Irish composer Donnacha Dennehy appears to spend his time working out how best to persecute unsuspecting percussionists. Glamour Sleeper II begins with the relentless stuttering of an imposing kick drum that interrupts and disrupts and stabilises our sense of tempo all at once. Add to that an equally tempestuous piano part that scratches and plucks pitches from the body of the instrument, a violin that seems to be stuck on a singular note and a clarinet that provides some semblance of harmonic relief, and the piece is almost, but never quite, complete.

Conducted incisively by William Conway, this work was a brutal and intolerant stampede across all the cliches of contemporary music. Yet there was a modesty and humour to Dennehy's music, as if it were compelled by its form rather than its ego.

The Hebrides Ensemble's appearance at this lunchtime concert was essentially to facilitate the excellent performance of work by composition students at the Royal Scottish Academy of Music and Drama, as part of the annual Plug festival. Joel Harding and Kirsty Blackwood were this year's featured composers, and each showed they were capable of producing work of note. Similarly, each of the young composers adhered to the belief that their music could be a domain that allowed them to pose certain abstract or existential questions.

The musical material generated is presumably an expression of some kind of answer or response to such questions, and the result can be described, often loosely and ambiguously, as an exploration of ideas. One can't help feeling, though, that this kind of explanatory rhetoric rarely does justice to either the questions posed or, indeed, the piece that is produced.