The German composer Charlotte Seither's new choral and orchestral piece, Language of Leaving, had its premiere in the BBC Symphony Orchestra's ninth Prom of the season, conducted by the Catalan Josep Pons. Seither admits to a fascination with the human voice, and, in this work, her treatment of the 24 members of the BBC Singers was unusual: they effectively became instruments, as she pointed out in her programme note. Their sung text – a fragmented version of a small poem about leaving hope behind by the 17th-century Italian Francesco de Lemene – disappeared into the overall texture.

Yet, curiously, the purely instrumental aspects of the work, notably a flamboyant use of percussion instruments, especially swanee whistles and flexatones, made a more obvious impact than the subtle vocal colourings threaded through it. There was a highly refined ear for sonority at work here, though the result felt less focused than the three smaller pieces heard in the revealing Composer Portrait presented earlier at the Royal College of Music.

The BBC Singers also contributed a couple of Stravinsky's short a cappella works to the programme in the shape of his Russian Orthodox settings of the Ave Maria and the Lord's Prayer, though their tone remained resolutely Anglican.

Pons began the programme with a vital and warmhearted account of Stravinsky's Scherzo à la Russe, and created an immaculately textured underlay for Frank Peter Zimmermann's lyrically rhapsodic approach to the Brahms Violin Concerto, though the soloist could have offered a more vehement attack on the music's stresses and strains and the sheer ebullience of the finale. Pons's energised yet observant account of Petrushka was purposeful throughout, with just the odd minor blip from the hardworking brass section tarnishing its spirited precision.

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