Star rating: ****

Edinburgh's nicely-named Calton Consort is a chorus of some 30 mixed voices, singing unaccompanied under Jason Orringe's directorship. Founded six years ago to raise money for a church roof, it now has its base at Canongate Kirk, below Calton Hill, where its carefully compiled concerts are winning acclaim.

The latest, on Saturday, was a case in point. With Shakespeare as its theme, it was structured around Orringe's own new setting of the eighth sonnet, Music to Hear, which gave the event its title and its question: is music something to hear or to listen to? Orringe's iridescent timbres were certainly atmospheric, thereby fulfilling both definitions, and so were Frank Martin's five Ariel songs, gentle samples of the gliding tonality for which this Franco-Swiss composer (now sadly neglected) was famed in the mid-twentieth century.

Vaughan Williams's Three Shakespeare Songs provided matter more robust, as did his Five English Folk Songs, but the performances steered clear of over-emphasis. Elgar's meaty Shelley setting, O Wild West Wind, seemed not quite the music for Canongate's rather unfocused acoustics - underpinned all evening by a distracting mechanical hum - but Britten's Five Flower Songs, neo-Tudor madrigals saved for the end of the programme, preserved the general feel of the occasion. Orringe's programme notes, explaining how the concert had come to be assembled, were exemplary.

A concert of Scottish music to celebrate Homecoming 2009 follows on June 13.