinctive fingerprint for species recognition. This paper reviews previous work in this area, outlines general computational methods used to extract this information, and presents results of automatic bird recognition using characteristics derived from the database.
Frequency selectivity in canaries with a hereditary hearing loss
Authors: Lauer Amanda M. , Dooling Robert J.
Published: October 2013

Sensorineural hearing loss is associated with reduced frequency selectivity due to the broadening of the auditory filters in mammals. In European starlings, hearing loss caused by the ototoxic drug kanamycin results in the widening of auditory filters at 5 kHz [Marean et al. (1998)]. In the present study, we examine frequency selectivity in a bird with a permanent hereditary hearing impairment, the Belgian Waterslager (BWS) canary. This strain of canary has long been bred for its loud, low-frequency song, and has been shown to have a hearing loss primarily at higher frequencies (2 kHz and above). Using operant conditioning and the method of constant stimuli, thresholds for detecting pure tones in flat-spectrum broadband noise were measured in BWS and non-BWS canaries. Critical ratios were calculated for comparison with other species of birds. At higher frequencies, critical ratios for BWS canaries were much larger than those of non-BWS canaries and other birds, suggesting reduced frequency selectivity in the region of the birds’ hearing loss. [Work supported by NIDCD R01DC001372 to RJD and Brenda M. Ryals.]
Computer synthesis of bird songs and calls
Authors: Kahrs Mark , Avanzini Federico
Published: October 2013

We describe the computer simulation of a one-mass source together with a simple transmission line model for a psittacine bird. The syrinx is modeled as a lumped mass subject to elastic restoring forces and internal dissipation. Nonlinear interaction with the airflow follows the Ishizaka and Flanagan glottal model. This is also used to model complete closure of the syrinx: during closure an additional restoring force is added and dissipation is increased. During the whole closed phase the syringeal flow is zero, and consequently its spectrum is broadened and higher partials are generated. The vocal tract transmission lines are implemented with fractional delay lines and the transmission lines are assumed lossless. The beak is implemented as two complementary fifth order Butterworth filters. The pole trajectory for the filters approximates the nonlinear path of the beak cutoff as discussed by Fletcher. [M.K. was supported by the Fulbright Foundation as well as Tekes. F.A. was funded by the Sound Source Modeling Project. Both authors were supported in part by the Academy of Finland.]
Acoustic correlates of human responses to domestic cat (felis
catus) vocalizations
Authors: Nicastro Nicholas
Published: October 2013

As part of ongoing research on coevolution of vocal communication between humans and domestic cats, perceptual data were collected on participants as they listened to recorded cat vocalizations. In experiment 1, human subjects were asked to rate the pleasantness of 100 meows along a 7-point scale, from most to least pleasant. In experiment 2, a different group of participants was asked to rate the urgency of the same meows along a 7-point scale, from most to least urgent. Linear regression analysis of the results showed a strong inverse correlation between pleasantness and urgency. Acoustic correlates of pleasantness included reduced frequency modulation, a downward shift in fundamental frequency, and fewer noisy segments. Correlates of urgency included increased duration, higher Wiener entropy, and acute spectral tilt. It is speculated that humans’ affective responses to these acoustic qualities, in conjunction with contextual cues, may form the basis of the communication of more specific meanings by cats to humans.
The effect of inharmonic partials on pitch of piano tones
Authors: Anderson Brian E.
Published: October 2013

Piano tones have partials whose frequencies are sharp relative to harmonic values. A listening test was conducted to determine the effect of inharmonicity on pitch for piano tones in the lowest three octaves of a piano. Nine real tones from the lowest three octaves of a piano were analyzed to obtain frequencies and amplitude of their partials. Synthetic inharmonic tones were produced from these results. Synthetic harmonic tones, each with a twelfth of a semitone increase in the fundamental, were also produced. A jury of 10 listeners matched each synthetic inharmonic tone to one of the synthetic harmonic tones. The effect of the inharmonicity on pitch was determined from an average of the listeners’ results. For the nine piano tones studied, inharmonicity increased pitch from a twelfth of a semitone to nearly a semitone.
Public policy and the ASA
Authors: Walsh E. J.
Published: October 2013

At the Ft. Lauderdale meeting of the Acoustical Society of America, the President of the Society authorized the formation of an ad hoc public policy committee to be named the Panel on Public Policy (PoPP). The Panel’s mission is to serve the public interest by addressing and commenting on societal issues that fall within the broad range of disciplines that define the scope of the Society. The Panel’s goal is to guide the development of ASA policies on, and responses to, questions that arise in relation to those issues. The operational plan calls for the Panel to execute its responsibility by generating and releasing Executive Council mandated and approved position statements, reports, or results of in-depth studies on issues affecting public health and welfare for use by appropriate legislative and policy-making entities. The structure, composition, and operational plan of the Panel will be discussed in general terms and specific prospective projects will be summarized.
Noise regulations that serve the community
Authors: Barnes James D.
Published: October 2013

State and local governments have adopted a variety of regulations over the past 40 years to protect the public against unreasonable noise. These regulations, which may be be qualitative in nature, may prohibit particular activities (e.g., barking dogs or loud radios) or outlaw nuisance noise in general (e.g., sounds disturbing to a resident). In addition, these regulations may be quantitative and define specific sound limits for a source at property line or community locations. The quantitative approach may typically include absolute limits that account for many factors, such as the time of day or week, the type of source and receptor, and the character of the sound; or in the case of Massachusetts, may include relative limits that account for the ambient background sound levels. A significant increase in community sound levels that is caused by a source is a useful indicator of a potential noise problem, but should this factor be considered when setting regulatory limits for individual projects? The presentation shall explore this issue and its effect on the process of siting, permitting, designing, and operating industrial facilities.
Acoustically excited surface waves on empty or fluid-filled cylindrical and spherical shells
Authors: Ahyi A. Claude , Cao H. , Raju P. K. , Werby M. F. , Bao X. L. , Überall H.
Published: October 2013

A comparative study is presented of the acoustical excitation of circumferential (surface) waves on fluid-immersed cylindrical or spherical metal shells, which may be either evacuated, or filled with the same or a different fluid. The excited surface waves can manifest themselves by the resonances apparent in the sound scattering amplitude, which they cause upon phase matching following repeated circumnavigations of the target object, or by their re-radiation into the external fluid in the manner of head waves. We plot dispersion curves versus frequency of the surface waves, which for evacuated shells have a generally rising character, while the fluid filling adds an additional set of circumferential waves that descend with frequency. The resonances of these latter waves may also be interpreted as being due to phase matching, but they may alternately be interpreted as constituting the eigenfrequencies of the internal fluid contained in an elastic enclosure.
Acoustic resonances of fluid-immersed elastic cylinders and spheroids: Theory and experiment
Authors: Niemiec Jan , Überall Herbert , Bao X. L.
Published: October 2013

Frequency resonances in the scattering of acoustic waves from a target object are caused by the phase matching of surface waves repeatedly encircling the object. This is exemplified here by considering elastic finite cylinders and spheroids, and the phase-matching condition provides a means of calculating the complex resonance frequencies of such objects. Tank experiments carried out at Catholic University, or at the University of Le Havre, France by G. Maze and J. Ripoche, have been interpreted using this approach. The experiments employed sound pulses to measure arrival times, which allowed identification of the surface paths taken by the surface waves, thus giving rise to resonances in the scattering amplitude. A calculation of the resonance frequencies using the T-matrix approach showed satisfactory agreement with the experimental resonance frequencies that were either measured directly (as at Le Havre), or that were obtained by the interpretation of measured arrival times (at Catholic University) using calculated surface wave paths, and the extraction of resonance frequencies therefrom, on the basis of the phase-matching condition. Results for hemispherically endcapped, evacuated steel cylinders obtained in a lake experiment carried out by the NSWC were interpreted in the same fashion.
Diffraction correction for precision SAW velocity measurements
Authors: Ruiz M. Alberto , Nagy Peter B.
Published: October 2013

Surface acoustic wave (SAW) dispersion measurements can be used to nondestructively characterize shot-peened, laser shock-peened, and other surface-treated specimens. In recent years, there have been numerous efforts to separate the contribution of surface roughness from those of near-surface material variations, such as residual stress, texture, and increased dislocation density. This talk addresses the problem that a perceivable dispersive effect, similar to the one found on rough shot-peened specimens, is exhibited by untreated smooth surfaces as well. The dispersion measurements were performed using laser-ultrasonic scanning combined with special digital signal-processing methods. The observed dispersion effect is on the order of 0.1%, which is comparable to the expected velocity change produced by near-surface compressive residual stresses in metals below their yield strength. The cause of this apparent dispersion is the diffraction of the SAW as it travels over the surface of the specimen. It is demonstrated that a diffraction correction may be introduced to increase the accuracy of surface wave dispersion measurements. A simple diffraction correction model was developed for surface waves; this correction was subsequently validated by laser-interferometric surface wave velocity measurements on 2024-T351 aluminum specimens.
Using resonance ultrasound spectroscopy to study colossal magnetoresistance in thin films
Authors: Pradhan Rajdeep , So Jin H. , Gladden J. R. , Maynard J. D.
Published: October 2013

Materials displaying colossal magnetoresistance (CMR) are candidates for important applications such as high density data storage. When the CMR material is in the form of a thin film on a substrate, the strain which results from lattice mismatch with the substrate alters the behavior of the material. As for CMR materials in bulk form, there should be a correlation between the CMR behavior and the structural and elastic properties of the strained thin films. Measurements of the elastic properties of thin films are obtained using a novel small sample resonant ultrasound spectroscopy (RUS) technique. Thin films of the magnetic material are deposited on a substrate and the difference in natural frequencies are then used to obtain the elastic constants of the film. The dominant CMR materials are perovskite manganites, a transition metal oxide. They exhibit a variety of exotic structural, magnetic and electrical behaviors, which is yet to be understood. In this paper measurements of the electrical resistance and elastic constants of 200 and 400 nm thin films, as well as unstrained samples, of the CMR material La(0.7)Ca(0.3)MnO3 are presented. [Work supported by ONR.]