The functional anatomy of the rodent larynx in relation to audible and ultrasonic cry production

Rodents are well known for the production of physically quite different audible and ultrasonic cries. Both of these cries are known to be produced in the larynx, but the anatomy of the larynx is practically unknown, it thus being difficult to analyse how the cries are produced. The anatomy of the larynx of Mus musculus is described in detail and is found to be essentially typical of that of other mammals that can fix the thorax and make independent use of the forelimbs. Unlike the larynx of microchiropteran bats, no modifications for ultrasound production are apparent, although the laryngeäl structure is ideal for the production of audible cries. However, the audible and ultrasonic cries differ so markedly that they are unlikely to be produced by the same mechanism. The lack of laryngeal specialization therefore makes the ultrasound production mechanism largely an enigma.     

Correlation of respiration and ultrasound production in rodents and bats

Audible and ultrasonic cries of five species of myomoph rodent pups were generally found to be closely associated with the onset of the expiratory phase of respiration (recorded with a hot wire anemometer). Consideration of the patterns found and possible laryngeal mechanisms may help to explain the origin of the ultrasounds which differ considerably in physical structure from the typically "vocal" audible cries. Echolocation cries of the constant frequency bat Rhinolophus luctus were always associated with expiration, whereas the much shorter cries of two vespertilionids, Eptesicus serotinus and Plecotus auritus , although occurring at the onset of expiration at low repetition rates, could occur throughout the respiratory cycle at the highest rates recorded. The patterns found may well be adapted for the echolocation requirements of these bats. Using a simpler technique the long ultrasounds of adult rats were also found to be associated with expiration.     

Sound production by infant Peromyscus maniculatus (Rodentia: Myomorpha)

Peromyscus maniculatus pups were found to emit both partly audible and purely ultrasonic sounds in response to cold stress and tactile stimulation. The two pulse types could be correlated with the two different conditions and variations with age of the intensity, frequency structure and rate of production were studied. Audible pulses are more characteristic of young pups subjected to cold stress and ultrasonic pulses are more characteristic of older pups subjected to tactile stimulation. These results are discussed in relation to previous work on infant rodent sound production and its effects on maternal behaviour.     

Sound Production in the Salientia: Mechanism and Evolution of the Emitter

Frog sounds involve expulsion of air through the larynx. Inmating, release, rain, and territorial calls, the air vibratesvocal cords and/or arytenoid cartilages. Sound is amplifiedand radiated by the distended buccal cavity and vocal sacs.Distress calls are emitted with open mouth, with minimum laryngealmodulation. The trunk is filled by inflation cycles, but airis driven out by synchronized contractions of the body wallmusculature. The pressure levels are more than five times thoseduring ventilation. In the release call of Bufo valliceps the dilatators and constrictorsof the larynx fire simultaneously keeping the larynx closed.As the pulmonary pressure reaches a peak they cease firing.The arytenoids then separate and vibrate, as do the vocal cords.The dilatators terminate the sound pulse by pulling vibratorsout of the air stream, hence the very sharp termination. Prolongedrelease call sequences include interpulse Teinflations thatreturn air from buccal cavity to lung. Frogs apparently evolved from amphibians too small to use aspirationbreathing. Vocalization represented a critical factor in theirsocial organization and its importance locked these animalsinto reliance upon pulse-pumping rather than the more efficientaspiration breathing.     

Development of the nasal cavity and formation of the nostrils in human embryogenesis

The development of nasal cavity was traced in human embryos. The identity in the primitive formation of the mouth cavity and that of the nasal cavity is stated. During embryogenesis, the primitive nasal cavities are demonstrated to change their position concerning the mouth cavity. Epithelial "cluster" formation in the area of the nostrils is examined: it appears in embryos of 16-19 mm long, is mostly prominent in embryos of 50-55 mm long, is absent in fetuses of 5.5 months old. By comparing the terms and dynamics in the development of epithelial adhesion in the larynx an the nostrils, the importance of these temporal structures for protecting the respiratory tract of the embryo from amniotic fluid is demonstrated.     

人为疼痛刺激下金色中仓鼠幼鼠叫声的发育过程

金色中仓鼠幼鼠可以利用可听声和超声信号与母鼠进行交流,这些声音可以反映个体的寒冷、饥饿、疼痛等不同生理状态和需求。因疼痛诱发的叫声对于维持幼鼠的存活也有着重要意义。本实验通过录制人为疼痛刺激下,不同日龄金色中仓鼠的叫声,分析并比较了5 - 30 日龄金色中仓鼠不同发声信号特征(可听声出现频次、可听声持续时程、可听声主频率、超声出现频次、超声持续时程、超声主频率)的性别差异;同时记录了幼鼠的两种发声随日龄的变化趋势。结果发现:幼鼠两种叫声的各种参数均未表现性二型现象。幼鼠超声发生频次随日龄增加而逐渐减少。而可听声却正相反,随日龄增加而逐渐上升,并在20 日龄时达到最高峰,之后逐渐下降。可听声持续时程也随日龄而增加。综上,在人为疼痛刺激下,随着日龄增加,幼鼠更倾向于使用可听 声而非超声与母兽进行交流。     

High Frequency Responsiveness in Rodents at the Level of the Inferior Colliculus

PREVIOUS work on the cochlear microphonic (CM) response of three species of rodents showed a second peak of sensitivity coinciding in frequency with the ultrasound emitted in each species¹. It was indicated that the microphonic response did not necessarily represent hearing, but Sewell's² finding that Apodemus can hear the ultrasonic cries of its young makes an investigation into the neural response to ultrasound seem necessary. The gross inferior collicular (IC) response of the same three species, Apodemus sylvaticus Linnaeus, Clethrionomys glareolus Schreber and Meriones shawi Rozet, has now been studied together with the CM response of the same individuals.     

Comparative study on isolation calls emitted from hamster pups.

Waveforms of isolation calls emitted from hamster pups, which were Syrian hamsters, Djungarian hamsters, and Chinese hamsters, were compared in a basic study on improving reproduction by decrease of cannibalism, because it was reported that maternal behavior was induced by isolation calls in rodents. Isolation calls of hamster pups, isolated from their mother and receiving cold stress, were collected by Real-Time Spectrogram (RTS), and calculated to spectrograms and power spectra by SIGNAL. Isolation calls consisted of ultrasonic vocalizations (USVs) and audible vocalizations (ADVs) in each species. Waveforms of isolation calls emitted by the hamster pups, were shown to have several characteristic features. In this study, the species specificity of isolation calls was shown in hamster pups. It would seem that the species specificity originates in the differences of sensitivity to cold stress via the autonomic nerve in hamsters.     

Resting-Associated Vocalization Emitted by Captive Asian House Shrews (Suncus murinus): Acoustic Structure and Variability in an Unusual Mammalian Vocalization

Shrews have rich vocal repertoires that include vocalizations within the human audible frequency range and ultrasonic vocalizations. Here, we recorded and analyzed in detail the acoustic structure of a vocalization with unclear functional significance that was spontaneously produced by 15 adult, captive Asian house shrews (Suncus murinus) while they were lying motionless and resting in their nests. This vocalization was usually emitted repeatedly in a long series with regular intervals. It showed some structural variability; however, the shrews most frequently emitted a tonal, low-frequency vocalization with minimal frequency modulation and a low, non-vocal click that was clearly noticeable at its beginning. There was no effect of sex, but the acoustic structure of the analyzed vocalizations differed significantly between individual shrews. The encoded individuality was low, but it cannot be excluded that this individuality would allow discrimination of family members, i.e., a male and female with their young, collectively resting in a common nest. The question remains whether the Asian house shrews indeed perceive the presence of their mates, parents or young resting in a common nest via the resting-associated vocalization and whether they use it to discriminate among their family members. Additional studies are needed to explain the possible functional significance of resting-associated vocalizations emitted by captive Asian house shrews. Our study highlights that the acoustic communication of shrews is a relatively understudied topic, particularly considering that they are highly vocal mammals.     

Environmental ultrasound in laboratories and animal houses: a possible cause for concern in the welfare and use of laboratory animals

Many laboratory animals are known to be sensitive to sounds (ultrasounds) beyond the nominal upper limit (20 kHz) of the human hearing range. Sources of sound in laboratories and animal houses were examined to determine the extent of ambient ultrasound. Of 39 sources monitored, 24 were found to emit ultrasonic sounds. Many of these (e.g. cage washers and hoses) also produced sound in the audible range. Running taps, squeaky chairs and rotating glass stoppers created particularly high sound pressure levels and contained frequencies to over 100 kHz. The oscilloscopes and visual display units investigated provided particular cause for concern as they emitted sounds that were entirely ultrasonic and therefore were apparently silent. Ambient ultrasound therefore appears to be common in laboratories and animal houses. It is suggested that its effect on laboratory animals should be investigated and guidelines on acceptable levels be formulated.     

Echolocation in the large molossid bats Eumops glaucinus and Nyctinomops macrotis

Eumops glaucinus and Nyctinomops macrotis, the largest molossid bats in Cuba, were investigated. Both species of bats share the same guild in the island and are similar in size, which allow the prediction of overlapping echolocation inventories following both the "vocal plasticity hypothesis" and the "scaling hypothesis." In addition, large body size predicts the emission of low frequency calls in the human audible range. Calls recorded during hunting show that the bats' echolocation repertoires are very similar and of low frequency, with most differences in search calls. Matches were found in the calls' design, duration, slope, bandwidth, and spectral parameters. Statistical differences between search calls are consistent with the predictions from the "scaling hypothesis," considering that E. glaucinus is only slightly larger than N. macrotis. The echolocation calls emitted by both species are in the frequency range below 20-25 kHz, which identifies both species as the only ones with echolocation in the human audible range in Cuba.     

Thermal versus tactile stimuli and audible vocalization in rat pups

The influences of thermal and tactile stimuli on the audible vocalization in pup rats,Rattus norvegicus were investigated. Mother rats and their litters were exposed to ambient temperature (AT) depression by 5°C for 2 hours every other day from 3 to 11 days postpartum. Nearly all audible calls emitted by pups were recorded during tactile contact with the mother. AT depression alone neither prolonged the total duration of pup-licking by mother nor intensified audible vocalization. It was found, however, that the frequency (No./h.) of nest exiting by the dam doubled during the cooling and that the sum of audible peeps emitted by cooled pups in 4 cooling days was higher than sum of peeps emitted by the control pups. This difference is apparently related to an increase in the mother's motor activity, especially nest-building activity, during cooling. Analysis of circumstances accompanying peep emission supports the hypothesis that the tactile stimuli delivered by mother play the predominant role in causing audible vocalization in pup rats. This investigation was supported by Project CPBP-04.01. of the Polish Academy of Science     

Acoustic characterisation of thoracic body tissues in the audible frequency range

A previous study by Jones and Thomas [2] suggests that data relating to the physiological condition within the thoracic cavity may be obtainable utilising low frequency acoustic signals applied to the mouth and detected on the chest wall. In order to evaluate the contribution to the mouth to chest wall frequency response of the separate elements within the thorax, and to estimate the effect on this response when the lung physiology changes, an acoustic model of the thorax is required. To aid the development of this model, experiments have been carried out in order to establish the frequency dependence of the acoustic attenuation and speed of propagation through thoracic tissue samples in the audible frequency range 20–500 Hz. Samples from the porcine family were used due to their physical similarity to those of humans and their being obtainable within a short time of death.The results of this work can be utilised in the development of an acoustic model of the human thorax, this in turn enabling simulation and analysis of low frequency acoustic transmission from the trachea to the chest wall.     

Effect of the stage of the reproductive cycle on vocalization and behaviour in female bank voles

Females of several species of rodents are known to emit audible and ultrasonic sounds during same-sex encounters. There is very little information about factors affecting this vocalization. The present study was undertaken to investigate the effect of the stage of the reproductive cycle on vocalization and behaviour of adult bank vole females during various same-sex encounters. Pregnancy and lactation were studied as important phases of female life. The possible role of ovarian hormones in the emission of acoustic signals was also investigated as these hormones are known to be important in the regulation of other female social behaviour. The behaviour and vocalization of sexually naive, ovariectomized, pregnant and lactating females were studied using 10-min confrontation tests. The results demonstrate that the behaviour displayed and the emission of sounds in female–female bank vole encounters depend on the phase of reproductive cycle. Ultrasounds are produced more often by sexually naive and ovariectomized females which present mainly non-aggressive behaviour than by more aggressive lactating females. Audible sounds are emitted only occasionally by naive and by ovariectomized females but pregnant and especially lactating females emitted such calls more often, with shorter latencies and for longer than the unmated groups. Ultrasonic vocalization therefore seems to be related to non-aggressive behaviour and audible vocalization to aggression.     

Vocalizations of nine species of rat (Rattus; Muridae)

The sounds produced by seven species of Rattus native to Australia and the Black rat ( R. rattus ) and the Brown rat ( R. norvegicus ), were investigated in the laboratory. Both audible and ultrasonic sounds were recorded and the ontogeny of the different vocalizations investigated. All nine species had the same basic repertoire of seven more or less discrete calls. Some calls varied more between the different species than did others. Similarly there were species' differences in the ease with which some calls could be elicited. Two major continua were identified, one audible and one ultrasonic. An attempt was made to put the vocalizations recorded into an evolutionary perspective.     

The temperature relations of vocalization in infant Golden hamsters and Wistar rats

Environmental temperature changes are capable of evoking ultrasonic responses from the young of Wistar rats and Golden hamsters. The changes with age in the intensity of these sounds and the rate of calling are found to be related to the pattern of development of homiothermy in the two species. In the Golden hamster, the same temperature changes also evoke audible calls which show a different pattern of variation with age. These findings are discussed in comparison with those previously reported for albino mice.     

AURITA: an affordable,autonomous recording device for acoustic monitoring of audible and ultrasonic frequencies

Passive acoustic monitoring can be used for many purposes including biodiversity and habitat assessments and studying the ecology of populations, communities and soundscapes. As such, acoustic recording devices are essential data collection tools for bioacousticians and soundscape ecologists. Currently available commercial options are typically expensive and limited to recording either ultrasonic or audible frequencies. Here, we present the AURITA (Audible and Ultrasonic Recording In TAndem) for the autonomous collection of both audible and ultrasonic acoustic data. This self-contained, modular unit combines the Solo, an open-source, Raspberry-Pi-based recorder and a commercially available bat recorder, the Peersonic RPA2, enabling it to capture sounds from 60 Hz to 192 kHz in WAV format. The configuration presented costs ~£350 (excluding memory cards and batteries) to produce and can be maintained and repaired in the field. Two nine-week field tests involving 12 AURITA units were conducted in 2016 and 2017 and confirmed their reliability, resulting in 34,093 h of audible data and 551 h of ultrasonic data; all units were retrieved successfully and intact. The AURITA proved to be reliable in the field and produced high-quality acoustic data, making it ideal for simultaneous monitoring in both audible and ultrasonic frequencies over continuous periods of time.     

Isolation calls and retrieving behavior in laboratory and wild-derived golden hamsters—No sign for inbreeding depression

Isolated juvenile golden hamsters produce ultrasonic and audible vocalizations, so-called isolation calls, as a reaction to being separated from their mother and nest and their cooling down. Their aim is to stimulate mothers to search and retrieve the pups. In this work, the vocalization of juvenile laboratory (Zoh:GOHA; Institute of Zoology, Martin-Luther-University Halle-Wittenberg) and juvenile wild-derived golden hamsters (captured in northern Syria and southern Turkey) from birth up to the age of 18 days were digitally recorded, analyzed and compared using an ultrasonic microphone and the software Avisoft. Furthermore, the retrieving behavior of the mothers was observed and compared. The results showed that the number of isolation calls was age-specific and the structure of the calls was influenced by body temperature, body mass and sex of the pups. The age of the pups determined retrieval by the maternal golden hamsters; however these did not discriminate between their own pups or foreign pups. In spite of enormous genetic differences between wild-derived and laboratory golden hamsters, only minor differences between the strains were found.     

Developmental changes in the shape of the supralaryngeal vocal tract in chimpanzees

The hyoid bone and larynx in human neonates are positioned as high as in other mammals. However, during postnatal life, they descend relative to the hard palate more rapidly compared with the horizontal growth of the oral cavity. This process is completed through the descent of the laryngeal skeleton relative to the hyoid, and through the descent of the hyoid relative to the cranial base. Thus, the human supralaryngeal vocal tract (SVT) develops to form a two-tube configuration with equally long horizontal and vertical parts. Longitudinal studies on living chimpanzee infants show that the descent of the larynx is more rapid than the horizontal growth of the oral cavity. This is primarily attributed to the descent of their larynges relative to the hyoid bone, but this is not accompanied by the descent of the hyoid. The present study, using embalmed specimens of chimpanzees, also shows that the horizontal and vertical parts of the SVT grow in chimpanzees similarly to humans during infancy. However, in chimpanzees, the horizontal part of the SVT grows greatly, whereas the vertical part of the SVT grows only slightly during the juvenile period. As a result, the chimpanzee larynx does not descend rapidly relative to the oral elongation during that period. Such differences may be related to the structural and morphological development of the facial skeleton and mandible, which affects prognathism and hyoid descent. These results support the hypothesis that the descent of the larynx evolved in at least two steps during hominoid evolution.     

Effects of motherhood on physiological and subjective responses to infant cries in teenage mothers: a comparison with non-mothers and adult mothers

The present study was designed to determine whether becoming a mother during the adolescent period changes maternal responsiveness or maternal motivation, assessed through hormonal, autonomic, and hedonic responses to recorded infant cries and interactions with their babies. Fifty-six teen mothers were compared to 58 teen non-mothers and 49 adult mothers. Teen mothers reported more sympathy and alertness in response to recorded infant cries compared to non -mother teens; however, among the teen women there were no differences between mothers and non-mothers in heart rate and cortisol responses to infant cries. In contrast, in comparison to adult mothers, teen mothers reported the same levels of sympathy and alertness to infant cries; however, adult mothers showed an 'alerted' pattern of heart rate and cortisol response to infant cries not seen in the teen mother group. Inclusion of the covariate, fathers' employment classification as an index of SES or time of testing and cortisol sampling did not affect this pattern of results. Taken together, these results show that where self-report is used as a measure of maternal responsiveness, teen mothers are no different in responsiveness than adult mothers; however, where physiological and interactional measures of responsiveness are considered, teen mothers are less likely to show heightened or selective responses to infant cries or respond 'attentively' to the infant.