bluuebunny/crossref_metadata_2025 huggingface dataset:
Practical approach to forward and reciprocal sequential array measurements
Authors: Klein Johannes , Vorländer Michael
Published: May 2015

Room impulse response measurements including directivity are becoming a vital component of room acoustics. The results of these measurements allow for the room acoustical analysis regarding specific source receiver combinations and enable the realistic simulation of acoustical scenarios in virtual environments. Besides the widely applied microphone-arrays, electroacoustic sources with a steerable directivity are necessary to retain all degrees of freedom during the measurements. Due to the relatively large dimensions of the transducers, the number of possible physical transducers in a loudspeaker-array is very limited, resulting in a low spatial resolution. A solution to this problem are sequential measurement methods, which virtually enlarge the number of transducers by moving the source during the measurement and superposing the results. The attainable high spatial resolution is ideal for substituting the most complex source or receiver directivity in forward or reciprocal measurements. However, sequential measurement methods are very susceptible to time variances, which diminish the achievable accuracy. This study is an experimental approach with various source receiver combinations to evaluate the practically achievable accuracy in forward and reciprocal sequential loudspeaker-array measurements in different environments and the corresponding sources of error.
Exploring the vocal ontogeny of North Atlantic right whales
Authors: Root-Gutteridge Holly , Cusano Dana , Conger Lisa , Van Parijs Sofie , Parks Susan
Published: May 2015

The vocal ontogeny of species can provide insight into their physical and social development and capacity for social learning. North Atlantic right whales (Eubalaena glacialis) are an endangered species with a complex range of vocalizations used in a wide range of social contexts. In this study, we systematically characterize developmental changes in sound production from birth through adulthood. Calls have been recorded as part of ongoing North Atlantic right whale research projects spanning 2001 through 2015, and include data from calves as young as 1 month of age. Data included recordings from single hydrophones, hydrophone arrays, and non-invasive digital acoustic recording tags. Only calls which could be confidently attributed to a specific whale of known age were used in the analysis. Developmental periods consisted of 0–3 months, 3–6 months, 6–12 months, and then discrete ages by year. Calls of both male and female calves were included in the analysis. Calls were also classified to age categories using discriminant function analysis (DFA) to determine whether a calf could be aged by its call. Analyses indicate a gradual maturation of sound production with increasing age of individuals.
Comparison of managed care and wild walrus source characteristics
Authors: Denes Samuel L. , Miksis-Olds Jennifer L. , Mellinger Dave , Otjen Eric , Bowles Ann E.
Published: May 2015

Male Pacific walruses perform acoustic displays while in rut. The purpose of these displays is unknown but are hypothesized to be for territory defense or mate advertisement. Understanding source characteristics will allow the estimation of perceptibility by conspecifics. The displays occur in the Bering Sea in late winter where direct human observation is difficult. Working with an animal in managed care provided the ability to make direct observations of a male producing breeding vocalizations and the direct calculation of source level. Source characteristics from recordings of managed care and wild walruses were analyzed. The mean peak source level of the impulsive knocks produced by the managed care male was 183 dB (re: 1 μPa). The mean peak source level from the wild recordings was 177 dB (re: 1 μPa). For both wild and managed care vocalizations, a significant relationship between ambient noise level and source level was identified. An increase of approximately 5 dB in source level was found for an increase in 10 dB of noise level.
Mobility of dinoflagellates measured by high-frequency ultrasound
Authors: Kim Hansoo , Bok Tae-Hoon , Nam Kweon-Ho , Kim Juho , Paeng Dong-Guk , An So-Jeong , Lee Joon-Baek
Published: May 2015

The importance of phytoplankton contributing more than 50% of the global amount of photosynthesis has been emphasized for a long time. Sometimes, the over-growth of phytoplankton causes the negative influence such as red-tide phenomenon on marine ecological environments. Therefore, the measurement of the mobility of phytoplankton is important. In this study, the mobility of the benthic dinoflagellate, Amphidinium carterae Hulburt (A. Carterae) incubated by f/2 medium was investigated using high-frequency ultrasound. Backscattering signal from A. Carterae was measured for 2 s in every 2 min by a 40-MHz ultrasound transducer, and the integrated backscattering power calculation was followed. The mobility of A. carterae in response to the light was illustrated by M-mode image of the echoed signals. The mobility of A. carterae was estimated to about 0.4 mm/s for the upward movement in response to light, while its sedimentation rate was measured to about 0.1 mm/s in a dark environment. This study suggests that mobility of benthic dinoflagellates responding to light can be measured by M-mode imaging of high-frequency ultrasound. (This research was a part of the project titled “Measurement of cells division and photosynthesis of phytoplankton using ultrasound”, funded by the Ministry of Oceans and Fisheries, Korean.)
The vibroacoustical environment in two nuclear reactors
Authors: Hrisko Joshua , Garrett Steven L. , Smith Robert W. , Smith James A. , Agarwal Vivek
Published: May 2015

Laboratory experiments have suggested that thermoacoustic engines can be incorporated within nuclear fuel rods. Such engines would radiate sounds that could be used to measure and acoustically-telemeter information about the operation of the nuclear reactor (e.g., coolant temperature or fluxes of neutrons or other energetic particles) or the physical condition of the nuclear fuel itself (e.g., changes in porosity due to cracking, swelling, evolved gases, and temperature) that are encoded as the frequency and/or amplitude of the radiated sound [IEEE Measurement and Instrumentation 16(3), 18–25 (2013)]. For such acoustic information to be detectable, it is important to characterize the vibroacoustical environments within reactors. We will present measurements of the background noise spectra (with and without coolant pumps) and reverberation times within the 70,000 gallon pool that cools and shields the fuel in the 1 MW research reactor on Penn State’s campus using two hydrophones, a piezoelectric projector, and an accelerometer. Background vibrational measurement taken at the 250 MW Advanced Test Reactor, located at the Idaho National Laboratory, from accelerometers mounted outside the reactor’s pressure vessel and on plumbing, will also be presented to determine optimal thermoacoustic frequencies and predict signal-to-noise ratios under operating conditions. [Work supported by the U.S. Department of Energy.]
Use of evanescent plane waves for low-frequency energy transmission across material interfaces
Authors: Woods Daniel C. , Bolton J. S. , Rhoads Jeffrey F.
Published: May 2015

The transmission of sound across high-impedance difference interfaces, such as an air-water interface, is of significant interest for a number of applications. Sonic booms, for instance, may affect marine life, if incident on the ocean surface, or impact the integrity of existing structures, if incident on the ground surface. Reflection and refraction at the material interface, and the critical angle criteria, generally limit energy transmission into higher-impedance materials. However, in contrast with classical propagating waves, spatially decaying incident waves may transmit energy beyond the critical angle. The inclusion of a decaying component in the incident trace wavenumber yields a nonzero propagating component of the transmitted surface normal wavenumber, so energy propagates below the interface for all oblique incident angles. With the goal of investigating energy transmission using incident evanescent waves, a model for transmission across fluid-fluid and fluid-solid interfaces has been developed. Numerical results are shown for the air-water interface and for common air-solid interfaces. The effects of the incident wave parameters and interface material properties are also considered. For the air-solid interfaces, conditions can be found such that no reflected wave is generated, due to impedance matching among the incident and transmitted waves, which yields significant transmission increases over classical incident waves.
Outdoor measurements of shock-wave propagation from exploding balloons
Authors: Young Sarah M. , Gee Kent L. , Neilsen Traclanne B. , Leete Kevin M.
Published: May 2015

Previous anechoic measurements of exploding latex balloons filled with stoichiometric mixes of acetylene and oxygen revealed how these sources could be used to study weak-shock decay over relatively short ranges [M. B. Muhlestein et al., J. Acoust. Soc. Am. 131, 2422–2430 (2012)]. This paper describes an experiment conducted using a larger balloon over much longer propagation ranges at the Bonneville Salt Flats, which represents a hard, flat, relatively homogeneous ground surface. Measurements of a 0.56 m balloon were made along a propagation radial from 0.31 m from the balloon surface to 1600 m. Data were collected at a sampling rate of 204.8 kHz using piezoresistive pressure gauges and Type-1 condenser microphones. Described are waveform and spectral characteristics, as well as comparisons of the peak pressure decay with the weak-shock model employed previously. Waveform inspection and the comparison indicate that weak shocks are present out to at least 305 m and the amplitude decay rate can be predicted reasonably well using the model. Deviations from the model may be evidence of Mach-like reflections [K. M. Leete et al., Four Corners Ann. Meet. Am. Phys. Soc. 59, I7.00007 (2014)]. This work extends the previous laboratory experiments and serves as a foundation for further studies using this relatively low-cost source.
Mach reflections in the propagation of outdoor acoustic shocks generated by exploding balloons
Authors: Leete Kevin M. , Gee Kent L. , Neilsen Tracianne B. , Young Sarah M. , Truscott Tadd T. , Pendlebury Jonathon R.
Published: May 2015

When a shock wave reflects off a rigid surface, for certain combinations of shock strength and incident angle to the surface a Mach reflection can occur. This is when the incident and reflected shock waves merge to create a stronger shock wave (called a Mach stem) that travels parallel to the reflecting surface and whose height grows with distance. This phenomenon has been studied extensively for large explosions and for steady shock waves, but is less understood for acoustic weak shocks, where current models for Mach stem formation and growth do not agree with experimental observations. A weak-shock propagation experiment has been conducted at the Bonneville Salt Flats using blast waves generated by acetylene-oxygen filled balloons located at a fixed height above the ground. Analysis of acoustic data at various distances from the source and high-speed camera footage both identify a merging of the direct and ground-reflected waves and the formation of a Mach stem at locations closer to the source than theory would otherwise predict.
Underwater laser acoustic source control using shaped plasmas
Authors: Jones Theodore G. , Helle Michael , Kaganovich Dmitri , Ting Antonio , Nicholas Michael , Calvo David , DiComo Gregory , Caron James
Published: May 2015

NRL is developing an intense laser acoustic source using underwater shaped plasmas. Recent experiments include near-field acoustic source characterization using high energy lens-focused pulses of a Q-switched Nd:YAG 532 nm laser. The laser-generated plasma evolves into a piston expanding at supersonic speed, which launches an intense shock in the near field. The size and shape of this super-heated piston determines the acoustic waveform and energy spectral density (ESD). We have demonstrated the ability to change the ESD centroid from 15 kHz to a few MHz, with lower frequencies generated using highly elongated plasmas generated by a single laser pulse. We will discuss ongoing laser acoustic source experiments and research plans at NRL involving shaped underwater plasmas, including both demonstrated single-laser-pulse techniques and proposed two-laser-pulse techniques (T. G. Jones, et al., “Two laser generation of extended underwater plasma,” U.S. patent application 13/711,752). Two-laser-pulse acoustic generation hold promise for creating meter-scale plasmas, thereby lowering the acoustic ESD to the few-kHz frequency range, which is useful for long-range applications including sonar and communications. Acoustic source characterization includes acoustic waveform and directivity measurements using hydrophones sensitive from 1 Hz to 15 MHz. [This work was supported by NRL Base Funds.]
Updating and orientation in auditory space
Authors: Genzel Daria , MacNeilage Paul , Wiegrebe Lutz
Published: May 2015

For stable sound localization in space, a listener has to account for self-motion. This requires a head-to-world coordinate transformation by combining proprioceptive and vestibular inputs with the binaural cues for sound localization. Proprioceptive and vestibular information influence the evaluation of spatial auditory cues as indicated by the numerous proprioceptive and vestibular neural inputs into the auditory brainstem. First, we evaluate the relative influence of vestibular and proprioceptive cues on updating the world-centered position of auditory targets during active and passive head and/or body rotations in azimuth. Our results show that both vestibular and proprioceptive signals are used to update the spatial representations of auditory targets, but that vestibular inputs contribute more than proprioceptive inputs. Second, we explore the interplay of spatial audition and self-motion in subjects for which auditory space evaluation is of utmost importance, namely, for blind humans relying on echolocation. Again, the techniques and paradigm allow disentangling vestibular and proprioceptive components for effective orientation based on the auditory analysis of the echoes of self-generated sounds. Our data show how good human biosonar can get for spatial orientation and how self motion helps suppressing orientation biases by lateral walls and front-back confusions.
Perceived auditory motion is inaccurate during smooth head rotation
Authors: Freeman Tom C. , Culling John F. , Akeroyd Michael A. , Brimijoin W Owen
Published: May 2015

Hearing is confronted by a similar problem to vision as the observer moves. Movement of the sensors creates image motion that remains ambiguous until the observer knows the velocity of eye and head. The visual system solves this problem using motor commands, proprioception, and vestibular information (so-called “extra-retinal signals”), but the solution is not always perfect. Here, we compare the auditory errors made during head rotation with the visual mistakes made during eye movement. Real-time measurements of head velocity were used to change the gain relating head movement to source movement across a loudspeaker array. The gain at which “extra-cochlear signals” (encoding head rotation) was perceptually matched to “acoustic signals” (encoding source motion across the ears), thus yielding the perception of a stationary source, was small and positive. The gain varied depending on context, e.g., average source direction with respect to head. Two possible accounts of analogous findings in vision will be discussed, one based on differences in neural signal accuracy and the other based on Bayesian estimates that resolve differences in neural signal precision. We consider the degree to which these explanations can be applied to auditory motion perception in moving listeners.
Navigating the world using echo flow patterns
Authors: Warnecke Michaela , Moss Cynthia F.
Published: May 2015

As an animal moves through the environment, it experiences flow of sensory information from stationary objects. Animals that relylargely on visual information to guide their movement experience optic flow patterns as they navigate, which can be used to measure the relative distance of objects in the environment (Gibson, 1958, Besl, 1988). For example, honeybees use optic flow patterns to center themselves in a flight corridor, and experimental manipulations of the visual patterns on the walls directly influence the animal’s navigation path (Srinivasan et al., 1996). Other animals instead show wall-following behavior, choosing to navigate close to visual obstacles (Scholtyssek et al., 2014). Here, we report on the navigation paths of animals that rely on acoustic signals to guide their movement. Echolocating bats emit ultrasonic signals that reflect from objects in the path of their sound beam, and we are studying how these animals use echo flow to guide their flight path through a corridor. In this study, we flew echolocating big brown bats through tunnels of horizontally and vertically hung PVC pipes to investigate how acoustic patterns influence the bat’s flight and echolocation behavior.
Aurally aided visual search performance for stationary and walking listeners
Authors: Brungart Douglas , Kwiatkowski Tricia , Kruger Sarah E. , Cohen Julie , Heil Thomas A. , Zion Danielle
Published: May 2015

One of the most important functions of spatial hearing is to facilitate the rapid shift of visual gaze in the direction of newly detected sound sources that might represent potential targets or threats in our environment. Some of the most dangerous threats can emerge when listeners are walking, so it is useful to know what impact walking might have on audiovisual target detection and identification in complex scenes. This study used a virtual environment consisting of a motorized treadmill surrounded by a 180° projection screen mounted in front of a 64-loudspeaker array to evaluate how quickly participants were able to detect a visual target displayed in the presence of multiple distracters. The distracters were small clusters containing 2 or 4 dots, and the target was a small cluster containing 1 or 3 dots that was presented from the same location as a pulsed broadband noise. The task was to find the target as quickly as possible and press a button to indicate if it had 1 or 3 dots. Data were also collected in an auditory localization condition that required listeners to move a cursor to the location of the sound source and a visual-only condition that required participants to perform the visual search task with no auditory cue. The results show that target identification times were generally reduced when the listener was walking, suggesting that the increased motor activation caused by walking may enhance the ability to perform audiovisual searches. [Research Supported by DoD PHTBI award (W81XWH-12-2-0068).]
Maximum equivalent pressure output and maximum stable gain of a light-activated contact hearing device that mechanically stimulates the umbo: Temporal bone measurements
Authors: Puria Sunil , Perkins Rodney , Santa Maria Peter
Published: May 2015

The non-surgical contact hearing device (CHD) consists of a light-activated balanced-armature tympanic-membrane transducer (TMT) that drives the middle ear through contact with the umbo, and a behind-the-ear unit with a widely vented light-emitter Assembly inserted into the ear canal that encodes amplified sound into pulses of light that drive and power the TMT. In comparison to acoustic hearing aids, the CHD is designed to provide higher levels of maximum equivalent pressure output (MEPO) over a broader frequency range and a significantly higher maximum stable gain (MSG). No artificial middle-ear model yet exists for testing the CHD, so we instead measured it using fresh human cadaveric temporal bones. To calculate the MEPO and MSG, we measured the pressure close to the eardrum and stapes velocity for sound drive and light drive using the CHD. The baseline sound-driven measurements are consistent with previous reports in temporal bones. The average MEPO (N = 4) varies from 116 to 128 dB SPL in the 0.7 to 10 kHz range, with the peak occurring at 7.6 kHz. From 0.1–0.7 kHz, it varies from 83 to 121 dB SPL. For the average MSG, a minimum of about 10 dB occurs in the 1–4 kHz range, above which it rises as high as 42 dB at 7.6 kHz. From 0.2 to 1 kHz, the MSG decreases linearly from about 40 dB to 10 dB. The measurements of MEPO and MSG are compared with predictions from circuit-model calculations. The CHD may offer a way of providing broad-spectrum amplification appropriate to treat listeners with mild-to-severe hearing impairment.
Effect of some basic and premium hearing aid technologies on non-speech sound acceptability
Authors: Xu Jingjing , Johnson Jani A. , Cox Robyn M.
Published: May 2015

Acceptability of everyday non-speech sounds is closely related to hearing aid (HA) satisfaction. Acceptability is determined by a listener’s overall impression of a sound when its different aspects, such as loudness, naturalness, and clarity, are considered. Various HA features, especially digital noise reduction (DNR), are designed to improve acceptability. Compared to basic HAs, premium HAs have more advanced DNR functions, as well as other unique features that are not included in basic HAs. Manufacturers often claim that everyday non-speech sounds are more acceptable when listening with premium HAs relative to basic HAs. However, there is minimal evidence to support this claim. This study evaluated acceptability of non-speech sounds in laboratory and real-world settings when using exemplars of basic and premium HAs. Forty-five older adults with mild-to-moderate hearing loss were bilaterally fitted with four pairs of BTEs (two basic and two premium) from two major manufacturers. Outcomes were obtained for each pair after a four-week field trial. Laboratory data were acceptability ratings of 21 real-time produced everyday sounds with different durations and intensities. Self-report data were rating scores from three questionnaires. No evidence was found in this study to show that premium HAs yield greater acceptability than basic. (Work supported by NIDCD.)
Effect of spectral amplitude elevation for vowel identification in simulated combined electric-and-acoustic hearing
Authors: Chen Fei
Published: May 2015

Though the benefits of combined electric-and-acoustic stimulation (EAS) have been widely reported, its underlying mechanisms responsible are not well understood yet. This study assessed the effect of balanced spectral amplitudes between acoustic and electric portions in EAS to vowel identification via two experiments. Four vowels (i.e., /iy/, /eh/, /oo/ and /ah/) were synthesized using pure-tone harmonic components. In Experiment 1, the spectral amplitudes of natural vowels were elevated for either acoustic (below 600 Hz) or electric portions (above 600 Hz) from 5 dB to 30 dB. Vowel identification scores were collected from eight normal-hearing listeners. In Experiment 2, the synthesized vowel stimuli were processed by the signal processing condition simulating the electric-and-acoustic stimulation. The results of identifying synthesized vowels and synthesized EAS-processed vowels in the two experiments showed the similar patterns of declined identification rates as a function of (acoustic or electric) spectral amplitude elevation. Furthermore, the specific loudness pattern computed from Moore et al.'s model was used to predict the vowel identification score, yielding a good prediction performance (i.e., r = 0.9). The results in the present work suggested the importance to maintain the balance between the spectral amplitudes of acoustic and electric portions for vowel identification in EAS hearing.
Can you say that again? Aging and repetition effects in different types of maskers
Authors: Helfer Karen S. , Freyman Richard L. , Costanzi Angela , Laakso Sarah , Merchant Gabrielle
Published: May 2015

The most common strategy used by listeners when they cannot understand an utterance is a request for repetition. Repetition may improve perception in a number of ways, including priming the target message via sharpening the representation of aspects of the signal centrally, buying additional time for the listener to process the message, and enhancing the coding of information into memory. In the present study, the benefit of hearing an utterance a second time was measured in three different types of maskers (competing speech, single-channel envelope modulated noise, and steady-state speech shaped noise) using two different tasks: immediate recognition of the target sentence and memory for words presented during a previous block of trials. For the latter task, participants were presented with isolated words and were asked if those words appeared in the previous set of sentences. Participants (younger, middle-aged, and older adults) also completed a battery of cognitive tasks that included measures of processing speed, attentional control, and working memory. This presentation will describe results of analyses comparing the benefit of repetition for immediate recall and memory among the listener groups in the presence of different types of maskers. (Work supported by NIDCD R01 DC012057.)
Listener consistency in identifying speech mixed with particular “bubble” noise instances
Authors: Mandel Michael I. , Yoho Sarah E. , Healy Eric W.
Published: May 2015

Previous work has shown that the intelligibility of mixtures of the same exact speech token with different instances of “bubble” noise is highly dependent on the configuration of the random time-frequency glimpses it provides. In the current study, the consistency of these judgments was measured for such mixtures involving six consonants, /t/, /d/, /f/, /v/, /t͡ʃ/, /d͡ʒ/, in an /a/-consonant-/a/ context. Intra-subject consistency on ten repetitions each of 60 mixtures was found to be high, as was inter-subject consistency between five normal-hearing subjects on 1200 mixtures. In addition, the noise level at a small subset of time-frequency points was significantly correlated with the overall intelligibility of the mixtures of a given token, suggesting that these regions contribute more strongly to correct identification than others. The current study finds that these regions are quite consistent across the five subjects. For example, for the token /ada/, these points surround the stop burst and the resolved harmonics following the onset of voicing. These results show the promise of the “bubbles” methodology for identifying time-frequency regions of individual utterances that contribute most to their intelligibility, permitting future study of such regions for different types of speech and listeners. [Work supported by NIH.]
The effect of amplitude envelope on spatial ventriloquism
Authors: Beauregard Cazabon Dominique , Schutz Michael
Published: May 2015

Spatial ventriloquism occurs when a visual event and an auditory event happen simultaneously; location judgments for the sound source become biased toward the location of the visual event. Evidence suggests the brain attributes greater weight to spatial information provided by the visual stimulus because the visual system offers better spatial acuity; when the visual stimulus is deteriorated, the visual bias is reduced. Thus, the brain performs optimal bimodal integration: greater weight is given to the modality which provides more information. The present study aims to determine whether the amplitude envelope of sounds provides spatial localization information to the perceptual system. We used a psychophysical staircase procedure to measure spatial ventriloquism experienced by participants for sounds with percussive, flat, and time-reversed percussive envelopes. We hypothesize that percussive and reverse-percussive sounds provide more information and thus better sound localization acuity than flat sounds, which would result in smaller degrees of spatial ventriloquism for the former than the latter. The results yield insight into the brain’s use of auditory cues in audio-visual integration.
Envelope-power based prediction of auditory masking and speech intelligibility
Authors: Biberger Thomas , Ewert Stephan D.
Published: May 2015

In natural surroundings, people are often part of challenging acoustical scenarios (noise) interferers and reverberation. Amplitude modulations (AM) are fundamental acoustic features used to extract information in such situations. It has been shown that the envelope power spectrum model [EPSM; Ewert and Dau, J. Acoust. Soc. Am. 108, 1181 (2000)] can account for psychoacoustic AM detection and masking data by considering the long-term envelope signal-to-noise-ratios (SNR) at the output of modulation filters. Recently, this concept was extended to consider short-term envelope SNRs to predict speech intelligibility in fluctuating maskers and in reverberation [mr-sEPSM; Jørgensen et al., J. Acoust. Soc. Am. 134, 1475 (2013)]. In this study, the EPSM was further extended to consider envelope power SNRs (AM cues) on various time scales and “classic” power SNRs (intensity cues). The goal was to develop an auditory model for jointly predicting psychoacoustic masking and speech intelligibility. The model was demonstrated to account for a broad variety of psychoacoustic effects as AM detection, AM discrimination, AM masking, spectral masking, forward masking, intensity just-noticeable-differences (JNDs) and hearing threshold. Speech intelligibility was predicted comparable to Jørgensen et al.. Implications for future modeling including applications to audio and speech quality assessment are discussed.
Masked speech recognition in a single-talker or a single-talker-plus-noise masker in school-age children and adults
Authors: Porter Heather , Leibold Lori J. , Buss Emily
Published: May 2015

Previous work has shown that masked speech perception is poorer in younger children than older children and adults, particularly when the masker is composed of speech. The present study tested the hypothesis that young children’s poor performance in speech maskers is due to reduced ability to benefit from transient improvements in the target-to-masker ratio (TMR). Listeners were normal-hearing school-age children (5–15 years) and adults. The target words and masker speech were produced by two different female talkers. Target stimuli were disyllabic words, and the masker was either: (1) speech-only or (2) speech-plus-noise. Both maskers included a continuous 60-dB-SPL stream of speech. The speech-plus-noise masker also included a continuous 50-dB-SPL speech-shaped noise. A four-alternative forced choice task was used, and target level was adapted to estimate threshold. Thresholds were higher for younger children than older children or adults for both masker conditions. While the inclusion of speech-shaped noise increased thresholds for all listeners, it had a smaller detrimental effect on younger children than on older children and adults. This result is consistent with the idea that greater susceptibility to speech-on-speech masking in younger children is related to a reduced ability to benefit from transient improvements in TMR.
An algorithm that generalizes to novel noise segments to improve speech intelligibility for hearing-impaired listeners
Authors: Healy Eric W. , Yoho Sarah E. , Chen Jitong , Wang Yuxuan , Wang DeLiang
Published: May 2015

Machine-learning algorithms to extract speech from background noise hold considerable promise for alleviating limitations associated with hearing impairment. One of the most important considerations for implementing these algorithms into devices such as hearing aids and cochlear implants involves their ability to generalize to conditions not employed during the training stage. A major challenge involves the generalization to novel noise segments. In the current study, sentences were extracted from multi-talker babble and from cafeteria noise using an algorithm that estimates the ideal ratio mask by employing deep neural networks. Importantly, the algorithm was trained on segments of noise and tested using entirely different segments of the same nonstationary noise type. The training set was expanded through a noise-perturbation technique. Substantial benefit was observed for hearing-impaired listeners in both noise types, despite the use of unseen noise segments during the operational stage. Interestingly, normal-hearing listeners displayed benefit in babble but not in cafeteria noise. These results highlight the importance of evaluating these algorithms not only in human subjects, but in members of the actual target population. [Work supported by NIH.]
Speaking while listening: Broadbent revisited
Authors: Iyer Nandini , Thompson Eric , Simpson Brian , Romigh Griffin
Published: May 2015

Air Force operators are often required to listen to several channels of ongoing radio communications while simultaneously responding to some or all of these messages. Broadbent (1952) showed that performance in such speaking-while-listening tasks typically resulted in a significant degradation. However, it was not clear if this decrement in performance was due to a competition of the resources required for simultaneous message comprehension and response formulation, or some other factor influencing the representation (such as poor signal quality). A replication of Broadbent’s study was undertaken to measure the ability of subjects to perform in speaking-while-listening tasks. Listeners responded to a series of yes-no queries posed by a recorded talker regarding the presence/location of items on a visual display. Responses were scored based on a subject's ability to (1) respond to their assigned call-sign, (2) use the correct querier call sign in their response, and (3) provide a response to the question about the query item. Two variables were manipulated: rate of incoming messages and fidelity of the recordings (additive noise or radio communications). Results indicate that changing the rate of incoming messages had the largest impact on accuracy of responses, while the fidelity of the message had a relatively minor impact on performance, suggesting that limitations in these tasks may be largely due to an interference with response formulation.
Research on listening effort: History and methods, theory, and practice
Authors: Francis Alexander L. , Füllgrabe Christian
Published: May 2015

The notion of listening effort has enjoyed a resurgence in recent years, with new work appearing in both theoretically and clinically oriented venues, and researchers pursuing this topic with an increasingly inventive suite of methods. Listening effort is often associated with perceptual and/or cognitive processing demands for understanding speech, terms that are often (but not necessarily) identified with mechanisms such as attention and working memory. Much of the recent research involving listening effort has arisen in the context of studies of people with hearing impairment and of people listening in adverse or sub-optimal conditions, thus highlighting a particular need to distinguish between measures of effort and more traditional measures of listening performance such as intelligibility. However, there is considerable terminological variety within the field, and significant debate concerning both the theoretical characterization and the clinical implications of all of these concepts. The goal of this talk is to provide a broad introduction to current research on listening effort, situating it within the context of a longer history of psychological studies of human performance and task demands and surveying some of the more common behavioral and psychophysiological methods used to assess listening effort for research and clinical purposes.
Listening effort and the division of auditory processing resources
Authors: Gallun Frederick J.
Published: May 2015

When a listener is asked to simultaneously perform two different tasks, the results can reflect a wide range of factors. This presentation will describe data showing that performance reflects not only the division of a single resource shared between the tasks, but also the structure of the tasks themselves. Thus, if two tasks share structural resources (such as the same auditory pathway or the same memory representations) there may be interference even if there is still spare capacity at the level of other cognitive resources. Similarly, reduced effort may reflect independent structural constraints rather than increased capacity. For example, if the structure of the tasks allows the listener to rely upon a memory representation for one or both tasks, then a task in which the stimuli are presented simultaneously can be processed serially by relying on the memory trace to do the secondary task. The implications of this framework for studies examining listening effort will be discussed, along with ideas about ways to improve the design of experiments seeking to probe the capacity of a single shared resource.
High-frequency broadband seafloor backscatter in a sandy estuarine environment
Authors: Bajor Eric J. , Weber Thomas C. , Ward Larry , Rzhanov Yuri , Hu Han
Published: May 2015

Seafloor backscatter collected with high-frequency (>100 kHz) hydrographic echosounders has become an important aspect of seafloor characterization for benthic ecologists and other scientists. The mechanisms that control acoustic scattering at these high frequencies are not completely understood, although surficial roughness and the presence of large scatterers (e.g., shell hash) are likely contributors. To further our understanding of these mechanisms, broadband (100–250 kHz) acoustic measurements were taken at a grazing angle of 45 degrees in a shallow-water, sandy environment with a known presence of shell hash. Stereo imagery was collected simultaneously to quantify the roughness spectrum of the seafloor. Sediment samples were also collected on site of the experiment to quantitatively analyze the content of shell hash. The frequency dependence of the seafloor backscatter will be discussed in terms of its consistency, or lack thereof, with surficial roughness and shell-fragment scattering models.
Statistics of very high frequency sound scattered from wind-driven waves
Authors: Walstead Sean , Deane Grant B.
Published: May 2015

The amplitude, Doppler spread, and temporal coherence of VHF scattering is important for the performance of high frequency sonars and underwater communications systems in operating scenarios where energy from the sea surface cannot be screened. For this talk, the amplitude and arrival time statistics of very high frequency (50 kHz–2000 kHz) sound scattered from a rough wind-driven wave surface are modeled. Saturation occurs in the normalized second moment of acoustic intensity when the surface correlation length exceeds a Fresnel zone length. Fluctuations in arrival time do not saturate and increase proportionally to the dominant surface wave component. Data collected at 300 kHz agree with the model results. Energy is first detected in the wind-driven surface wave field at wavelengths of 1.7 cm and 3.4 cm. The former wave corresponds to a gravity-capillary wave whose phase speed is at a minimum. The principal appearance of this type of wave has threshold implications for the range of acoustic transmission frequencies susceptible to saturation in amplitude statistics.
Nonlinear interaction of monochromatic wave with noise
Authors: Yang Desen , Liu Qing , Shi Shengguo , Shi Jie , Hu Bo
Published: May 2015

The nonlinear interaction of monochromatic wave with noise is studied theoretically, and that is based on the theory of O. V. Rudenko about interactions of intense noise waves and the theory of G. H. Du about nonlinear interaction of finite amplitude irregular waves. The effect on shifting of noise energy by the intensity and frequency of monochromatic wave is discussed during the propagation of the monochromatic wave and noise. Some numerical simulations about this process are conducted under different initial conditions to investigate the changes of their spectrum. The agreement between theoretical analysis and numerical simulation demonstrates that under some conditions the noise can be modulated and the noise spectrum becomes flatter and broader with the increasing distance.
Experimental results of adaptive multichannel decision feedback equalization in shallow channel
Authors: Sheng XueLi , Fan LiNa , Song Aijun , Badiey Mohsen
Published: May 2015

A kind of underwater communication receiver combined with mean-squared error adaptive error adaptive algorithm and multichannel decision feedback equalization (AMDFE) is studied, which can address the problem of underwater communications over a time-varying multipath channel in the presence of worse intersymbol interference and waveform distortion. Its performances in different range and sound profile have been analyzed by simulated shallow water channels in the earlier paper. In this paper, the performances of AMDFE in different underwater channels with different parameters are mainly demonstrated by the experiments on the lake and sea. The anti-multipath ability and parameters selection regulation of AMDFE in both near and long range are proved by real data in shallow water.
Experimental demonstration of multiband underwater acoustic transmissions based on single carrier communication
Authors: Han Xiao , Yin Jingwei , Yu Ge , Liu Bing
Published: May 2015

In a recent shallow water experiment, multiband transmissions were carried out using a vertical array with six sensors uniformly spaced every 0.5 m. The entire frequency band (2–8 kHz) was divided into two sub-bands, each of which is about 2.55 kHz in width. Time reversal processing is first used to compress severe multipath spread, following by a single channel decision feedback equalizer (DFE) to remove residual inter-symbol-interference (ISI). Using experimental data, this paper demonstrates that multiband transmissions are very beneficial to improve the throughput of underwater acoustic communications, achieving a data rate of 6k bits/s using QPSK modulation with almost error free performance.
Experimental demonstration of under ice acoustic communication
Authors: Yin Jingwei , Du Pengyu , Wang Xin , Guo Jiahao
Published: May 2015

Under ice acoustic communication experimental was done in Songhua River, Harbin, China, in January 2015. Minus 20–30 degrees work environment brings a great challenge to the under ice experimental. A series of underwater acoustic communication tests including spread spectrum, OFDM, pattern time delay shift coding (PDS) and CDMA have been achieved. Experimental result shows that the under ice channel is relatively stable and the closer to the ice the simpler the channel structure is. All of the under ice acoustic communication tests achieve low bit error rate communication at 1 km range with different received depth. Under ice CDMA multiuser acoustic communication shows that as many as 12 users can be supported simultaneously with as few as five receivers in under ice channels, using the time reversal mirror combined with the differential correlation detectors.
Fading statistics variation and optimum Mary frequency shift keying system design in sea surface fluctuation
Authors: Dandan Xue , Park Kyu-Chil , Park Jihyun , Yoon Jong R.
Published: May 2015

The underwater acoustic channel can be expressed as a frequency selective fading channel due to multipath, sea surface roughness, and propagation medium change with time and space. Therefore the fading statistics varies with time, space, and frequency. Inherent factor of this fading change is related to a frequency dependent constructive or destructive interference change with time, space, and frequency. The magnitude of interference depends on closely on sea surface roughness. In this study, channel fading statistics are analyzed with delay spread and Doppler spread using pseudo noise (PN) signals. Based on this channel fading statistics, a low data rate M-ary frequency shift keying (MFSK) system of 1kbit/s, is designed for a command/control of navigation or an equipment status monitoring system. The forward error correcting code of convolution code is also applied. Experimental work is conducted in shallow water and it is found that the design parameters of MFSK system can be optimized using the measured fading statistics deduced from PN signal.
What acousticians need to know about the third party sound transmission class testing process and acoustical materials performance validation
Authors: Wolfram Eric P.
Published: May 2015

The architectural product industry demonstrates sound transmission loss performance by commissioning third party tests from accredited laboratories performed according to the ASTM E90 standard. This presentation will provide insight into the materials testing process, laboratory quality management, and explanation of the report documents. The presenter will share experience and advice for the use of test results to evaluate acoustical product performance. Acousticians, architects, and engineers must play a role in improving quality of published data by demanding more complete information from manufacturer's marketing departments regarding product acoustical performance.
Laymon Miller, distinguished consultant in noise control engineering at Bolt Beranek and Newman
Authors: Beranek Leo
Published: May 2015

Laymon Miller was employed in Harvard’s Underwater Sound Lab (HUSL), under the direction of Professor F. V. Hunt during World War ll. When that laboratory closed, Laymon joined the consulting staff at Bolt Beranek and Newman (BBN). Laymon became BBN’s leading expert on the reduction of noise and vibration in ventilating systems. One of his important jobs was noise reduction at New York’s Lincoln Center’s Philharmonic Hall. He also became expert in vibrations transmitted through the earth. In particular, he designed the vibration isolation pads used to reduce the transmission of railroad track vibrations into adjacent buildings in a number of cities, including Boston’s Back Bay and Montreal. Practically every important building acoustics project that came into BBN received his attention. He gained the reputation of more chargeable consulting time each month than any other employee. Besides mentoring numerous new BBN employees he taught highly sought after courses on noise reduction for architects, building, industrial and plant engineers, as well as for other acoustical consultants.
Origin and history of the Laymon Miller noise course
Authors: Keith Reginald H.
Published: May 2015

For 20 years, starting in 1969, Laymon Miller produced and taught a seminal course in noise and vibration control in many different venues and settings. In this paper, I will present information as to the origins of this course, my recollections of first attending the course in 1977, and our experiences in the continuation of the course since 1989.