Reverberation as afterlife

I just heard this phrase on Radio National in a discussion about an exhibition on surveillance. A man talking about walking into a cathedral, hearing a choir, and even after the choir stopped, the overhang that still filled the space, suggestive of afterlife. It's that silence - impure silence, overhang - that follows the moment. The quality of the air when the voices stop. The voice is lost, but this exhibition gathers together the lost notes, the notes floating on the air three decades later, after the Hobbytex tin was closed for the last time. There had to be a last time the tin was used, rediscovered decades later, rusted on. The tiny noise of the last metal-on-metal sound of the sprung metal hoop closing over the top of the tin.