"I envy public love," Jessye Norman sings, the words deriving from the song cycle Spirits in the Well by American composer Richard Danielpour, written for Norman to texts by Toni Morrison. The sentiment, however, strikes one as somewhat incongruous. "Public love," far from being an object of envy, is something on which Norman seemingly thrives, assiduously courting - and gaining - the adulation of her audiences.
A spotlight picks her out as she sweeps on to the platform to acknowledge the riotous cheers, in which she basks with regal obeisances. Singing Schumann's Widmung (Dedication) as an encore, she folds her hands over her heart when she gets to the words: "Your love gives me my worth."
Her pianist, Mark Markham, is then sent off stage to get the music for her next encore, while Norman receives her standing ovation alone. People rush forward to offer her flowers and she extends her hands for them to kiss.
These are the trappings of royalty, and many still believe that Norman is music's reigning queen. Yet royalty can be fallible, and Norman's voice is not what it was. The famous velvet tone is thinning, its beauty diminished. It sails forth at climactic moments in Mahler's Rückert Lieder and Beethoven's Gellert Songs, but we hear it too infrequently.
The plush, earthy low notes that once sent shivers down your spine are less in evidence. When she sings Duparc's L'Invitation au Voyage, you begin to realise that the sound itself no longer quite incarnates "luxe, calme et volupté".
Danielpour's song cycle, receiving its UK premiere, carefully avoids extremes of range and surrounds Norman's voice with hovering piano chords, reminiscent here of Debussy, there of Samuel Barber. Its subject is the progress of artistic creativity, from childhood fantasy - the titular spirits, whose influence lingers into adulthood - to a final sense of fulfilment, even satiety. "There are no new songs and I have sung all the songs there are," its last lines run. Whether the cycle contains autobiographical references, as far as Norman is concerned, is something we are not told, though in some respects it sums her up.
A star and a cult figure is what she has made of herself and what she remains in the eyes of many - but we must also acknowledge that her once-great artistry is fading.
· At Symphony Hall, Birmingham, on Friday. Box office: 0121-780 3333.
