As a fluent speaker of four languages, people frequently ask me how I acquire a language. When I ask why, they respond by saying: 'Well, you speak it so well.' I counter with: 'But what do you mean by 'well''?
The typical definition I receive is: 'You sound like a native.' Pause at 'sound'. While language experts unanimously agree that accent is not an accurate prediction of a speakers' proficiency level, recent research on polyglots provides evidence that there is a link between a person's sensitivity toward sounds, or phonemes (the technical term used by linguists), and language learning ability.
For example, a recent cognitive neuroscience study conducted at University College London showed a difference in brain structure between sound-sensitive people and those who are not. Likewise, previous research demonstrated a discrepancy in grey structure matter for musically inclined people.
So does this spell bad news for adults and/or tone-deaf people? Not exactly. It is widely agreed that young children are able to pick up a large range of sounds with few difficulties. As for older learners, two concurrent studies conducted by Dr Paul Iverson and Dr Valerie Hazan of the UCL Centre for Human Communication are trying to prove that adult learners can be trained to become more acute toward foreign sounds.
Participants were native Japanese speakers who went through a training programme to help them distinguish between the English 'l' and 'r' sounds. Initial results showed an average 18 per cent improvement in sound recognition.
Although I am not a psycholinguist, I can substantiate their claims through my own experiences as both an English language learner and teacher. One of the keys for acquiring the vocabulary, syntax and accent of a language is contingent on being able to differentiate and process individual and combinations of sounds into meaningful units.