Whenever I am presented with an excerpts recording, I often wonder what it is that I am supposed to be listening to. In this case, we have a sixty-minute survey of eleven of Bach's greatest mezzo-soprano landmarks including, of course, Et exsultavit from the Magnificat, Erbarme dich from the St Matthew Passion and Laudamus te from the B Minor Mass.

I think, it is safe to say, that these arias are very much the servant of the performer. They give the angel-voiced virtuoso of Magdalena Kozená a showcase for her undoubted talents. Supported by a diligent and sensitive period instrument accompaniment by Musica Florea, she delivers elegant phrases, sensible articulation and apt ornamentation. All of this is delightful and I am indeed pleased to have been introduced to this accomplished artist, but I regret to say that the whole of this recording is not greater than the sum of its parts.

There are a number of reasons for this. In the first place, I think that Magdalena is more soprano than mezzo-soprano. She certainly does have some warmth in the middle register, but she is thin lower down. I did not detect that fruitiness of tone that really distinguishes a great mezzo-soprano. The sleeve notes imply comparison with such names as Janet Baker, Kathleen Ferrier, Christa Ludwig and Anne Sofie von Otter, but I am bound to disagree. Voice-type is not a question of how high or how low a voice travels, but of the quality of tone that it produces throughout the vocal range. Magdalena's crystalline tone just could not quite fill the phrase in Erbarme dich - I have to say in her defence that it was taken foolishly under tempo, especially for an aria out of context. On those long tied notes and extended melismas, I want to hear a voice grow in anguish. I need to hear a fully committed tonal development, not a correct but self-conscious crescendo. Beautiful though it was, this performance did not move me. What I heard was too ascetic, too low-fat, too cerebral and not nearly visceral enough. I do not particularly want to hear the voice of an angel floating in the spheres in an aria about the agonies of man.

I love to hear authentic performances - they open the antique phial and give us a fascinating whiff of long-lost fragrances. The only inherent danger is that the worthy scholarship that leads to period performance can become over-intellectualised. Attention to detail to the deft articulation of each note-group can lead an artist to forget the longer phrase. I felt that this happens frequently in these performances: whilst we may not have romantic eight-bar legatos, there is no reason why baroque phrases should be denied their full height and depth. I cannot blame the soloist for this entirely - she was let down by the conductor who showed too much reserve and not enough flair.

Contrary to the sleeve notes, Magdalena does not display "a depth of emotional insight that belies her age" but, I freely admit, she does have a fine voice that she controls with considerable skill. I could not therefore fully recommend to Bach lovers a compilation of out-of-context arias as virtuoso set-pieces. (Small wonder that the drama and excitement of their provenance did not come with them.) If a new voice is your bag, then this might be of more interest, though I think that Magdalena Kozená has been wrongly labelled and undersold.

Crispin Woodhead