deaf cats‘ meow is different!
 
 

Cats are considered vocal non-learners: their vocalizations are inborn and do not require learning. This significantly differs from e.g. many bird species that learn their songs from their parents and some even develop local „dialects“.


However, it is difficult to imagine that an inborn neuronal pattern generator, like the one responsible for vocalizations, does not require any feedback. In complete absence of feedback the motor pattern might easily get disturbed by ongiong developmental changes (like growth in body size and thus of vocal apparatus). In case of vocalizations this would interfere with their communicative role. The auditory feedback may therefore be more important than previously thought. To investigate whether cat vocalizations are indeed independent of hearing or not, we analyzed over 13,000 vocalizations recorded from hearing kittens, hearing impaired kittens and deaf cats and performed a detailed statistical acoustical analysis for comparison (Hubka et al. 2015).


We observed several interesting effects: 1) There was a developmental change in the vocalizations in hearing kittens. 2) In hearing impaired animals, the variability in the spectral components increased, but the developmental sequence was essentially unchanged. 3) In congenitally deaf cats, not only were vocalizations louder and had lower pitch, also their spectral development was arrested. Many different vocalization parameters were affected (Hubka et al. 2015). This correlated with the observations of experienced animal keepers that reported calls of the deaf cats being different from hearing cats.


Several different mechanisms of these changes are possible, including a cross-modal reorganization with somatosensory control of vocalizations and a low-level motor-auditory interaction that is required for stability of the cat calls. The data further support the continuity hypothesis suggested by Arriaga and Jarvis (2013).


 

deafness affects cats vocalizations

Development of the mean spectrograms of isolation calls („meow“) in hearing, hearing-impaired and deaf cats. Change in pitch and in the initial FM component of the calls is evident. Ages: 1-3 months after birth. From Hubka et al., 2015.
Spectrogram of an individual vocalization from a hearing cat. The isolation call („meow“) covers the whole hearing range of humans (up to 20 kHz) and can last more than 1.5 sec. It contains many harmonics and sometimes non-linear components (biphonations or frequency jumps). For details, see Hubka et al., 2015.