People with a gift for other languages could have different brains from those of other people, a study suggests.
The French and Hindi 'd' sounds were played to participants
Neuroscientists at University College London say they have more "white brain matter" in a part of the brain which processes sound.
Their brains could also be less symmetrical than others.
It is hoped the research, published in the journal Cerebral Cortex, could be used help to identify reasons for language difficulties.
Those involved in the trial - all native French speakers - were asked to distinguish between two similar sounds from different languages.
The first was the "d" sound found in their own language which is made by placing the tip of the tongue against the top teeth.
The second was a "d" found in Hindi, which is pronounced by curling the tongue upwards towards the roof of the mouth.
Both types of d were followed by the letter a, so the participants heard "da".
The differences between the sounds are heard in the first 40 milliseconds.
Researchers tested the speed at which participants could process the information.
Those who identified more than 80% of sounds correctly were then asked to listen to even more acoustically similar sounds.
Some of the fastest learners were able to tell these apart within a few minutes, while the slowest learners were only able to make random guesses at the less difficult stage after 20 minutes of training.
Dr Narly Golestani from UCL's Institute of Cognitive Neuroscience said the brain's white matter was involved in the efficient processing of sound information into the lower levels of the brain - known as the primary cortex.
Its fibres are involved in connecting brain regions together. Fast language learners had a greater volume, and that may mean they have more or perhaps thicker fibres, she said.
"The bigger picture is that we are starting to understand that brain shape and structure can be informative about people's abilities or pathologies - why people are good at some things and not others is evident from these scans," she said.
White brain matter is involved in connecting different parts of the brain together, and greater amounts of this could indicate an increased ability to process sound.
In faster learners, brain scans showed a greater volume of white matter in the left auditory region known as Heschl's gyrus, where sound is processed.
And there was a difference in its position in the right brain hemisphere between faster and slower learners.
The researchers also found there was greater asymmetry in the volume of the parietal lobes, which are also involved in the processing of speech sound in the left hemisphere of the brain.
Previous research suggested that having a talent for music was linked to the structure of grey matter in the brain.
This latest research could be extended to other applications, Dr Narly said.
"We can start to make predictions regarding whether people will be good at something or not based on their brain structure," she said," or diagnose clinical problems."
Brain structure predicts the learning of foreign speech sounds, by Narly Golestani, Nicolas Molko, Stanislas Dehaene, Denis LeBihan and Christophe Pallier, is published in the journal Cerebral Cortex.
Heschl's gyrus in slower and faster language learners (copyright Dr N Golestani)