A sperm whale cautionary tale about estimating acoustic cue rates for deep divers.

Passive acoustic density estimation has been gaining traction in recent years. Cue counting uses detected acoustic cues to estimate animal abundance. A cue rate, the number of acoustic cues produced per animal per unit time, is required to convert cue density into animal density. Cue rate information can be obtained from animal borne acoustic tags. For deep divers, like beaked whales, data have been analyzed considering deep dive cycles as a natural sampling unit, based on either weighted averages or generalized estimating equations. Using a sperm whale DTAG (sound-and-orientation recording tag) example we compare different approaches of estimating cue rate from acoustic tags illustrating that both approaches used before might introduce biases and suggest that the natural unit of analysis should be the whole duration of the tag itself.

Highly Conductive and Sensitive Wearable Strain Sensors with Metal/Nanoparticle Double Layer for Noninterference Voice Detection.

Human voice recognition via skin-attachable devices has significant potential for gathering important physiological information from acoustic data without background noise interference. In this study, a highly sensitive and conductive wearable crack-based strain sensor was developed for voice-recognition systems. The sensor was fabricated using a double-layer structure of Ag nanoparticles (NPs) and Ag metal on a biocompatible polydimethylsiloxane substrate. The top metal layer acts as a conducting active layer, whereas the bottom Ag NP layer induces channel cracks in the upper layer, effectively hindering current flow. Subsequently, the double-layer film exhibits a low electrical resistance value (<5 × 10-5 Ω cm), ultrahigh sensitivity (gauge factor = 1870), and a fast response/recovery time (252/168 µs). A sound wave was detected at a high frequency of 15 kHz with a signal-to-noise ratio (SNR) over 40 dB. The sensor exhibited excellent anti-interference characteristics and effectively differentiated between different voice qualities (modal, pressed, and breathy), with a systematic analysis revealing successful detection of the laryngeal state and glottal source. This ultrasensitive wearable sensor has potential applications in various physiological signal measurement methods, personalized healthcare systems, and ubiquitous computing.

Mechanical-acoustical analogy: From laboratory to home during the COVID-19 pandemic.

A clear comprehension of the oscillatory nature of sound for acoustics undergraduate students is of paramount importance. In this paper, two online experiments were implemented to aid teaching of the oscillatory nature of sound through the analogy between a mechanical mass-spring model and a Helmholtz resonator. The study was conducted among undergraduate students taking a science course in the Electronic and Electrical Engineering career curriculum. These in-class experiments were conducted during the COVID-19 pandemic via the Zoom platform. Students measured the Helmholtz resonant frequency of a plastic bottle with a smartphone application and compared its oscillatory behavior with that of a conventional harmonic oscillator under a professor-student collaborative environment. The results of this study suggest that, with careful experiment design, students can effectively benefit from the use of common technology tools, which, in turn, poses these methodologies as a rather satisfactory alternative to face-to-face laboratory sessions.

Perforated Concave Earplug (pCEP): A Proof-of-Concept Earplug to Improve Sound Localization without Compromising Noise Attenuation.

Combat soldiers are currently faced with using a hearing-protection device (HPD) at the cost of adequately detecting critical signals impacting mission success. The current study tested the performance of the Perforated-Concave-Earplug (pCEP), a proof-of-concept passive HPD consisting of a concave bowl-like rigid structure attached to a commercial roll-down earplug, designed to improve sound localization with minimal compromising of noise attenuation. Primarily intended for combat/military training settings, our aim was an evaluation of localization of relevant sound sources (single/multiple gunfire, continuous noise, spoken word) compared to 3M™-Combat-Arms™4.1 earplugs in open-mode and 3M™-E-A-R™-Classic™ earplugs. Ninety normal-hearing participants, aged 20-35 years, were asked to localize stimuli delivered from monitors evenly distributed around them in no-HPD and with-HPD conditions. The results showed (1) localization abilities worsened using HPDs; (2) the spoken word was localized less accurately than other stimuli; (3) mean root mean square errors (RMSEs) were largest for stimuli emanating from rear monitors; and (4) localization abilities corresponded to HPD attenuation levels (largest attenuation and mean RMSE: 3M™-E-A-R™-Classic™; smallest attenuation and mean RMSE: 3M™-Combat-Arms™4.1; pCEP was mid-range on both). These findings suggest that the pCEP may benefit in military settings by providing improved sound localization relative to 3M™ E-A-R™-Classic™ and higher attenuation relative to 3M™-Combat Arms™-4.1, recommending its use in noisy environments.

Augmented-Reality Presentation of Household Sounds for Deaf and Hard-of-Hearing People.

Normal-hearing people use sound as a cue to recognize various events that occur in their surrounding environment; however, this is not possible for deaf and hearing of hard (DHH) people, and in such a context they may not be able to freely detect their surrounding environment. Therefore, there is an opportunity to create a convenient device that can detect sounds occurring in daily life and present them visually instead of auditorily. Additionally, it is of great importance to appropriately evaluate how such a supporting device would change the lives of DHH people. The current study proposes an augmented-reality-based system for presenting household sounds to DHH people as visual information. We examined the effect of displaying both the icons indicating sounds classified by machine learning and a dynamic spectrogram indicating the real-time time-frequency characteristics of the environmental sounds. First, the issues that DHH people perceive as problems in their daily lives were investigated through a survey, suggesting that DHH people need to visualize their surrounding sound environment. Then, after the accuracy of the machine-learning-based classifier installed in the proposed system was validated, the subjective impression of how the proposed system increased the comfort of daily life was obtained through a field experiment in a real residence. The results confirmed that the comfort of daily life in household spaces can be improved by combining not only the classification results of machine learning but also the real-time display of spectrograms.

Increased temporal binding during voluntary motor task under local anesthesia.

Temporal binding refers to a systemic bias in the perceived time interval between two related events, most frequently voluntary motor actions and a subsequent sensory effect. An inevitable component of most instrumental motor actions is tactile feedback. Yet, the role of tactile feedback within this phenomenon remains largely unexplored. Here, we used local anesthesia of the index finger to temporarily inhibit incoming sensory input from the finger itself, while participants performed an interval-estimation task in which they estimated the delay between a voluntary motor action (button press) and a second sensory event (click sound). Results were compared to a control condition with intact sensation. While clear binding was present in both conditions, the effect was significantly enhanced when tactile feedback was temporarily removed via local anesthesia. The results are discussed in light of current debates surrounding the underlying mechanisms and function of this temporal bias.

In-situ hearing threshold estimation using Gaussian process classification.

One in six Americans suffers from hearing loss. While treatment with amplification is possible for many, the acceptance rate of hearing aids is low. Poor device fitting is one of the reasons. The hearing aid fitting starts with a detailed hearing assessment by a trained audiologist in a sound-controlled environment, using standard equipment. The hearing aid is adjusted step-by-step, following well-described procedures based on the audiogram. However, for many patients in rural settings, considerable travel time to a hearing center discourages them from receiving a hearing test and treatment. We hypothesize that hearing assessment with the patient's hearing aid can reliably substitute the hearing test in the clinic. Over-the-counter hearing aids could be programmed from a distance and fine-tuned by the hearing aid wearer. This study shows that a patient-controlled hearing assessment via a hearing aid in a non-clinical setting is not statistically different from an audiologist-controlled hearing assessment in a clinical setting. The differences in hearing obtained with our device and the Gaussian Process are within 3 dB of the standard audiogram. At 250 Hz, the sound delivery with the hearing aid used in this study added an additional reduction of sound level, which was not compensated.

Detection of cetacean and fish sounds using normalized summation of harmonics and spectrogram masking.

There is a growing interest in the ability to detect and classify animal vocalizations in large scale bioacoustic databases for the purposes of conservation and research. To aid in this, two methods are proposed for the quick and accurate detection of harmonic cetacean and fish vocalizations: Normalized summation of sound harmonics and spectrogram masking. These methods utilize a normalization scheme that enables robust performance, achieving 30% more precision and recall than traditional spectrogram cross correlation in the presence of wideband noise and low signal-to-noise ratios. The proposed methods also perform up to 135 times faster than spectrogram cross correlation.

Examining explainable clinical decision support systems with think aloud protocols.

Machine learning tools are increasingly used to improve the quality of care and the soundness of a treatment plan. Explainable AI (XAI) helps users in understanding the inner mechanisms of opaque machine learning models and is a driver of trust and adoption. Explanation methods for black-box models exist, but there is a lack of user studies on the interpretability of the provided explanations. We used a Think Aloud Protocol (TAP) to explore oncologists' assessment of a lung cancer relapse prediction system with the aim of refining the purpose-built explanation model for better credibility and utility. Novel to this context, TAP is used as a neutral methodology to elicit experts' thought processes and judgements of the AI system, without explicit prompts. TAP aims to elicit the factors which influenced clinicians' perception of credibility and usefulness of the system. Ten oncologists took part in the study. We conducted a thematic analysis of their verbalized responses, generating five themes that help us to understand the context within which oncologists' may (or may not) integrate an explainable AI system into their working day.

Lumped element models of sound conduction in the human ear: A systematic review.

Lumped element models facilitate investigating the fundamental mechanisms of human ear sound conduction. This systematic review aims to guide researchers to the optimal model for the investigated parameters. For this purpose, the literature was reviewed up to 12 July 2023, according to the PRISMA guidelines. Seven models are included via database searching, and another 19 via cross-referencing. The quality of the models is assessed by comparing the predicted middle ear transfer function, the tympanic membrane impedance, the energy reflectance, and the intracochlear pressures (ICPs) (scala vestibuli, scala tympani, and differential) with experimental data. Regarding air conduction (AC), the models characterize the pathway from the outer to the inner ear and accurately predict all six aforementioned parameters. This contrasts with the few existing bone conduction (BC) models that simulate only a part of the ear. In addition, these models excel at predicting one observable parameter, namely, ICP. Thus, a model that simulates BC from the coupling site to the inner ear is still lacking and would increase insights into the human ear sound conduction. Last, this review provides insights and recommendations to determine the appropriate model for AC and BC implants, which is highly relevant for future clinical applications.

Auditory masking in odobenid and otariid carnivoresa).

As the only living species within the odobenid lineage of carnivores, walruses (Odobenus rosmarus) have no close relatives from which auditory information can be extrapolated. Sea lions and fur seals in the otariid lineage are the nearest evolutionary outgroup. To advance understanding of odobenid and otariid hearing, we conducted behavioral testing with two walruses and one California sea lion (Zalophus californianus). Detection thresholds for airborne sounds were measured from 0.08 to at least 16 kHz in ambient noise conditions and then re-measured in the presence of octave-band white masking noise. Walruses were more sensitive than the sea lion at lower frequencies and less sensitive at higher frequencies. Critical ratios for the walruses ranged from 20 dB at 0.2 kHz to 32 dB at 10 kHz, while critical ratios for the sea lion ranged from 16 dB at 0.2 kHz to 35 dB at 32 kHz. The masking values for these species are comparable to one another and to those of terrestrial carnivores, increasing by about 3 dB per octave with increasing frequency. Despite apparent differences in hearing range and sensitivity, odobenids and otariids have a similar ability to hear signals in noisy conditions.

Soundscape experience of public spaces in different world regions: A comparison between the European and Chinese contexts via a large-scale on-site surveya).

The influence of cultural background on the soundscape experience in public spaces has been widely acknowledged. However, most studies have not used standardized protocols for soundscape perception data collection, nor have they gathered large datasets across different regions of the world to investigate possible cultural differences. This study explored the relationships between soundscape descriptors, perceived dominance of sound sources, and overall soundscape qualities and whether these relationships differ across world regions. A database of over 2000 soundscape surveys was collected in situ in outdoor public spaces in Europe and China. Results highlighted differences in how European and Chinese participants perceived the pleasantness and dominance of different sound sources. Specifically, the positive correlation between perceived pleasantness and natural sounds was stronger for European participants. For Chinese participants, vibrant soundscapes were positively correlated with perceived dominance of natural sounds, whereas in Europe, they were associated more with human-generated sounds. Perceived loudness had a greater effect on the appropriateness dimension for the Chinese sample than that for the European sample. This study provides a deeper understanding of how the geographical/cultural context can influence soundscape perception in public spaces and suggests that such country-specific factors should be considered when designing urban soundscapes.

Comment on: "Variability in humpback whale songs reveals how individuals can be distinctive when sharing a complex vocal display" [J. Acoust. Soc. Am. 153, 2238-2250 (2023)].

Lamoni, Garland, Allen, Coxon, Noad, and Rendell [(2023). J. Acoust. Soc. Am. 153, 2238-2250] analyzed variations in humpback whale song structure to assess how individual singers can produce distinctive patterns that communicate desirable individual qualities to potential mates. Their analyses revealed that singers rarely produced individually specific sound patterns and that singers varied subjectively distinctive structural features of songs differently across years. These findings provide the strongest evidence to date that singing humpback whales are not varying song structure in ways that reliably reveal individual singers' physical or cognitive characteristics. Surprisingly, the authors appear to reach the opposite conclusion. Objective strategies for quantitatively comparing song properties are crucial for evaluating competing hypotheses regarding the nature and function of humpback whale songs, but the value of such strategies is reduced when the objectivity of the analyses is suspect and when negative evidence is framed as supporting prior beliefs.

A robust and compact population code for competing sounds in auditory cortex.

Cortical circuits encoding sensory information consist of populations of neurons, yet how information aggregates via pooling individual cells remains poorly understood. Such pooling may be particularly important in noisy settings where single-neuron encoding is degraded. One example is the cocktail party problem, with competing sounds from multiple spatial locations. How populations of neurons in auditory cortex code competing sounds have not been previously investigated. Here, we apply a novel information-theoretic approach to estimate information in populations of neurons in mouse auditory cortex about competing sounds from multiple spatial locations, including both summed population (SP) and labeled line (LL) codes. We find that a small subset of neurons is sufficient to nearly maximize mutual information over different spatial configurations, with the labeled line code outperforming the summed population code and approaching information levels attained in the absence of competing stimuli. Finally, information in the labeled line code increases with spatial separation between target and masker, in correspondence with behavioral results on spatial release from masking in humans and animals. Taken together, our results reveal that a compact population of neurons in auditory cortex provides a robust code for competing sounds from different spatial locations.NEW & NOTEWORTHY Little is known about how populations of neurons within cortical circuits encode sensory stimuli in the presence of competing stimuli at other spatial locations. Here, we investigate this problem in auditory cortex using a recently proposed information-theoretic approach. We find a small subset of neurons nearly maximizes information about target sounds in the presence of competing maskers, approaching information levels for isolated stimuli, and provides a noise-robust code for sounds in a complex auditory scene.

The variable influence of anthropogenic noise on summer season coastal underwater soundscapes near a port and marine reserve.

Monitoring soundscapes is essential for assessing environmental conditions for soniferous species, yet little is known about sound levels and contributors in Oregon coastal regions. From 2017 to 2021, during June-September, two hydrophones were deployed near Newport, Oregon to sample 10-13,000 Hz underwater sound. One hydrophone was deployed near the Port of Newport in a high vessel activity area, and another 17 km north within a protected Marine Reserve. Vessel noise and whale vocalizations were detected at both sites, but whales were recorded on more days at the Marine Reserve. Median sound levels in frequencies related to noise from various vessel types and sizes (50 - 4,000 Hz) were up to 6 dB higher at the Port of Newport, with greater diel variability compared to the Marine Reserve. In addition to documenting summer season conditions in Oregon waters, these results exemplify how underwater soundscapes can differ over short distances depending on anthropogenic activity.

How 'visual' is the visual cortex? The interactions between the visual cortex and other sensory, motivational and motor systems as enabling factors for visual perception.

The definition of the visual cortex is primarily based on the evidence that lesions of this area impair visual perception. However, this does not exclude that the visual cortex may process more information than of retinal origin alone, or that other brain structures contribute to vision. Indeed, research across the past decades has shown that non-visual information, such as neural activity related to reward expectation and value, locomotion, working memory and other sensory modalities, can modulate primary visual cortical responses to retinal inputs. Nevertheless, the function of this non-visual information is poorly understood. Here we review recent evidence, coming primarily from studies in rodents, arguing that non-visual and motor effects in visual cortex play a role in visual processing itself, for instance disentangling direct auditory effects on visual cortex from effects of sound-evoked orofacial movement. These findings are placed in a broader framework casting vision in terms of predictive processing under control of frontal, reward- and motor-related systems. In contrast to the prevalent notion that vision is exclusively constructed by the visual cortical system, we propose that visual percepts are generated by a larger network-the extended visual system-spanning other sensory cortices, supramodal areas and frontal systems. This article is part of the theme issue 'Decision and control processes in multisensory perception'.

Cochlear Implant Upper Stimulation Levels: eSRT vs. Loudness Scaling.

OBJECTIVE: To assess the difference in speech recognition and sound quality between programming upper stimulation levels using behavioral measures (loudness scaling) and electrically evoked stapedial reflex thresholds (eSRTs). STUDY DESIGN: Double-blinded acute comparison study. SETTING: Cochlear implant (CI) program at a tertiary medical center. PATIENTS: Eighteen adult (mean age = 60 years) CI users and 20 ears. MAIN OUTCOME MEASURES: Speech recognition scores and sound quality ratings. RESULTS: Mean word and sentence in noise recognition scores were 8 and 9 percentage points higher, respectively, for the eSRT-based map. The sound quality rating was 1.4 points higher for the eSRT-based map. Sixteen out of 20 participants preferred the eSRT-based map. CONCLUSIONS: Study results show significantly higher speech recognition and more favorable sound quality using an eSRT-based map compared with a loudness-scaling map using a double-blinded testing approach. Additionally, results may be understated as 18 of 20 ears had eSRTs measured before study enrollment. Results underscore the importance of incorporating eSRTs into standard clinical practice to promote best outcomes for CI recipients.

Auditory cortex ensembles jointly encode sound and locomotion speed to support sound perception during movement.

The ability to process and act upon incoming sounds during locomotion is critical for survival and adaptive behavior. Despite the established role that the auditory cortex (AC) plays in behavior- and context-dependent sound processing, previous studies have found that auditory cortical activity is on average suppressed during locomotion as compared to immobility. While suppression of auditory cortical responses to self-generated sounds results from corollary discharge, which weakens responses to predictable sounds, the functional role of weaker responses to unpredictable external sounds during locomotion remains unclear. In particular, whether suppression of external sound-evoked responses during locomotion reflects reduced involvement of the AC in sound processing or whether it results from masking by an alternative neural computation in this state remains unresolved. Here, we tested the hypothesis that rather than simple inhibition, reduced sound-evoked responses during locomotion reflect a tradeoff with the emergence of explicit and reliable coding of locomotion velocity. To test this hypothesis, we first used neural inactivation in behaving mice and found that the AC plays a critical role in sound-guided behavior during locomotion. To investigate the nature of this processing, we used two-photon calcium imaging of local excitatory auditory cortical neural populations in awake mice. We found that locomotion had diverse influences on activity of different neurons, with a net suppression of baseline-subtracted sound-evoked responses and neural stimulus detection, consistent with previous studies. Importantly, we found that the net inhibitory effect of locomotion on baseline-subtracted sound-evoked responses was strongly shaped by elevated ongoing activity that compressed the response dynamic range, and that rather than reflecting enhanced "noise," this ongoing activity reliably encoded the animal's locomotion speed. Decoding analyses revealed that locomotion speed and sound are robustly co-encoded by auditory cortical ensemble activity. Finally, we found consistent patterns of joint coding of sound and locomotion speed in electrophysiologically recorded activity in freely moving rats. Together, our data suggest that rather than being suppressed by locomotion, auditory cortical ensembles explicitly encode it alongside sound information to support sound perception during locomotion.

SONAR enables cell type deconvolution with spatially weighted Poisson-Gamma model for spatial transcriptomics.

Recent advancements in spatial transcriptomic technologies have enabled the measurement of whole transcriptome profiles with preserved spatial context. However, limited by spatial resolution, the measured expressions at each spot are often from a mixture of multiple cells. Computational deconvolution methods designed for spatial transcriptomic data rarely make use of the valuable spatial information as well as the neighboring similarity information. Here, we propose SONAR, a Spatially weighted pOissoN-gAmma Regression model for cell-type deconvolution with spatial transcriptomic data. SONAR directly models the raw counts of spatial transcriptomic data and applies a geographically weighted regression framework that incorporates neighboring information to enhance local estimation of regional cell type composition. In addition, SONAR applies an additional elastic weighting step to adaptively filter dissimilar neighbors, which effectively prevents the introduction of local estimation bias in transition regions with sharp boundaries. We demonstrate the performance of SONAR over other state-of-the-art methods on synthetic data with various spatial patterns. We find that SONAR can accurately map region-specific cell types in real spatial transcriptomic data including mouse brain, human heart and human pancreatic ductal adenocarcinoma. We further show that SONAR can reveal the detailed distributions and fine-grained co-localization of immune cells within the microenvironment at the tumor-normal tissue margin in human liver cancer.

The sound production of Aplodinotus grunniens in the presence of boat sounds.

Archived soundscape data from Lake Champlain, New York, were used to examine the effect of anthropogenic sounds produced by recreational boating on freshwater drum (Aplodinotus grunniens) soniferous behavior. Drum progressed from sporadic calling during the day to calls that increasingly overlapped culminating in a chorus in the late afternoon and evening. The response of drum to boat noise appeared to differ among these states, perhaps reflecting differences in the underlying behaviors. In response to boat noise, freshwater drum spawning choruses occurred later in the day, thus avoiding the noisiest periods. The peak frequency and knock rate of calls also increased in the presence of boat noise. Of the acoustical adjustments observed, the most strongly shown were those which increased the likelihood of signal reception, suggesting a Lombard effect response. Therefore, these data suggest freshwater drum have plasticity in their acoustical behavior, potentially shifting chorusing time, and altering sound characteristics to optimize communication in the presence of anthropogenic noise. However, additional work is needed to further clarify the response of freshwater drum to anthropogenic noise.