Grimeborn, the self-styled "hippest opera festival in London", had a major coup two summers ago with the UK premiere of Philip Glass's "dance opera" Les Enfants Terribles. For this year's festival it has conjured up another Glass stage work never seen here before: The Sound of a Voice, first performed in 2003.

Based upon a pair of short stories by David Henry Hwang, who also wrote the text, The Sound of a Voice is an operatic diptych – a pair of self-contained two-handers that both explore themes of growing old, loneliness and the possibilities of intimacy between people who have insulated themselves from it. In the first half, also called The Sound of a Voice, an aging samurai warrior visits a woman living as a hermit deep in the forest, though who is preying on whom remains ambiguous right to the end; in The Hotel of Dreams, a seventysomething writer visits a brothel for old men, and develops a curious dependency upon the elderly madam who runs it.

They are mysterious, if slight tales, in which emotions are tightly reined in. Glass's scoring includes oriental instruments – the Chinese pipa, the Japanese shakuhachi – alongside flute, cello and percussion, and the vocal lines are spare and conversational. Both pieces work dramatically without ever really engaging with the audience, though they might cast more of a spell in another space – the Arcola Tent (a temporary venue during renovations in the main theatre) is hardly impervious to noise from the busy street outside. But Andrea Ferran's production does what is needed, and the performances from all four singers – Catherine May and Rodney Clarke in Voice, Geraldine McGreevy and Christopher Foster in Hotel – are nicely detailed.