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Passive acoustic monitoring is a promising tool for monitoring at-risk populations of vocal species, yet, extracting relevant information from large acoustic datasets can be time-consuming, creating a bottleneck at the point of analysis. To address this, an open-source framework for deep learning in bioacoustics to automatically detect Bornean white-bearded gibbon (Hylobates albibarbis) "great call" vocalizations in a long-term acoustic dataset from a rainforest location in Borneo is adapted. The steps involved in developing this solution are described, including collecting audio recordings, developing training and testing datasets, training neural network models, and evaluating model performance. The best model performed at a satisfactory level (F score = 0.87), identifying 98% of the highest-quality calls from 90 h of manually annotated audio recordings and greatly reduced analysis times when compared to a human observer. No significant difference was found in the temporal distribution of great call detections between the manual annotations and the model's output. Future work should seek to apply this model to long-term acoustic datasets to understand spatiotemporal variations in H. albibarbis' calling activity. Overall, a roadmap is presented for applying deep learning to identify the vocalizations of species of interest, which can be adapted for monitoring other endangered vocalizing species. [ABSTRACT FROM AUTHOR]

This study aims to detect the bioacoustics signal in the underwater soundscape, specifically those produced by snapping shrimp, using adaptive iterative transfer learning. The proposed network is initially trained with pre-classified snapping shrimp sounds and Gaussian noise, then applied to classify and remove snapping-free noise from field data. This separated ambient noise is subsequently used for transfer learning. This process was iterated to distinguish more effectively between ambient noise and snapping shrimp sounds characteristics, resulting in improved classification. Through iterative transfer learning, significant improvements in precision and recall were observed. The application to field data confirmed that the trained network could detect signals that were difficult to identify using existing threshold classification methods. Furthermore, it was found that the rate of false detection decreased, and detection probability improved with each stage. This research demonstrates that incorporating the noise characteristics of field data into the trained network via iterative transfer learning can generate more realistic training data. The proposed network can successfully detect signals that are challenging to identify using existing threshold classification methods. [ABSTRACT FROM AUTHOR]

Fish bioacoustics, or the study of fish hearing, sound production, and acoustic communication, was discussed as early as Aristotle. However, questions about how fishes hear were not really addressed until the early 20th century. Work on fish bioacoustics grew after World War II and considerably in the 21st century since investigators, regulators, and others realized that anthropogenic (human-generated sounds), which had primarily been of interest to workers on marine mammals, was likely to have a major impact on fishes (as well as on aquatic invertebrates). Moreover, passive acoustic monitoring of fishes, recording fish sounds in the field, has blossomed as a noninvasive technique for sampling abundance, distribution, and reproduction of various sonic fishes. The field is vital since fishes and aquatic invertebrates make up a major portion of the protein eaten by a signification portion of humans. To help better understand fish bioacoustics and engage it with issues of anthropogenic sound, this special issue of The Journal of the Acoustical Society of America (JASA) brings together papers that explore the breadth of the topic, from a historical perspective to the latest findings on the impact of anthropogenic sounds on fishes. [ABSTRACT FROM AUTHOR]

The oyster toadfish, Opsanus tau, has been a valuable biomedical model for a wide diversity of studies. However, its vocalization ability arguably has attracted the most attention, with numerous studies focusing on its ecology, behavior, and neurophysiology in regard to its sound production and reception. This paper reviews 30 years of research in my laboratory using this model to understand how aquatic animals detect, integrate, and respond to external environment cues. The dual vestibular and auditory role of the utricle is examined, and its ability to integrate multimodal input is discussed. Several suggestions for future research are provided, including in situ auditory recording, interjecting natural relevant ambient soundscapes into laboratory sound studies, adding transparency to the field of acoustic deterrents, and calls for fish bioacoustics teaching modules to be incorporated in K-12 curricula to excite and diversify the next generation of scientists. [ABSTRACT FROM AUTHOR]

My research in fish bioacoustics started in the mid-1980s and comprised the diversity in sound-generating mechanisms and sound production in various contexts such as dyadic contests. I worked on European freshwater and marine fish, but mainly on tropical fish from Southeast Asia (gouramis) and the Amazonian River system (pimelodid, doradid catfishes, piranhas). The diversity of sonic organs raised the question if general patterns of innervation of sonic muscles in vocal fishes exist. Different vocal (sonic) motor nuclei were identified in the brainstem and rostral spinal cord for pectoral and swim bladder vibration mechanisms. In addition, I wanted to find out if vocal fish differ from nonvocal species in hearing abilities. Measurements applying the auditory evoked potential technique revealed a large diversity of auditory sensitivities depending on the presence or lack of accessory hearing structures independently of sound production. Furthermore, I investigated the anatomy, ultrastructure of inner ears, and hearing enhancement by auxiliary hearing structures. Recently, we studied sound-induced motion of swim bladders, auditory ossicles, and otoliths using x-ray phase contrast imaging. A large part of my studies was carried out in cooperation with laboratories in the USA, Germany, Italy, Portugal, and Brasilia which made my research interesting. [ABSTRACT FROM AUTHOR]

I have been studying fish hearing since 1966. Over that time, my interests have evolved from basic mechanisms of hearing to "translational fish bioacoustics" where I help apply basic science to the protection of fishes from potential harm arising from anthropogenic sources. Yet, I am still most interested in basic science questions. Thus, this paper focuses on basic questions on fish hearing and shares my personal view of some of the interesting and important questions I think need to be asked about fish hearing by future investigators. Accordingly, I am not focusing on what has been learned, but, rather, I focus on the questions raised by what we have learned. Moreover, my focus is comparative—there are more than 34 000 extant fish species—and we know little about hearing in any one species. Indeed, most of our knowledge comes from about 100 species! Therefore, considering the immense importance of fishes, it is my contention that we need to know a great deal more about the sense that gives fishes rapid and highly directional information, often at a great distance, about the world around them. [ABSTRACT FROM AUTHOR]

Fish bioacoustics is about the sounds produced by fish, how fish hear, and what they hear. The focus of this article is on the hypothesis that some late pelagic stage reef fish larvae use the marine soundscape to locate reef settlement habitat. The hypothesis is evaluated by consideration of the nature of reef sound, hearing ability in late-stage larval fish, and direct behavioral evidence for orientation to reef sound. [ABSTRACT FROM AUTHOR]

My interest in fish bioacoustics was ignited more than 50 years ago and resulted in a zigzag time travel between various interesting problems that were unsettled at the time. The present paper gives a brief overview of the main topics I have worked on in the field of fish hearing, i.e., auditory function of the swim bladder, directional hearing, function of the lateral line system, and infrasound sensitivity. Rather than being a comprehensive review of these issues, the paper is autobiographical and limited. The aim is to show young scientists that experimental science can be exciting, diverse, and rewarding—and open doors to a rich collegial network, collaboration, and friendships. [ABSTRACT FROM AUTHOR]

This paper gives a brief synopsis of the research career of S.C. in fish bioacoustics with an emphasis on dipole near fields. The hydroacoustic nature of the dipole near field and the effective stimuli to lateral line and auditory systems combine to produce a multisensory, range-fractionated region that is critically important to many fish behaviors. The mottled sculpin and goldfish lateral lines encode the spatial complexities of the near field as spatial excitation patterns along the body surface to provide instantaneous snapshots of various source features such as distance, orientation, and direction of movement. In contrast, the pressure-sensitive channel of the goldfish auditory system [the anterior swim bladder (SB)-saccule complex] encodes the spatial complexities in a temporal fashion whenever the position or orientation of the source changes with respect to the anterior SB. A full appreciation for how these somatotopic and egocentric representations guide fish behavior requires an understanding of how multisensory information, including vision, is combined in sensorimotor regions of the brain to effect behavior. A brief overview of vertebrate brain organization indicates that behaviors directed to or away from hydroacoustic sources likely involve a variety of mechanisms, behavioral strategies, and brain regions. [ABSTRACT FROM AUTHOR]

Passive acoustic monitoring is emerging as a low-cost, non-invasive methodology for automated species-level population surveys. However, systems for automating the detection and classification of vocalizations in complex soundscapes are significantly hindered by the overlap of calls and environmental noise. We propose addressing this challenge by utilizing an acoustic vector sensor to separate contributions from different sound sources. More specifically, we describe and implement an analytical pipeline consisting of (1) calculating direction-of-arrival, (2) decomposing the azimuth estimates into angular distributions for individual sources, and (3) numerically reconstructing source signals. Using both simulation and experimental recordings, we evaluate the accuracy of direction-of-arrival estimation through the active intensity method (AIM) against the baselines of white noise gain constraint beamforming (WNC) and multiple signal classification (MUSIC). Additionally, we demonstrate and compare source signal reconstruction with simple angular thresholding and a wrapped Gaussian mixture model. Overall, we show that AIM achieves higher performance than WNC and MUSIC, with a mean angular error of about 5°, robustness to environmental noise, flexible representation of multiple sources, and high fidelity in source signal reconstructions. [ABSTRACT FROM AUTHOR]

Deep learning is one established tool for carrying out classification tasks on complex, multi-dimensional data. Since audio recordings contain a frequency and temporal component, long-term monitoring of bioacoustics recordings is made more feasible with these computational frameworks. Unfortunately, these neural networks are rarely designed for the task of open set classification in which examples belonging to the training classes must not only be correctly classified but also crucially separated from any spurious or unknown classes. To combat this reliance on closed set classifiers which are singularly inappropriate for monitoring applications in which many non-relevant sounds are likely to be encountered, the performance of several open set classification frameworks is compared on environmental audio datasets recorded and published within this work, containing both biological and anthropogenic sounds. The inference-based open set classification techniques include prediction score thresholding, distance-based thresholding, and OpenMax. Each open set classification technique is evaluated under multi-, single-, and cross-corpus scenarios for two different types of unknown data, configured to highlight common challenges inherent to real-world classification tasks. The performance of each method is highly dependent upon the degree of similarity between the training, testing, and unknown domain. [ABSTRACT FROM AUTHOR]

Environmental and ecological factors can trigger changes in the acoustic repertoire of cetaceans. This study documents the first use of a well-established passive acoustic monitoring device (C-POD) to analyze echolocation sounds and behavior of franciscana dolphins in different habitats: estuary [Babitonga Bay (BB)] and open sea [Itapirubá Beach (IB)]. A total of 10 924 click trains were recorded in BB and 6 093 in IB. An inter-click interval < 10 ms (so called "feeding buzzes") was used as a proxy for foraging activity. The main difference in the acoustic parameters between the two habitats was related to the frequency spectrum, with higher maximum and lower modal and minimum click frequencies in BB, and a train frequency range of 17 kHz, against 10 kHz in IB. Also, the click emission rate (clicks/s) was almost 20% higher in BB. Both studied habitats showed a high proportion of feeding buzzes (BB = 68%; IB = 58%), but with a higher probability of occurrence in BB (p < 0.001) and at night (p < 0.001) in both habitats. The C-PODs showed great potential to monitor occurrence, bioacoustics parameters, and echolocation behavior of franciscana dolphins. Longer-term temporal and spatial monitoring are necessary for elucidating several issues raised in this study. [ABSTRACT FROM AUTHOR]

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To browse the latest copy of our catalog, visit our website at https://acousticalsociety.org/download-catalog/. Comments are welcomed on all material in Acoustical Standards News. This Acoustical Standards News section in JASA, as well as the National Catalog of Acoustical Standards and other information on the Standards Program of the Acoustical Society of America, are also available via the ASA Standards home page: https://acousticalsociety.org/acoustical-society-standards/. [ABSTRACT FROM AUTHOR]

The Atlantic cod (Gadus morhua) is among the commercially most important fish species in the world. Since sound plays such an important role in the lives of Atlantic cod and its related species, understanding of their bioacoustics is of great importance. Moreover, since cod are amenable to studies of hearing, especially in open bodies of water, they have the potential to become a “model species” for investigations of fish hearing. To serve as the basis for future studies, and to bring together what is now known about cod hearing, this paper reviews the literature to date. While there is some discussion of other species in the paper, the focus is upon what is already known about cod hearing, and what now needs to be known. An additional focus is on what knowledge of cod hearing tells about hearing in fishes in general. [ABSTRACT FROM AUTHOR]

An acoustic record from Cross Seamount, southwest of Hawaii, revealed sounds characteristic of beaked whale echolocation at the same relative abundance year-around !270 of 356 days", occurring almost entirely at night. The most common sound had a linear frequency upsweep from 35 to 100 kHz !the bandwidth of recording", an interpulse interval of 0.11 s, and duration of at least 932 !s. A less common upsweep sound with shorter interpulse interval and slower sweep rate was also present. Sounds matching Cuvier’s beaked whale were not detected, and Blainville’s beaked whale sounds were detected on only one occasion.

The spectral and temporal properties of echolocation clicks and the use of clicks for species classification are investigated for five species of free-ranging dolphins found offshore of southern California: short-beaked common !Delphinus delphis", long-beaked common !D. capensis", Risso’s !Grampus griseus", Pacific white-sided !Lagenorhynchus obliquidens", and bottlenose !Tursiops truncatus" dolphins. Spectral properties are compared among the five species and unique spectral peak and notch patterns are described for two species. The spectral peak mean values from Pacific white-sided dolphin clicks are 22.2, 26.6, 33.7, and 37.3 kHz and from Risso’s dolphins are 22.4, 25.5, 30.5, and 38.8 kHz. The spectral notch mean values from Pacific white-sided dolphin clicks are 19.0, 24.5, and 29.7 kHz and from Risso’s dolphins are 19.6, 27.7, and 35.9 kHz. Analysis of variance analyses indicate that spectral peaks and notches within the frequency band 24–35 kHz are distinct between the two species and exhibit low variation within each species. Post hoc tests divide Pacific white-sided dolphin recordings into two distinct subsets containing different click types, which are hypothesized to represent the different populations that occur within the region. Bottlenose and common dolphin clicks do not show consistent patterns of spectral peaks or notches within the frequency band examined !1–100 kHz".

The acoustic calls of blue whales off California are described with visual observations of behavior and with acoustic tracking. Acoustic call data with corresponding position tracks are analyzed for five calling blue whales during one 100-min time period. Three of the five animals produced type A-B calls while two produced another call type which we refer to as type D. One of the animals producing the A-B call type was identified as male. Pauses in call production corresponded to visually observed breathing intervals. There was no apparent coordination between the calling whales. The average call source level was calculated to be 186 dB re: 1 Pa at 1 m over the 10 – 110-Hz band for the type B calls. On two separate days, female blue whales were observed to be silent during respective monitoring periods of 20 min and 1 h.

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact asastds@acousticalsociety.org. Comments are welcomed on all material in Acoustical Standards News This Acoustical Standards News section in JASA, as well as the national catalog of Acoustical Standards and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. [ABSTRACT FROM AUTHOR]

Humpback whale songs have been described worldwide and studies exploring non-song vocal behavior continue to expand; however, studies on the transition periods when whales shift to and from the seasonal behavioral state of singing are lacking and may be potentially informative regarding the proximal factors controlling the onset and offset of humpback whale male singing. Acoustic recorders collected data off eastern Canada continuously from the Bay of Fundy in the fall of 2015 and near-continuously off northeast Nova Scotia in the spring of 2016. Humpback whale acoustic occurrence and behavior were identified by systematically reviewing a subset of acoustic recordings for presence before analyzing the highest quality recordings for behavior. The onset of singing in the fall was gradual over a period of about three weeks with an intermediate form, termed "song fragment," occurring prior to full songs. In comparison, singing in the spring seemed to end abruptly with few song fragments. Song fragments could be produced by juveniles learning to sing for the first time or mature males preparing for breeding activities prior to migrating to southern breeding grounds. The authors propose an alternative hypothesis that the timing and manner of transitions could be driven by physiological processes similar to those documented in songbirds. [ABSTRACT FROM AUTHOR]

Envelope and periodicity cues may provide redundant, additive, or synergistic benefits to speech recognition. The contributions of these cues may change under different listening conditions and may differ for younger and older adults. To address these questions, younger and older adults with normal hearing listened to interrupted sentences containing different combinations of envelope and periodicity cues in quiet and with a competing talker. Envelope and periodicity cues improved speech recognition for both groups, and their benefits were additive when both cues were available. Envelope cues were particularly important for older adults and for sentences with a competing talker. [ABSTRACT FROM AUTHOR]

The article discusses the contributions of zoophysiologist Per Stockfleth Enger to fish bioacoustics. Topics include the early life of Enger, his education, and findings on early studies of the hearing abilities of fishes. The experiments conducted by Enger which showed differences in the response of goldfish exposed to sounds are discussed.

In this work, a convolutional neural network based method is proposed to automatically detect odontocetes echolocation clicks by analyzing acoustic data recordings from a passive acoustic monitoring system. The neural network was trained to distinguish between click and non-click clips and was subsequently converted to a full-convolutional network. The performance of the proposed network was evaluated using synthetic data and real audio recordings. The experimental results indicate that the proposed method works stably with echolocation clicks of different species. [ABSTRACT FROM AUTHOR]

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact asastds@acousticalsociety.org. Comments are welcomed on all material in Acoustical Standards News. This Acoustical Standards News section in JASA and other information on the Standards Program of the Acoustical Society of America are available via the ASA home page: http://acousticalsociety.org. [ABSTRACT FROM AUTHOR]

Sri Lankan pygmy blue whale song consists of three repeated units: (1) low frequency pulsive unit, (2) frequency modulated (FM) upsweep, and (3) long tonal downsweep. The Unit 2 FM unit has up to three visible upsweeps with energy concentrated at approximately 40, 50, and 60 Hz, while the Unit 3 (∼100 Hz) tonal downsweep is the most distinct unit lasting 20–30 s. Spectral characteristics of the Units 2 and 3 song elements, along with ocean sound levels, were analyzed in the Indian Ocean from 2002 to 2013. The peak frequency of the tonal Unit 3 calls decreased from approximately 106.5 to 100.7 Hz over a decade corresponding to a 5.4% decrease. Over the same time period, the frequency content of the Unit 2 upsweeps did not change as dramatically with only a 3.1% change. Ambient sound levels in the vocalization bands did not exhibit equivalent patterns in amplitude trends. Analysis showed no increase in the ambient sound or compensated peak amplitude levels of the tonal downsweeps, eliminating the presence of a Lombard effect. Here it is proposed that each song unit may convey different information and thus may be responding to different selective pressures. [ABSTRACT FROM AUTHOR]

During a cue-distractor task, participants repeatedly produce syllables prompted by visual cues. Distractor syllables are presented to participants via headphones 150 ms after the visual cue (before any response). The task has been used to demonstrate perceptuomotor integration effects (perception effects on production): response times (RTs) speed up as the distractor shares more phonetic properties with the response. Here it is demonstrated that perceptuomotor integration is not limited to RTs. Voice Onset Times (VOTs) of the distractor syllables were systematically varied and their impact on responses was measured. Results demonstrate trial-specific convergence of response syllables to VOT values of distractor syllables. [ABSTRACT FROM AUTHOR]

Detecting marine mammal vocalizations in underwater acoustic environments and classifying them to species level is typically an arduous manual analysis task for skilled bioacousticians. In recent years, machine learning and other automated algorithms have been explored for quickly detecting and classifying all sound sources in an ambient acoustic environment, but many of these still require a large training dataset compiled through time-intensive manual pre-processing. Here, an application of the signal decomposition technique Empirical Mode Decomposition (EMD) is presented, which does not require a priori knowledge and quickly detects all sound sources in a given recording. The EMD detection process extracts the possible signals in a dataset for minimal quality control post-processing before moving onto the second phase: the EMD classification process. The EMD classification process uniquely identifies and labels most sound sources in a given environment. Thirty-five recordings containing different marine mammal species and mooring hardware noises were tested with the new EMD detection and classification processes. Ultimately, these processes can be applied to acoustic index development and refinement. [ABSTRACT FROM AUTHOR]

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact asastds@acousticalsociety.org. Comments are welcomed on all material in Acoustical Standards News. This Acoustical Standards News section in JASA and other information on the Standards Program of the Acoustical Society of America are available via the ASA home page: http://acousticalsociety.org. [ABSTRACT FROM AUTHOR]

A tone-scramble is a random sequence of pure tones. Previous studies have found that most listeners (≈ 70%) perform near chance in classifying rapid tone-scrambles composed of multiple copies of notes in G-major vs G-minor triads; the remaining listeners perform nearly perfectly [Chubb, Dickson, Dean, Fagan, Mann, Wright, Guan, Silva, Gregersen, and Kowalski (2013). J. Acoust. Soc. Am. 134(4), 3067–3078; Dean and Chubb (2017). J. Acoust. Soc. Am. 142(3), 1432–1440]. This study tested whether low-performing listeners might improve with slower stimuli. In separate tasks, stimuli were tone-scrambles presented at 115, 231, 462, and 923 notes per min. In each task, the listener classified (with feedback) stimuli as major vs minor. Listeners who performed poorly in any of these tasks performed poorly in all of them. Strikingly, performance was worst in the task with the slowest stimuli. In all tasks, most listeners were biased to respond "major" ("minor") if the stimulus ended on a note high (low) in pitch. Dean and Chubb introduced the name "scale-sensitivity" for the cognitive resource that separates high- from low-performing listeners in tone-scramble classification tasks, suggesting that this resource confers sensitivity to the full gamut of qualities that music can attain by being in a scale. In ruling out the possibility that performance in these tasks depends on speed of presentation, the current results bolster this interpretation. [ABSTRACT FROM AUTHOR]

Evanescent waves emerge from a small sound source that radiates into a waveguide with a larger cross-sectional area, but unlike planar waves, do not propagate far from the source. Evanescent waves thus contaminate in-ear calibration of acoustic stimuli. Measurements with an otoacoustic-emission (OAE) probe inserted at the entrance of long tubes of various diameters show a decline in the evanescent wave with distance from the source when advancing a probe tube through the OAE probe and into the long tube. The amplitude of the evanescent pressure increases with frequency and depends strongly on the diameter of the long tube. Modifying the shape of the aperture of the probe's sound source, thus effectively enlarging its diameter and redirecting acoustic flow, greatly reduced evanescent waves. The reduction in evanescent-wave pressure was observed in calibration cavities used to determine the Thévenin-equivalent source pressure and impedance of the probe. Errors in source calibrations were considerably larger in the unmodified configuration. An alternative method is proposed for calculation of acoustic source parameters that models the evanescent-wave pressure and reduces its influence on the calculation. This reduction greatly improves the quality of source calibrations, which should improve the accuracy of ear-canal impedance measurements and related quantities. [ABSTRACT FROM AUTHOR]

Articulatory variability is reduced for people with flatter palates [Bakst and Lin (2015). Proceedings of the 18th International Congress of Phonetic Sciences; Brunner, Fuchs, and Perrier (2009). J. Acoust. Soc. Am. 125(6), 3936–3949]. Brunner, Fuchs, and Perrier [(2009). J. Acoust. Soc. Am. 125(6), 3936–3949] hypothesized that this is because the mapping between articulation and acoustics depends on palate depth. Articulatory synthesis was used with three different palate shapes to generate productions of /r/. The parameter spaces of the articulatory synthesizers were searched for vocal tract configurations that result in low F3 (the hallmark acoustic cue for /r/). Palate shape influences not only the sensitivity of the articulatory-acoustic mapping, but also the effect of each individual articulatory parameter on F3. [ABSTRACT FROM AUTHOR]

The identity of a speech sound can be affected by the long-term spectrum of a preceding stimulus. Poor spectral resolution of cochlear implants (CIs) may affect such context effects. Here, spectral contrast effects on a phoneme category boundary were investigated in CI users and normal-hearing (NH) listeners. Surprisingly, larger contrast effects were observed in CI users than in NH listeners, even when spectral resolution in NH listeners was limited via vocoder processing. The results may reflect a different weighting of spectral cues by CI users, based on poorer spectral resolution, which in turn may enhance some spectral contrast effects. [ABSTRACT FROM AUTHOR]

Many blind people learn to use sound reflections to localize objects. However, precedence-effect research has reported evidence both for and against the possibility to improve lateralization of lag clicks preceded by lead clicks. This training study used stimuli more relevant to human echolocation than did previous training studies. One participant, the author, practiced lateralizing a lag-click inter-aural level difference (ILD) of 10 dB for 60 days, with performance measured in the lag–lead peak amplitude ratio at threshold. Clear improvements were observed at interclick intervals of 2–18 ms, suggesting that extracting a large lag-click ILD may improve with practice. [ABSTRACT FROM AUTHOR]

The purpose of the study was to analyse human identification of Polish vowels from static and dynamic durationally slowed visual cues. A total of 152 participants identified 6 Polish vowels produced by 4 speakers from static (still images) and dynamic (videos) cues. The results show that 59% of static vowels and 63% of dynamic vowels were successfully identified. There was a strong confusion between vowels within front, central, and back classes. Finally, correct identification strongly depended on speakers, showing that speakers differ significantly in how “clearly” they produce vowel configurations. [ABSTRACT FROM AUTHOR]

Theories of cross-linguistic phonetic category perception posit that listeners perceive foreign sounds by mapping them onto their native phonetic categories, but, until now, no way to effectively implement this mapping has been proposed. In this paper, Automatic Speech Recognition systems trained on continuous speech corpora are used to provide a fully specified mapping between foreign sounds and native categories. The authors show how the machine ABX evaluation method can be used to compare predictions from the resulting quantitative models with empirically attested effects in human cross-linguistic phonetic category perception. [ABSTRACT FROM AUTHOR]

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact asastds@acousticalsociety.org. Comments are welcomed on all material in Acoustical Standards News. This Acoustical Standards News section in JASA, as well as the national catalog of Acoustical Standards and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. [ABSTRACT FROM AUTHOR]

The Australian snubfin dolphin (Orcaella heinsohni) is endemic to Australian waters, yet little is known about its abundance and habitat use. To investigate the feasibility of Passive Acoustic Monitoring for snubfin dolphins, biosonar clicks were recorded in Cygnet Bay, Australia, using a four-element hydrophone array. Clicks had a mean source level of 200 ± 5 dB re 1 μPa pp, transmission directivity index of 24 dB, mean centroid frequency of 98 ± 9 kHz, and a root-mean-square bandwidth of 31 ± 3 kHz. Such properties lend themselves to passive acoustic monitoring, but are comparable to similarly-sized delphinids, thus requiring additional cues to discriminate between snubfins and sympatric species. [ABSTRACT FROM AUTHOR]

The echolocation signals of most beaked whale species are still unknown. In fact, out of the 22 species comprising the family Ziphiidae, only the echolocation pulses for 7 species have been clearly described. This study describes two distinct beaked whale echolocation signals recorded in the Cook Strait region using passive acoustic technology. These signals differ from previously described Ziphiid species clicks. A description of the time-frequency characteristics of the two signals is provided. Understanding the characteristics of these signals is necessary to correctly identify species from their echolocation signals and enables future monitoring of beaked whales using passive acoustics techniques. [ABSTRACT FROM AUTHOR]

This paper describes phase-sensitive and phase-insensitive processing of monaural echolocation waveforms to generate target maps. Composite waveforms containing both the emission and echoes are processed to estimate the target impulse response using an audible sonar. Phase-sensitive processing yields the composite signal envelope, while phase-insensitive processing that starts with the composite waveform power spectrum yields the envelope of the autocorrelation function. Analysis and experimental verification show that multiple echoes form an autocorrelation function that produces near-range phantom-reflector artifacts. These artifacts interfere with true target echoes when the first true echo occurs at a time that is less than the total duration of the target echoes. Initial comparison of phase-sensitive and phase-insensitive maps indicates that both display important target features, indicating that phase is not vital. A closer comparison illustrates the improved resolution of phase-sensitive processing, the near-range phantom-reflectors produced by phase-insensitive processing, and echo interference and multiple reflection artifacts that were independent of the processing. [ABSTRACT FROM AUTHOR]

The sensitivity of human hearing to gliding rippled spectrum patterns of sound was investigated. The test signal was 2-oct wide rippled noise with the ripples gliding along the frequency scale. Both ripple density and gliding velocity were frequency-proportional across the signal band; i.e., the density was specified in ripples/oct and the velocity was specified in oct/s and ripple/s. The listener was required to discriminate between a test signal with gliding ripples and a non-rippled reference signal. Limits of gliding velocity were measured as a function of ripple density. The ripple gliding velocity limit decreased with an increasing ripple density: from 388.9 oct/s (388.9 ripple/s) at a ripple density of 1 ripple/oct to 11.3 oct/s (79.1 ripple/s) at a density of 7 ripple/oct. These tendencies could be approximated by log/log regression functions with slopes of 1.71 for the velocity expressed in oct/s and 0.71 for the velocity expressed in ripple/s. A qualitative model based on combined action of the excitation-pattern and the temporal-processing mechanism is suggested to explain the results. [ABSTRACT FROM AUTHOR]

Performance was measured on seven common psychoacoustical tasks for about 75 highly trained subjects. Because some psychoacoustical outcomes varied by race, the subjects were partitioned into White and Non-White categories for analysis. Sex, race, and menstrual-cycle differences in performance are described in a companion paper [McFadden, Pasanen, Maloney, Leshikar, and Pho (2018). J. Acoust. Soc. Am. 143, 2338–2354]. Also measured for all subjects were three types of otoacoustic emissions (OAEs): spontaneous otoacoustic emissions (SOAEs), click-evoked otoacoustic emissions (CEOAEs), and distortion-product otoacoustic emissions (DPOAEs). The experimental question was whether and how OAEs were correlated with psychoacoustical performance. In accord with past findings, the SOAEs and CEOAEs exhibited substantial sex and race differences, but the DPOAEs did not. Somewhat surprisingly, the correlations between OAEs and psychoacoustical performance were generally weak. No form of OAE was highly correlated with any psychoacoustical task for both sexes within a race category. Thus, there was no compelling evidence that the mechanisms underlying OAEs also contribute systematically to performance in any of the simultaneous or temporal masking tasks studied here. Especially surprising were the weak correlations between OAEs and detection of a tone in the quiet. Apparently individual differences in psychoacoustical performance reside more in post-cochlear (neural) mechanisms than in individual differences in the cochlear (“mechanical”) mechanisms underlying the OAEs measured here. [ABSTRACT FROM AUTHOR]

Spoken language manifests itself as change over time in various acoustic dimensions. While it seems clear that acoustic-phonetic information in the speech signal is key to language processing, little is currently known about which specific types of acoustic information are relatively more informative to listeners. This problem is likely compounded when considering reduced speech: Which specific acoustic information do listeners rely on when encountering spoken forms that are highly variable, and often include altered or elided segments? This work explores contributions of spectral shape, f0 contour, target duration, and time varying intensity in the perception of reduced speech. This work extends previous laboratory-speech based perception studies into the realm of casual speech, and also provides support for use of an algorithm that quantifies phonetic reduction. Data suggest the role of spectral shape is extensive, and that its removal degrades signals in a way that hinders recognition severely. Information reflecting f0 contour and target duration both appear to aid the listener somewhat, though their influence seems small compared to that of short term spectral shape. Finally, information about time varying intensity aids the listener more than noise filled gaps, and both aid the listener beyond presentation of acoustic context with duration-matched silence. [ABSTRACT FROM AUTHOR]

For a frontal target in spatially symmetrically placed interferers, normal hearing (NH) listeners can use “better-ear glimpsing” to select time-frequency segments with favorable signal-to-noise ratio in either ear. With an ideal monaural better-ear mask (IMBM) processing, some studies showed that NH listeners can reach similar performance as in the natural binaural listening condition, although interaural phase differences at low frequencies can further improve performance. In principle, bilateral cochlear implant (BiCI) listeners could use the same better-ear glimpsing, albeit without exploiting interaural phase differences. Speech reception thresholds of NH and BiCI listeners were measured in three interferers (speech-shaped stationary noise, nonsense speech, or single talker) either co-located with the target, symmetrically placed at ±60°, or independently presented to each ear, with and without IMBM processing. Furthermore, a bilateral noise vocoder based on the BiCI electrodogram was used in the same NH listeners. Headphone presentation and direct stimulation with head-related transfer functions for spatialization were used in NH and BiCI listeners, respectively. Compared to NH listeners, both NH listeners with vocoder and BiCI listeners showed strongly reduced binaural benefit from spatial separation. However, both groups greatly benefited from IMBM processing as part of the stimulation strategy. [ABSTRACT FROM AUTHOR]

This study compared the effects of supra-aural and insert receivers on the prevalence of noise-induced hearing loss (NIHL) in young adults. NIHL prevalence was found to be substantially higher when hearing thresholds were obtained with supra-aural compared to insert receivers on the same subjects. Real-ear sound pressure levels at 4000, 6000, and 8000 Hz were the major predictors of notched-audiograms obtained with supra-aural headphones. Distortion-product otoacoustic emissions were not significantly different between ears with and without notched-audiograms obtained with supra-aural headphones. The results demonstrated that supra-aural transducer-related artifacts can mimic a notch-like pattern leading to overestimation of NIHL prevalence. [ABSTRACT FROM AUTHOR]

Near-field head-related transfer functions (HRTFs) of human subjects are essential to those researching spatial hearing. By using a carefully designed measurement system, near-field HRTFs of human subjects were measured and a database was constructed. The database includes 56 Chinese human subjects, seven source distances from 0.2 to 1.0 m, and 685 directions at each distance for each subject. In the present work, the technique of near-field HRTF measurement is outlined, the performance of the measurement system is assessed and validated, and the resultant database is reported. The database can provide fundamental data for future research. [ABSTRACT FROM AUTHOR]

Grouper, a family of marine fishes, produce distinct vocalizations associated with their reproductive behavior during spawning aggregation. These low frequencies sounds (50–350 Hz) consist of a series of pulses repeated at a variable rate. In this paper, an approach is presented for automatic classification of grouper vocalizations from ambient sounds recorded in situ with fixed hydrophones based on weighted features and sparse classifier. Group sounds were labeled initially by humans for training and testing various feature extraction and classification methods. In the feature extraction phase, four types of features were used to extract features of sounds produced by groupers. Once the sound features were extracted, three types of representative classifiers were applied to categorize the species that produced these sounds. Experimental results showed that the overall percentage of identification using the best combination of the selected feature extractor weighted mel frequency cepstral coefficients and sparse classifier achieved 82.7% accuracy. The proposed algorithm has been implemented in an autonomous platform (wave glider) for real-time detection and classification of group vocalizations. [ABSTRACT FROM AUTHOR]

The medial olivocochlear efferent fibers control outer hair cell responses and inhibit the cochlear-amplifier gain. Measuring efferent function is both theoretically and clinically relevant. In humans, medial efferent inhibition can be assayed via otoacoustic emissions (OAEs). OAEs arise by two fundamentally different mechanisms—nonlinear distortion and coherent reflection. Distortion and reflection emissions are typically applied in isolation for studying the efferent inhibition. Such an approach inadvertently assumes that efferent-induced shifts in distortion and reflection emissions provide redundant information. In this study, efferent-induced shifts in distortion and reflection emissions (click-evoked and stimulus frequency OAEs) were measured in the same subjects—5- to 10-yr-old children. Consistent with the OAE generation theory, efferent-induced shifts in distortion and reflection emissions did not correlate, whereas the two reflection emission shifts correlated. This suggests that using either OAE types provides fragmented information on efferent inhibition and highlights the need to use both distortion and reflection emissions for describing efferent effects. [ABSTRACT FROM AUTHOR]

Stimulus frequency otoacoustic emissions (SFOAEs) can have multiple time varying components, including multiple internal reflections. It is, therefore, necessary to study SFOAEs using techniques that can represent their time-frequency behavior. Although various time-frequency schemes can be applied to identify and filter SFOAE components, their accuracy for SFOAE analysis has not been investigated. The relative performance of these methods is important for accurate characterization of SFOAEs that may, in turn, enhance the understanding of SFOAE generation. This study using in silico experiments examined the performance of three linear (short-time Fourier transform, continuous wavelet transform, Stockwell transform) and two nonlinear (empirical mode decomposition and synchrosqueezed wavelet transform) time-frequency approaches for SFOAE analysis. Their performances in terms of phase-gradient delay estimation, frequency specificity, and spectral component extraction are compared, and the relative merits and limitations of each method are discussed. Overall, this paper provides a comparative analysis of various time-frequency methods useful for otoacoustic emission applications. [ABSTRACT FROM AUTHOR]

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact Neil B. Stremmel. Comments are welcomed on all material in Acoustical Standards News. This Acoustical Standards News section in JASA, as well as the National Catalog of Acoustical Standards and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) imaging and ultrasound experimental measurements were combined to reconstruct the acoustic properties (density, velocity, and impedance) of the head from a deceased Indo-Pacific humpback dolphin (Sousa chinensis). The authors extracted 42 soft forehead tissue samples to estimate the sound velocity and density properties at room temperature, 25.0  °C. Hounsfield Units (HUs) of the samples were read from CT scans. Linear relationships between the tissues' HUs and velocity, and HUs and density were revealed through regression analyses. The distributions of the head acoustic properties at axial, coronal, and sagittal cross sections were reconstructed, suggesting that the forehead soft tissues were characterized by low-velocity in the melon, high-velocity in the muscle and connective tissues. Further, the sound velocities of melon, muscle, and connective tissue pieces were measured under different temperatures to investigate tissues' velocity response to temperature. The results demonstrated nonlinear relationships between tissues' sound velocity and temperature. This study represents a first attempt to provide general information on acoustic properties of this species. The results could provide meaningful information for understanding the species' bioacoustic characteristics and for further investigation on sound beam formation of the dolphin. [ABSTRACT FROM AUTHOR]

Flying in swarms, e.g., when exiting a cave, could pose a problem to bats that use an active biosonar system because the animals could risk jamming each other's biosonar signals. Studies from current literature have found different results with regard to whether bats reduce or increase emission rate in the presence of jamming ultrasound. In the present work, the number of Eastern bent-wing bats (Miniopterus fuliginosus) that were flying inside a cave during emergence was estimated along with the number of signal pulses recorded. Over the range of average bat numbers present in the recording (0 to 14 bats), the average number of detected pulses per bat increased with the average number of bats. The result was interpreted as an indication that the Eastern bent-wing bats increased their emission rate and/or pulse amplitude with swarm size on average. This finding could be explained by the hypothesis that the bats might not suffer from substantial jamming probabilities under the observed density regimes, so jamming might not have been a limiting factor for their emissions. When jamming did occur, the bats could avoid it through changing the pulse amplitude and other pulse properties such as duration or frequency, which has been suggested by other studies. More importantly, the increased biosonar activities may have addressed a collision-avoidance challenge that was posed by the increased swarm size. [ABSTRACT FROM AUTHOR]