The 27-year-old woman, known as ES, is a synaesthete - someone who experiences sensation in more than one sense from the same stimulation, researchers said on Wednesday.

   

When ES hears tone intervals, the difference in pitch between two tones, she not only can see the musical notes as different colours, but can taste the sounds.

   

"This is a special case of a musician who, when she hears tone intervals, she has a perception of a taste of a tone," psychologist Michaela Esslen, of the University of Zurich in Switzerland, said.

   

"She doesn't imagine the taste, she really tastes it."

 

Exceptional

   

The case of ES as reported in Nature is exceptional because seeing letters or digits in a certain colour is more common in synaesthesia. It may also involve seeing a musical tone as a colour.

   

"We found that
ES's tone-interval identification
was perfect"

University of Zurich researchers

But ES sees the colours and depending on the tone intervals a symphony could be bittersweet, salty, sour or creamy.

   

"Whenever she hears a specific musical interval, she automatically experiences a taste on her tongue that is consistently linked to that particular interval," the scientists said in the journal.

   

They tested ES's ability by applying solutions tasting sour, bitter, salty or sweet to her tongue and asking her to identify the tone intervals, a difficult task that requires musical training.

   

When the applied tastes corresponded with the intervals she was able to identify them quicker than other musicians.

   

"We found that ES's tone-interval identification was perfect," the researchers said.