The Bruce Nauman installation at Tate Modern is almost invisible. Only discreet loudspeakers can be found in the Turbine Hall which in the past has seen such popular attractions as the Weather Project.
Curator Emma Dexter says that the installation needs an audience. So maybe it will be watching other people in the Turbine Hall trying to listen to the 21 different audio tracks that is the exhibition.
There is no beginning or end to the messages but if you enter from the top of the slope at the west end then the welcoming words are "Thank you Thank you".
The climax is "world peace" but the artist, although American, says he does not mean to link this to Iraq or the Presidential election. The latter will be long over when this show ends next March.
Above the bridge where surely most visitors will exit hoping for relief there is the final message "think think".
It is difficult to know what to think as the artist is better known for his sculpture. But it is interesting to find that the programme of sounds was sketched out in the peace of The Savoy across the river. Nauman says that since this is his own work he might manage to stay in the Turbine Hall for half a day.
He admits to being interested to know the reaction of guests at the opening party and more important the effect on usually noisy school parties entering the Hall. They usually miss the low hum which is always in the Turbine Hall and comes from the surviving electricity switching station in the building. This sound has been enhanced by Nauman and is being broadcast from the ceiling. It sounds like an angry bee trapped in the impressive structure.
This is the last in the current series sponsored by Unilever. Its chairman Patrick Cesau has just announced a further extension for three years claiming that his staff benefit from visiting the installations.
Unilever's sponsorship began more than a century ago with the hanging of local artists' work in the Port Sunlight Canteen. At Tate Modern the noise does not penetrate the restaurant.
• Bruce Nauman is at Tate Modern until Monday 28 March: admission free.