By Caroline Briggs
Arts and culture reporter, BBC News
One of Jim Aitchison's 'sound maps' based on a Rothko painting
Thousands of people have visited Mark Rothko's Seagram Murals since they went on display in London last September.
While they have brought a visual and intellectual treat to all, few would have paused in Tate Modern's cathedral-like setting to consider how the modern-day masterpieces may sound.
But to composer Jim Aitchison - a Henry Moore fellow at the Royal Academy of Music - thinking about how a piece of art may sound is second nature.
He "re-imagines" contemporary and historical artworks as notations of sound, and creates a musical score based on the expressive and structural content of the piece.
The Tate asked Aitchison to respond musically to its Rothko exhibition - something he admits was "daunting".
"It was an unbelievable opportunity, but I was initially a little reticent," he says. "I had a very short time frame and because it's just the biggest thing I could have imagined having to do.
"Rothko is the most significant 20th Century artist and no-one is going to take that challenge lightly. I was pretty terrified!"
When writing a musical score for a painting or sculpture, Mr Aitchison uses the artwork itself as a visual reference for his music.
He looks at the shape and form to create "sound maps" - drawing the picture onto manuscript paper and placing musical notes on top.
"I was pretty stuck with Rothko," Mr Aitchison admits. "I went to see the show and afterwards I sat in the cafe thinking 'what on earth am I going to do?'
"I absent-mindedly drew out some of the shapes onto manuscript paper and began sticking notes in the corners and something seemed to click.
"The simplicity of that was really important. The paintings are fundamentally simple shapes but they have all sorts of complex resonances which Rothko obviously wants us to take in."
Murals from Tate Modern's iconic Rothko Room were reunited with nine other works from Japan for the exhibition.
The vast murals were originally commissioned for The Four Seasons Restaurant in the Seagram Building in New York, but were never installed. They are among the most enigmatic in contemporary art.
Rothko constructed their striking surfaces by overlapping matt and translucent paints, depth was created by allowing the underlayers to shine through.
Mr Aitchison had to consider Rothko's rhythmic composition, dramatic brushstrokes, and the oppressive resonance of the paintings when composing his piece.
"I can think of hundreds of pieces of music that would already fit the ambience, and I went into the exhibition with a lot of pieces of music in my mind," explains Mr Aitchison.
"I thought 'oh my goodness the opening of Wagner's Parsifal would go with that, or Charles Ives's Unanswered Question, or this piece or that piece'.
Jim Aitchison has previously worked with Anthony Gormley
"I had banish all of those pieces to the back of my mind and try and start afresh.
"The paintings are so powerful. I spent a lot of time there to try and get a sense of the emotional terrain I feel they are trying to convey to me."
Mr Aitchison has previously worked with other artists, including Turner Prize-winning sculptor Anthony Gormley.
That collaboration culminated in a 45-minute piece of music, performed in Gormley's central London studio.
'Iconic and terrifying'
"The Angel of the North figures very strongly in that piece," Mr Aitchison explained.
"I didn't want to go anywhere near it because it is so iconic and terrifying, but I went to see it and was so overwhelmed I thought I just had to go for it.
"I had to find a way of translating some of the ways Anthony works into sound. His Domain Field pieces are made of matrices of T-shapes - bits of metal welded together - so I made my own musical matrices based on T-shapes.
"But you can't do it as an exact translation, it has to be more of an illusion rather than a direct, crude mechanical transfer of dimensions."
While some people with a rare form of synaesthesia - a condition where senses intermingle - can "hear" what they see, Mr Aitchison believes it is something we can all tap into.
"We are all totally familiar and used to experiencing aspects of visual culture with sound," he says.
"We all watch films and there are very few films that don't have a soundtrack. In that sense it should be something that we are all potentially totally comfortable with.
"If you are open to it, music can enhance your experience of the artwork."
The Kreutzer Quartet will perform Mr Aitchison's score at the Tate Modern on Monday evening. The Rothko exhibition continues at Tate Modern until 1 February.