‘When I play it with the right tempo, everybody recognises it,’ said Dr Bueti, a neuroscientist from the International School for Advanced Studies (SISSA) in Trieste, Italy. People are amazed by how different the two sound, she says.

Processing time is important for many daily activities from walking to playing sports. It helps coordinate movements, like knowing when to hit a tennis ball.

Dr Bueti is studying how our brain makes sense of short time intervals ranging from hundreds of milliseconds to just a few seconds. Short durations are what we perceive while listening to music, for instance. They are also crucial for understanding speech, since pauses between syllables and words affect meaning.

‘We use regularities in speech to predict how language will unfold and it’s also important for language acquisition,’ said Dr Alan Langus, a neuroscientist at the University of Potsdam’s BabyLab in Germany. ‘When young infants don’t understand a language yet they can use rhythmic cues to understand where words begin and how words are grouped into sentences.’

Much of how our brain perceives time – and hence rhythm – is still a mystery. Although there are dedicated brain regions for receiving and decoding sensory information, such as what we see and hear, others seem to be involved in processing time. But how these regions communicate – and the mechanisms they use to process durations – are unclear. Likewise, we still don’t know whether the same mechanisms process different types of rhythmic information such as speech and music.

Better understanding this should help reveal whether there is a link between rhythm in speech and music, says Dr Langus. If this is the case, musical training could also benefit language skills, he adds.

Rhythm

Dr Langus and his colleagues studied how the brain processes rhythm in speech and music for a project called RHYTHMSYNC.

Previous research has tried to either measure reaction times, such as tapping to a beat, for example, or has directly looked at brain activity. But the team took a novel approach, using eye tracking – a cheaper technique than brain scans – to see whether people’s pupils change size in time with rhythm.

‘It’s spontaneous so we don’t have to tell participants to tap to a rhythm, or to synchronise their behaviour,’ said Dr Langus. ‘The brain is doing that automatically.’

In trials, participants listened to either speech or music alone, then there was switching between the two. The team found that volunteers’ pupils pulsated to a rhythmic beat irrespective of whether it came from speech or music.

This suggests that the brain uses the same mechanism to process rhythm in music and speech and that it doesn’t distinguish between the different stimuli on a temporal level.[…]