bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting pharyngeal diameter from anterior tongue pellet positions in Swedish
Authors: Jackson Michel T-T. , McGowan Richard S.
Published: October 2013

One goal of phonetics is to quantitatively understand articulation in human speech production. As part of this goal, we are interested in the extent to which some vocal tract dimensions, specifically midsagittal pharyngeal diameters, are predictable from flesh points of the anterior tongue. In a reanalysis of x rays of speakers producing Swedish vowels, we modified previous procedures [Whalen et al., J. Speech, Lang. Hear. Res. 42, 592–603 (1999); Nix et al., J. Acoust. Soc. Am. 99, 3707–3717 (1996)] to predict pharyngeal diameters from pseudo-pellet positions. We used principal component analysis to reduce the number of pellet degrees of freedom from eight to three prior to applying linear regression from these three independent variables to each of several dependent pharyngeal diameters. Except for the regions around the laryngopharynx and uvula, the pharynx dimensions predictable from linear regressions were significant at the p<0.05 level. Numerical experiments show that it is crucial to reduce the number of independent variables in tests of statistical significance. [Work supported by Grant No. NIDCD-001247 to CReSS LLC.]
Identification of brief vowel sequences by young and elderly listeners
Authors: Kewley-Port Diane , Humes Larry , Fogerty Daniel
Published: October 2013

Aging generally has a negative impact on temporal processing. Four experiments using vowel sequences are presented from a large series of temporal processing studies of age-related changes across three sensory modalities. These four experiments used adaptive tracking to determine the smallest temporal difference between the onsets of vowels (SOA) that preserved identification of either the vowel sequences or ear presented. Vowels in the four words (pit, pet, pot, put) from a male speaker were processed using STRAIGHT to have the same length (70 ms) and F0 (100 Hz) and equated for rms level. Young (N=40) and elderly (N=40; 60–79 years) adults identified the vowels in isolation with better than 90% accuracy. Preliminary analyses based on 40% of the data are summarized here. Baseline performance by young listeners in the monaural, two-vowel sequence task was SOA=20 ms. For the other three conditions (monaural four-vowel sequences, dichotic two-vowel sequences, and dichotic two-vowel sequences for ear presented), SOA values increased by three to four times. This pattern of SOA values was similar for the elderly listeners. However, as expected, SOA values were significantly longer for the elderly group, but only by a small percentage (<30%). [Work supported by NIA R01 AG022334-02.]
An acoustical study of English constant-vowel (CV) syllables
Authors: Yang Byunggon
Published: October 2013

This study examined acoustic characteristics of 900 CV syllables produced by five English native speakers downloaded from http://www.nsi.edu/users/patel/download.html. Those target syllables were produced quite synchronously between the syllable /ba/ twenty times. The syllables were segmented and normalized by the maximum intensity value of each syllable and were divided into consonant or vowel sections by a few visible acoustic criteria. Intensity values were collected at 100 relative time points per syllable. Also, cumulative intensity values and consonant and vowel durations along with the ratio of the onset consonant to each syllable were measured using Praat scripts. Results showed as follows: First, the consonantal section amounted to a quarter of the syllable in terms of both the cumulative intensity and duration. Second, the consonantal ratio by the cumulative intensity was similar to that by the duration. Finally, the sum of the cumulative intensity values in each syllable partially coincided with the order of consonant groups on the current sonority scale while the vowel section of each syllable showed almost comparable intensity curve. Further studies would be desirable on more reliable acoustical measurements and sophisticated perceptual experiments on the English syllables.
Salience of dynamic virtual formants in diphthongs
Authors: Fox Robert Allen , Jacewicz Ewa , Chang Chiung-Yun
Published: October 2013

Variations in the quality of a synthesized vowel can be produced by changing the frequency of its steady-state formants or the amplitude of closely-spaced static spectral components—the latter effect a function of auditory spectral integration. Recent studies have demonstrated that dynamic modification of the amplitude ratios of these spectral components can give rise to the perception of virtual diphthongs. This study examines the extent to which spectral integration of these dynamic components is uniform across a range of frequency separations of these spectral components (previous work [Fox et al., ‘‘Title,’’ J. Acoust. Soc. Am. 120, 3252 (2006)] demonstrated the integration of static components beyond 3.5 bark). Two synthetic vowel series were created by modifying the rise or fall of F2 producing [■i]-[■:]-[■u] and [i■]-[■:]-[u■] series. Next, several different series were created in which this dynamic F2 was replaced by two static spectral components whose amplitude ratios were varied over time (virtual F2 glides). The spectral separation of these two components varied from 2.0 to 4.0 bark. A single-interval 2AFC identification task was used to obtain estimates of vowel quality. Results will be discussed in terms of whether the spectral integration effects decline as the frequency separation between components increases. [Work supported by NIDCD R01DC00679-01A1.]
Formant amplitude in the perception of /i/ and /u/
Authors: Kiefte Michael , Enright Teresa , Marshall Lacey
Published: October 2013

Although recent evidence reconfirmed the importance of spectral peaks in vowel identification [M. Kiefte and K.R. Kluender, J. Acoust. Soc. Am. 117, 1395–1404 (2005)], the roles of formant bandwidth and amplitude in perception have not been firmly established. Although several studies have shown changes in vowel categorization with changes in bandwidth and amplitude, such manipulations often result in peaks that have very little local spectral contrast or which may be perceptually masked by other spectral prominences. This study compares local contrast and masking of spectral peaks in vowel perception. A stimulus continuum ranging from /i/ to /u/ in both the amplitude of the second formant as well as that of higher formants was presented to listeners for identification. Both full-spectrum and incomplete-spectrum stimuli were used to demonstrate the effects of local spectral contrast and simultaneous masking. A second experiment was used to determine if listeners were able to detect the presence of the second spectral peak in the same stimuli. Results from both experiments indicated that both masking and spectral contrast play a role in vowel perception.
Cross-linguistics differences in non-speech perception
Authors: Babel Molly , Johnson Keith
Published: October 2013

This research explores listeners perception of non-speech stimuli across languages. We will report on two experiments conducted with the same stimuli. The stimuli were synthesized from naturally produced vowel-fricative-vowel sequences consisting the fricatives [f, th, s, sh, x, h], and the vowel environments [i—i, a—a, u—u]. The vowels were synthesized using sine wave synthesis and appended onto the natural fricative. Tokens will be presented to two groups of Dutch and English listeners over headphones with a 100 ms interval. Listeners will be told that the stimuli is non-speech. The first experiment is a simple AX discrimination task where the listener decides whether the tokens were same or different. The second experiment is a rating task where the listener is asked to rate the similarity of the two tokens on a five-point equal interval scale. It is predicted that results of both experiments will be the same for both groups of listeners. These results will be compared to the results of the same experiment with non-synthesized speech [K. Johnson and M. Babel, J. Acoust. Soc. Am. 120, 3292 (2006)]. [Work supported by the NIH.]
Probabilistic descriptions of low-frequency passive sonar signals
Authors: Jemmott Colin W. , Ballard Jeffrey A. , Culver R. Lee , Sibul Leon H.
Published: October 2013

The overall goal of our research is to develop a method whereby knowledge of environmental variability is incorporated into a passive sonar detector. The Estimated Ocean Detector (EOD) is a maximum likelihood receiver that incorporates statistical knowledge of signal uncertainty in the form of signal parameter probability density functions (pdf’s). The structure and performance of the EOD depends fundamentally on accurate probabilistic models of received signal and noise parameters, the so-called prior distributions. Previous work has concentrated on Monte Carlo to make use of deterministic and statistical knowledge of the uncertain and variable ocean environment to predict signal parameter pdf’s. This talk presents a statistical analysis of signals recorded during the SWellEX-96 measurement that took place in shallow water off the coast of California. The data consist of CW signals transmitted simultaneously from moving sources at two different depths and received at a horizontal array. The statistical analysis includes estimates of time-varying moments of signal parameters and coherence of signal amplitude, frequency, and phase. [Work supported by ONR Undersea Signal Processing Code 321US.]
Environmental and signal models for acoustic models for acoustic propagation through a variable ocean
Authors: Culver Richard Lee , Camin H. John
Published: October 2013

Acoustic signals propagating through the ocean are refracted, scattered, and attenuated by the ocean volume and boundaries. Although much about the ocean environment and its effect on acoustic propagation is understood, there is always variability associated with both environment parameters and the received signal, and uncertainty in our knowledge of both. Environment and signal models (e.g., sound speed, bottom loss, and received level) often include only mean values, but they can include the higher order moments that parametrize variability. Interest in relating environmental and signal models and variability is motivated by recent efforts to capture ocean environmental uncertainty that have enhanced understanding and models of environmental parameters, and by advances in ocean acoustic signal processing that indicate how to exploit knowledge of signal variability in order to improve sonar performance. These two developments can be connected if the relationship between environmental and signal parameters (or models) is understood. We show that when a signal prediction must reflect realistic, environment-driven variability over a particular space-time interval, the environmental models used to construct the signal model must contain the environmental variability present during this same interval. [Work supported by ONR Undersea Signal Processing Code 321US.]
Statistical characterization of very low frequency communication channels at ocean basin-scales
Authors: Spiesberger John , Green Dale
Published: October 2013

The bit rate for incoherent communication is estimated for low frequency sounds (75 Hz, 0.03 s resolution) transmitted 3115 km between a bottom-mounted source and a towed array. A model for short term fluctuations of sound agrees with measurements without tuning the model to the data. In particular, measured and modeled probability distributions for multipath coherence time and amplitude fluctuations are similar. Temporal evolution of the oceanographic component of the model is governed by the linear dispersion relation for internal gravity waves. The acoustic component of the model is based on the sound-speed insensitive parabolic approximation. This is the third attempt to use the model to predict short-term acoustic fluctuations at basin-scales. All three attempts yielded results similar to measurements. If further comparisons between the model and data are successful, the model could be used to design and implement low frequency communication systems. A simulation yields 4 bits per second for a Benthos modem using an incoherent communication scheme via frequency shift keying. [Work supported by the ONR.]
Some effects of spatial randomness along the length of the cochlear on its performance
Authors: Elliott Stephen , Ku Emery , Lineton Ben
Published: October 2013

If the active cochlear is modelled as having a uniform distribution of parameters, the system is stable even for high gains in the cochlear amplifiers, resulting in very significant active enhancements of its response, of the order of 90 dB. In a real biological system, however, such uniform distributions will always be disrupted by random spatial variations, and a state space model of the cochlea has been developed that can be used to investigate the effects of such random variations. One effect is found to be that the cochlear amplifier gains have to be reduced to maintain stability, so that maximum active enhancements of the cochlear response is more typically 40 dB. The cochlear amplifier, however, is nonlinear as well as active, and unstable poles in the linear model generate instabilities that settle into limit cycle oscillations at discrete frequencies in the nonlinear model. These oscillations are thought to be the origin of spontaneous otoacoustic emissions, and have a significant effect on sound detection at low level. At higher sound pressure levels the nonlinearity in the cochlear amplifier suppresses such oscillations and the sound detection has a more uniform frequency response, although the amplification is reduced.
Music and acoustics for Catholic churches: history and modernity
Authors: Torres Rendell R. , Galiè Kevin
Published: October 2013

The paradoxical challenge of providing crisp speech intelligibility and lush musical reverberance in Catholic liturgical spaces has long vexed acousticians, architects, and church building committees. Compounding the complexity is the variety of musical and liturgical styles, including ethereal Gregorian chant, post-Reformation strophic hymnody, and modern ‘‘praise music’’ (e.g., folk, gospel, and amplified pop music). In this paper we first survey official Catholic documents on music and sound in liturgy. Then we consider melodic structures and tempi of various kinds of liturgical music and relate them to acoustical decay parameters. Finally, we present a sample outline of music for a Catholic Mass and discuss attendant requirements from acoustical and musical perspectives.
Sound parameters in mosques
Authors: Orfali Wasim Asaad
Published: October 2013

Unlike auditoriums, there are no defined recommendations or rules for the acoustical parameters inside mosques. Most of the existing recommendations are developed for multipurpose halls, for opera or dramatic theaters, and for structures built for organ music. But regarding mosques the elaboration of general sound parameters requires a specific understanding of the acoustical and spiritual environment expected in such structures. Newly defined acoustical parameter values with regard to mosque volumes and types will be addressed here. New treatment rules for closed or courtyard structures are introduced. Especially so-called mosque volume dependent parameters are derived. They allow optimizing the secondary structure of a mosque by considering the primary structure determined by the architecture. Such parameters deal with optimal reverberation time or intelligibility considered for all praying modes at once. Target of the research is to get standard acoustic parameter values especially applicable for mosques.
Performance of a high frequency thermoacoustic cooler at high pressures
Authors: El-Gendy Husam , Symko Orest G.
Published: October 2013

By raising the pressure of the working gas in a thermoacoustic cooler, the sound intensity level, at fixed electrical power input to the acoustic driver, is increased. In order to take advantage of this boost in acoustic intensity for cooling, significant adjustments need to be made inside the cooler. As the pressure is raised the thermal and viscous penetration depths are reduced; this requires an increase of stack filling factor accordingly. For the cooler presented here, operating at 4 kHz, the stack consists of a random arrangement of cotton wool, with fibers 10 microns in diameter. The stack is typically quite loose between the heat exchangers at each end. High levels of sound at the stack lead to volumetric forces on the fibers of the stack and viscous drag forces caused by acoustic streaming; both increase with the sound level. Moreover the heat capacity of the stack becomes insufficient to maintain the T1=0 condition at the interface with the working gas. Studies of such effects at high pressures will be presented.
Performance of annular high-frequency acoustic engines
Authors: Rodriguez Ivan A. , Symko Orest G.
Published: October 2013

Thermoacoustic engines operating in the standing wave mode are limited in their efficiency by a high degree of irreversibility that is inherent in how they work. Better performance can be achieved by using traveling waves in the thermoacoustic device. This has led to the development of an annular high-frequency thermoacoustic prime mover consisting of a regenerator, which is a random stack in-between heat exchangers, inside an annular waveguide. Miniature devices were developed with operating frequencies in the range of 2–3 kHz. This corresponds to an average ring circumference of 11 cm for the 3-kHz device; the resonator bore is 6 mm. A similar device of 11 mm bore and length of 18 cm was also investigated; its resonant frequency is 2 kHz. Sound power was extracted by an impedance-matching side arm to the annular structure. The spectrum of the acoustic power did not have harmonics, indicative of all traveling wave components. The efficiency is high, being over 40% of Carnot. This type of device shows much promise as a high efficiency energy converter; it can be quite simply reduced in size for microcircuit applications.
Synchronization of small thermoacoustic oscillators
Authors: Gillman Brenna , Symko Orest G.
Published: October 2013

Small high-frequency thermoacoustic oscillators can achieve high power densities in the conversion of heat to sound. In order to achieve high sound power output, it is advantageous to use arrays of such devices. Being a group of self-sustained oscillators, they switch on with a random phase at the threshold for oscillations. Moreover, small variations in the geometry of each device will affect the resonant frequency of each; the array will then not be in unison. This can be corrected by synchronizing them through global coupling; maximum power output will then be achieved. The strength of the coupling is assumed to be the ratio of mass of one thermoacoustic oscillator to the total mass of all devices and of the support to which they are mounted. By varying the strength of the coupling, the acoustic devices show synchronization, which for weak coupling is out-of-phase and at strong coupling is in-phase. Results are presented on the coupling of two prime movers operating near 2.5 kHz as well as for similar devices in an array consisting of five units. The synchronized behavior opens the field for large array systems and their applications.
Comparison of behavioral and auditory brainstem measures of hearing loss in rats exposed to loud sound
Authors: Heffner Henry E. , Koay Gimseong
Published: October 2013

Behavioral thresholds for 400-ms pure-tone pulses (2/s, 10 ms rise-decay) were determined for monaural rats using the method of conditioned suppression. Auditory brainstem response (ABR) thresholds for 1-ms tone pulses (27.7/s, 0.5 ms rise-decay) were determined in the same animals for the same frequencies (2, 4, 8, 16, and 45 kHz). A hearing loss was then induced by exposing an isoflurane-anesthetized animal to a loud tone (110 or 120 dB) for 10 min. A behavioral pure-tone threshold was determined one hour after exposure followed immediately by an ABR threshold for the same frequency. The animals were retested on subsequent days until their thresholds stabilized. So far (n=10), no simple relationship has been found between the ABR-estimated hearing loss and the actual hearing loss. Although the ABR tended to overestimate the hearing loss, the range of both over- and under-estimates was more than 25 dB. The difference between the two measures may be because of the different stimulus parameters used in the two procedures or because the ABR is a measure of neural synchrony as well as absolute sensitivity. Work is in progress to determine if a more reliable estimate of sensorineural hearing loss can be obtained from the ABR.
The effect of the inter-target delay on informational and energetic masking of speech in younger and older adults
Authors: Li Liang , Huang Ying , Huang Qiang , Chen Xun , Qu Tianshu , Wu Xihong
Published: October 2013

In a reverberant environment where several people talk simultaneously, perceptual grouping of the direct wave emanating from a talker with its reflections is essential for both distinguishing different talkers and identifying attended speech. Older-adult listeners often feel it difficult to understand attended speech in reverberant environments. In this study, the effect of changing the time interval between target speech and its simulated reflection on recognition of target speech was investigated in both younger and older adults with normal or near normal hearing. When the masker was competing speech, the intelligibility of target speech was markedly improved in younger participants as the inter-target delay was reduced from 64 to 0 ms, particularly when the signal-to-masker ratio was sufficiently low (−6 or −8 dB). In older participants, the release induced by decreasing the inter-target delay was marked but smaller than that in younger participants especially at long inter-target delays (16 or 32 ms). Moreover, reduced release of target speech occurred if speech masker was replaced by noise masker. The results suggest that there is an age-related decline of the ability to perceptually integrate target speech with its reflections. This ability is particularly important for releasing speech from informational masking in reverberant environments.
Reductions in gain from pre-masker stimulation at the signal frequency
Authors: Jennings Skyler , Strickland Elizabeth
Published: October 2013

Normal hearing individuals can detect a short duration signal at a lower signal-to-masker ratio when the signal is delayed from masker onset compared to near it. This is often referred to as the temporal effect. This effect is interesting because it may be related to changes in cochlear gain. It has been proposed that gain is high at masker onset and decreases, in a frequency specific manner, through the course of the masker. If this hypothesis was true, it is expected that frequency selectivity also decreases through the course of the masker. Using a forward masking paradigm, the current study examines the hypothesis that frequency selectivity decreases with pre-masker stimulation at the signal frequency. Growth of masking (GOM) functions and psychophysical tuning curves (PTC) were measured for the signal using a short masker preceded by a long duration precursor set at the signal frequency or well below the signal frequency. Preliminary results reveal a relatively broader PTC and a steeper GOM function when the precursor was at the signal frequency and are consistent with the hypothesis that preceding stimulation at the signal frequency reduces gain. [Work supported by the Hazelton Fund.]
Effect of hearing loss on the ability to process synchronous and asynchronous cues for speech identification
Authors: Hall Joseph W. , Buss Emily , Grose John H.
Published: October 2013

This study investigated the effect of sensori-neural hearing loss on the ability to identify speech in noise for vowel-consonant-vowel tokens that were unprocessed, modulated synchronously across frequency, or modulated asynchronously across frequency. The modulator was a 20-Hz raised square wave. One goal of the study was to determine whether hearing-impaired listeners have a deficit in the ability to integrate asynchronous spectral information in the perception of speech. Speech tokens were presented at a high, fixed sound level and the level of a speech-shaped noise was changed adaptively to estimate the masked speech identification threshold. The performance of the hearing-impaired listeners was generally worse than that of the normal-hearing listeners, but the impaired listeners showed particularly poor performance in the synchronous modulation condition. The results did not suggest that the hearing-impaired listeners have a general deficit in the ability to integrate asynchronous spectral information in the perception of speech. Results will be discussed in terms of common mechanisms that might account for poor speech identification performance by hearing-impaired listeners when either the masking noise or the speech is synchronously modulated.
Gap detection in modulated noise: Across-frequency facilitation and interference
Authors: Grose John H. , Hall Joseph W. , Buss Emily
Published: October 2013

This study tested the hypothesis that a detection advantage for gaps in comodulated noise can be demonstrated in conditions of continuous noise and perceptually salient envelope fluctuations. Gap detection was measured using 25-Hz-wide bands of noise that were either Gaussian or were characterized as low-fluctuation noise or staccato (choppy) noise. The signal band was centered at 1000 Hz, and the flanking bands were centered at 444, 667, 1500, and 2250 Hz. Results from six observers confirmed that a gap detection advantage exists in continuous comodulated noise for Gaussian and staccato noise, but not for low-fluctuation noise. No gap detection advantage was found for a gated mode of presentation. Effects of temporal fringe and asynchrony suggested that the advantage was due to across-frequency processing and bore some resemblance to comodulation masking release (CMR). However, differences between CMR and the gap detection advantage were noted in terms of the effects of flanking band number and the absence of a detection advantage in gated conditions. This study demonstrates that, under some conditions, a detection advantage for gaps carried by a narrow band of noise can occur in the presence of comodulated flanking bands of noise. [Work supported by NIDCD R01-DC01507.]
Numerical and experimental study of bone conducted sound and the occlusion effect
Authors: Brault Lynn M. , Melamed Sara , Lansing Charissa R. , Chambers Ron D. , O’Brien William D.
Published: October 2013

Numerical techniques are used to study bone conduction hearing mechanisms. The military has an interest in bone conducted sound as personnel continue to experience hearing loss despite availability of full hearing protection. Particularly they need to identify better hearing protection over the entire audio range. A joint numerical/experimental program has been undertaken to quantify bone-conducted sound, identify paths along which sound propagates, and determine frequency-dependent characteristics of this conducted pressure. Specific cases in this work include coupling sound to the mastoid and measuring resultant pressures in the ear canal with and without earplugs. Canal pressure can be higher with ears blocked as plugs will trap conducted sound in a resonance mode, a phenomenon known as occlusion. In order to simulate this effect, digital images of a skull CT scan were used as the finite difference grid. Experimental results, based on behavioral and physiologic responses, were obtained from participants at UIUC to provide validation of the simulation. In both cases the occlusion effect is shown to be frequency dependent. The simulation software offers the possibility of evaluating the effect over a wide range of parameters such as earplug type, skull shape, and location of inputs. [Work supported by AFOSR FA9550-06-1-0128.]
Interaction of word stress, focus, and sentence type in English
Authors: Liu Fang , Xu Yi
Published: October 2013

This study investigates prosodic differences between statements and declarative questions in American English by examining their interaction with focus, as manifested in the local and global pitch range variations, and in the underlying pitch targets of the stressed syllables in the pre-, post-, and on-focus content words. Five native speakers read 24 sentences eight times. Results of F0 analyses indicate that focus has no effect on the prefocus region for either statements or questions. In the on-focus region, the pitch range of the stressed syllable is raised in statements, but lowered in questions. The postfocus pitch range is compressed and lowered in statements, but compressed and raised in questions. Furthermore, the pitch target of the stressed syllable in a content word is high or falling in statements and low or rising in questions, depending on the focus condition and on the word’s stress and syllabic pattern. Comparisons of duration and spectral balance in each statement-question pair yielded no significant difference. These results suggest that a particular combination of word stress, focus, and sentence type in an English utterance largely determines its local and global pitch contours. Only after these communicative functions are identified can the associated forms be explained.
Parsing of ambiguous phrases: Single versus multiple prosodic cues
Authors: Good Erin M.
Published: October 2013

In English, two prosodic contours that differ acoustically in their pitch and the location of the pauses involved can be used to disambiguate two-word phrases. The list contour, which has a fall-rise in pitch over the first word and a pause (approximately 22 ms) between the words is distinguished from the compound contour, which has a rise-fall in the pitch over both words and no pause. In this experiment target words recorded with relatively flat pitch were spliced together to make phrases with either 10 or 40 ms between each word. Participants treated items containing the 10-ms pauses as if they were compounds and items with 40-ms pauses as lists even without a pitch cue. This was true for lexically ambiguous phrases where either prosodic contour was appropriate and for nonsense phrases where the prosodic contour alone made it possible to select the correct answer. There was no statistical difference between the responses to items with just the pause cue and to items with the full prosodic contour. While many prosodic phenomena have multiple cues, the data suggest that in some cases a single cue can be used in place of multiple cues to the same effect.
Multi-channel detection of weak narrow-band signals in the presence of Gaussian and impulsive noise
Authors: Gur Berke M. , Niezrecki Christopher
Published: October 2013

Signal detection in the presence of noise is a commonly encountered problem in underwater acoustic signal processing and arises in many applications involving active and passive sonar. The detection problem becomes especially challenging if the signal to be detected is weak compared to background noise. In this work, the problem of detecting weak narrow-band bio-acoustic signals in noisy underwater acoustic environments is addressed. In contrast to most previous work, multi-channel setups are also considered and improvements in detector performances using multi-channel setups are investigated. Both Gaussian and non-Gaussian impulsive noise models are studied. Several parametric and nonparametric detectors are developed and implemented. The detection performance and range of these detectors in detecting manatee vocalizations buried in actual underwater acoustic noise recordings dominated by boat noise and snapping shrimp crackles are evaluated. Preliminary results indicate that these detectors outperform previously developed ad hoc detectors, thereby increasing the detection range and effectiveness of a proposed automated manatee avoidance system that is envisioned to reduce watercraft-manatee collisions.
Active acoustic time reversal for underwater acoustic barriers
Authors: Jesus Sérgio M.
Published: October 2013

This work addresses the possibility of using successive transmissions of time delayed channel probe pulses between two closely spaced acoustic sensor arrays for forming an acoustic barrier for target detection in shallow water. One array is a transmit-receive array (TRA) while the other is a receive only vertical line array (VLA). The two arrays are connected via cable or wireless. Time reversed replicas of the acoustic channel response to the probe signals are retransmitted into the ocean propagation plane to form focus peaks at each VLA element. It is shown both theoretically and with simulated data that an optimum disturbance detector can be built from the data received at the VLA. This detector becomes sub-optimal due to usual time reversal drawbacks such as ocean non-stationarity and spatial sampling limitations. Real data tests are foreseen to take place during summer 2007 to answer questions such as allowable ranges and frequencies of operation [Work supported by FCT (Portugal) under project POCI/MAR/59008/2004].
Time courses of cortical beta and gamma-band activity during listening to metronome sounds in different tempi.
Authors: Fujioka Takako , Large Edward , Trainor Laurel , Ross Bernhard
Published: October 2013

Oscillatory cortical activities in beta-band (13–20 Hz) are related to a somatomotor system, and gamma-bands (20 Hz) are involved with feature binding in perception. Previously gamma-band activity in electroencephalography was found to modulate with musical pulse with a two-beat metric accent. The present study examined beta- and gamma-band activities in auditory cortices recorded via magnetoencephalography (MEG) when subjects listened to musical pulse in various tempi. Tones were presented with intervals of (1) 390 ms, (2) 585 ms, and (3) 780 ms, and (4) with irregular intervals between 390 and 780 ms. In addition, the same tones were presented with a 390-ms interval using a two-beat accent, while occasionally either (5) an accented tone or (6) an unaccented tone was omitted. Beta-band activity decreased immediately after the stimulus and returned to the previous level just before the next stimulus, regardless of the tempo, except in the irregular condition. The tone omission resulted in an extra beta rebound. Gamma-band activity increased right after the pulse or the omission. We propose that beta oscillations may encode the timing of the next sound in a regular pulse sequence, whereas gamma oscillations likely reflect processing of the current auditory events including omissions.
Dynamics of emotional communication in performed music.
Authors: Chapin Heather , Large Edward , Jantzen Kelly , Kelso J. A. S. , Steinberg Fred
Published: October 2013

Musicians vary performance parameters, such as tempo and sound intensity, to express emotion dynamically. Our goals were to link specific parameters of performance expression with listeners' emotional responses and neural activity. Ten musically trained and ten untrained participants listened to two versions of a romantic piano composition. The expressive performance included variations in timing and sound intensity. The mechanical performance maintained constant tempo and sound intensity throughout. Participants reported emotional responses in a two-dimensional response space (emotional intensity and valence) before and after fMRI scanning. In the fMRI scanner, participants listened to both versions without reporting emotional responses. Ratings of emotional intensity were positively correlated with tempo. The fMRI analysis revealed a main effect of performance, showing increased BOLD responses for the expressive performance in an emotion-related network. A main effect of training showed increased BOLD responses for trained participants in areas associated with emotion processing and reward. We also observed BOLD responses that were temporally correlated with tempo fluctuations. In summary, performance expression predicted listeners' dynamic ratings of emotional intensity. Moreover, limbic areas responded to expressive versus mechanical performances, and dynamic BOLD changes tracked performance expression and reported emotional intensity over time. [Work supported by NSF BCS-0094229.]
Retuning speech sound categories: An eyetracking study.
Authors: Idemaru Kaori , Holt Lori
Published: October 2013

Speech categories are defined by multiple probabilistic acoustic cues. Fundamental frequency (F0) and voice onset time (VOT) are correlated in the English stop voicing contrast, for example. However, such correlations are often imperfect—especially in cases of non-native or disordered speech. The present experiments investigate listeners’ ability to adjust perceptual cue weighting in online perception in response to changes in the cue correlations experienced across time. Native-English listeners heard minimal-pair words beginning with stop consonants varying along a VOT series. The F0 of the words was gradually shifted over the course of the experiment from the canonical English correlation (higher F0 for voiceless stops) to the opposite pattern (lower F0 for voiceless stops). Categorization was assessed via explicit responses while eye gaze data were simultaneously recorded using the visual world paradigm. Both data types revealed that the influence of F0 on voicing categorization changed in response to changes in F0/VOT correlation. Some listeners use of F0 reversed such that higher F0 led to more voiced responses; other listeners discontinued use of F0 in voicing categorization. These patterns suggest that listeners are continually monitoring the input for regularity and retuning acoustic cue use in an online manner to accommodate these regularities.
Phonetic discrimination is affected by native language phonology.
Authors: Maye Jessica
Published: October 2013

English and Japanese speakers were tested on discrimination of phonetic contrasts that vary in their phonemic status according to phonological context. The presence versus absence of /u/ in English stimulus pair ebzo-ebuzo is nonphonemic in Japanese due to phonological syllable structure constraints, but in word-initial position (stimulus pair zobe-uzobe the same contrast is phonemic. Similarly, the contrast between Japanese /d/ versus /r/ is nonphonemic in the foot-medial position in American English due to an allophonic flapping process, but in word-initial position the two sounds are perceived as the English phonemic contrast /d/ versus /l/ (Japanese stimulus pairs gudo-guro and dogu-rogu. Participants were tested in a four-token oddball task on all four stimulus sets in a blocked design. Each participant group (Japanese and English) showed significantly poorer discrimination of the non-native contrast when it appeared in the phonological context in which it is nonphonemic in their native language (p’s < 0.001). This result was equally robust even for stimuli in which the contrastive portion of the stimulus (zo-uzo, do-ro) was spliced from the nonphonemic context and pasted into the phonemic context. These data indicate that phonological context plays an integral role in the perception of phonetic signals.
Phase fluctuations and horizontal refraction of low-frequency sound signals in shallow water in presence of internal waves.
Authors: Badiey Mohsen , Luo Jing , Katsnelson Boris , Tskhoidze Alexander , Lynch James , Moum James
Published: October 2013

Fluctuations of the sound pulse phase front propagating approximately perpendicular to the direction of motion of a train of intensive internal waves in the experiment Shallow Water 2006 (SW06) are studied. Acoustic data received by a horizontal/vertical line array (WHOI-Shark array) during 3 h are analyzed. Low-frequency modulated signals with a carrying frequency of 300 Hz were transmitted, propagating approximately along coastal line at the source-receiver distance of 20 km. During this time, a train of intense internal waves (Rosey) was moving toward the New Jersey coast. Internal waves were being monitored by the ship radars (aboard R/V Sharp and R/V Oceanus) and by the thermistor chains. It is shown that phase fluctuations of the acoustic pulses arise with the appearance of internal waves at the source-receiver acoustic track and they correspond to horizontal refraction of the sound pulses. For the low-frequency sound pulses, modal decomposition of received signals is used both for the processing of experimental data and for the theoretical analysis. Experimental data are compared with theoretical estimation of horizontal refraction. [Work was supported by ONR code 321OA and by CRDF, Grant BP3C10].
An overview of the 2005 YFIAE: Yellow Sea Oceanic Front and Internal Waves Acoustic Experiment.
Authors: Wang Ning , Liu Jin Zhong , Gao Da Zhi , Gao Wei , Wang Hao Zhong
Published: October 2013

An overview of the Yellow Sea Oceanic Front and Internal Waves Acoustic Experiment 2005 conducted in the South Yellow Sea is presented. The experiment was a multi-institutional effort which acquired high quality environmental and acoustic data. Two of its goals were to observe internal waves including linear random and nonlinear and cold water mass of South Yellow Sea to understand and describe their effects on acoustic signals. The talk contains three primarilary experimental results. First, a comparison of data from VLA and thermistor string record suggests that nonlinear internal waves cause coherent variations of arrival time structure in frequency bands 600–800 Hz. Second, normal mode coupling due to the South Yellow Sea Front (SYSF) is observed during the experiment and is used to monitor the boundary motions of the SYSF. Finally, to interpret the “frequency dispersion” in inverted effective sound speed of sea bottom, a new fast algorithm for the inversion of bottom acoustic parameters is proposed.
Viscoelastic response of cylindrical vessels surrounded by gelatin and excited using impulsive ultrasound radiation force.
Authors: Urban Matthew , Rosario Daniel , Bernal Miguel , Aquino Wilkins , Greenleaf James
Published: October 2013

The objective of this study was to assess the potential for noninvasively identifying viscoelastic material properties in arterial vessels using ultrasound radiation force and modern computational inverse problem techniques. A rubber tube embedded in gelatin was excited at different points along the axis using impulsive ultrasound radiation force. The resulting mechanical waves were measured using a laser vibrometer and pulse-echo ultrasound. The inverse problem was cast as an optimization problem, in which the discrepancy between the measured dynamic response and the computed finite element model response was minimized with respect to viscoelastic material parameters. The model was very sensitive to the tube’s viscoelastic parameters and relatively insensitive to those of the gelatin. The viscoelastic properties of the tube obtained from the inverse problem were compared to the results obtained from a dynamic mechanical analyzer (DMA). For the overlapping range of frequencies (130–190 Hz), the results of the inverse problem gave an equivalent modulus that range from 7.3–8.5 MPa, while the DMA values range from 6.0–9.2 MPa. These results have important implications for using ultrasound radiation force in noninvasive characterization of the viscoelastic properties of arteries in vivo. [This work was supported in part by Grant No. EB002640 from NIH.]
Work of Hank Bass in the mid-eighties to develop a comprehensive model of sound propagation through the atmosphere.
Authors: White Michael
Published: October 2013

The success of stealth technologies in the mid-eighties simultaneously raised the importance of other possible modes of discovery, one of them being acoustic detection. Bass initiated work on a comprehensive model for predicting sound transmission through the atmosphere in order to better assess the propagation. The model first considered atmospheric absorption and ground reflection of sound and would render predictions for single frequencies and spectra. Variability in received signals seemed to be explained by the strong effects of atmospheric temperature refraction, wind advection, and turbulence, but few direct comparisons of measurement to theory existed. To address this, Hank formed several collaborations using ray-tracing, fast-field, and parabolic equation methods for modeling refraction and advection, leading to benchmarks for outdoor sound propagation in 1993. Measurements of the short-term distributions of phase and amplitude over a few hundred meter distance revealed separate scattering regimes, with each being accessible by theory and numerical computation.
Coupling of airborne sound into the earth.
Authors: Sabatier James
Published: October 2013

While a student at the University of Southwestern Louisiana in 1982, I was attracted to the Physical Acoustics Research Group at the University of Mississippi after reading a list of physical acoustics publications left by Professor Gordon Baird on a graduate student recruitment trip. I made a brief visit to UM and met Hank, Bolen, and Crum. Hank offered me an assistantship ten times greater than the one at USL. I recall him saying the U.S. Army had a seismic sensor to detect tanks, but when helicopters flew overhead, the sensors alarmed. Aspects of this work were described in the paper, of Bass and Bolen [“Coupling of airborne sound into the earth: Frequency dependence,” J. Acoust. Soc. Am. 67, (1980)]. During graduate years at UM, I met Keith Attenborough and was introduced to the work of Keith, Hank, and Lee on microphones buried in soils and rigid frame porous media acoustics. Under their direction, my graduate acoustics education was spent applying Biot poroelasticity to first foot of the ground. In this talk, I will summarize the acoustic-to-seismic work that was done with Hank.
Optoacoustics in liquids and gasses.
Authors: Cheyne Stanley
Published: October 2013

Optoacoustics, the production of sound from light, was studied experimentally and theoretically during the 1980s at the University of Mississippi. Bass’s primary interest in optoacoustics was to understand the physical processes at the molecular level. In one paper [Ali et al., “Spectrophone measurements in sulfur hexafluoride,” IEEE UFFC-33, 615 (1986)], a detailed analysis of the energy transfer processes from IR laser radiation to the dissipation of the generated sound wave was investigated. In a second paper [Thompson et al., “Optoacoustic observation of internal relaxation in liquid CS2,” J. Acoust. Soc. Am. 85, 2405 (1989)], it was shown that a liquid with relatively slow relaxation times affected the temporal shape of the optoacoustic signal. Finally, in a third paper [S. A. Cheyne and H. E. Bass, “Observation of optoacoustic amplitude in CS2 at high input energies,” J. Acoust. Soc. Am. 88, 1842 (1990)], it was shown that the amplitude of the optoacoustic signal changed nonlinearly with input energy due to molecular interactions.
The wave propagation in porous material: A continuum from Biot solids to thermoacoustic heat engines.
Authors: Arnott William
Published: October 2013

Wave propagation in poroelastic materials has applications ranging from ground motion induced by atmospheric sound to thermoacoustic heat engines. Bass was involved with research in this entire continuum, including both basic and applied problems. This paper will especially cover the wave propagation formulation of thermoacoustics as it was applied by Bass and others to understand and predict the behavior of thermoacoustic prime movers. Some recollections of Bass as a statesman, scientist, and enjoyable character to be with will be presented. My first meeting with Bass and some of his guidance will also be discussed.