Barbara Hendricks has chosen well: these arias are just the vehicle for the scale and timbre of her voice and its carefully self-imposed interpretative limits. The naive simplicity of the 11-year-old Mozart's ''Betracht dies Herz'', a Good Friday piece striking in its prophecy of Pamina's ''Ach ich fuhl's'', is captured exactly. Hendricks outlines with tender clarity the gently unpredictable melody, breathing out the voice's sighs in turn with those of the strings with an instinctive sense of proportion. Her capacity for under-statement comes into its own, too, in the faultlessly traced perky little ''Laudate Dominum'' from the Vesperae de Dominica, sung almost without vibrato.
When it comes to the other ''Laudate Dominum'', K339, Hendricks's limitations become all too apparent. She takes it extremely slowly depriving it of the sensuousness within its sublimity. The ''Et incarnatus est'' from the Mass in C minor, too, needs more fullness of response, more generous arching of the melody, more ripe life in the core of its high repeated notes. Again, one misses a sense of affirmation within the serenity which Hendricks can create so well.
The Exsultate functions very much at the level of air and angels; fair enough, perhaps, as it is addressed to the animae heatae. But one longs for the ''Alleluia'' to shine out: it is sung immaculately, but the lack of inner light starves it of the life-force it needs for its coloratura passages.
Hendricks remains at her best in meditation. The ''Aznus Dei'' from the Litaniae Lauretanae which Emstein described as ''one of the most unearthly pieces Mozart ever composed'', and that from the Coronation Mass both breathe a sense of awe-full wonder which is not to be underestimated. The Academy orchestra provide a trim discreet presence: the occasional choral entries sound to me a little edited-in.
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