When dogs hear their owners speak, they are listening for consonants in words rather than vowels, a new study suggests, apparently mimicking a similar human bias that is found across many languages.

Although dogs don’t have language, they live in a speech-rich environment, says at Eötvös Loránd University in Hungary.

“We knew from our previous studies that dogs care about what we speak and how we speak, but until now there was no evidence that dogs’ experience with speech can actually shape how their brains function,” says Andics.

To investigate how a life with humans and listening to constant talk has impacted dogs’ brains, Andics and his colleagues recruited 20 adult human Hungarian speakers and 20 companion dogs with Hungarian owners.

Andics says while many Eastern European languages are consonant heavy, Hungarian isn’t.

“There are some studies suggesting that consonant bias during speech segmentation is weaker, or not there, in people who mostly listen to Mandarin or Danish, in which languages consonants are not, or not that much, more informative about word boundaries than vowels,” he says.

During the experiment, the human and dog participants separately listened to continuous, unsegmented speech streams of nonsense words while connected to EEG monitors, measuring the electrical activity of the participants’ brains.

Consonants and vowels alternated throughout these streams, with no pauses or other acoustic cues separating them, says Andics.

There were three types of nonsense streams. In the first, recurring consonant patterns formed consecutive three-syllable words – such as “mozite”. In the second, stronger vowel patterns formed the skeleton of the words – such as “zobefu”. And in the third, there were no recurring patterns at all, with syllables in a random order – such as “fumoza”.

He says the team made use of a phenomenon called “neural synchronisation”, in which brain activity can take on the rhythm that we detect in the sounds we hear.

“The more reliably we detect that rhythm, the more rhythmic the brain response becomes,” says Andics. “We expected that if a species’ brain has a preference for consonants, it should follow the rhythm of the words more easily when consonants form the structure of those words.”

The difference was substantial, the scientists found. In dogs, the neural response to consonant-based regularities was 42 per cent stronger than the response to vowel-based regularities, and 55 per cent stronger than the response to the random stream.

“So, this is how much more dog brains tracked word rhythm when consonants defined the words,” says Andics.

In humans, the response to consonant-patterned words was nearly 25 per cent higher than to vowel-based regularities and 77 per cent higher than to the random condition.
The team thinks that dogs who weren’t exposed to human speech wouldn’t have this bias, although they haven’t yet tested this idea.

“We argue that the only reason companion dogs have a consonant bias is that human speech, and specifically the characteristics of words, reshaped their brains,” says Andics.

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at the University of Sydney, Australia, says the team convincingly shows that these dogs display more sensitivity to statistical patterns in consonants, rather than in vowels.

But with some important caveats – especially that these are Hungarian dogs, living with Hungarian speakers.

“There’s 7000 different languages in the world and some of them rely a lot more on things like tonal distinctions,” says Enfield. But if you do want your dog to pay attention to you, there may be a practical take home, he says.

“The lesson here may be to give your dog a name with more consonants in it than one with more vowels.”

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