Vocal Behavior Research Articles

Listening to your partner: serotonin increases male responsiveness to female vocal signals in mice.

The context surrounding vocal communication can have a strong influence on how vocal signals are perceived. The serotonergic system is well-positioned for modulating the perception of communication signals according to context, because serotonergic neurons are responsive to social context, influence social behavior, and innervate auditory regions. Animals like lab mice can be excellent models for exploring how serotonin affects the primary neural systems involved in vocal perception, including within central auditory regions like the inferior colliculus (IC). Within the IC, serotonergic activity reflects not only the presence of a conspecific, but also the valence of a given social interaction. To assess whether serotonin can influence the perception of vocal signals in male mice, we manipulated serotonin systemically with an injection of its precursor 5-HTP, and locally in the IC with an infusion of fenfluramine, a serotonin reuptake blocker. Mice then participated in a behavioral assay in which males suppress their ultrasonic vocalizations (USVs) in response to the playback of female broadband vocalizations (BBVs), used in defensive aggression by females when interacting with males. Both 5-HTP and fenfluramine increased the suppression of USVs during BBV playback relative to controls. 5-HTP additionally decreased the baseline production of a specific type of USV and male investigation, but neither drug treatment strongly affected male digging or grooming. These findings show that serotonin modifies behavioral responses to vocal signals in mice, in part by acting in auditory brain regions, and suggest that mouse vocal behavior can serve as a useful model for exploring the mechanisms of context in human communication.

An integrated passive acoustic monitoring and deep learning pipeline for black-and-white ruffed lemurs (Varecia variegata) in Ranomafana National Park, Madagascar.

The urgent need for effective wildlife monitoring solutions in the face of global biodiversity loss has resulted in the emergence of conservation technologies such as passive acoustic monitoring (PAM). While PAM has been extensively used for marine mammals, birds, and bats, its application to primates is limited. Black-and-white ruffed lemurs (Varecia variegata) are a promising species to test PAM with due to their distinctive and loud roar-shrieks. Furthermore, these lemurs are challenging to monitor via traditional methods due to their fragmented and often unpredictable distribution in Madagascar's dense eastern rainforests. Our goal in this study was to develop a machine learning pipeline for automated call detection from PAM data, compare the effectiveness of PAM versus in-person observations, and investigate diel patterns in lemur vocal behavior. We did this study at Mangevo, Ranomafana National Park by concurrently conducting focal follows and deploying autonomous recorders in May-July 2019. We used transfer learning to build a convolutional neural network (optimized for recall) that automated the detection of lemur calls (57-h runtime; recall = 0.94, F1 = 0.70). We found that PAM outperformed in-person observations, saving time, money, and labor while also providing re-analyzable data. Using PAM yielded novel insights into V. variegata diel vocal patterns; we present the first published evidence of nocturnal calling. We developed a graphic user interface and open-sourced data and code, to serve as a resource for primatologists interested in implementing PAM and machine learning. By leveraging the potential of this pipeline, we can address the urgent need for effective primate population surveys to inform conservation strategies.

Effect of debonding on stress indicators in cows and calves in a cow-calf contact system

Premature separation, entailing a mixture of stressful events, follows a period of cow-calf contact in dairy production. We hypothesized that timing and length of debonding (i.e., gradually adapting cow and calf to separation) may affect behavioral responses indicating stress and reinstatement of the cow-calf bond. Initially, cows had 24 h/d smart-gate access to their calves before reduction to 12 h/d, 6 h/d, and finally 0 h/d, either commencing at 4 wk after birth over 28 d: long debonding (LDB, n = 16 pairs), or at 6.5 wk, over 10 d: short debonding (SDB, n = 14 pairs). We aimed to compare the vocal response (high- and low-pitched vocalizations) and proximity (<1 m to separation barrier) of LDB versus SDB cows and calves at each reduction of access and finally at 0 h/d contact. We also aimed to assess the impact of calf supplemental milk intake on their vocal behavior. Direct observations (2 h × 2 d) were performed during the following different phases: 24 h/d access (baseline, BL24h), once cow access was reduced (separation, SEP12h), once pairs were habituated to the change (BL12h), after cow access was further reduced (SEP6h), once pairs were habituated (BL6h), and at 0 h/d contact (SEP0h). Mixed effect linear regression models indicate that overall, treatment did not affect cow behaviors nor the main indicator of separation stress, high-pitched vocalizations. Both calves and cows responded with vocal and reinstatement behavior once cows' access was reduced, with great individual variation. The LDB calves spent less time close to separation barrier and emitted more low-pitched vocalizations. Otherwise, the effect of treatment differed with phase: SDB calves emitted more high-pitched vocalizations in response to the initial reductions of cow access than LDB calves. The LDB cows (but not calves) produced more high- and low-pitched vocalizations when access was reduced to 6 h/d and 0 h/d. Calves drinking >1.5 L of supplemental milk/d emitted fewer high-pitched vocalizations. In conclusion, a longer debonding period initiated at a lower age before separation may alleviate the initial behavioral response to separation, especially for calves. The vocal response of calves increases with age at separation but is modulated by intake of supplemental milk. For cows, our results indicate that the studied debonding methods affected the behavioral response to separation only to a limited degree.

Antarctic Minke Whale (Balaenoptera bonaerensis) Bio-Duck Call Detection in the Río de la Plata, Uruguay

Passive acoustic monitoring (PAM) has become a popular method for studying both marine mammal behavior and distribution, especially among cetaceans. The Antarctic minke whale (Balaenoptera bonaerensis) occurs in the Southern Hemisphere, and our knowledge concerning its vocal behavior is very limited. Along the coast of Uruguay, minke whales constitute one of the species with the most stranding data collected. Until now, sounds of Antarctic minke whales had never been recorded off the Uruguayan coast. Two different bio-duck call types were recorded along the Atlantic Ocean and the Río de la Plata River coasts by employing PAM stations off the coast of Uruguay in five different positions. One call was recorded off the Atlantic coast, and the four other calls were recorded along the Río de la Plata River, including the classic bio-duck call. In addition to the aforementioned bio-duck call, evidence of a novel call, the bio-duck pulse train, was found. This call was produced in an environment very different from the oceanic environment. The bio-duck pulse train has never been described in previous works, making the findings of the present work all the more novel.

Self-perception of voice, hearing, and general health in screening for voice changes in older women.

To verify the association between sociodemographic factors, vocal behavior, morbidities, and self-perception of voice, hearing, and general health in older women with voice disorders. The sample had 95 older women aged 60 to 84 years (mean of 69,5). They were interviewed with a structured questionnaire on sociodemographic aspects, health, and vocal behavior. The Screening Protocol for Voice Disorders in Older Adults (RAVI) was used to identify the presence of voice disorders. Participants who had finished high school and were retired predominated. The number of older women with voice disorders according to RAVI was 46.3%. Physical sensations such as dry throat, throat clearing, and itchy throat were the most common complaints. The group of older women with voice disorders had worse self-perception of voice quality, hearing, and general health and a higher frequency of upper airway infections than those without voice disorders (p ≤ 0.05). The vocal self-assessment measured with RAVI was statistically associated with self-perception of voice quality, hearing, general health, sore throat, sinusitis, and respiratory allergies.

Autopercepção da voz, audição e saúde geral no rastreio de distúrbio vocal em idosas

ABSTRACT Purpose To verify the association between sociodemographic factors, vocal behavior, morbidities, and self-perception of voice, hearing, and general health in older women with voice disorders. Methods The sample had 95 older women aged 60 to 84 years (mean of 69,5). They were interviewed with a structured questionnaire on sociodemographic aspects, health, and vocal behavior. The Screening Protocol for Voice Disorders in Older Adults (RAVI) was used to identify the presence of voice disorders. Results Participants who had finished high school and were retired predominated. The number of older women with voice disorders according to RAVI was 46.3%. Physical sensations such as dry throat, throat clearing, and itchy throat were the most common complaints. The group of older women with voice disorders had worse self-perception of voice quality, hearing, and general health and a higher frequency of upper airway infections than those without voice disorders (p ≤ 0.05). Conclusion The vocal self-assessment measured with RAVI was statistically associated with self-perception of voice quality, hearing, general health, sore throat, sinusitis, and respiratory allergies.

Females counter-sing, but response to male song differs by sex in Alston's singing mouse.

Vocal display behaviours are common throughout the animal kingdom, play important roles in both courtship and aggression, and are frequent subjects of behavioural research. Although females of many species vocalize, an overwhelming fraction of behavioural research has focused on male display. We investigated vocal display behaviours in female singing mice (Scotinomys teguina), small muroid rodents in which both sexes produce songs consisting of trills of rapid, downward frequency sweeps. Previous research established that male singing mice increase song production and engage in precisely timed counter-singing behaviour in response to playback of conspecific male song. We tested whether female singing mice also increased their rate of singing in response to playback of male song, whether they counter-sing, and whether there are sexual dimorphisms in song effort. Our results demonstrate that much like males, female singing mice increase their song effort and counter-sing in response to playback of male song; however, females sing fewer and shorter songs compared to males. This study further informs the understanding of female vocal behaviour and establishes the singing mouse as a valuable model for investigating female vocal display.

High Speed Video Observations of Vocal Fold Kinematics While Playing a Clarinet.

In this pilot study, flexible high-speed video (HSV) technology with synchronized audio is used to visualize vocal fold behavior in a wind instrumentalist. Specifically, this study aims to contribute to describing the vocal fold behavior of a professional clarinet musician playing varying tones and melodies. Vocal folds of a healthy 26-year-old professional clarinet musician were recorded utilizing a HSV camera coupled to a flexible endoscope, which allowed the synchronous recording of audio with vocal fold movement at the onset, playing, and offset of playing. Two raters experienced with analyzing vocal folds described vocal fold motion of each sample. Samples were processed through a software model to determine the vocal fold movement relative to their position at rest. Digital kymograms (DKGs) were additionally obtained to visualize vocal fold micromovements throughout each sample. At the onset of playing, the raters observed the vocal folds moving to a paramedian position. Vocal fold adduction varied according to the task performed and ranged from 58% to 77% of the original resting glottis width. The calculated changes in glottis width and DKGs were consistent with the descriptions by the raters. This study demonstrates the utility of flexible HSV in observing vocal fold motion before, during, and after events other than sustained phonation. The incomplete adducted vocal fold postures observed while playing the clarinet not only differ from phonation but also differ depending on task. These various postures may contribute to voice fatigue in wind instrumentalists or to various disorders experienced during their careers.

Characterization of the vocal behavior of the miniature and transparent fish model, Danionella cerebruma).

Danionella cerebrum has recently been proposed as a promising model to investigate the structure and function of the adult vertebrate brain, including the development of vocal-auditory neural pathways. This genetically tractable and transparent cypriniform is highly vocal, but limited information is available on its acoustic behavior and underlying biological function. Our main goal was to characterize the acoustic repertoire and diel variation in sound production of D. cerebrum, as well as to investigate the relationship between vocal behavior and reproduction. Sound recordings demonstrated high vocal activity, with sounds varying from short sequences of pulses known as "bursts" (comprising up to 15 pulses) to notably longer sounds, termed "long bursts", which extended up to 349 pulses with over 2.7 s. Vocal activity peaked at midday and it was very low at night with only a few bursts. While the number of pulses was higher during the daytime, the interpulse interval was longer at night. In addition, calling time was positively associated with the number of viable eggs, suggesting that acoustic communication is important for reproduction. These preliminary findings reveal the potential of using D. cerebrum to investigate vocal plasticity and the implications for sexual selection and reproduction in a novel vertebrate model for neuroscience.

Empirical Distribution of Glottal Edges (EDGE): A Statistical Assessment of Vocal Fold Kinematics Using High-Speed Videoendoscopy.

Although laryngeal high-speed videoendoscopy (HSV) is crucial for studying vocal fold vibrations, its translation to clinical practice has been hindered by the large volume of data it produces and the difficulty in interpreting current analysis methods. Although image processing techniques have been developed to map spatial-temporal data into two-dimensional representations, they alter the geometrical construction of the glottis and do not provide standard quantitative features, thus challenging clinical interpretation. In response, we propose a new visualization and analysis framework for assessing the dynamics of vocal folds based on the empirical distribution of the glottal edge using HSV. This procedure analyzes vocal fold oscillations by preserving the shape of the glottis and quantifying the asymmetry between right and left vocal fold displacements along the anterior-posterior axis. This method was evaluated on four groups of participants: ten with normal voices, ten with vocal fold nodules, ten with muscle tension dysphonia, and two with unilateral vocal fold paralysis. The proposed method produces distinct representations for normal and pathological vocal fold vibratory behaviors and derived features based on amplitude and phase asymmetry metrics that show statistically significant differences between normal and pathological groups. Comparative analysis with state-of-the-art techniques indicates that our proposed method can complement the assessment of vocal fold vibration and enhance the clinical translation of HSV.

Vocal Self-Perception of Singers During COVID-19 Pandemic.

to compare the self-perception of vocal fatigue and use of singing voice during the COVID-19 pandemic between professional and amateur singers and to relate this self-perception with vocal use characteristics during this period. Participants were 121 singers divided into professional singers group (PSG) (12 men and 20 women) comprising singers who depended exclusively on singing as a profession and an amateur singers group (ASG) (37 men and 52 women) of singers who did not depend exclusively on singing for their livelihood. All answered online questionnaires through Google Forms ®. Sociodemographic and vocal characteristics were investigated before and during the pandemic; symptoms of vocal fatigue were assessed through the vocal fatigue index (VFI); and self-perception of use of singing voice through the evaluation of the ability to sing easily protocol for Brazil (EASE-Br). In the comparison between groups, the PSG presented higher scores of vocal fatigue in fatigue and vocal limitation (P=0.045), vocal restriction (P=0.002), and recovery with vocal rest (P=0.008) domains than did the ASG. There was no difference between the groups regarding the use of singing voice. Based on the relationship between self-perception and vocal use characteristics during the pandemic, it was observed that the presence of vocal complaint was the only factor associated with self-perception of fatigue symptomatology in both groups. Regarding the self-perception of the current status of the singing voice, singing time, the presence of vocal complaints, the need to increase visual concentration, and the perception of vocal worsening during the pandemic were considered predictive for amateur singers. For professional singers, vocal complaints and vocal training were predictors for self-perception of the current status of the singing voice. Professional singers presented with higher scores of vocal fatigue than did amateur singers. The symptomatology of vocal fatigue was associated with the presence of vocal complaints in both groups. However, self-perception of the current status of the singing voice was different between the groups and was associated with vocal training for professional singers and characteristics of vocal demand of singing voice during the pandemic period for amateur singers.

Characteristics and spatiotemporal variation of sei whale (Balaenoptera borealis) downsweeps recorded in Atlantic Canada.

The call characteristics and vocal behaviour of sei whales (Balaenoptera borealis) off eastern Canada, including potential spatiotemporal variation, is poorly understood. Such information can improve the performance of automated detector-classifiers, enhancing the accuracy and efficiency of identifying sei whales in large acoustic datasets. Ultimately, these data can be used to understand the occurrence, distribution, and population structure of sei whales in Atlantic Canada. We measured sei whale downsweep characteristics recorded from six locations off Nova Scotia (NS) and Newfoundland and Labrador (NFLD), Canada over a two-year period (2015-2017), and examined variation between call subtypes (singlets, doublets, triplets+), and seasons (Spring, Summer, Fall, Winter). We found that downsweeps had a mean duration of 1.58 s, sweeping from 75.66 to 34.22 Hz, with a peak frequency of 43.89 Hz and an intra-call interval of 2.22 s. Most call characteristics did not vary between location, subtype, or season; however, significantly longer downsweeps occurred off NS, within doublet calls, and in fall months. We also found that NFLD had a higher proportion of doublets (70%) than NS (52%). This variation may be evidence of acoustically diverging sei whale populations, as well as useful for improving detector-classifiers of sei whales in the region.

A neural circuit for vocal production responds to viscerosensory input in the songbird.

Motor performance is monitored continuously by specialized brain circuits and used adaptively to modify behavior on a moment-to-moment basis and over longer time periods. During vocal behaviors, such as singing in songbirds, internal evaluation of motor performance relies on sensory input from the auditory and vocal-respiratory systems. Sensory input from the auditory system to the motor system, often referred to as auditory feedback, has been well studied in singing zebra finches (Taeniopygia guttata), but little is known about how and where nonauditory sensory feedback is evaluated. Here we show that brief perturbations in air sac pressure cause short-latency neural responses in the higher-order song control nucleus HVC (used as proper name), an area necessary for song learning and song production. Air sacs were briefly pressurized through a cannula in anesthetized or sedated adult male zebra finches, and neural responses were recorded in both nucleus parambigualis (PAm), a brainstem inspiratory center, and HVC, a cortical premotor nucleus. These findings show that song control nuclei in the avian song system are sensitive to perturbations directly targeted to vocal-respiratory, or viscerosensory, afferents and support a role for multimodal sensory feedback integration in modifying and controlling vocal control circuits.NEW & NOTEWORTHY This study presents the first evidence of sensory input from the vocal-respiratory periphery directly activating neurons in a motor circuit for vocal production in songbirds. It was previously thought that this circuit relies exclusively on sensory input from the auditory system, but we provide groundbreaking evidence for nonauditory sensory input reaching the higher-order premotor nucleus HVC, expanding our understanding of what sensory feedback may be available for vocal control.

Machine learning reveals that climate, geography, and cultural drift all predict bird song variation in coastal Zonotrichia leucophrys

Abstract Previous work has demonstrated that there is extensive variation in the songs of White-crowned Sparrow (Zonotrichia leucophrys) throughout the species range, including between neighboring (and genetically distinct) subspecies Z. l. nuttalli and Z. l. pugetensis. Using a machine learning approach to bioacoustic analysis, we demonstrate that variation in song is correlated with year of recording (representing cultural drift), geographic distance, and climatic differences, but the response is subspecies- and season-specific. Automated machine learning methods of bird song annotation can process large datasets more efficiently, allowing us to examine 1,913 recordings across ~60 years. We utilize a recently published artificial neural network to automatically annotate White-crowned Sparrow vocalizations. By analyzing differences in syllable usage and composition, we recapitulate the known pattern where Z. l. nuttalli and Z. l. pugetensis have significantly different songs. Our results are consistent with the interpretation that these differences are caused by the changes in characteristics of syllables in the White-crowned Sparrow repertoire. This supports the hypothesis that the evolution of vocalization behavior is affected by the environment, in addition to population structure.

Conspecific density and habitat quality drive the defence and vocal behaviour of a territorial passerine

Territorial defence depends on highly interrelated factors such as food abundance and conspecific density. We used Dupont's Lark Chersophilus duponti as a model species to evaluate the response of a territorial bird to a foreign male playback, examining how conspecific density, habitat quality and male body condition impact responses. The study was conducted in central Spain with variable male density. Response (yes/no), latency time, distance to the playback speaker, and the number of songs and other vocalizations were monitored for 5 min. Habitat quality was estimated using BlueNDVI vegetation index extracted from high‐resolution drone imagery, which is a proxy for arthropod prey biomass. Conspecific density (Kernel Density Estimator) and male body condition were calculated to assess their effect on response and intensity. We applied generalized linear mixed models (GLMMs) to determine which factors predicted the response and its intensity. There was a greater response probability in areas with a higher density of conspecifics and in areas of poorer habitat quality (i.e. lower BlueNDVI values). In contrast, latency time was longer in areas with lower conspecific density. Intrasexual communication (singing and calling rates) increased with habitat quality. Intraspecific communication (other vocalizations) increased in poorer quality habitats and at a higher density of conspecifics. Body condition was not related to any variables. Our results suggest that male density, sometimes used as an indicator of an area being well conserved for the species, may reflect areas of poorer habitat quality occupied by unpaired floater males, whereas paired territorial males would occupy and defend higher quality areas, leading to lower density.

Frequency jumps and subharmonic components in calls of female Odorrana tormota differentially affect the vocal behaviors of male frogs

Studies have demonstrated that the sounds of animals from many taxa with nonlinear phenomena (NLP)—caused by nonlinear characteristics of vocal organ dynamics that lead to nonlinear vocal phenomena—can influence the behavior of receivers. However, the specific functions of different NLP components have received less attention. In most frog species, females produce few or no vocalizations; in contrast, female Odorrana tormota exhibit a diverse range of calls that are rich in NLP components. Previous field playbacks have shown that the female calls can elicit responses from male frogs. Therefore, we conducted a phonotaxis experiment to investigate the differential effects of different NLP calls by female O. tormota on the vocal behavior of male frogs. The results revealed that calls with subharmonics elicited a greater number of short calls and answering calls from male frogs compared to calls with frequency jumps. However, calls with frequency jumps triggered more staccato calls from males than calls with subharmonics. Additionally, during the phonotaxis experiments, we recorded the initial vocalizations of males in response to playbacks of female calls. The majority of males first produced short calls. Under calls with frequency jumps, most of male frogs approaching within 10 cm of the loudspeaker produced staccato calls instead of “meow” calls or short calls. While under calls with subharmonics, most male frogs preferred to produced short calls. Our findings demonstrate that frequency jumps and subharmonic components in the calls of female O. tormota have different effects on male vocal behaviors. The current study lays a foundation for a further understanding of the function of anuran NLP components.

Effect sizes of divergence in urban noise and song minimum frequency of grey‐cheeked fulvettas Alcippe morrisonia morrisonia

Noise pollution, one of the most prominent features of urbanization, is an important factor influencing the vocal behavior of urban wildlife. Studies have reported that many songbirds raise their song minimum frequencies in response to urban noise. It has been proposed that this increased minimum frequency (IMF) of songs is an adaptation that allows urban populations to cope with the masking effect of noise pollution. However, urban populations of some songbirds do not exhibit significant IMF compared with non‐urban populations; thus, the notion that IMF is an adaptation to urban noise has been questioned. Furthermore, the effects of IMF might be influenced by both noise levels and the acoustic structures of songs. Here, we employed dichotomous and gradient effect size approaches to investigate IMF regarding two distinct acoustic structures (whistled and harmonic) in songs of six grey‐cheeked fulvetta Alcippe morrisonia morrisonia populations in Taiwan, three with high noise pollution and three with low noise pollution. We found that when using the dichotomous approach, paired populations with significant divergence in noise levels exhibited weak or insignificant divergence in the minimum frequencies for both whistled and harmonic phrases. In contrast, we found that when using the gradient approach, the effect size of noise‐level divergence was strongly correlated with the effect size of divergence in the minimum frequency of the harmonic phrase and only moderately correlated with the effect size of divergence in the minimum frequency of the whistled phrase. These findings suggest that noise pollution has a more pronounced effect on the divergence in the minimum frequency of harmonic phrases used in short‐range communication, compared to the whistled phrases used in long‐range communication. For population comparisons on the IMF, adopting a gradient approach could provide insights into the impact of noise pollution on the acoustic structures of songs across various communication ranges.

Understanding the effect of vocal behaviors in high-conflict situations in personal relationships.

Understanding the effect of vocal behaviors in high-conflict situations in personal relationships.

Raise your pitch! Changes in the acoustic emissions of resident bottlenose dolphins in the proximity of vessels

AbstractMaritime traffic is a major contributor of anthropogenic disturbance for cetaceans, especially for coastal populations, such as that of resident common bottlenose dolphins (Tursiops truncatus) in the Sado estuary (Portugal). Animals have been found to adjust their vocal behavior by changing vocal rates, or call frequency and/or duration, to overcome masking effects of underwater noise. To evaluate the potential impacts of boat traffic on the acoustic behavior of these dolphins, emission rates and acoustic characteristics of whistles and burst‐pulsed signals were analyzed with and without boats operating nearby. In this study, no significant differences were found for emission rates of each type of vocal element in the presence of vessels. However, significant differences were found in acoustic parameters, namely changes in frequency and duration, for whistles and for pulsed sounds (creaks, grunts, squeaks, and gulps). These changes, such as a shift in vocal frequencies and production of shorter signals, may represent behavioral strategies to compensate for the noisy environment. Although resident bottlenose dolphins in the Sado region seem to have developed some tolerance to vessel noise, continuous noise exposure and noise‐induced frequency shifts in vocal outputs could have indirect fitness costs for this population.

Communication in Cook Inlet beluga whales: Describing the vocal repertoire and masking of calls by commercial ship noise.

Many species rely on acoustic communication to coordinate activities and communicate to conspecifics. Cataloging vocal behavior is a first step towards understanding how individuals communicate information and how communication may be degraded by anthropogenic noise. The Cook Inlet beluga population is endangered with an estimated 331 individuals. Anthropogenic noise is considered a threat for this population and can negatively impact communication. To characterize this population's vocal behavior, vocalizations were measured and classified into three categories: whistles (n = 1264, 77%), pulsed calls (n = 354, 22%), and combined calls (n = 15, 1%), resulting in 41 call types. Two quantitative analyses were conducted to compare with the manual classification. A classification and regression tree and Random Forest had a 95% and 85% agreement with the manual classification, respectively. The most common call types per category were then used to investigate masking by commercial ship noise. Results indicate that these call types were partially masked by distant ship noise and completely masked by close ship noise in the frequency range of 0-12 kHz. Understanding vocal behavior and the effects of masking in Cook Inlet belugas provides important information supporting the management of this endangered population.