Vocal production learning is a rare communication skill and has only been found in selected avian and mammalian species 1–4. Although humans use learned formants and voiceless sounds to encode most ...lexical information 5, evidence for vocal learning in other animals tends to focus on the modulation pattern of the fundamental frequency 3, 4. Attempts to teach mammals to produce human speech sounds have largely been unsuccessful, most notably in extensive studies on great apes 5. The limited evidence for formant copying in mammals raises the question whether advanced learned control over formant production is uniquely human. We show that gray seals (Halichoerus grypus) have the ability to match modulations in peak frequency patterns of call sequences or melodies by modifying the formants in their own calls, moving outside of their normal repertoire’s distribution of frequencies and even copying human vowel sounds. Seals also demonstrated enhanced auditory memory for call sequences by accurately copying sequential changes in peak frequency and the number of calls played to them. Our results demonstrate that formants can be influenced by vocal production learning in non-human vocal learners, providing a mammalian substrate for the evolution of flexible information coding in formants as found in human language.
•Vocal learning is crucial for language acquisition but relatively rare in animals•We tested whether gray seals can copy melodies and human formants•Seals were versatile vocal learners copying vowels and peak frequency of melodies•Seals used the same supra-laryngeal structures as humans when copying model sounds
Speech information in voiced human sounds is encoded in resonances in the supra-laryngeal tract that emphasize the energy content of selected harmonics. Stansbury and Janik show that gray seals can learn to modify emphasized frequency bands called formants to copy human vowels and melodies, making them an ideal model of human speech development.
Pinnipeds have been identified as one of the best available models for the study of vocal learning. Experimental evidence for their learning skills is demonstrated with advanced copying skills, ...particularly in formant structure when copying human speech sounds and melodies. By contrast, almost no data are available on how learning skills are used in their own communication systems. We investigated the impact of playing modified seal sounds in a breeding colony of grey seals (
Halichoerus grypus
) to study how acoustic input influenced vocal development of eight pups. Sequences of two or three seal pup calls were edited so that the average peak frequency between calls in a sequence changed up or down. We found that seals copied the specific stimuli played to them and that copies became more accurate over time. The differential response of different groups showed that vocal production learning was used to achieve conformity, suggesting that geographical variation in seal calls can be caused by horizontal cultural transmission. While learning of pup calls appears to have few benefits, we suggest that it also affects the development of the adult repertoire, which may facilitate social interactions such as mate choice.
This article is part of the theme issue ‘Vocal learning in animals and humans’.
Anthropogenic noise can have negative effects on animal behaviour and physiology. However, noise is often introduced systematically and potentially provides information for navigation or prey ...detection. Here, we show that grey seals (Halichoerus grypus) learn to use sounds from acoustic fish tags as an indicator of food location. In 20 randomized trials each, 10 grey seals individually explored 20 foraging boxes, with one box containing a tagged fish, one containing an untagged fish and all other boxes being empty. The tagged box was found after significantly fewer non-tag box visits across trials, and seals revisited boxes containing the tag more often than any other box. The time and number of boxes needed to find both fish decreased significantly throughout consecutive trials. Two additional controls were conducted to investigate the role of the acoustic signal: (i) tags were placed in one box, with no fish present in any boxes and (ii) additional pieces of fish, inaccessible to the seal, were placed in the previously empty 18 boxes, making possible alternative chemosensory cues less reliable. During these controls, the acoustically tagged box was generally found significantly faster than the control box. Our results show that animals learn to use information provided by anthropogenic signals to enhance foraging success.
Past researchers have found that gray seals (Halichoerus grypus) are capable of classifying vocal signals by call type using a trained set, but were unable to generalize to novel exemplars (Shapiro, ...Slater, & Janik, 2004). Given the importance of auditory categorization in communication, it would be surprising if the animals were unable to generalize acoustically similar calls into classes. Here, we trained a juvenile gray seal to discriminate novel calls into 2 classes, "growls" and "moans," by vocally matching call types (i.e., the seal moaned when played a moan and growled when played a growl). Our method differed from the previous study as we trained the animal using a comparatively large set of exemplars with standardized durations, consisting of both the seal's own calls and those of 2 other seals. The seal successfully discriminated growls and moans for both her own (94% correct choices) and the other seals' (87% correct choices) calls. We used a generalized linear model (GLM) and found that the seal's performance significantly improved across test sessions, and that accuracy was higher during the first presentation of a sound from her own repertoire but decreased after multiple exposures. This pattern was not found for calls from unknown seals. Factor analysis for mixed data (FAMD) identified acoustic parameters that could be used to discriminate between call types and individuals. Growls and moans differed in noise, duration and frequency parameters, whereas individuals differed only in frequency. These data suggest that the seal could have gained information about both call type and caller identity using frequency cues.
Auditory sensitivity in aquatic animals Lucke, Klaus; Popper, Arthur N; Hawkins, Anthony D ...
The Journal of the Acoustical Society of America,
06/2016, Letnik:
139, Številka:
6
Journal Article
Recenzirano
Odprti dostop
A critical concern with respect to marine animal acoustics is the issue of hearing "sensitivity," as it is widely used as a criterion for the onset of noise-induced effects. Important aspects of ...research on sensitivity to sound by marine animals include: uncertainties regarding how well these species detect and respond to different sounds; the masking effects of man-made sounds on the detection of biologically important sounds; the question how internal state, motivation, context, and previous experience affect their behavioral responses; and the long-term and cumulative effects of sound exposure. If we are to better understand the sensitivity of marine animals to sound we must concentrate research on these questions. In order to assess population level and ecological community impacts new approaches can possibly be adopted from other disciplines and applied to marine fauna.
With increased polar anthropogenic activity, such as from the oil and gas industry, there are growing concerns about how Arctic species will be affected. Knowledge of species’ sensory abilities, such ...as auditory sensitivities, can be used to mitigate the effects of such activities. Herein, behavioral audiograms of two captive adult Arctic foxes (
Vulpes lagopus
) were measured using a yes/no paradigm and descending staircase method of signal presentation. Both foxes displayed a typical mammalian U-shaped audiometric curve, with a functional hearing range of 125 Hz–16 kHz (sensitivity ≤ 60 dB re: 20 μPa) and average peak sensitivity of 24 dB re: 20 μPa at 4 kHz. The foxes had a lower frequency range and sensitivity than would be expected when compared to previous audiograms of domestic dogs (
Canis familiaris
) and other carnivores. These differences indicate Arctic foxes (
V. lagopus
) may have a lower frequency range than previously expected, which was similar to the only other fox species tested to date, kit foxes
(Vulpes macrotis
). Alternatively, differences may be due to testing constraints, such as masking of test signals by ambient noise and/or an unintentionally trained conservative response bias, which most likely resulted in underestimated hearing curves. While results of this study should be interpreted with caution due to its limitations, findings indicate that foxes have a narrower frequency range than formerly presumed. Anthropogenic activities near fox habitats can mitigate their impacts by reducing noise at frequencies within the functional hearing range and peak sensitivities of this species.
Anthropogenic noise can have negative effects on animal behaviour and physiology. However, noise is often introduced systematically and potentially provides information for navigation or prey ...detection. Here, we show that grey seals (Halichoerus grypus) learn to use sounds from acoustic fish tags as an indicator of food location. In 20 randomized trials each, 10 grey seals individually explored 20 foraging boxes, with one box containing a tagged fish, one containing an untagged fish and all other boxes being empty. The tagged box was found after significantly fewer non-tag box visits across trials, and seals revisited boxes containing the tag more often than any other box. The time and number of boxes needed to find both fish decreased significantly throughout consecutive trials. Two additional controls were conducted to investigate the role of the acoustic signal: (i) tags were placed in one box, with no fish present in any boxes and (ii) additional pieces of fish, inaccessible to the seal, were placed in the previously empty 18 boxes, making possible alternative chemosensory cues less reliable. During these controls, the acoustically tagged box was generally found significantly faster than the control box. Our results show that animals learn to use information provided by anthropogenic signals to enhance foraging success.
Aquatic facility-associated illness and injury in the United States include disease outbreaks of infectious or chemical etiology, drowning, and pool chemical-associated health events (e.g., ...respiratory distress or burns). These conditions affect persons of all ages, particularly young children, and can lead to disability or even death. A total of 650 aquatic facility-associated outbreaks have been reported to CDC for 1978-2012. During 1999-2010, drownings resulted in approximately 4,000 deaths each year in the United States. Drowning is the leading cause of injury deaths in children aged 1-4 years, and approximately half of fatal drownings in this age group occur in swimming pools. During 2003-2012, pool chemical-associated health events resulted in an estimated 3,000-5,000 visits to U.S. emergency departments each year, and approximately half of the patients were aged <18 years. In August 2014, CDC released the Model Aquatic Health Code (MAHC), national guidance that can be adopted voluntarily by state and local jurisdictions to minimize the risk for illness and injury at public aquatic facilities.
2013.
The Network for Aquatic Facility Inspection Surveillance (NAFIS) was established by CDC in 2013. NAFIS receives aquatic facility inspection data collected by environmental health practitioners when assessing the operation and maintenance of public aquatic facilities. This report presents inspection data that were reported by 16 public health agencies in five states (Arizona, California, Florida, New York, and Texas) and focuses on 15 MAHC elements deemed critical to minimizing the risk for illness and injury associated with aquatic facilities (e.g., disinfection to prevent transmission of infectious pathogens, safety equipment to rescue distressed bathers, and pool chemical safety). Although these data (the first and most recent that are available) are not nationally representative, 15.7% of the estimated 309,000 U.S. public aquatic venues are located in the 16 reporting jurisdictions.
During 2013, environmental health practitioners in the 16 reporting NAFIS jurisdictions conducted 84,187 routine inspections of 48,632 public aquatic venues. Of the 84,187 routine inspection records for individual aquatic venues, 78.5% (66,098) included data on immediate closure; 12.3% (8,118) of routine inspections resulted in immediate closure because of at least one identified violation that represented a serious threat to public health. Disinfectant concentration violations were identified during 11.9% (7,662/64,580) of routine inspections, representing risk for aquatic facility-associated outbreaks of infectious etiology. Safety equipment violations were identified during 12.7% (7,845/61,648) of routine inspections, representing risk for drowning. Pool chemical safety violations were identified during 4.6% (471/10,264) of routine inspections, representing risk for pool chemical-associated health events.
Routine inspections frequently resulted in immediate closure and identified violations of inspection items corresponding to 15 MAHC elements critical to protecting public health, highlighting the need to improve operation and maintenance of U.S. public aquatic facilities. These findings also underscore the public health function that code enforcement, conducted by environmental health practitioners, has in preventing illness and injury at public aquatic facilities.
Findings from the routine analyses of aquatic facility inspection data can inform program planning, implementation, and evaluation. At the state and local level, these inspection data can be used to identify aquatic facilities and venues in need of more frequent inspections and to select topics to cover in training for aquatic facility operators. At the national level, these data can be used to evaluate whether the adoption of MAHC elements minimizes the risk for aquatic facility-associated illness and injury. These findings also can be used to prioritize revisions or updates to the MAHC. To optimize the collection and analysis of aquatic facility inspection data and thus application of findings, environmental health practitioners and epidemiologists need to collaborate extensively to identify public aquatic facility code elements deemed critical to protecting public health and determine the best way to assess and document compliance during inspections.
The aerial audiograms of two captive adult, male Arctic fox ( Alopex lagopus) were measured using a two-alternative, forced-choice paradigm, and a descending staircase method of stimulus presentation ...at the Columbus Zoo and Aquarium. Both Arctic fox displayed a typical mammalian U-shaped audiometric curve, with a functional aerial hearing range of 125 Hz to 16 kHz (at a sensitivity of ≤ 60 dB re: 20 µPa) and an average peak sensitivity of 22 dB re: 20 µPa at 4 kHz. This range is similar to airborne hearing thresholds previously measured for closely related species, the kit fox (Vulpes marotis) and the domestic dog ( Canis familiaris). There was little variability around threshold and there was no significant difference between the hearing curves of the two fox. The peak sensitivities of the Arctic fox overlaps their vocal range, the vocal range of prey species, such as field voles (Microtus agrestis ), collared lemmings (Dicrostonyx groenlandicus), Canada geese (Branta canadensis), and the hearing range of the polar bear (Ursus maritimus). Ambient noise levels were monitored and test frequencies below 5 kHz were possibly masked. Potential response biases of the Arctic fox were examined using Receiver Operator Characteristic analyses. Overall, the Arctic fox had conservative responses. Masking effects and a conservative response bias may have resulted in slightly underestimated hearing curves.
PDF
