Is it all about the pitch? Acoustic determinants of dog-directed speech preference in domestic dogs, Canis familiaris

Abstract

Dogs, similarly to infants, have been shown to be sensitive to human speech especially when it is directed to them. However, what essential acoustic, paralinguistic and lexical features of dog-directed speech are responsible for this preference in dogs is largely unknown. In the present study, generalized dog (DDS)-, infant (IDS)- and adult (ADS)-directed speech stimuli were created by using prerecorded sentences of multiple female speakers and these composite (averaged) stimuli were then manipulated to control for linguistic content as well as to equalize their mean fundamental frequency (F0) value. All three possible pairwise combinations of these acoustic stimuli were then presented to adult dogs in a two-way choice task where two identical target objects were used to indicate the sound sources. We found a significant preference towards the target object associated with DDS in the DDS versus ADS condition and suggest that, for dogs, mean F0 difference is not essential for DDS–ADS discrimination. However, we did not find evidence of selection bias when IDS was simultaneously presented either with DDS or ADS. Interestingly, our results also showed that dogs were more willing to approach the ‘more prosodic’ location (i.e. DDS or IDS versus ADS) when the prosodically more prominent sound stimulus was presented on their left side which suggests right-hemispheric specialization for neural processing of prosodic sounds in this domestic species. We also found that dogs made their choice faster when the ‘more prosodic’ stimulus was given first which suggests that they can perceive the difference not only between DDS and ADS, but also between IDS and ADS and between IDS and DDS. In conclusion, the composite DDS, IDS and ADS stimuli in the present study proved to be an effective technique in exploring the acoustic determinants of dog-directed speech preference in dogs.