tonedeaf

This Week

Can't name that tune
22 Sep 01

For some people, music makes as much sense as a foreign
language

                                DO PEOPLE cover their ears when you step up to the karaoke mike?
                                Can't tap your foot in time to a melody? Can't even recognise a simple
                                tune like Happy Birthday? If the answer is yes, you're not just
                                tone-deaf, you're "tune-deaf".

                                "For these patients, listening to music is like listening to a foreign
                                language," says Isabelle Peretz of Montreal University in Canada, who
                                identified congenital amusia four years ago. Tune-deaf people are
                                perfectly normal in other ways, she explains. They are intelligent,
                                have no history of mental illness and were exposed to music as
                                children. They just cannot comprehend the basic components of
                                melody such as meter, rhythm and pitch and consequently do not feel
                                any emotion when listening. The disorder seems to affect men and
                                women equally.

                                Peretz's research-including one study on 11 people-has shown that
                                tune-deaf people cannot distinguish intervals of about two semitones
                                or less. A semitone is the smallest interval in Western scales and most
                                people can detect an interval of half that. Tune-deaf people also
                                have difficulty recognising "wrong" notes in popular tunes and
                                spotting musical dissonance.

                                In research presented at a recent meeting of the Association for
                                Research in Otolaryngology in Florida, a team led by Tim Griffiths at
                                the University of Newcastle upon Tyne described one person who
                                can't detect sound patterns in music. The woman was asked if she
                                could tell the difference between two notes. In one test the notes
                                differed in the amount of vibrato (pitch variation) while in another
                                they differed in the amount of tremolo (volume variation). In both
                                cases, the differences had to be huge for her to notice. Tests showed
                                that there was nothing wrong with her hearing.

                                Interestingly, other work by Peretz suggests that tune-deafness
                                does not seem to impair language ability. People don't have difficulty
                                recognising voices or spotting intonation in language such as the
                                upward inflection at the end of a question. This may be because pitch
                                jumps in speech tend to be quite large and obvious. It also implies
                                that there are specific modules in the brain dedicated to processing
                                music which are separate from speech modules.

                                But Mireille Besson of the Centre for Research in Cognitive
                                Neurosciences in Marseille has found contrary evidence implying that
                                music and language processing are linked. Her group showed that the
                                brain responds similarly to an unexpected jump in a melody and an
                                unexpected sentence intonation, such as a voice going down in pitch
                                at the end of a question. "Peretz's work is good evidence for the
                                modular view," she says, "but there are other ways to interpret the
                                data. The brain is very plastic."

                                Griffiths says no one is sure how common the disorder is, but he
                                believes that there are more sufferers than we realise because people
                                don't admit to it. "Sufferers might put CDs on when friends come
                                round to dinner in an effort to pretend they like music," he says.

James Randerson
From New Scientist magazine, vol 171 issue 2309, 22/09/2001, page 21