Vocalization Rate Research Articles

Behavioral responses of territorial red squirrels to natural and experimental variation in population density

The relative scarcity of studies at the intersection of behavioral and population ecology is surprising given the presumed importance of behavior in density-dependent population regulation. Here we tested whether North American red squirrels (Tamiasciurus hudsonicus) adjust their behavior in response to local population density and whether they use rates of territorial vocalizations in their local neighborhood to assess density. We examined these relationships using 18 years of live trapping and 20 years of behavioral data that were collected across natural variation in local population density. To disentangle the effects of population density on behavior from those due to changes in per capita food abundance or changes in the frequency of antagonistic interactions with neighbors, we also experimentally manipulated population density with long-term food supplementation as well as perceived population density with long-term playbacks of territorial vocalizations. The frequency with which squirrels emitted territorial vocalizations was positively associated with local population density. In contrast, antagonistic physical interactions observed between squirrels and territorial intrusions were rare and the frequency of intrusions was weakly and negatively, not positively, associated with population density. Squirrels experiencing naturally and experimentally high density conditions spent less time in the nest and feeding but more time being vigilant. Similar density-dependent changes in behavior were observed in response to our manipulations of perceived population density, indicating that vocalization rates and not physical interactions or food abundance were the mechanism by which squirrels assessed and responded behaviorally to changes in local density.

The relationship between the behavioral activity and the underwater vocalization of the beluga whale (Delphinapterus leucas)

The underwater vocalizations of the beluga whale summering in Onega Bay (64°24′N, 35°49′E) were recorded in June–July of 2008. The vocalizations were classified into five major whistle types, four types of pulsed tones, click series, and noise vocalizations. To determine the relationship between the behavioral activity and the underwater vocalizations, a total of fifty-one 2 minute-long samples of the audio records were analyzed in the next six behavioral contexts: directional movements, quiet swimming, resting, social interactions, individual hunting behavior, and the exploration of hydrophones by beluga whales. The overall vocalization rate and the percentage of the main types of signals depend on the behavior of the belugas. We suggest that one of the whistle types (the “stereotype whistle”) is used by belugas for long-distance communications, while other whistle types (with the exception of “squeaks”) and three types of pulsed tones (with the exception of “vowels”) are used for short distance communication. The percentage of “squeaks” and “vowels” was equally high in all the behavioral situations. Thus, we assume that “squeaks” are contact signals. “Vowels” have a specific physical structure and probably play a role in identification signals. A high rate of the click series was observed in the process of social interactions.

Frequent Vocalizing Is Negatively Associated with Brood Parasitism in a Host of the Brown-headed Cowbird

Abstract. Brood parasitism by the Brown-headed Cowbird (Molothrus ater) can substantially affect host species' reproductive success. The “host-activity” hypothesis suggests that parasites eavesdrop on conspicuous behaviors to locate and parasitize hosts, and several studies of cowbird hosts support this hypothesis. In contrast, a recent study of the Least Bell's Vireo (Vireo bellii pusillus) reported a negative association between the host's vocalization rate near the nest and brood parasitism. This contradictory pattern is intriguing because Bell's Vireo is a common cowbird host and vocalizes near and on its nests. We tested a key assumption of the host-activity hypothesis in a different subspecies (V. b. arizonae) to determine whether the contradictory pattern reported in V. b. pusillus is an anomaly or could be generalized to other subspecies. Unparasitized vireos vocalized more frequently than parasitized birds, confirming that the pattern in Bell's Vireos is the opposite of that reported for other co...

Validation of a Pediatric Vocal Fold Nodule Rating Scale Based on Digital Video Images

We sought to create a validated scale of vocal fold nodules in children, based on digital video clips obtained during diagnostic fiberoptic laryngoscopy. We developed a 4-point grading scale of vocal fold nodules in children, based upon short digital video clips. A tutorial for use of the scale, including schematic drawings of nodules, static images, and 10-second video clips, was presented to 36 clinicians with various levels of experience. The clinicians then reviewed 40 short digital video samples from pediatric patients evaluated in a voice clinic and rated the nodule size. Statistical analysis of the ratings provided inter-rater reliability scores. Thirty-six clinicians with various levels of experience rated a total of 40 short video clips. The ratings of experienced raters (14 pediatric otolaryngology attending physicians and pediatric otolaryngology fellows) were compared with those of inexperienced raters (22 nurses, medical students, otolaryngology residents, physician assistants, and pediatric speech-language pathologists). The overall intraclass correlation coefficient for the ratings of nodule size was quite good (0.62; 95% confidence interval, 0.52 to 0.74). The p value for experienced raters versus inexperienced raters was 0.1345, indicating no statistically significant difference in the ratings by these two groups. The intraclass correlation coefficient for intra-rater reliability was very high (0.89). The use of a dynamic scale of pediatric vocal fold nodule size most realistically represents the clinical assessment of nodules during an office visit. The results of this study show a high level of agreement between experienced and inexperienced raters. This scale can be used with a high level of reliability by clinicians with various levels of experience. A validated grading scale will help to assess long-term outcomes of pediatric patients with vocal fold nodules.

Territorial defence behaviour in red squirrels is influenced by local density

While many animals defend territories to secure resources such as food and mates, little is known about why territory owners of the same species vary in their territorial defence behaviour. We tested whether potential intruder pressure, defence of offspring, resource-holding potential or aggressiveness of the individual territory owner best explained intraspecific differences in territorial defence in a wild population of North American red squirrels (Tamiasciurus hudsonicus). We assessed territorial defence behaviour of individual red squirrels by recording whether or not they produced territorial vocalizations, known as rattles, both in response to a territorial playback and during natural observation sessions without an experimental stimulus. We compared the relative fit of four a priori models to explain territorial defence intensity in red squirrels and found that rattling behaviour in red squirrels under natural conditions was best explained by the intruder pressure hypothesis. Red squirrels were more likely to vocalize if they were surrounded by a higher density of conspecifics on neighbouring territories, indicating that they adjust territorial defence in response to potential intruder pressure. However, vocalization responses of red squirrels to the playback were not affected by local density, which was reflected in similar support for the four a priori models. The differing effects of local density on red squirrel vocalization rate during natural observations and following playbacks indicates that the effects of local density on the territorial behaviour of red squirrels depends on the particular context in which this behaviour is expressed.

Inhibition of maternal behaviour by central infusion of corticotrophin-releasing hormone in marmoset monkeys.

Stress can inhibit maternal behaviour and increase rates of child abuse in humans and other animals; however, the neuroendocrine mechanisms are not known. To determine whether corticotrophin-releasing hormone (CRH) plays a role in stress-induced disruption of maternal behaviour in primates, we characterised the effects of acute i.c.v. infusions of CRH on maternal and abusive behaviour in common marmoset monkeys (Callithrix jacchus). Nulliparous females were implanted with indwelling i.c.v. guide cannulae before conception. Between 18 and 58 days after the birth of her first infants, each female underwent a series of i.c.v. infusions of human CRH (0, 2, 8 and 25 μg) in 8 μl of artificial cerebrospinal fluid. In the 70 min after infusion, marmosets were tested with one of their infants, first in their home cage and, subsequently, in an unfamiliar cage in which the infant was confined in a transparent box on the cage floor. In the home cage, the highest dose of CRH significantly reduced the amount of time that mothers spent carrying their infants, as compared to vehicle alone, although it did not reliably affect aggression toward the infant or other behaviours. In the confined-infant test, the highest dose of CRH significantly reduced the amount of time that mothers spent on the cage floor, increased mothers' vocalisation rates, and tended to reduce their activity levels and time spent in proximity to their infant. Twenty-five micrograms of CRH also elicited significant elevations in plasma adrenocorticotrophic hormone and cortisol concentrations compared to vehicle. These results indicate that i.c.v.-administered CRH reduces maternal behaviour in marmoset mothers, in both familiar and unfamiliar environments, but does not increase infant abuse.

Passive acoustic methods for surveying visually cryptic frog species

Passive acoustic survey methods have great potential for assessing cryptic species that are vocally active. The tiny Moss Frogs (genus Arthroleptella) that inhabit seepages on remote mountain tops in the Western Cape of South Africa are a case in point. Many species are restricted to individual mountains and most are on the IUCN Red List. Surveys are prohibitively expensive because each individual capture involves three to four person-hours of searching. However, males can be heard calling throughout the winter. Using a portable recorder, we gathered acoustic data from which abundance can be estimated and populations monitored. This involves estimation of both the spatial "footprint" of the acoustic array (i.e., what area it effectively surveys) and animal vocalization rates. Ideally both should be estimated as an integral part of the survey, rather than obtained from outside the survey. By combining recently developed mark-recapture methods that take explicit account of the spatial location of microphones, with data on acoustic signal strength and/or time-difference-of-arrival at different microphones, it is possible to do this. We describe the survey and estimation methods, which have many other potential applications. In the case of these frogs, acoustic survey is hundreds of times more efficient than methods involving physical capture.

Targeted Training of Ultrasonic Vocalizations in Aged and Parkinsonian Rats

Voice deficits are a common complication of both Parkinson disease (PD) and aging; they can significantly diminish quality of life by impacting communication abilities. 1, 2 Targeted training (speech/voice therapy) can improve specific voice deficits,3, 4 although the underlying mechanisms of behavioral interventions are not well understood. Systematic investigation of voice deficits and therapy should consider many factors that are difficult to control in humans, such as age, home environment, age post-onset of disease, severity of disease, and medications. The method presented here uses an animal model of vocalization that allows for systematic study of how underlying sensorimotor mechanisms change with targeted voice training. The ultrasonic recording and analysis procedures outlined in this protocol are applicable to any investigation of rodent ultrasonic vocalizations. The ultrasonic vocalizations of rodents are emerging as a valuable model to investigate the neural substrates of behavior.5-8 Both rodent and human vocalizations carry semiotic value and are produced by modifying an egressive airflow with a laryngeal constriction.9, 10 Thus, rodent vocalizations may be a useful model to study voice deficits in a sensorimotor context. Further, rat models allow us to study the neurobiological underpinnings of recovery from deficits with targeted training. To model PD we use Long-Evans rats (Charles River Laboratories International, Inc.) and induce parkinsonism by a unilateral infusion of 7 μg of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle which causes moderate to severe degeneration of presynaptic striatal neurons (for details see Ciucci, 2010).11, 12 For our aging model we use the Fischer 344/Brown Norway F1 (National Institute on Aging). Our primary method for eliciting vocalizations is to expose sexually-experienced male rats to sexually receptive female rats. When the male becomes interested in the female, the female is removed and the male continues to vocalize. By rewarding complex vocalizations with food or water, both the number of complex vocalizations and the rate of vocalizations can be increased (Figure 1). An ultrasonic microphone mounted above the male's home cage records the vocalizations. Recording begins after the female rat is removed to isolate the male calls. Vocalizations can be viewed in real time for training or recorded and analyzed offline. By recording and acoustically analyzing vocalizations before and after vocal training, the effects of disease and restoration of normal function with training can be assessed. This model also allows us to relate the observed behavioral (vocal) improvements to changes in the brain and neuromuscular system.

Targeted Training of Ultrasonic Vocalizations in Aged and Parkinsonian Rats

Voice deficits are a common complication of both Parkinson disease (PD) and aging; they can significantly diminish quality of life by impacting communication abilities. 1, 2 Targeted training (speech/voice therapy) can improve specific voice deficits,3, 4 although the underlying mechanisms of behavioral interventions are not well understood. Systematic investigation of voice deficits and therapy should consider many factors that are difficult to control in humans, such as age, home environment, age post-onset of disease, severity of disease, and medications. The method presented here uses an animal model of vocalization that allows for systematic study of how underlying sensorimotor mechanisms change with targeted voice training. The ultrasonic recording and analysis procedures outlined in this protocol are applicable to any investigation of rodent ultrasonic vocalizations.The ultrasonic vocalizations of rodents are emerging as a valuable model to investigate the neural substrates of behavior.5-8 Both rodent and human vocalizations carry semiotic value and are produced by modifying an egressive airflow with a laryngeal constriction.9, 10 Thus, rodent vocalizations may be a useful model to study voice deficits in a sensorimotor context. Further, rat models allow us to study the neurobiological underpinnings of recovery from deficits with targeted training.To model PD we use Long-Evans rats (Charles River Laboratories International, Inc.) and induce parkinsonism by a unilateral infusion of 7 μg of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle which causes moderate to severe degeneration of presynaptic striatal neurons (for details see Ciucci, 2010).11, 12 For our aging model we use the Fischer 344/Brown Norway F1 (National Institute on Aging).Our primary method for eliciting vocalizations is to expose sexually-experienced male rats to sexually receptive female rats. When the male becomes interested in the female, the female is removed and the male continues to vocalize. By rewarding complex vocalizations with food or water, both the number of complex vocalizations and the rate of vocalizations can be increased (Figure 1).An ultrasonic microphone mounted above the male's home cage records the vocalizations. Recording begins after the female rat is removed to isolate the male calls. Vocalizations can be viewed in real time for training or recorded and analyzed offline. By recording and acoustically analyzing vocalizations before and after vocal training, the effects of disease and restoration of normal function with training can be assessed. This model also allows us to relate the observed behavioral (vocal) improvements to changes in the brain and neuromuscular system.

Cutting the vagus nerve below the diaphragm prevents maternal potentiation of infant rat vocalization

In maternal potentiation, the rate of vocalization by a young organism during isolation is greatly enhanced if that isolation has been immediately preceded by an interaction with the mother (or other adult female in the case of rats). The enhancement in isolation-induced vocalization rate does not occur if the young animal had an interaction with other social companions like littermates or with familiar inanimate stimuli like home cage shavings. The present study demonstrates that pups whose vagus nerve is cut below the diaphragm do not potentiate vocalization after an interaction with their dam. The vocalization rates of denervated pups in a first isolation, in the presence of the dam, and during cold exposure do not differ from control pups. Their non-vocal behaviors also appear unaffected by the surgery. Similar to what has been shown in studies of fever-induced behavioral changes, an intact vagus nerve from the gut is necessary for young rat pups to show normal social mediation of their isolation-induced vocal responses.

Behavioural and cardiac responses towards conspecific distress calls in domestic pigs (Sus scrofa)

In domestic pigs, vocalisation can be an indicator of distress and negative emotional states. It might play a role in the transfer of emotion between individuals (‘emotional contagion’ or ‘empathy’), which could result in impaired animal welfare on a group level based on the distress in an individual member of the group. The aim of this study was to characterise the responses of pigs to conspecific distress calls. We performed a playback experiment in an open arena with 24 juvenile German Landrace pigs, during which individual subjects were exposed to both conspecific distress calls and an artificial sine tone (control) on consecutive experimental days. Both behavioural (locomotion, vocalisation, elimination and distance to the speakers) and physiological responses (heart rate and heart rate variability) were measured for 2min before, during and after the playback of the stimuli (distress calls/control). Subjects showed decreased locomotion and vocalisation rates during both stimuli, suggesting that the animals responded to both stimuli. Heart rates decreased at the onset of both stimuli due to an activation of the parasympathetic system, indicating an orientation response to sudden stimuli. However, heart rates decreased after the end of the distress calls but not after control stimuli, illustrating that conspecific calls and other sounds are evaluated differently. We conclude that pigs exposed to isolation are attentive to conspecific distress vocalisation and hence the information about threat possibly conveyed in it, but they do not share the distress of the caller. Therefore, we could not find direct effects of distress calls of unfamiliar conspecifics on the welfare of isolated juvenile pigs. However, the state of heightened attention elicited by conspecific distress calls may affect a pig's subsequent evaluation of its environment.

The effects of environmental enrichment in the chick anxiety-depression model

As a validation step of an animal simulation, the effects of environmental enrichment were tested in the anxiety-depression model, in which socially raised chicks are placed in isolation for a 2 h test period. Isolated chicks display an initial high rate of distress vocalizations, constituting the anxiety-like phase, followed by a marked decline and plateau in rates of vocalizations for the remainder of time in isolation, characterizing the depression-like phase. Four separate groups of domestic fowl chicks were group housed under enriched, impoverished (i.e., non-enriched) or a combination of the two housing conditions for six days and tested at 7 d posthatch in the aforementioned isolation procedure. Rates of distress vocalizations in the anxiety-like (2–3 min) or depression-like (30–120 min) phases were not affected by housing conditions. However, chicks continuously housed in enriched environments and chicks housed in the enriched environments on days 4–6 displayed a delay in the onset of the depression-like phase. The beneficial effect of environmental enrichment on the depression-like phase is consistent with other stress paradigms and provides another step towards validating the chick anxiety-depression model as a clinical simulation.

An Investigation of Extinction-Induced Vocalizations

Children with autism have significant communication delays. Although some children develop vocalizations through shaping and differential reinforcement, others rarely exhibit vocalizations, and alternative methods are targeted in intervention. However, vocal language often remains a goal for caregivers and clinicians. Thus, strategies to increase frequency of vocalizations are needed. In the present study, the authors examined the effect of extinction of previously acquired signed mands on vocalizations in three children diagnosed with autism. Experiment 1 examined the effects of differential reinforcement of vocalizations and extinction of signed mands combined. In Experiment 1, it was unknown whether the reinforcement of vocalizations alone could have produced the effects; therefore, Experiment 2 isolated the effects of reinforcement and extinction by reinforcing vocalizations in baseline. An increase in rate of vocalizations occurred following the application of extinction of signed mands and differential reinforcement of vocalizations in Experiment 1 and following extinction of signed mands in Experiment 2.

Social context influences the vocalizations of a home-raised African Grey parrot (Psittacus erithacus erithacus).

Home-raised African Grey parrots (Psittacus erithacus erithacus) exhibit strong social bonding with their human companions. We examined how 1 parrot's vocal production (speech and nonword sounds) changed with social context with respect to descriptive measures of the vocalizations and their thematic content. We videotaped the parrot in 4 social conditions: subject home alone, subject and owner in the same room, owner in a separate room within hearing range, and owner and experimenter conversing in the same room as the parrot but ignoring her. Linguistic analysis revealed the parrot's repertoire consisted of 278 "units" ranging in length from 1 to 8 words or sounds. Rate of vocalization and vocabulary richness (i.e., the number of different units used) differed significantly, and many vocalizations were context-specific. For example, when her owner was in the room and willing to reciprocate communication, the parrot was more likely to use units that, in English, would be considered solicitations for vocal interaction (e.g., "Cosmo wanna talk"). When she and her owner were in separate rooms, the subject was significantly more likely to use units that referenced her spatial location and that of her owner (e.g., "Where are you"), suggesting she uses specific units as an adaptation of the wild parrot contact call. These results challenge the notion that parrots only imitate speech and raise interesting questions regarding the role of social interaction in learning and communicative competence in an avian species.

Developmental vitamin D (DVD) deficiency alters pup-retrieval but not isolation-induced pup ultrasonic vocalizations in the rat

Evidence from animal experiments now demonstrates that prenatal vitamin D levels influence brain development. The aims of this study were to examine isolation-induced pup ultrasonic vocalizations and maternal-infant interactions using a pup-retrieval test in developmental vitamin D (DVD) deficient and control rats. Sprague-Dawley rats were fed a vitamin D deficient diet or control diet six weeks prior to mating until birth and housed under UVB-free lighting conditions. In two separate experiments we recorded ultrasonic vocalizations at 46KHz in isolated pups and we performed a pup-retrieval test on the day of birth. There was no significant effect of maternal diet on the calling rate of isolation-induced ultrasonic vocalizations by pups. We found that DVD-deficient dams retrieved their pups sooner than control dams and engaged in more pup directed activities (sniffing and carrying pups) and had a longer latency for self-grooming and rearing than control dams. We also assessed vitamin D related measures from a terminal blood sample immediately after the pup-retrieval test and found that DVD-deficient dams and pups had significantly lower levels of 25 OH D₃, 1,25 (OH)₂D₃ and phosphate, elevated levels of parathyroid hormone (PTH) but there was no significant effect of maternal diet on calcium levels. We speculate that the altered maternal-pup interactions identified in the DVD model may impact on early periods of brain development and behaviour.

Detecting marine mammals with an adaptive sub-sampling recorder in the Bering Sea

Adaptive sub-sampling overcomes the hardware and power limitations of continuous recorders by reducing the amount of data acquired and yet maintains a high probability of detection and classification of targeted signals. This enables data collection for a full year at a high sampling rate from a small, relatively lightweight recorder. The Passive Aquatic Listener (PAL) collects short, high temporal resolution (100 kHz) time series, called “sound bites” at intervals on the order of minutes. Power spectra are stored and provide a description of the background physical environment with a temporal resolution of minutes. Sound bites are only saved if they contain targeted signals of interest, e.g. marine mammals, and can be used to provide an audio confirmation for these sound sources. The estimated probability of detecting a particular marine mammal species depends on, among other physical propagation characteristics, (1) vocalization characteristics for a particular species or activity, (2) an estimate of the percentage of time that active sound is produced, and (3) an estimate of the duration of a typical calling bout. A PAL deployment in the Bering Sea demonstrates the detection of marine mammal signals within a dynamic background sound field. In addition to the automatic detections, post-processing of the sound bites revealed secondary marine mammal detections. These secondary detections demonstrate the wealth of information that can be obtained from short sound clips. Species with high vocalization rates and long calling bouts (fin whales, bowhead whales, and bearded seals) were more likely to be recorded incidentally compared to species with low vocalization rates and short calling bouts (right whales). Acknowledging that physical propagation characteristics associated with detectability must also be addressed, this work illustrates how the combination of spectral data and short sound clips obtained with small, low duty cycle recorders can provide the information needed to address questions of species richness, temporal presence of animals, and response to changes in the environment without the large volume of data obtained by continuous recorders.

Altered ultrasonic vocalizations in a tuberous sclerosis mouse model of autism

Tuberous sclerosis (TSC) is an autosomally dominant neurocutaneous disease notable for its high comorbidity with autism in human patients. Studies of murine models of tuberous sclerosis have found defects in cognition and learning, but thus far have not uncovered deficits in social behaviors relevant to autism. To explore social communication and interaction in TSC2 heterozygous mice, we recorded ultrasonic vocalizations (USV) and found that although both wild-type (WT) and heterozygous pups born to WT dams showed similar call rates and patterns, baseline vocalization rates were elevated in pups born to heterozygous dams. Further analysis revealed several robust features of maternal potentiation in all but WT pups born to heterozygous dams. This lack of potentiation is suggestive of defects in mother-pup social interaction during or before the reunion period between WT pups and heterozygous dams. Intriguingly, male pups of both genotypes born to heterozygous dams showed particularly heightened call rates and burst patterns. Because our maternal retrieval experiments revealed that TSC2(+/-) dams exhibited improved defensive reactions against intruders and highly efficient pup retrieval performance, the alterations in their pups' USVs and maternal potentiation do not appear to result from poor maternal care. These findings suggest that a pup's interaction with its mother strongly influences the pup's vocal communication, revealing an intriguing dependence of this social behavior on TSC2 gene dosage of both parties involved. Our study of this murine model thus uncovers social abnormalities that arise from TSC haploinsufficiency and are suggestive of autism.

Investment in fighting in relation to body condition, age and dominance rank in the male fallow deer, Dama dama

According to life history theory, males of iteroparous species are expected to trade off investment between current and future reproduction based on age (mating strategy or terminal investment hypotheses) or body condition (individual quality hypothesis). However, although central to this latter model, the question concerning whether and to what extent condition regulates competitive investment in polygynous species is unknown. Consequently, we investigated this issue with reference to fight structure in fallow deer contests. Support for the individual quality hypothesis was limited: males with larger necks as determined by prerut neck girth fought for longer than males with smaller necks. However, prime-aged males had higher investment in fighting than preprime- or postprime-aged males indicating that investment in fighting might be age related. Other aspects of our results also failed to support condition-related predictions; although we found that jump clashing and vocal rate were related to weight loss and decline in neck girth, respectively, there was no relationship between investment in fighting and prerut measures of body size. Moreover, we also found that rank was predicted by investment in fighting (backward pushing) rather than body condition. Our results show that, in addition to body condition and age, variation in competitive investment between individuals also influences reproductive effort in the fallow deer.

Time course of vocal modulation during isolation in common marmosets (Callithrix jacchus)

Common marmosets vocalize phee calls as isolation calls, which seem to facilitate their reunion with family groups. To identify multiple acoustic properties with different time courses, we examined acoustic modulations of phees during different social contexts of isolation. Subject marmosets were totally isolated in one condition, were visually isolated and could exchange vocalizations in another condition, and were visually isolated and subsequently totally isolated in a third condition. We recorded 6,035 phees of 10 male-female marmoset pairs and conducted acoustic analysis. The marmosets frequently vocalized phees that were temporally elongated and louder during isolation, with varying time courses of these changes in acoustic parameters. The vocal rates and sound levels of the phees increased as soon as the marmosets saw their pair mates being taken away, and then gradually calmed down. The phee duration was longer in conditions during which there were no vocal responses from their pair mates. Louder vocalizations are conspicuous and seem to be effective for long-distance transmission, whereas shorter call duration during vocal exchanges might avoid possible vocal overlap between mates.

The Effect of Teaching Experience and Specialty (Vocal or Instrumental) on Vocal Health Ratings of Music Teachers

The current study sought to determine the relationship among music teachers’ length of teaching experience, specialty (vocal or instrumental), and ratings of behaviors and teaching activities related to vocal health. Participants ( N = 379) were experienced ( n = 208) and preservice ( n = 171) music teachers, further categorized by specialty, either vocalists ( n = 198) or instrumentalists ( n = 181). Teachers provided demographic information, vocal health ratings for selected behaviors, and ratings of perceived vocal stress in selected teaching activities. Years of teaching experience had a significant effect for four behaviors and one teaching activity. Specialty had a significant effect for two behaviors and three teaching activities. The interaction of years of teaching experience and specialty was significant for the following behaviors: clearing the throat, getting adequate sleep, and breathing secondhand smoke. The interaction of years of teaching experience and specialty was significant for the following teaching activities: verbal instruction while students play instruments, speaking over noisy classroom conditions, hall duty, and lunch duty. Overall, ratings provided by preservice teachers tend to reflect healthier practices. Suggestions for further research include instrumentalists’ perceived vocal stress, how perceptions can be shaped to aid prevention of vocal disorders in teachers, and vocal health opinions where diverse experience levels are explored more deeply.