Beginning in the early days of sound art and continuing through our era, when every group show seems to include a token video work, one of the biggest challenges facing curators of noise-generating objects is how to deal with their ability to interfere in each other's sonic footprint. For a long time, exhibition spaces were partitioned into muffling isolation booths, confining each work to its own miniature gallery, but more and more curators have taken to embracing the audio bleed that inevitably occurs between works, using overlapping sounds to create new experiences of individual objects. One of the most ambitious examples to date is 'Ensemble,' at Philadelphia's Institute of Contemporary Art through December 16th. Visiting curator Christian Marclay has taken on the role of composer, filling the ICA's galleries with sound-emanating work by well-known artists, including Terry Adkins, Doug Aitken, Pierre Huyghe, and Yoko Ono, and allowing the noises that they generate to flow into one another, turning the entire exhibition into a large soundscape--with the 30-foot ceiling of the main gallery acting as an amplifier.