The Man Who Mistook His Wife For A Hat, Lyric Hammersmith<br></br>Anna Caterina Antonacci, St John's Smith Square, London

Most dramas revolve around relationships rather than the technicalities of the professional background against which they are set. This is why people who don't know a defibrillator from a doorstop can watch ER with their hearts in their mouths. This is also why those who not only understand defibrillators but can rewire them while blindfolded enjoy ER rather less. So pity the poor singers of Norway's Opera Vest, whose first-night performance of The Man Who Mistook His Wife For A Hat – Michael Nyman's 1986 chamber opera based on Dr Oliver Sacks' neurological case study of the same name – was given in the company of 560 emminent delegates from the World Congress of Neurology.

Audience dynamics are unpredictable at the best of times, but when an audience is composed of specialists the entire focus is shifted. Imagine singing Billy Budd for the Royal Navy; the sailors might admire your vocal colour, but they'd probably be deeply critical of your ability to tie a knot. And so it was for Opera Vest. Instead of attending to the human tragedy of Dr P's agnosia (the technical term for confusing your wife's head with a hat), the production was scrutinised for clinical authenticity. Was Dr S tapping the wrong joints as he tested the reflexes of the unfortunate Dr P? I wouldn't know, but the German neurologist to my right was snickering behind her programme and she was not the only one.

Despite this, and despite Michael McCarthy's threadbare direction, Ketil Hugaas (Dr P) and Itziar Martinez Galdos (Mrs P) gave strong portrayals of their characters and showed how healthy interdependency can enrich two lives threatened by mental illness. Hugaas's coppery bass proved rich and ample from the very lowest notes to his final, bewildered falsetto at the opera's close. Martinez Galdos – a Straussian soprano in the making – soared over the strings in Ingar Bergby's over-amplified and abrasive Bit20 Ensemble, and what she lacked in diction was compensated for by sincerity. Not so Julian Pike, whose ill-tuned account of Dr S appeared to have been modelled on the late Alan Clark. "How does he tie his shoelaces?" barked Pike, in a tone of outraged disgust (a tone familiar to those who remember Clark before he was miraculously rehabilitated as a lovable eccentric). Perhaps it would not have jarred so much had the opera not been introduced by the soft-voiced Dr Sacks himself.

The Man Who Mistook... is a fascinating work but I'm not convinced that it's a good opera. To pull in the other brain specialists for a moment, you have to wonder at the psychology at play here. Was Nyman – a composer who has been criticised for emotional coldness – being deliberately provocative by choosing a "clinical" subject and using the lieder of Schumann – a composer whose emotional range is unsurpassable – to encapsulate the only security left to the increasingly enfeebled Dr P? Nyman's writing does not, in fact, lack emotion. Confusion, sensory bombardment and panic are all well painted. So too is desolation (the unwinding of momentum at the close of the opera), and the brief moment of control as Drs S and P play chess to an even pizzicato string pattern. But unlike Schumann, Nyman uses only one pigment – a tonal deficit that the occasional alteration in intensity cannot disguise. His broken chords and propulsive pedal figures are not painful to listen to across an opera, but in much the same way as being poked repeatedly with a foam-rubber sword might annoy over time – regardless of rhythmic variations – they do too. And as Hugaas sang Ich grolle nicht and quoted Auf einer Burg, it was diffcult to resist the impulse to leave the theatre and head for the nearest recital of Dichterliebe or Liederkreis. If that's the point – if Nyman is comparing agnosia to a world without musical beauty or emotional variety – it's a very, very risky gambit.

Somewhere in my soul lurks a DJ of the old school, whose chief delight is cheesy segues. And that, I'm afraid, was the reason I went along to Anna Caterina Antonacci's recital of Mad Songs (geddit?) at the Lufthansa Festival, rather than any nostalgia for her rather passive, lipstick-and-cleavage 1998 Rodelinda at Glyndebourne. Well, ha, and ha. Antonacci's early 17th-century Italian programme was devoid of Mad Songs, with the dubious exception of a reduced version of Giramo's madrigal parody La Pazza (the madwoman) – and if you're going to extend this highly formalised English Restoration genre (which in any case might be more accurately termed Erotic Obsessive Disorder Songs) to include Giramo, then you might as well sling in most of Sances, Strozzi, Monteverdi and D'India too. But it didn't matter a jot: this recital was one of the best I've heard in years, and the finest by far in this repertoire.

In recital – and in charge – Antonacci is transformed. She has the communicative immediacy of Sarah Vaughan, the vocal impact of Callas, the dramatic delivery of Piaf, and the idiomatic intelligence of Maria Cristina Kiehr. (Not that these things should matter, but she also has the face of Ashley Judd, and the figure of Cindy Crawford.) Through vocal colouring that ranged from gun-metal to pure gold, through physical gesture and sheer interpretive conviction, Antonacci captured the improvisational ideal of the Florentine Camerata. Her Lamento d'Arianna blazed with frustrated desire and fury. La Pazza flew by in a brilliant flash of biting Neapolitan argot. But the high point was Monteverdi's Combattimento di Tancredi e Clorinda, in which Antonacci took all three roles – a re-invention I thought absurdly self-aggrandising until I heard it. It was totally captivating, and superbly accompanied by Ivor Bolton and the St James's Baroque Players. This woman is hot stuff; a superb musician with a glorious voice and more than enough intelligence to know how to use it.

a.picard@independent.co.uk