Swedish composer Andrea Tarodi has written a new concerto for the Amatis Trio and the National Youth Orchestra of Scotland, and the tints, she tells Ken Walton, are silvery, dark green and purple.

When Andrea Tarrodi composes, colours determine the notes on the page. Blessed with synaesthesia – the condition through which the brain “hears” musical sounds as colours – the Swedish composer is in good company. Scriabin, Sibelius, Messiaen and Ligeti all experienced the same sensory phenomenon. “It feels like a sort of sixth sense,” Tarrodi explains. “I particularly like music that goes in purple and yellow, sometimes in gold.”

In her new concerto Moorlands and Beyond…, written for the Amatis Trio and the National Youth Orchestra of Scotland (NYOS), the tints, she says, are silvery, dark green and purple. “When I write I see colours in the back of my head triggered by certain soundscapes. I don’t know if I use it on purpose, it’s just something that’s there.”

True enough, take just a sample of the 42-year-old’s substantial compositional output to date – the kaleidoscopic radiance of the Mediterranean-scented Liguria, performed by NYOS five years ago, or the melancholic pastel tones of her cello concerto Highlands for instance – and the predominant character of Tarrodi’s music is its richness of texture and shade, vibrant energy, and that stinging Nordic clarity you associate with the likes of Sibelius.

Expect all of that when her new concerto is premiered in Edinburgh and Glasgow next month. It’s the bold opener to an ambitious NYOS Summer Concert programme, directed by former RCS Leverhulme Conducting Fellow Teresa Riveiro Böhm, that also features Grieg’s Norwegian Dances and Stravinsky’s dazzling Petrushka.

The seeds of Moorlands and Beyond… lie both in a previous composition, Moorlands, and in Tarrodi’s creative response six years ago to the wild Scottish landscape. The earlier chamber work was also written for the Amatis Trio, who encouraged its physical quirks. “Together we had this idea that the musicians were not all on stage from the start but would enter and join the performance one by one,” Tarrodi explains. “Also, I’d just been on an amazing road trip around Scotland and vivid images of moorlands and nature were fresh in my mind, so I let them inspire the music.”

When the commissioning of the new concerto for NYOS was later mooted by the same Dutch-based piano trio, Tarrodi turned her thoughts back to Moorlands as a starting point. “I thought I’ll just use some parts of the earlier piece then create something new, but when I saw what I was writing I realised how much more creative potential existed within the original, thus the title Moorlands and Beyond… .”

It’s not an uncommon creative urge. Composers like Boulez and James MacMillan frequently expanded earlier works to extraordinary, original effect. “This new piece has a life of its own,” she insists. “Not just because it includes a full orchestra, but it’s now much more dramatic, more expressive than the original.”

The biggest challenge, she admits, was how to calibrate the distinction between the solo trio unit and full orchestra. “It’s hard to see these three people in the same way you view the individual soloist in a standard concerto.” Her solution was to explore the shifting possibilities arising from such a tantalising dynamic. “So the trio can be both soloists and part of the orchestra, or something in between.”

Did she consult the most obvious precursor, Beethoven’s Triple Concerto, for pointers? “No, I thought about it, but preferred to use my own music for inspiration,” she explains. That included the same accumulative walk-on ploy of Moorlands, except this time it’s the orchestra that enters section by section.

For Tarrodi, such theatrical idiosyncrasies are likely inborn, coming from a colourful musical family. Her father, trombonist and composer Christian Lindberg, famously performed Jan Sandström’s Motorbike Odyssey in full leathers aboard a Harley-Davidson with the BBC SSO at Glasgow’s 2006 Proms in the Park. “He and I now run a festival together in the Stockholm archipelago,” she says.

Musically, though, she believes in clarity and simplicity, which is handy when composing for a young collective like NYOS. “I don’t write really complex or hard music, and I like it when limits are placed on what I can do.” Except, of course, when it comes to colour.

The Amatis Trio and the National Youth Orchestra of Scotland perform Andrea Tarrodi’s Moorlands and Beyond… at the Usher Hall, Edinburgh, 12 July and the City Halls, Glasgow, 13 July, see www.nyos.co.uk

When Andrea Tarrodi composes, colours determine the notes on the page: ‘It feels like a sort of sixth sense’