Noise may delay baby's development

Noise may delay a baby's first word and be responsible for the increase in language learning disorders noted by doctors over the last few decades, say researchers in California.

Background noise may limit mental development by swamping an infant's brain, hindering its ability to recognise sounds, they say.

Modern homes are filled with noise from televisions and radios, traffic, aircraft and domestic appliances, potentially damaging the hearing centre of a baby's brain, says Prof Michael Merzenich's team at the University of California, San Francisco, USA.

In Science, his team describes how it reared young rats amid continuous noise, which masked normal sounds. The rats' auditory cortex took three or four times longer than normal to mature. The findings are likely to apply to humans because all mammals share similar patterns of brain development.

© The Telegraph Group Limited, London 2003