Our ability to hear and understand a second language becomes more and more difficult with age, but the adult brain can be
retrained to pick up foreign sounds more easily again. This finding, reported by Dr Paul Iverson of the UCL Centre for Human
Communication, at the "Plasticity in Speech Perception 2005" workshop - builds on an important new theory that the
difficulties we have with learning languages in later life are not biological and that, given the right stimulus, the brain
can be retrained.
International Speech Communication Association (ISCA) workshop on plasticity in speech perception held by UCL at Beverage
Hall, Senate House, 15th - 17th June
It is an accepted fact that the younger the child, the easier it is for them to learn a second language. Children are able to
understand words and hear small sound differences that adults often miss - making understanding more difficult for adults.
For example, Polish students of English have difficulty differentiating between vowels such as "pen" and "pan" while German
students must learn to hear a difference between the v in "vest" and the w in "west".
Scientists used to believe that the adult brain could not be retrained later in life to distinguish between these sounds: in
other words the brain's plasticity (or ability to change) was set.
Dr Iverson shows that adults can retune their brains to hear these differences again. Scientists now believe that the
difficulties are caused by our experience which teaches us to ignore certain sounds so that we are able to give our full
attention to the sounds that (in our native language) matter most to understanding a sentence.
Two studies jointly worked on by Dr Paul Iverson and Dr Valerie Hazan, UCL's Department of Phonetics and Linguistics, have
examined whether it is possible to retune how the brain processes speech sounds, and hope that their findings will help make
language learning easier for adults. In one study, Japanese subjects were retrained to hear the difference between r's and
l's (something that Japanese students of English tend to find particularly difficult). The study tested 63 native Japanese
subjects in Japan and London, and had them complete a 10-session training course. Before and after training, the subjects
were given a number of perceptual tests to evaluate their perception of acoustic cues. Similar tests were carried out in
London on Sinhalese (from Sri Lanka) and German speakers who had lived in the UK for more than 20 years.
In the Japanese training study, the subjects improved their recognition of l's and r's by an average of 18%. So, for example,
if an individual could identify the difference between r and l 60% of the time, at the end of training they would be able to
get this correct 78% of the time - supporting the view that the brain can be retuned.
Talking at the UCL workshop, which brings together specialists in language, speech and speech perception, Dr Iverson said:
"Adult learning does not appear to become difficult because of a change in neural plasticity. Rather, we now think that
learning becomes hard because experience with our first language 'warps' perception. We see things through the lens of our
native language and that 'warps' the way we see foreign languages.
"It is very difficult to undo this learning. That is, we change our perception during childhood so that it becomes
specialized to hear the speech sounds in our first language. This specialization can conflict with our ability to learn to
distinguish sounds in other languages. Through training, we can essentially change our 'perceptual warping' to make
second-language learning easier. I hope that this research will lead to new ways of training adults to learn second
languages."
Contact: Alex Brew
a.brewucl.ac
44-207-679-9726
University College London
ucl.ac