The innovative vocal ensemble welcome theorbo player Paula Chateauneuf to the Ulster Museum

If you’ve never seen a theorbo before, the sight can be a little startling. The oval body is innocuous enough, but the priapic, giraffe-like neck extension, enabling extra bass strings to be added, gives a whole new meaning to the concept of air guitar playing. It must be a brute to lug around in cars or aeroplanes.

Paula Chateauneuf is one of the leading exponents of the medieval instrument, and her contributions anchor The Pain & The Pleasure, a delectable evening of music by Monteverdi and his contemporaries, performed by the Northern Irish vocal ensemble Sestina at the Ulster Museum.

Part one of the recital showcases Monteverdi’s pioneering activities as a writer of madrigals, with three pieces from 'Book Eight', the so-called Madrigali dei guerrieri et amorosi (‘Madrigals of War and Love’).

Working with a basic consort of six singers, conductor Mark Chambers elicits performances which expertly blend the interleaving sensuality of Monteverdi’s part-writing with the biting drama of his word-setting.

The second stanza of 'Altri canti d’Amor' (‘Let others sing of Love’) shows the composer at his most combustible, the vocal effects mimicking the ‘fearsome combats’ of Mars, God of war, where ‘swords clash and sparks fly thick and fast'.

The rapid hocketing of syllables between the singers is thrilling, the rhythmic attack tight and well co-ordinated. The becalmed sestet is, by contrast, mellifluously negotiated by bass-baritone Brian McAlea, currently a student at New College, Oxford.

Another Northern Irish singer, soprano Fiona Flynn, is showcased in the solo part of 'Lamento della Ninfa', her light, tremulous vibrato sensitively delineating the emotional sufferings of the abandoned maiden, yearning for past happiness. There is neat counter-balancing here of the three male voices who narrate and comment on the ‘miserella’’s cruel predicament.

Punctuating the Monteverdi items are brief instrumental pieces by Marini and Merula, their gentle melancholy a perfect counterfoil to the bracing vocal pieces. Chateauneuf’s caressing, sentient theorbo is again an alluring presence, in combination with the Baroque violins of Carolyn Hall and Colin Norrby.

'Hor che’l ciel e la terra e’l vento tace' (‘Now that the sky, earth and wind are silent’) concludes part one, the remarkably lugubrious tonal mixes in the opening section suggesting the love that burns and simmers, and the ‘sweet suffering’ of the poet who is enslaved by longing.

Occasionally the strong, confident tenors of Matthew Long and Thomas Herford – guest artists and mentors for the younger Sestina singers on this particular project – marginally overface the other voices, but generally this is another sharply communicative interpretation.

The operatic experience of Long and Herford comes into its own in part two of the evening, effectively one long encore featuring the high jinks and musical mimetics of Adriano Banchieri’s 'Festino nella sera del giovedì grasso avanti cena' (‘Feast for the eve of Fat Thursday of Carnival’).

‘Fat Thursday’ is a Christian festival at which appetites for drink and confectioneries can be sated before the abstemiousness of Lent commences. Banchieri’s collage of comic madrigals accordingly depicts sundry scenes of merriment and carousing, with animal noises, imitations of musical instruments, men with trousers falling down and a ‘Brindisi’ (‘drinking song’) recreating the medieval equivalent of a raucous contemporary shot session.

Long and Herford are lead energisers of the revelry, re-located from an upstairs gallery of the Ulster Museum to the downstairs café area, where an enthusiastic audience nibble appropriately on traybakes, and sip libations.

This is, all told, an effervescent evening’s entertainment, and another colourful feather in the cap of Sestina, a group fast developing a reputation for classy, intelligent programming of Baroque music, idiomatically sung and expertly accompanied on instruments of the period.

And there are big plans in the offing – 2015 will bring a major Venetian Festival, culminating in a performance of Monteverdi’s magnificent Vespers of 1610, spatially exploiting the atrium hallway of the Ulster Museum. The date, April 12, should be in every local music lover’s diary.

Visit the Ulster Museum website for information on forthcoming events.