AS I placed my face directly over one of the floor speakers at James Webb's new installation Prayer, a voice from the speaker said: 'you are above me…' Was a CCTV camera also installed in the red carpet? No, mere serendipity was at work.

There were many speakers on the carpet, each one repeating several prayers from dozens of different faith groups in Nottingham. I could have chosen any of them, but as luck would have it, the first prayer seemed to speak directly to me.

It was a strange, unnerving and personal moment in an exhibition which at one level presents a collective portrait of Nottingham through its diverse religious beliefs and, at another level, provides intimate connections with the individual but unseen people reciting the prayers.

Webb's first version of Prayer was shown in his native Cape Town in South Africa a decade ago and he has since produced another adaptation for Huddersfield. In Nottingham, he has gone out and recorded the prayers of some 40 religious and spiritual groups and then piped them through around a dozen small speakers set out on a plain red carpet in the Djanogly Art Gallery.

You are encouraged to get down close to the speakers, in a prayer-like posture, to hear each prayer. But standing back from the speakers you hear a sound that is slightly cacophonous as the many different voices mix together and waft upwards towards heaven together – a sound portrait of Nottingham's spiritual beliefs, but also a portrait of the city's cultural and language diversity.

None of the prayers are labelled and you can set yourself an informal quiz by trying to identify which religion, group or denomination each prayer belongs to.

The mellifluous sung prayers must be Muslim; one language from the Indian sub-continent suggests Hinduism; a strong Caribbean accent hints that one of the Christian churches is rooted in the West Indies, and so on.

If there is a problem with this installation, it is its visually dull presentation. The style is minimalist to say the least. The intention, no doubt, to concentrate your attention on the voices.

But, with the gallery main lights on permanently, the effect is akin to seeing an exhibition in somebody's front room.

Some images or dim lights would enhance the atmosphere.

The second half of Webb's show is a separate sound piece titled Autohagiography where you listen to a recording of Webb talking while he was under hypnosis. A shiny black couch is provided where the sound issues in stereo from speakers on either side of your head, the scenes described providing a haunting line straight into Webb's unconscious.

At one point Webb talks about being a little girl in the winter; at another, he is a soldier wearing bits of metal and leather. Yet he can interpret these images no more than we can.

As with Prayer, the impact here mostly stems from sound. However, with the Freudian couch and the absurdly grandiose exhibition title added in, it's obvious that Webb is also making fun of the artistic ego.

See Prayer at Djanogly Art Gallery, Lakeside Arts Centre, Nottingham. Until August 8.