Temporal pattern of vocalization type usage in singing sessions of male tyrant flycatchers (Tyranninae)

It has been hypothesized that variation (e.g., of repertoire elements) in prolonged vocalization sessions of passerine birds can serve to minimize habituation by conspecifics. The repertoire of vocalization types limited in suboscine passerines, raising the question of how a limited set of elements can create patterns that minimize habituation. This question was studied by computational analysis of recorded singing sessions of 20 suboscine species from the subfamily Tyranninae, family Tyrannidae (tyrant flycatchers). The recordings of 12 of the species included two or more distinct vocalization types (VTs). In these species, the interval between vocalization units when the VT changed was on average shorter than that when the VT remained the same. In addition, when the VT changed, the mean interval length between successive vocalization units differed depending on which VT preceded the interval and which VT followed it. On the other hand, species with just a single VT in the session analyzed showed a surprisingly high degree of absolute difference between adjacent vocalization units with respect to both the length of the vocalization and percentage of time elapsed until peak amplitude. A change in the rhythm of vocalization accompanying a change in VT provided a potential means of drawing a conspecific listener's attention to the change in VT. The results showed that tyrant flycatchers use temporal patterning to achieve a high level of variety in vocalization sessions despite a limited vocal repertoire.     

Human auditory cortical activation during self-vocalization

During speaking, auditory feedback is used to adjust vocalizations. The brain systems mediating this integrative ability have been investigated using a wide range of experimental strategies. In this report we examined how vocalization alters speech-sound processing within auditory cortex by directly recording evoked responses to vocalizations and playback stimuli using intracranial electrodes implanted in neurosurgery patients. Several new findings resulted from these high-resolution invasive recordings in human subjects. Suppressive effects of vocalization were found to occur only within circumscribed areas of auditory cortex. In addition, at a smaller number of sites, the opposite pattern was seen; cortical responses were enhanced during vocalization. This increase in activity was reflected in high gamma power changes, but was not evident in the averaged evoked potential waveforms. These new findings support forward models for vocal control in which efference copies of premotor cortex activity modulate sub-regions of auditory cortex.     

Singing in the Face of Danger: the Anomalous Type II Vocalization of the Splendid Fairy-Wren

Males of certain species of fairy-wrens (Aves: Maluridae) emit a unique vocalization, the Type II vocalization, in response to the calls of potential predators. We conducted field observations and playback experiments to identify the contexts in which the Type II vocalization is emitted by splendid fairy-wren ( Malurus splendens ) males, and to examine social and genetic factors that influence its occurrence. In field observations and controlled playback experiments, Type II vocalizations were elicited most consistently by calls of the predatory gray butcherbird ( Cracticus torquatus ). Some vocalizations from other avian species also elicited Type II vocalizations, and the majority of these were vocalizations from avian predators. Splendid fairy-wrens are cooperative breeders, and males that responded with Type II vocalizations to playbacks of butcherbird calls tended to be primary rather than secondary males, had larger cloacal protuberances, and were older than those that did not respond. In addition, secondary males that were sons of resident females were more likely than non-sons to respond with a Type II vocalization. In another playback experiment, females responded similarly to the Type I song and Type II vocalizations of their mates. Although the Type II vocalization is emitted primarily in response to predator calls, it is inconsistent with an alarm call explanation. Patterns of reproductive success among Type II calling males suggest that it does not function as an honest signal of male quality. At present, the function of the vocalization remains anomalous, but indirect fitness benefits may play a role in its explanation.     

The three isoforms of nitric oxide synthase distinctively affect mouse nocifensive behavior

Nitric oxide synthases (NOSs) have been shown to modulate thermal hyperalgesia and mechanical hypersensitivity in inflammatory and neuropathic pain. However, little is known about the effect of NOSs on baseline function of sensory nerve fibers. Using genetic deficiency and pharmacologic inhibition of NOSs, we examined the impact of the three isoforms NOS1, NOS2, and NOS3 on baseline nocifensive behavior by measuring current vocalization threshold in response to electrical stimulation at 5, 250, 2000 Hz that preferentially stimulate C, Aδ, and Aβ fibers. In response to 5, 250 and 2000 Hz, NOS1-deficient animals had significantly higher current vocalization thresholds compared with wild-type. Genetic deficiency of NOS2 was associated with higher current vocalization thresholds in response to 5 Hz (C-fiber) stimulation. In contrast, NOS3-deficient animals had an overall weak trend toward lower current vocalization thresholds at 5 Hz and significantly lower current vocalization threshold compared with wild-type animals at 250 and 2000 Hz. Therefore, NOSs distinctively affect baseline mouse current vocalization threshold and appear to play a role on nocifensive response to electrical stimulation of sensory nerve fibers.     

电刺激猫中脑中央灰质发音区的反应及该区的传入联系

刺激猫中脑中央灰质发音区可引起动物发音、情绪反应以及心律异常、血压升高等变化。同时,本研究还揭示,分别在中脑中央灰质嘴侧和尾侧发音区注入辣根过氧化物酶后,其逆行标记神经元分布相类似;但是,中脑中央灰质发音区和非发音区的传入联系则互不相同。     

A review of automatic recognition technology for bird vocalizations in the deep learning era

Birds are considered critical indicators of ecosystem condition. Automatic recording devices have emerged as a trending tool to assist field observations, contributing to biodiversity monitoring on large spatio-temporal scales. However, manually processing huge volumes of recordings is challenging. Consequently, there has been a growing interest in automatic bird vocalization recognition in recent years. Automatic bird vocalization recognition technology has advanced from classical pattern recognition to deep learning (DL), with significantly improved recognition performance. This paper reviews related works on DL-based automatic bird vocalization recognition technology in the last decade. In this review, we present the current state of research in the three key areas of pre-processing, feature extraction and recognition methods involved in automatic bird vocalization recognition. The related datasets, evaluation metrics and software are also summarized. Finally, existing challenges along with opportunities for future work are highlighted. We conclude that, while DL-based automatic bird vocalization recognition has made recent advances in specific species, more robust denoising approaches, larger public datasets, and stronger generalization capabilities of feature extraction and recognition are required to achieve reliable and general bird recognition in the wild. We expect that this review will serve as a firm foundation for new researchers working in the field of DL-based automatic bird vocalization recognition technologies, as well as become an insightful guide for computer science and ecology experts.     

Purring and similar vocalizations in mammals

The terms purr and purring have been used for vocalizations produced by a variety of mammalian species in different orders. A few other mammalian vocalizations that are structurally somewhat similar to felid purring but have been given another term have also been described in the literature. Because use of the same term implies ‘sameness’, which in an evolutionary sense can only mean that the vocalizations so named are homologous (= share the same ancestral vocalization type), the terms purr and purring ought to be restricted to vocalizations homologous with felid purring, and any mammalian vocalization homologous with felid purring ought to be named accordingly. According to present knowledge ‘true’ purring is established only in the families Viverridae and Felidae of the Carnivora. Vocalizations very similar in structure occur in matching behavioural contexts in other families of the Carnivora and several other mammalian orders. Most of these vocalization types are likely to have evolved convergently.     

Humming in bears: a peculiar sustained mammalian vocalization

A peculiar sustained vocalization has long been known under various names in several bear species but not been studied in sufficient detail. Based on a critical survey of the relevant literature, analyses of tape recordings and pertinent own observations we tried to clarify the presence of this vocalization in the species of the Ursidae as well as its structural characteristics and specific mode of sound production. To avoid confusion with other vocalization types we introduce the term humming for it. Furthermore we discuss its communicatory and functional significance and formulate hypotheses as to its evolutionary origin against the background of acoustic communication signal repertoires known in the terrestrial Carnivora. Humming is present in all extant species of the Ursidae with the exception of the giant panda. It has similar structural characteristics and the same mode of sound production in all species. It is also known in adult bears but its occurrence is largely restricted to cubs. Humming is a synapomorphic vocalization type of the Ursidae which is not phylogenetically related to another vocalization type known in the terrestrial Carnivora. It is a rapid sequence of very short single sounds; long bouts of sustained exhalatory sound production are interrupted by very short inhalatory phases without sound. Both the sound and the body vibration accompanying its production are highly likely to be communication signals. Yet, controlled physiological experiments on bear mothers and cubs are still necessary to formulate and test specific hypotheses as to the communicatory function and adaptive significance of humming.     

Reduction in Ultrasonic Vocalizations in Pups Born to Rapid Eye Movement Sleep Restricted Mothers in Rat Model

The effects of rapid eye movement sleep restriction (REMSR) in rats during late pregnancy were studied on the ultrasonic vocalizations (USVs) made by the pups. USVs are distress calls inaudible to human ears. Rapid eye movement (REM) sleep was restricted in one group of pregnant rats for 22 hours, starting from gestational day 14 to 20, using standard single platform method. The USVs of male pups were recorded after a brief isolation from their mother for two minutes on alternate post-natal days, from day one till weaning. The USVs were recorded using microphones and were analysed qualitatively and quantitatively using SASPro software. Control pups produced maximum vocalization on post-natal days 9 to 11. In comparison, the pups born to REMSR mothers showed not only a reduction in vocalization but also a delay in peak call making days. The experimental group showed variations in the types and characteristics of call types, and alteration in temporal profile. The blunting of distress call making response in these pups indicates that maternal sleep plays a role in regulating the neural development involved in vocalizations and possibly in shaping the emotional behaviour in neonates. It is suggested that the reduced ultrasonic vocalizations can be utilized as a reliable early marker for affective state in rat pups. Such impaired vocalization responses could provide an important lead in understanding mother-child bonding for an optimal cognitive development during post-partum life. This is the first report showing a potential link between maternal REM sleep deprivation and the vocalization in neonates and infants.     

Aeroacoustics of the vocal organ of birds

A model is presented of aeroacoustical processes occurring in the avian syrinx during vocalization based on current anatomical and physiological knowledge. The physical circumstances governing the triggering of oscillations in the external tympaniform membranes are analysed. A theory of membrane excitation based on non-linear elasticity is described. Anatomical and physical factors controlling the level of sound power radiated are examined and the possibility is considered that elevated airflow rates during vocalization may increase power output by a process of convective amplification similar to that which has been described in certain engineering contexts.     

The effect of syringeal deafferentation on the stimulated vocalization in the domestic chick (Gallus gallus)

The r?le of syringeal feedback on the electrically elicited vocalization in chickens (Gallus gallus) was studied. The vocalization patterns elicited by stimulating the low-threshold "calling areas" in the midbrain, was examined before and after syringeal deafferentation obtained by cutting the X-XII anastomosis on either the left and right side. The results show that section of the X-XII anastomosis on the left side produces consistently a clear-cut lowering of the threshold for vocalization and an increase of the amplitude of the individual calls with no change in the repetition rate of the call sequences. All these effects are enhanced when the contralateral anastomosis is also severed. These results show that the bilateral syringeal deafferentation does not change the overall song pattern performance, that remains stereotyped both in duration and complexity, consistent with the hypothesis that, in adult birds, stable song patterns are not dependent on peripheral sources of feedback, but are ruled by a learned central control program. However the modification of vocalization threshold and amplitude suggests the hypothesis that the syringeal feedback plays an inhibitory r?le on vocalization by modulating the excitability of the central structures involved in the vocalization activity.     

The neighbor effect: Other groups influence intragroup agonistic behavior in captive chimpanzees

While intercommunity interactions are well documented in wild chimpanzees, the influence of neighboring captive groups on social behavior has not been investigated. This study examined the influence of vocalizations and noisy displays produced in neighboring groups (i.e., “neighbor vocalization”) on intragroup hooting, bluff displays, and agonistic behavior. Chimpanzees from two broadly differing housing conditions were selected in order to examine the effect of neighboring groups: “Wing Groups” (those living in indoor/outdoor pens with auditory access to large number of neighboring individuals) and “Building Groups” (those housed in one indoor building, able to hear the calls and noisy displays produced by a small number of neighboring individuals occupying the building). Data were collected on 58 adult and juvenile subjects living in social groups varying in size from two to 14 individuals. Observation sessions were divided into two categories depending on the level of neighbor vocalization. Wing Groups showed higher rates of hooting, bluff displays, and agonistic behavior against other group members when levels of neighbor vocalization were high. Building Groups showed the same pattern, with results for bluff displays reaching statistical significance. This effect was also found through an analysis of the time periods immediately surrounding incidents of neighbor vocalization: Hooting and bluff displays were significantly more common after than before neighbor vocalizations. In spite of variation between the two housing conditions with respect to overall levels of neighbor vocalization, degree of differences between the high and low vocalization levels, and methods of data collection, a consistent neighbor effect was detected. This effect is congruous with behavioral patterns observed in the wild, and is therefore considered an expression of species-typical behavior as opposed to an artifact of captivity. These results are relevant to captive management, and bear on the influence of housing condition on psychological well-being. © 1996 Wiley-Liss, Inc.     

The behavioral context of common dolphin (Delphinus sp.) vocalizations

Correlations between surface behavior and concurrent underwater vocalizations were modeled for common dolphins (Delphinus spp.) in the Southern California Bight (SCB) over multiple field seasons. Clicks, pulsed calls, and whistles were examined, with a total of 50 call features identified. Call features were used to classify behavior using random forest decision trees, with rates of correct classification reaching 80.6% for fast travel, 84.6% for moderate travel, 59.8% for slow travel, and 58% for foraging behavior. Common dolphins spent most of their time traveling. The highest number of clicks, pulsed calls, and complex whistles were produced during fast travel. In contrast, during foraging there were few pulsed calls and whistles produced, and the whistles were simple with narrow bandwidths and few harmonics. Behavior and vocalization patterns suggest nocturnal foraging in offshore waters as the primary feeding strategy. Group size and spacing were strongly correlated with behavior and rates of calling, with higher call rates in dispersed traveling groups and lower call rates in loosely aggregated foraging groups. These results demonstrate that surface behavior can be classified using vocalization data, which builds the framework for behavioral studies of common dolphins using passive acoustic monitoring techniques.     

Do newborn vocalizations affect the behavioral and hormonal responses of nonreproductive male common marmosets (Callithrix jacchus)?

Parental care in mammals is influenced by sensory stimuli from infants, such as sight and sound, and by changes in the hormone levels of caretakers. To determine the responsiveness of common marmoset (Callithrix jacchus) adult males with and without previous experience in caretaking to newborn sensory cues, we exposed twelve males to infant vocalization recordings and assessed their hormonal and behavioral responses. Males were placed in the testing cage for 10 min under two conditions: (a) control condition (exposure to adult conspecific vocalization recordings), and (b) experimental condition (exposure to infant vocalization recordings). We recorded the frequency of approach towards the sound source, the time spent near it and locomotion frequency of males in the cage under both conditions. Blood samples were collected after each test for cortisol, measured by the enzyme immunoassay method. Infant vocalization affects the behavioral and hormonal responses of non-reproductive male common marmosets. All males approached and spent more time near the sound source and showed an increase in locomotion during infant vocalization exposure compared to the control condition. Successive exposure to infant vocalization increased the responsiveness in inexperienced males. Cortisol levels were significantly higher following infant vocalization exposure compared to the control condition. These findings support the assumption that sound stimuli from the newborn are critical in initiating and maintaining caretaker responsiveness and that cortisol seems to be important for alertness to sensory stimuli, modulating their motivation to interact with infants.     

Environmental correlates of vocal communication of wild pygmy marmosets, Cebuella pygmaea

We quantified the acoustic characteristics of the habitats of two wild populations of pygmy marmosets, in Amazonian Ecuador to evaluate their effects on vocal signal structure. We obtained measures of ambient noise, sound attenuation and reverberation through recordings and broadcasts of exemplars of two short-range vocalizations and one long-range vocalization of the marmosets. Ambient noise levels differed among habitats. The calls of pygmy marmosets had frequencies that coincided with relatively quiet regions of the ambient noise spectra of the habitats. The three vocalization types were degraded similarly in all habitats. The two short-range signals, with a pulsatile structure, were more affected by reverberation than was the long-range, less pulsatile vocalization. This degradation could be used by the marmosets to estimate the distance of the caller animals. We obtained data on context of vocalizations from six groups of pygmy marmosets, three from each population, in both the dry and rainy seasons. The use of Trills, J calls and Long calls was related to the distance between the calling animal and the potential receivers suggesting that marmosets are using the calls in a way appropriate to the effects of habitat acoustics. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

The use of low-frequency vocalizations in African elephant(Loxodonta africana) reproductive strategies

Fertility-advertisement calls in females are predicted to occur in nonmonogamous species where males and females are widely separated in space. In African elephants, low-frequency vocalizations have thus been suggested as a reproductive strategy used by fertile females to attract mates. This study examined the use of low-frequency vocalizations with respect to different phases of the estrous cycle in African elephants by simultaneously monitoring vocalizations, behavior, and hormonal profiles. Subjects were one male and six female African elephants housed at Disney's Animal Kingdom. No acoustically distinct vocalizations were restricted to the ovulatory follicular phase. However, overall rate of low-frequency vocalization as well as the rate of one acoustically distinct vocalization changed over the estrous cycle, with highest rates of calling related to the first period of follicular growth, or anovulatory follicular phase. Elevated rates of vocalization thus were not restricted to behavioral estrus and occurred much earlier in the estrous cycle than in most species that produce fertility-advertisement calls. Both herd composition and elephant identity also affected rates of vocalization. Vocalizations therefore may not be reliable signals of actual fertility. However, the increase in vocalizations in advance of estrus may attract males to the herd prior to ovulation, facilitating both male-male competition and female choice. Once present in the herd, males may then switch strategies to use more reliable chemical and visual cues to detect ovulating females.     

Response variability in the mammalian auditory cortex: an objection to feature detection?

Research strategy in the auditory system has tended to parallel that in the visual system, where neurons have been shown to respond selectively to specific stimulus parameters. Auditory neurons have been shown to be sensitive to changes in acoustic parameters, but only rarely have neurons been reported that respond exclusively to only one biologically significant sound. Even at higher levels of the auditory system very few cells have been found that could be described as "vocalization detectors." In addition, variability in responses to artificial sounds have been reported for auditory cortical neurons similar to the response variability that has been reported in the visual system. Recent evidence indicates that the responses of auditory cortical neurons to species-specific vocalizations can also be labile, varying in both strength and selectivity. This is especially true of the secondary auditory cortex. This variability, coupled with the lack of extreme specificity in the secondary auditory cortex, suggests that secondary cortical neurons are not well suited for the role of "vocalization detectors."     

Primate phonation: Anterior cingulate lesion effects on response rate and acoustical structure

Four juvenile rhesus monkeys (Macaca mulatta) that were conditioned to emit a discriminative vocal response underwent unilateral and bilateral lesions of anterior cingulate gyrus in stepwise sequence. Pre- and post-lesion measures of vocal response rate and acoustical features (call duration, amplitude, and fundamental frequency) were obtained for the conditioned task and for vocalization in the home colony (spontaneous vocalization). Unilateral lesions produced little consistent change in spontaneous “coo” vocalization rate and call duration. Conditioned vocalization of the monkeys exhibited no significant change in rate at this stage, although call duration was reduced significantly. Bilateral lesions produced no further modifications in acoustic properties of spontaneous calls, while the vocal rate decreased slightly. Conditioned calls were not significantly altered in acoustic features at this stage, although the discriminative vocalization rate was significantly decreased for all monkeys. The results indicate limited control over vocal motor systems by anterior cingulate cortex, while suggesting that this region participates in initiation of voluntary phonation.