I love this thread.
My favorite sound app was Macromedia SoundEdit
It’s basically the exact program concept I still use for editing, as I can find it - closest to it on the mac currently is SoundStudio, though Audacity is close, too.
What neither have, though, was SoundEdit’s pitch bend tool which allowed you to draw a pitch shape to contort something. Gave a totally psycho rubberband effect that I became addicted to, and in a way losing access to SoundEdit once I moved from OS9 was good creatively, as I was leaning a bit on that trick.
I’ve since found Pitch Bend, exactly as implemented in some SONY products and in some Izotope ones, but it’s still relatively uncommon.
But I managed at one point to get OS9 running on a later version of Mac using SheepShaver. The most difficult part of this was finding an actual boot disc for OS9, requiring a few friends to look for there install discs from macs back - one good friend (thank you Amy) found her’s and I was able to install OS9 for SoundEdit to run. Still took a lot of work to bounce back and forth but for working in SoundEdit was always worth it. Funniest part of those old applications is how easy they are to move back and forth from one computer to another. No real dependant libraries, just the SoundEdit app file itself to run.
I don’t know if SheepShaver works in 64-bit macs, but should still for anything running 32-bit OS. This video suggests you can now grab OS9 boot files from the web, making this process much easier.