The Sound Festival, the north-east of Scotland's annual celebration of new music, is now in its 11th year. As the opening days of this year's programme proved, it has become an impressively diverse multi-arts festival.

The opening night concert, performed in the beautiful King's College Chapel of Aberdeen University, brought together two works inspired by astronomy. It was apt that the audience arrived under a clear night sky for the UK premiere of Estonian composer Urmas Sisask's Southern Sky, followed by the world premiere of Northern Skies by James Clapperton.

The compositions are, appropriately enough, and if you will forgive the pun, polar opposites. The Sisask is a pleasant and fun composition, the Clapperton a more serious affair.

In Sisask's piece echoes of Aboriginal Australian traditional music give way to moments of schmaltzy jazz. A charming piece for flute and clarinet represents the movement through the sky of the southern constellation known as "the goldfish".

The Aberdeen performance by Australia's Griffyn Ensemble combined Sisask's panoply of musical genres with a series of mini-lectures in the astronomy of the southern hemisphere by Professor Simon Driver.

Clapperton's piece, a co-commission by Sound and Scottish company Red Note Ensemble, is an altogether more coherent composition. Often achingly beautiful, its sweep through the northern polar sky veers between Romanticism and Modernist discordance.

The composer was raised, he tells us, in Aberdeenshire, the son of a geography professor at Aberdeen University. Now working as an arts producer in the northern Norwegian town of Harstad, the self-proclaimed Russophile promotes Norwegian-Russian cultural collaboration.

Northern Skies itself, an evocative piece intercut with readings from Pushkin in the original Russian, seems to acknowledge debts to Shostakovich and Stravinsky. One hopes that it will be recorded and broadcast in the near future.

Also early in the programme, the festival collaborated purposefully with the ever-inventive short play producer A Play, A Pie And A Pint to stage the music theatre piece The Wakeful Chamber. Written by Rebecca Sharp with a musical/sound score by Pippa Murphy and performed at the Lemon Tree arts venue, it collides the vastness of the universe (as seen through the obsession of a young astronomer) with the huge emotional stakes of fragile, human lives.

Despite the best efforts of Kim Allan as the astronomer, Sharp's script is better in the undoubted cleverness of its conception than in its somewhat difficult performance. Murphy's soundscape succeeds impressively in conveying a sense of tension and moving time as the painful reality of the protagonist's recent bereavement tries to impose itself on her compulsive work routine.

However, the encroachment of emotion into clinical science makes for a tricky transition for Allan. When she is joined by musician David Rankine, as the scientist's dead lover, one feels that the writer has sought a slightly easy resolution in sentimentality.

The chief sentiments of Matthew Collings's composition A Requiem For Edward Snowden are rage and trepidation. Produced by Magnetic North and performed at ACT (Arts Centre and Theatre), it brings together an urgent and affecting piece of music with a smart set of projected visuals by Jules Rawlinson.

Together, music and images urge us to meditate on the fates of people such as Snowden (in enforced exile in Russia), Julian Assange (still holed up in the Ecuadorian embassy in London) and Chelsea Manning (rotting in a military prison in the US). More than that, they provide a chilling commentary upon our surveillance society.

By turns politically muscular and poignantly nuanced, Collings's excellent piece is a heartening reminder of the quality of new music being created and performed in Scotland today.

Indeed, the programming of the piece in Aberdeen is testament to the ambition and courage of the Sound Festival and its director Fiona Robertson. A flick through the festival's 30-page brochure or a browse of its superb website should be enough to excite any arts lover.

I've often lobbied politicians, but rarely have I been lobbied by them myself. North-east region MSP Richard Baker is right, however, in expressing a desire for more support (not least from arts funding quango Creative Scotland) for a festival which has passion and enthusiasm beyond its current resources.

The Sound Festival continues until November 9. For further information, visit: sound-scotland.co.uk