In 1958 La Monte Young wrote the Trio for Strings, an hour made almost entirely of held tones. From there he tuned everything to simple whole-number ratios instead of equal temperament, and in 1966 he opened the first continuous sound environment in his Church Street loft. With Marian Zazeela's light it became the Dream House, in Tribeca since 1993 and still sounding: thirty-two sine waves held still, amber and blue, and a visitor who walks around inside the chord instead of sitting in front of it.

This follows what came out of that room, and what was happening beside it. The people who were in it, Tony Conrad, Henry Flynt, Terry Riley, Charlemagne Palestine. The ones who got there alone, above all Giacinto Scelsi, writing four pieces on a single note in Rome in 1959 without knowing any of it. Then just intonation as a discipline, the physics of two close frequencies held together, and the sustained tone reached by other roads.

Fifty-six records, in listening order.