If you're wondering what the circular black thing in the middle of Trafalgar Square is, it's an audio exhibition and part of the London Design Festival.
The BE OPEN Sound Portal looks a bit forbidding, but once inside it's a clean, white, round space, with speakers embedded in all the walls and partially overhead. What you hear depends on when you go as the music changes each day: today Nathaniel Robin Mann "evokes steam train frenetics, creaking organ bellows, pet shop cacophony and community choruses", tomorrow Jo Thomas has gone for a warmer sound, Saturday's piece by Tom Jenkinson is a recording of a single guitar with individual notes sounding out of different bits of the room and on Sunday it's all about ultrasound animal noises created by Jana Winderen.
We heard Ivan Pavlov's 12 Sonnets for Humankind, which says it wants to turn the room into a kind of chapel and create a "universal religious experience". To us it sounded more like recordings of aliens and was certainly ethereal, though more of the properly-freaking-out kind than devotional. As a demonstration of design you can't see it's certainly successful in creating an atmosphere, especially when the bass makes the entire construction and your blood vibrate. Lying back on the central mushroom-like stool, soaking up the sound and gazing up into the sky seems the most popular way to experience it.