Mammals are not only good at hearing sounds, they are especially tuned to voices. A new cross-species study compared humans, dogs, and pigs and mapped how fast the brain flags a voice, then sorts out whether it belongs to one of our own.

The researchers recorded tiny pulses of brain activity while participants listened to people, dogs, and pigs, plus everyday noises. The animals were awake, relaxed, and unmedicated, and the sessions used gentle scalp sensors, not implants.

A team from Eötvös Loránd University (ELU) focused on two questions that cut to the heart of social hearing in mammals.

The first was whether the brain treats vocal sounds as a distinct category, separate from other noises. The second was whether it goes a step further, recognizing and highlighting voices that belong to members of the same species – a process known as conspecific recognition.

Tracking brain signals to sound

The setup used non-invasive EEG sensors to track the brain’s fast electrical responses to sound. The signal components the team examined are called event-related potentials, and they are well suited for timing how processing unfolds.

Participants heard short clips such as laughs, barks, and grunts, alongside non vocal noises like traffic or a closing door.

The recordings let the researchers compare voice versus non-voice processing, then compare same species voices to all other sounds.

Two-step brain response

In humans and pigs, the brain marked any voice very quickly, within about 0.2 seconds after the sound began.

Later, after roughly 0.3 seconds and beyond, all three species showed a second step that tagged same species voices as a special category.

“These patterns were very similar despite the large evolutionary distance between the three species, pointing to shared neural mechanisms that likely predate the divergence of their lineages some 90 million years ago,” said Boglárka Morvai, the study’s lead author.

Dogs, pigs, and people

Dogs did not show the early “any voice” signal as clearly as humans and pigs, even though they live closely with people.

They did show the later step that marked dog sounds as different from other sounds, which matches the idea that same species calls matter most for social behavior.

Pigs showed both steps and did so on a similar time course to people. That pattern strengthens the case that the early voice flag is a general feature of mammal hearing, not a quirk of primates.

Voice areas in mammals

For two decades, brain imaging in humans has found voice sensitive regions in the superior temporal cortex, often called temporal voice areas.

A comprehensive review outlines how these regions support recognition of who is speaking, what they feel, and how the voice changes over time.

Dogs have their own voice sensitive patches too, and they align in function with human areas when both species listen to vocal sounds.

A comparative paper showed that dog and human brains both devote cortex to processing voices, including sensitivity to emotional tone.

Speed of voice detection

Past EEG work in people has reported early differences between voice and non-voice sounds on the order of a fifth of a second.

One open access article found effects emerging around 0.164 seconds and peaking near 0.2 seconds on frontotemporal sensors.

These timings line up with the early “any voice” response reported in the recent study. The later same species effect fits with known windows for categorical decisions in auditory cognition.

Pig brains and voices

Pigs are increasingly used in neuroscience because their brains share organizational features with ours.

Recent physiology work has mapped clear auditory event-related responses in healthy piglets using scalp EEG, strengthening their value as a model species. 

Finding the early voice flag in pigs suggests that this quick detection step is not limited to primates or carnivores. It likely reflects a basic property of mammalian hearing tuned by social life.

Evolutionary roots of voice

The two-step pattern, first voice detection, then same species sorting, makes evolutionary sense. Fast detection buys time to orient toward a biologically relevant sound, then a later pass adds the social label needed to decide how to react.

If distantly related species share both steps, the underlying circuitry likely traces back to a common ancestor. That is consistent with decades of work showing conserved organization for voice and affect processing across mammals.

All recordings relied on cooperative, awake participation. Dogs and pigs were measured in calm settings, often near their owners, and no training or sedation was required for them to rest while the sensors recorded.

The protocol emphasizes trust and low stress, which improves data quality and respects the welfare of companion animals. The approach also allows direct comparisons with human EEG.

Sorting same-species voices

Same-species voices carry information about identity, emotion, age, and intent. That richer meaning calls for more processing than a quick voice versus non-voice flag.

The later timing suggests a categorical decision process in which the brain checks acoustic features against learned templates for its own kind.

In humans, that machinery feeds into language, but it operates in social mammals that do not use speech.

Future of voice studies

Future studies can add more species and test a wider range of calls to see how acoustic structure shapes the early and late steps. Portable EEG could expand testing into natural settings where animals communicate most.

Combining EEG with imaging can also map the timing onto brain regions, tying the fast electrical signatures to specific circuits. That could clarify how the two steps interact during real world social listening.

Better models of voice processing can guide assistive tech for people with hearing or language challenges. They can also inform animal welfare by helping us detect stress or need from vocal cues in pets and livestock.

Cross species designs like this one keep us honest about what is uniquely human and what is widely shared. That distinction matters for both neuroscience and ethics.

The study is published in the journal NeuroImage.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–