For these patients, listening to music is like listening to a foreign language

Tim Griffiths, University of Newcastle

Tim Griffiths at the University of Newcastle-upon-Tyne, who has also carried out research into tune-deafness, said there may be people who keep silent about their problems.

"Sufferers might put CDs on when friends come round for dinner in an effort to pretend they like music."

He told a recent meeting of the Association for Research into Otolaryngology in Florida of one woman who could only distinguish changes in pitch using vibrato, where the pitch varies, or tremolo, where there is a rapid alteration between two notes.

In both cases the difference had to be very big before she noticed.

Spotting the difference

Dr Peretz has also carried out a number of studies into tune-deafness.

She looked at whether people could distinguish between notes that were two semitones - which equals a tone - or less apart and found tune -deaf people could not.

The semitone is the smallest interval in the traditional Western musical scale, and Dr Peretz said most people could tell the difference between notes which were just a semitone apart.

Tune-deaf people also failed to recognise wrong notes in familiar tunes or spot when something was dissonant - where notes seem to "clash" because they are not in harmony.

Researchers say the condition is not linked to lack of intelligence, mental illness, or lack of exposure to music in childhood.

But there is debate as to whether there is a link with language ability.

Dr Peretz said people who were tune-deaf did not seem to have problems recognising changes in inflection of vocal tone, possibly because the shift is large and obvious, or because different parts of the brain process speech and music.

But Mireille Besson, of the Centre for Research in Cognitive Neurosciences in Marseille, has found the brain does respond in the same way to an unexpected jump in a melody and an unexpected sentence intonation, such as at the end of a question.