Cat Vocalizations Research Articles

Towards Understanding Cat Vocalizations: A Novel Cat Sound Classification Model Based on Vision Transformers

Animal sound perception systems are highly developed compared to humans, crucial for survival in natural environments, with some species possessing specialized sensory capabilities such as vision, hearing, touch, and environmental awareness. Understanding animal sounds not only aids in their own communication and survival but also benefits humans in various fields including security, natural disaster prediction, ecological research, bioacoustics, precision agriculture, and search and rescue operations. Motivated by this fact, this study investigated the classification of cat sounds using deep learning models based on Vision Transformer (ViT) and Convolutional Neural Network (CNN) architectures. Cat vocalizations, represented as mel-spectrograms, were classified using models trained on a diverse dataset of cat sounds. Experimental results demonstrated the superiority of the proposed model based on Microsoft’s BERT Pre-Training of Image Transformers (BEiT) over the state-of-the-art as it obtained an exceptional accuracy of 96.95%. Additionally, it was observed that the proposed models based on ViT outperformed CNN-based models, highlighting the efficacy of transformer architectures in capturing complex patterns within audio data. These findings underscore the potential of ViT architectures in decoding animal communication systems and advancing wildlife conservation efforts.

Pitch affects human (Homo sapiens) perception of emotional arousal from diverse animal calls.

A growing body of research demonstrates that humans can accurately perceive the emotional states of animals solely by listening to their calls, highlighting shared evolutionary ancestry. Yet, the cognitive and perceptual mechanisms underlying heterospecific emotion perception have remained open to investigation. One hypothesis is that humans rely on simple acoustic heuristics to make such judgments, for example, perceiving higher-pitched calls as reflecting heightened emotional arousal (the "pitch rule"). This could lead to accurate judgments of emotion since in most mammals, as in humans, vocal fundamental frequency (the acoustic determinant of the pitch percept) does objectively correlate with emotional arousal. In the present study, we used digital pitch manipulation to create pairs of animal calls that were perceptually identical except for pitch, and we measured human perceptions of the caller's emotional arousal using an online survey. Calls of six phylogenetically diverse species were included as stimuli. Participants attributed slightly but statistically significantly higher arousal to higher-pitched versions of the same calls. Variation in application of the pitch rule across species was not well explained by familiarity, and prior experience with cats did not significantly predict sensitivity to pitch in cat vocalizations. Cross-species variation also did not align with phylogenetic distance from humans, or the hypothetical usefulness of pitch for making accurate judgments. Thus, the pitch rule may be a "mammalomorphic" heuristic leading to accurate emotion judgments in some taxa and call types and erroneous judgments in others, depending in part on phylogenetic distance and the mechanisms of call production. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Domestic cat larynges can produce purring frequencies without neural input

Most mammals produce vocal sounds according to the myoelastic-aerodynamic (MEAD) principle, through self-sustaining oscillation of laryngeal tissues.1,2 In contrast, cats have long been believed to produce their low-frequency purr vocalizations through a radically different mechanism involving active muscle contractions (AMC), where neurally driven electromyographic burst patterns (typically at 20-30Hz) cause the intrinsic laryngeal muscles to actively modulate the respiratory airflow. Direct empirical evidence for this AMC mechanism is sparse.3 Here, the fundamental frequency (fo) ranges of eight domestic cats (Felis silvestris catus) were investigated in an excised larynx setup, to test the prediction of the AMC hypothesis that vibration should be impossible without neuromuscular activity, and thus unattainable in excised larynx setups, which are based on MEAD principles. Surprisingly, all eight excised larynges produced self-sustained oscillations at typical cat purring rates. Histological analysis of cat larynges revealed the presence of connective tissue masses, up to 4mm in diameter, embedded in the vocal fold.4 This vocal fold specialization appears to allow the unusually low fo values observed in purring. While our data do not fully reject the AMC hypothesis for purring, they show that cat larynges can easily produce sounds in the purr regime with fundamental frequencies of 25 to 30Hz without neural input or muscular contraction. This strongly suggests that the physical and physiological basis of cat purring involves the same MEAD-based mechanisms as other cat vocalizations (e.g., meows) and most other vertebrate vocalizations but is potentially augmented by AMC.

Positive implicit association to human babies’ vocalization

Cuteness in infants has mainly been associated with their morphological facial features. Infant cuteness promotes social interaction, empathy, and caregiving behaviors. It has been suggested that cuteness could go beyond the visual aspect to infants’ auditory and olfactory characteristics. The current research examines whether there is a positive valence toward babies’ neutral vowel vocalizations. Adult participants completed four Single Category Implicit Association Tasks (SC-IAT) using baby, adult, kitten, and cat vocalizations. Baby and adult vocalizations were vowels synthesized using VLAM. In this task, adults had to sort positive and negative written words and the vocalizations in the correct category; response times were measured. Preliminary results (response time) show that infant voices were associated with positive dimensions (M = 0.27), whereas adult (M = 0.06), cat (M = 0.07), and kitten (M = 0.08) showed neither a positive nor negative implicit association. A similar study testing facial features obtained comparable results (Senese et al., 2013). These findings point to a positive implicit association to babies’ vocalizations, suggesting that there is an auditory cuteness component specific to human infants. We will also discuss ongoing work focused on elucidating the acoustic characteristics that specify auditory cuteness, the role it plays in infant development, and the underlying neural mechanisms.

The Study of Acoustic Phonetics on Frequency Cat Snoring Between Different Ages

Abstract: Cat purring is a sound that has been produced by cats made by several species of felids and two species of genetics. The domestic cat (Felis silvestris catus) is one of the most common domestic animals we hear of today. This cat also has its own specialties and uniqueness, among them is that the cat is able to produce very low frequencies and is able to provide benefits to all humans. (Wereski, Mike 2015). The first purpose was to study the frequencies that had been produced by both cats and to identify whether the age of the cats influenced the frequencies that had been produced. The second purpose was To identify whether different cat attitudes would influence the frequency produced by cats. The study subjects were two domestic cats where Domestic Cat A, named molly was a 4 -month -old female cat of mixed breed, while domestic cat B, named spooky, was a 36 - month -old female cat and domestic cat C named Neslo which was 17-month-old female cat.. The two study subjects were different mixed breeds. Both cats are domestic cats which have been cared for and cared for since childhood. The selection of the two cats was based on reasons for differences in age and behavior. Data recording using Iphone SE (2020) brand telephone equipment and for cat frequency data were collected while sleeping. This aims to collect standard cat vocalizations. The purs sound production of older domestic cats is higher than that of young domestic cats. In conclusion, sound can also become louder as the age. The older the cat is, the higher the frequency the cat produces.

The Study of Acoustic Phonetics on Frequency Cat Snoring Between Different Ages

Abstract: Cat purring is a sound that has been produced by cats made by several species of felids and two species of genetics. The domestic cat (Felis silvestris catus) is one of the most common domestic animals we hear of today. This cat also has its own specialties and uniqueness, among them is that the cat is able to produce very low frequencies and is able to provide benefits to all humans. (Wereski, Mike 2015). The first purpose was to study the frequencies that had been produced by both cats and to identify whether the age of the cats influenced the frequencies that had been produced. The second purpose was To identify whether different cat attitudes would influence the frequency produced by cats. The study subjects were two domestic cats where Domestic Cat A, named molly was a 4 -month -old female cat of mixed breed, while domestic cat B, named spooky, was a 36 - month -old female cat and domestic cat C named Neslo which was 17-month-old female cat.. The two study subjects were different mixed breeds. Both cats are domestic cats which have been cared for and cared for since childhood. The selection of the two cats was based on reasons for differences in age and behavior. Data recording using Iphone SE (2020) brand telephone equipment and for cat frequency data were collected while sleeping. This aims to collect standard cat vocalizations. The purs sound production of older domestic cats is higher than that of young domestic cats. In conclusion, sound can also become louder as the age. The older the cat is, the higher the frequency the cat produces.

Socio-spatial cognition in cats: Mentally mapping owner's location from voice.

Many animals probably hold mental representations about the whereabouts of others; this is a form of socio-spatial cognition. We tested whether cats mentally map the spatial position of their owner or a familiar cat to the source of the owner’s or familiar cat’s vocalization. In Experiment 1, we placed one speaker outside a familiar room (speaker 1) and another (speaker 2) inside the room, as far as possible from speaker 1, then we left the subject alone in the room. In the habituation phase, the cat heard its owner’s voice calling its name five times from speaker 1. In the test phase, shortly after the 5th habituation phase vocalization, one of the two speakers played either the owner’s voice or a stranger’s voice calling the cat’s name once. There were four test combinations of speaker location and sound: SamesoundSamelocation, SamesoundDifflocation, DiffsoundSamelocation, DiffsoundDifflocation. In line with our prediction, cats showed most surprise in the SamesoundDifflocation condition, where the owner suddenly seemed to be in a new place. This reaction disappeared when we used cat vocalizations (Experiment 2) or non-vocal sounds (Experiment 3) as the auditory stimuli. Our results suggest that cats have mental representations about their out-of-sight owner linked to hearing the owner’s voice, indicating a previously unidentified socio-spatial cognitive ability.

What's in a Meow? A Study on Human Classification and Interpretation of Domestic Cat Vocalizations.

Simple SummaryCat–human communication is a core aspect of cat–human relationships and has an impact on domestic cats’ welfare. Meows are the most common human-directed vocalizations and are used in different everyday contexts to convey emotional states. This work investigates adult humans’ capacity to recognize meows emitted by cats during waiting for food, isolation, and brushing. We also assessed whether participants’ gender and level of empathy toward animals in general, and toward cats in particular, positively affect the recognition of cat meows. Participants were asked to complete an online questionnaire designed to assess their knowledge of cats and to evaluate their empathy toward animals. In addition, they listened to cat meows recorded in different situations and tried to identify the context in which they were emitted and their emotional valence. Overall, we found that, although meowing is mainly a human-directed vocalization and should represent a useful tool for cats to communicate emotional states to their owners, humans are not good at extracting precise information from cats’ vocalizations and show a limited capacity of discrimination based mainly on their experience with cats and influenced by gender and empathy toward them.Although the domestic cat (Felis catus) is probably the most widespread companion animal in the world and interacts in a complex and multifaceted way with humans, the human–cat relationship and reciprocal communication have received far less attention compared, for example, to the human–dog relationship. Only a limited number of studies have considered what people understand of cats’ human-directed vocal signals during daily cat–owner interactions. The aim of the current study was to investigate to what extent adult humans recognize cat vocalizations, namely meows, emitted in three different contexts: waiting for food, isolation, and brushing. A second aim was to evaluate whether the level of human empathy toward animals and cats and the participant’s gender would positively influence the recognition of cat vocalizations. Finally, some insights on which acoustic features are relevant for the main investigation are provided as a serendipitous result. Two hundred twenty-five adult participants were asked to complete an online questionnaire designed to assess their knowledge of cats and to evaluate their empathy toward animals (Animal Empathy Scale). In addition, participants had to listen to six cat meows recorded in three different contexts and specify the context in which they were emitted and their emotional valence. Less than half of the participants were able to associate cats’ vocalizations with the correct context in which they were emitted; the best recognized meow was that emitted while waiting for food. Female participants and cat owners showed a higher ability to correctly classify the vocalizations emitted by cats during brushing and isolation. A high level of empathy toward cats was significantly associated with a better recognition of meows emitted during isolation. Regarding the emotional valence of meows, it emerged that cat vocalizations emitted during isolation are perceived by people as the most negative, whereas those emitted during brushing are perceived as most positive. Overall, it emerged that, although meowing is mainly a human-directed vocalization and in principle represents a useful tool for cats to communicate emotional states to their owners, humans are not particularly able to extract precise information from cats’ vocalizations and show a limited capacity of discrimination based mainly on their experience with cats and influenced by empathy toward them.

Only When It Feels Good: Specific Cat Vocalizations Other Than Meowing.

Simple SummaryAmong carnivore animals, domestic cats are those with the most extensive vocal repertoire. This is due to their social organization, nocturnal activity and long period of contact between the mother and the offspring. In order to identify vocalizations other than meowing in two different situations, a study was performed with 74 cats divided into two groups, one associated with a pleasant situation and another with an aversive situation. Only the group exposed to the positive stimulus of being offered a favorite snack produced specific vocalizations other than meowing: recognition or trill, squeak, purring and chatter. During the aversive situation of car transport, no vocalization other than meowing was observed. The present study indicates the relevance of applying the study of vocalizations to determine the state of emotional valence in cats.Our objective was to identify and characterize the types of vocalization other than meowing (VOM) in two contexts, a pleasant and an aversive situation, and to study the effect of the sex of the animal. A total of 74 cats (32 tom cats and 42 queens) living in the city of Curitiba, Brazil, participated in the study; in total, 68 (29 tom cats and 39 queens) were divided into two groups according to the stimulus they were exposed to: either a pleasant situation (PS), when they were offered a snack, or an aversive situation (AS), with the simulation of a car transport event. The other six animals (three tom cats and three queens) participated in both situations. Only the PS group presented VOM; of the 40 PS animals, 14 presented VOM, mostly acknowledgment or trill and squeak. No correlation was observed between vocalization and cat sex (p = 0.08; Pearson’s Chi-Square). Results show that VOM is exclusively associated with positive situations, suggesting that these vocalizations may be relevant for understanding the valence of cat emotional state. Further studies are warranted to advance knowledge on other VOMs and on the generalization of our findings to other situations.

Automatic Classification of Cat VocalizationsEmitted in Different Contexts.

Simple SummaryCat vocalizations are their basic means of communication. They are particularly important in assessing their welfare status since they are indicative of information associated with the environment they were produced, the animal’s emotional state, etc. As such, this work proposes a fully automatic framework with the ability to process such vocalizations and reveal the context in which they were produced. To this end, we used suitable audio signal processing and pattern recognition algorithms. We recorded vocalizations from Maine Coon and European Shorthair breeds emitted in three different contexts, namely waiting for food, isolation in unfamiliar environment, and brushing. The obtained results are excellent, rendering the proposed framework particularly useful towards a better understanding of the acoustic communication between humans and cats.Cats employ vocalizations for communicating information, thus their sounds can carry a wide range of meanings. Concerning vocalization, an aspect of increasing relevance directly connected with the welfare of such animals is its emotional interpretation and the recognition of the production context. To this end, this work presents a proof of concept facilitating the automatic analysis of cat vocalizations based on signal processing and pattern recognition techniques, aimed at demonstrating if the emission context can be identified by meowing vocalizations, even if recorded in sub-optimal conditions. We rely on a dataset including vocalizations of Maine Coon and European Shorthair breeds emitted in three different contexts: waiting for food, isolation in unfamiliar environment, and brushing. Towards capturing the emission context, we extract two sets of acoustic parameters, i.e., mel-frequency cepstral coefficients and temporal modulation features. Subsequently, these are modeled using a classification scheme based on a directed acyclic graph dividing the problem space. The experiments we conducted demonstrate the superiority of such a scheme over a series of generative and discriminative classification solutions. These results open up new perspectives for deepening our knowledge of acoustic communication between humans and cats and, in general, between humans and animals.

The socio-cognitive relationship between cats and humans – Companion cats (Felis catus) as their owners see them

Although domestic cats are among the most common companion animals, we still know very little about the details of the cat-human relationship. With a questionnaire, we asked 157 Hungarian cat owners about their pet’s behavior, cognitive abilities and social interactions. We analyzed the responses with PCA resulting in 11 traits. The effect of cats’ and owners’ demographic variables on the main components was further analyzed with GLM. The results showed strong similarity to the surveys performed with companion dogs, but we also found features that were mainly cat-specific. We found that women considered their cats to be more communicative and empathetic, than men did (p = 0.000). The higher education owners also considered their cat as being more communicative and empathetic (p = 0.000). We also found that owners use pointing signals more often if the cat is their only pet (p = 0.000), and otherwise they do not give verbal commands often to the cat (P = 0.001). Young owners imitated cat vocalization more often (p = 0.006); while emotional matching of the cat was more commonly reported by elderly owners (p = 0.001). The more an owner initiated playing with his/her cat, the imitation of cat vocalizations was also more common in his/her case (p = 0.001). Owners think that their cat shows stronger emotional matching if otherwise they experience human-like communicative capacity from the cat (p = 0.000). Owners use more pointing signals in the case of those cats that show attention-eliciting signals in more than one modality (p = 0.000). Owners who react to the meows of unfamiliar cats, initiated interactions more often with their own cats (p = 0.000). Owners also think that cats vocalize in every possible context, and this result was not affected significantly by any of the independent factors. Our results show that owners considered their cat as a family member, and they attributed well developed socio-cognitive skills to them. Because cats have an important role as a companion animal, it would be worthy to study cat behavior with similar thoroughness as with dogs. Our questionnaire may provide a good starting point for the empirical research of cat-human communication. The deeper understanding of cats’ socio-cognitive abilities may also help to improve cat welfare.

Visual classification of feral cat Felis silvestris catus vocalizations.

Cat vocal behavior, in particular, the vocal and social behavior of feral cats, is poorly understood, as are the differences between feral and fully domestic cats. The relationship between feral cat social and vocal behavior is important because of the markedly different ecology of feral and domestic cats, and enhanced comprehension of the repertoire and potential information content of feral cat calls can provide both better understanding of the domestication and socialization process, and improved welfare for feral cats undergoing adoption. Previous studies have used conflicting classification schemes for cat vocalizations, often relying on onomatopoeic or popular descriptions of call types (e.g., “miow”). We studied the vocalizations of 13 unaltered domestic cats that complied with our behavioral definition used to distinguish feral cats from domestic. A total of 71 acoustic units were extracted and visually analyzed for the construction of a hierarchical classification of vocal sounds, based on acoustic properties. We identified 3 major categories (tonal, pulse, and broadband) that further breakdown into 8 subcategories, and show a high degree of reliability when sounds are classified blindly by independent observers (Fleiss’ Kappa K = 0.863). Due to the limited behavioral contexts in this study, additional subcategories of cat vocalizations may be identified in the future, but our hierarchical classification system allows for the addition of new categories and new subcategories as they are described. This study shows that cat vocalizations are diverse and complex, and provides an objective and reliable classification system that can be used in future studies.

Mother-offspring recognition in the domestic cat: Kittens recognize their own mother's call.

Acoustic communication can play an important part in mother-young recognition in many mammals. This, however, has still only been investigated in a small range mainly of herd- or colony-living species. Here we report on the behavioral response of kittens of the domestic cat, a typically solitary carnivore, to playbacks of "greeting chirps" and "meows" from their own versus alien mothers. We found significantly stronger responses to the chirps from kittens' own mother than to her meows or to the chirps or meows of alien mothers. Acoustic analysis revealed greater variation between vocalizations from different mothers than for vocalizations from the same mother. We conclude that chirps emitted by mother cats at the nest represent a specific form of vocal communication with their young, and that kittens learn and respond positively to these and distinguish them from chirps of other mothers and from other cat vocalizations while still in the nest. © 2016 Wiley Periodicals, Inc. Dev Psychobiol 58: 568-577, 2016.

Pitch representations in the auditory nerve: two concurrent complex tones.

Pitch differences between concurrent sounds are important cues used in auditory scene analysis and also play a major role in music perception. To investigate the neural codes underlying these perceptual abilities, we recorded from single fibers in the cat auditory nerve in response to two concurrent harmonic complex tones with missing fundamentals and equal-amplitude harmonics. We investigated the efficacy of rate-place and interspike-interval codes to represent both pitches of the two tones, which had fundamental frequency (F0) ratios of 15/14 or 11/9. We relied on the principle of scaling invariance in cochlear mechanics to infer the spatiotemporal response patterns to a given stimulus from a series of measurements made in a single fiber as a function of F0. Templates created by a peripheral auditory model were used to estimate the F0s of double complex tones from the inferred distribution of firing rate along the tonotopic axis. This rate-place representation was accurate for F0s greater, similar900 Hz. Surprisingly, rate-based F0 estimates were accurate even when the two-tone mixture contained no resolved harmonics, so long as some harmonics were resolved prior to mixing. We also extended methods used previously for single complex tones to estimate the F0s of concurrent complex tones from interspike-interval distributions pooled over the tonotopic axis. The interval-based representation was accurate for F0s less, similar900 Hz, where the two-tone mixture contained no resolved harmonics. Together, the rate-place and interval-based representations allow accurate pitch perception for concurrent sounds over the entire range of human voice and cat vocalizations.

Spatial Representation of Neural Responses to Natural and Altered Conspecific Vocalizations in Cat Auditory Cortex

This study shows the neural representation of cat vocalizations, natural and altered with respect to carrier and envelope, as well as time-reversed, in four different areas of the auditory cortex. Multiunit activity recorded in primary auditory cortex (AI) of anesthetized cats mainly occurred at onsets (<200-ms latency) and at subsequent major peaks of the vocalization envelope and was significantly inhibited during the stationary course of the stimuli. The first 200 ms of processing appears crucial for discrimination of a vocalization in AI. The dorsal and ventral parts of AI appear to have different roles in coding vocalizations. The dorsal part potentially discriminated carrier-altered meows, whereas the ventral part showed differences primarily in its response to natural and time-reversed meows. In the posterior auditory field, the different temporal response types of neurons, as determined by their poststimulus time histograms, showed discrimination for carrier alterations in the meow. Sustained firing neurons in the posterior ectosylvian gyrus (EP) could discriminate, among others, by neural synchrony, temporal envelope alterations of the meow, and time reversion thereof. These findings suggest an important role of EP in the detection of information conveyed by the alterations of vocalizations. Discrimination of the neural responses to different alterations of vocalizations could be based on either firing rate, type of temporal response, or neural synchrony, suggesting that all these are likely simultaneously used in processing of natural and altered conspecific vocalizations.

Classification of domestic cat (Felis catus) vocalizations by naive and experienced human listeners.

To test for possible functional referentiality in a common domestic cat (Felis catus) vocalization, the authors conducted 2 experiments to examine whether human participants could classify meow sounds recorded from 12 different cats in 5 behavioral contexts. In Experiment 1, participants heard singlecalls, whereas in Experiment 2, bouts of calls were presented. In both cases, classification accuracy was significantly above chance, but modestly so. Accuracy for bouts exceeded that for single calls. Overall, participants performed better in classifying individual calls if they had lived with, interacted with, and had a general affinity for cats. These results provide little evidence of referentiality suggesting instead that meows are nonspecific, somewhat negatively toned stimuli that attract attention from humans. With experience, human listeners can become more proficient at inferring positive-affect states from cat meows.

Acoustic correlates of human responses to domestic cat (felis catus) vocalizations

As part of ongoing research on coevolution of vocal communication between humans and domestic cats, perceptual data were collected on participants as they listened to recorded cat vocalizations. In experiment 1, human subjects were asked to rate the pleasantness of 100 meows along a 7-point scale, from most to least pleasant. In experiment 2, a different group of participants was asked to rate the urgency of the same meows along a 7-point scale, from most to least urgent. Linear regression analysis of the results showed a strong inverse correlation between pleasantness and urgency. Acoustic correlates of pleasantness included reduced frequency modulation, a downward shift in fundamental frequency, and fewer noisy segments. Correlates of urgency included increased duration, higher Wiener entropy, and acute spectral tilt. It is speculated that humans’ affective responses to these acoustic qualities, in conjunction with contextual cues, may form the basis of the communication of more specific meanings by cats to humans.

Neuronal responses in cat primary auditory cortex to natural and altered species-specific calls

We investigated how natural and morphed cat vocalizations are represented in primary auditory cortex (AI). About 40% of the neurons showed time-locked responses to major peaks in the vocalization envelope, 60% only responded at the onset. Simultaneously recorded multi-unit (MU) activity of these peak-tracking neurons on separate electrodes was significantly more synchronous during stimulation than under silence. Thus, the representation of the vocalizations is likely synchronously distributed across the cortex. The sum of the responses to the low and high frequency part of the meow, with the boundary at 2.5 kHz, was larger than the neuronal response to the natural meow itself, suggesting that strong lateral inhibition is shaping the response to the natural meow. In this sense, the neurons are combination-sensitive. The frequency-tuning properties and the response to amplitude-modulated tones of the MU recordings can explain the responses to natural, and temporally and spectrally altered vocalizations. Analysis of the mutual information in the firing rate suggests that the activity of at least 95 recording sites in AI would be needed to reliably distinguish between the nine different vocalizations. This suggests that a distributed representation based on temporal stimulus aspects may be more efficient than one based on firing rate.

Factors influencing neural activity in parabrachial regions during cat vocalizations.

The parabrachial nucleus in mammals is intimately connected with other vocalization controlling brainstem structures. It, along with ventromedially adjacent structures, also has been identified as the pneumotaxic center, and as such shows strong respiratory related activity in the anesthetized cat. The current study examines the neuronal activity in cat parabrachial regions during production of instrumentally conditioned vocalizations. Most of the units in our sample show considerable activity during periods between vocalizations. For many units, firing rate fluctuates during the respiratory cycle, although apparently not as strongly as reported in the decerebrate cat. Also, there is often strong phasic activity during periods where animals are licking to ingest their food rewards. During the peri-vocalization period, various neural activity patterns can be recorded. Most common is an activity increase during the vocalization itself. Moreover, in some units, this activity increase has an auditory component. A smaller number of units show other activity patterns, including a suppression of activity during vocalization and activity increases preceding the vocalization. Overall, our results suggest that the parabrachial region's involvement in vocal control is quite complex, involving convergence of respiratory, acoustic, vocalization-related, and perhaps somatosensory influences.

The effects of articulation on the acoustical structure of feline vocalizations

Feline isolation calls were analyzed, and a model was developed to relate the acoustical features of these calls to the physical processes used in their production. Fifty isolation calls were recorded from each of five cats for a total sample of 250 vocalizations. By combinations of Fourier transform, autocorrelation, and linear prediction methods, the fundamental frequency (glottal-pulse period) F0, the energy of F0, the frequency having maximum energy Fmax (not always F0), and the energy at this frequency were computed. Mean F0 ranged from 400-600 Hz for individual cats. For some cats F0 was consistent within calls, but for other cats sudden shifts in F0 occurred within calls. Here, Fmax was almost a harmonic of F0 and generally ranged from 1-2 kHz. For individual cats, the energy ratio E = (energy of Fmax/energy of F0) varied from 1 to 60 and the grand average E over the time course of the call varied from about 12 to 38. The mean rms call intensity was an inverted-U function of time. Measured jaw opening was strongly correlated with acoustical features of call. A Bessel-horn model with time-varying flare gave a good account of acoustical parameters such as Fmax. The presence of formantlike resonances in cat vocalizations and the important role of jaw movements (vocal gestures) in the production of these calls suggest that cats may provide a useful model for some aspects of human vocal behavior.