Summary: Differences in sound properties, including pitch and timbre, help dogs to recognize the voice of their owners over that of a stranger.
A new study from the researchers of the Department of Ethology at Eötvös Loránd University (ELTE), Hungary reveals that dogs can recognize their owner by voice alone, and they make use of some of the same voice properties as humans do.
The study is published in Animal Cognition.
Sure, our dogs recognize us. But are they also capable of it, when neither vision nor smell is there to guide them, so by using voice alone? If so, what is it about voice, that helps them?
To find out, researchers at the Department of Ethology, ELTE, Hungary, invited 28 owner-dog pairs to play hide-and-seek in the lab. Dogs had to find their owner behind one of two hiding places while a stranger hid behind the other one.
They played the owner’s voice from the owner’s hiding place, and a stranger’s voice from the other hiding place, both reading out recipes in a neutral tone. The dogs’ task was to choose from a distance and find their owners.
The game had multiple rounds and the owner’s voice was paired with 14 different strangers’ voices, some more similar to the owner’s voice, some more different.
Dogs found their owner in 82% of the cases. To make sure that smells did not help dogs here, in the last two rounds the researchers played the owner’s voice from where the stranger hid, and the dogs still went for the voice showing that they did not use their nose in this task.
The researchers also explored what exactly in the voices helped dogs to choose.
“People mostly make use of three properties: pitch (higher or lower), noisiness (cleaner or harsher), and timbre (brighter or darker) to differentiate others. Dogs may make use of the same voice properties or different ones. If two voices differ in a property that matters for dogs, decisions should be easier,” explains Anna Gábor, lead author of the study.
The time dogs looked in the direction of the owner’s voice while waiting for the sign to go showed how sure they were in their decisions.
It turned out that if the owner’s and the stranger’s voice differed more in pitch and noisiness it helped dogs to recognize their owners voice, but timbre and other sound properties did not.
“This is the first demonstration that dogs can tell apart their owner’s voice from many others. The study also shows that dogs make use of some, but only some of the same voice properties as humans do to recognize who is talking” – concludes Andics Attila, leader of the Neuroethology of Communication Lab, where this study was conducted.
About this animal cognition research news
Author: Sara Bohm Source: ELTE Contact: Sara Bohm – ELTE Image: The image is in the public domain
The acoustic bases of human voice identity processing in dogs
Speech carries identity-diagnostic acoustic cues that help individuals recognize each other during vocal–social interactions. In humans, fundamental frequency, formant dispersion and harmonics-to-noise ratio serve as characteristics along which speakers can be reliably separated.
The ability to infer a speaker’s identity is also adaptive for members of other species (like companion animals) for whom humans (as owners) are relevant. The acoustic bases of speaker recognition in non-humans are unknown.
Here, we tested whether dogs can recognize their owner’s voice and whether they rely on the same acoustic parameters for such recognition as humans use to discriminate speakers.
Stimuli were pre-recorded sentences spoken by the owner and control persons, played through loudspeakers placed behind two non-transparent screens (with each screen hiding a person).
We investigated the association between acoustic distance of speakers (examined along several dimensions relevant in intraspecific voice identification) and dogs’ behavior.
Dogs chose their owner’s voice more often than that of control persons’, suggesting that they can identify it.
Choosing success and time spent looking in the direction of the owner’s voice were positively associated, showing that looking time is an index of the ease of choice. Acoustic distance of speakers in mean fundamental frequency and jitter were positively associated with looking time, indicating that the shorter the acoustic distance between speakers with regard to these parameters, the harder the decision.
So, dogs use these cues to discriminate their owner’s voice from unfamiliar voices. These findings reveal that dogs use some but probably not all acoustic parameters that humans use to identify speakers.
Although dogs can detect fine changes in speech, their perceptual system may not be fully attuned to identity-diagnostic cues in the human voice.