When we say "I've heard that before," we say it for a reason, after all.
Sounds are repeatable, representable entities (they endure through time) and sounds of the past intermingle with sounds of the present. Some "old" sounds present in new spaces, some new sounds occur within old spaces: these could be called "hybridized sonifacts."
Along with the concept and term sonifact, another helpful term is host-artifact: a tangible, perhaps even visible form that interacts with another form or being to produce a sonifact. Many moons ago, when I was an art student at St. Olaf College, I would routinely find myself falling asleep working on some project in the art building, but that was alright because the couches in the upstairs lounge were supremely comfortable. The security guard would make his evening walk through the building every night, so I (or I should say we, because I know I wasn't the only one) would listen for the jangle of those keys. And that's how I knew to hide under the counter in the printmaking studio, until he had passed through.
In this example the sonifact would be that very specific and unmistakable sound: thesoundofthesecurityguard'skeysintheartbuilding. There was nothing else like it and there will never be again. Each night, that sonifact, created by the host-artifacts of the keys and the resonant qualities of the spatial structure of the art building, would recur with negligible variability.
I think the ramifications of this conceptual change (which seems to be taking hold) are very interesting to think about. For instance: Should sound (and silence) have standing?
The Canoe Harp