Ana Silvera, Imogen Heap, Estonian Television Girls Choir, Holst Singers, Reverb 2012

Freud would have loved the final night of Reverb 2012's opening weekend. First came a screening of a mad early Surrealist film from Germaine Dulac and Antonin Artaud, in which a priest chases a woman's breasts that have turned into two seashells.

Then came the even madder sight of the Estonian Television Girls Choir dressed up in stripey national dress, coyly jellyfishing around the Roundhouse stage during their a cappella piece, while their long-haired conductor, Aarne Saluveer, beat time on an old metal plate. A dream logic was in fact at play throughout the evening. 

In the first half the Estonians teamed up with the up-and-coming singer-songwriter Ana Silvera. Together they delivered two stunning folkloric sagas. The first journeyed through seven eclectic songs, all of them meditating on a different musical and emotional world, all of them working themselves out with fluency and sophistication. Silvera's voice, which has a Björk-like spontaneity - an ability to be gritty and fragile one minute, warm, rich and ripe the next - bounced beautifully off the chamber ensemble (cello, violin, piano and percussion) and the glassy choir. Most exciting was the moment Silvera's voice suddenly took off in "I Draw You in a Circle of Chalk (The Test)", after several songs tenderly walking through the shadows. 

Heap delivered the panting sounds that accompany the priest on all fours

Her second cycle, "Step Onto the Ground, Dear Brother!" was captivating, mysterious and complex, the music full of dissonant cross-hatchings and choral shout-gesang. Most striking about both works was what a fruitful combination chorus and solo female voice can be when fully intertwined and fully counterpointed in this way. It can't be the easiest twosome to write for. Yet both Silvera and Imogen Heap proved themselves to be masters at the form. Neither let the tension or interest drop in any of their works.

In the second half, there was a switch of choirs, a switch of talented young female composers and a switch of conductors. Heap (pictured right by Chris Christodoulou) was now on stage with the Holst Singers and Hugh Brunt. Her score to the 1928 silent movie Le coquille et la Clergyman (The Seashell and the Clergyman), a bizarre but brilliantly sweaty run-around, was pitched perfectly. It never dominated the movie, but never shied away either. What resulted was a kind of vocal concerto, Heap's musical onomatopoeia a lovely foil to the rich choral backdrop. Brunt did a fantastic job marshalling the forces and keeping the many changes of musical tack in line with the film. Heap delivered much to remember - the panting sounds that accompany the priest when he's on all fours, the squeals as the priest approaches his female fantasy.

The encores brought things down to earth. Heap and Silvera offered two intimate numbers that united the choirs and the soloists in a jubilant act of communal grace. But the Estonians, in full Brighton Rock-like national dress, flung us back into Freudian outer space with their all-singing, all-jellyfishing bit of a cappella (four songs from compatriot Veljo Tormis), in which they floated around the stage like a human shoal.

• Reverb Festival 2012 continues until 4 March