Thank you Phillipe for your quick reply.
This is a actually a little bit more useful than what I’m currently doing: holding down Alt and repeatedly clicking the left mouse button. I’ll use the method you suggested for now. But it’s still not nearly as helpful as dragging the cursor across the waveform and hearing a microloop (15 ms for example) at the cursor start point. But in order for it to really work, you need a set microloop of a specific time, which your method does not have. Your method plays back until you move the cursor. Scrub is sort of like sending out a sonar pulse to gauge your position.
Scrub is essential for those of us who insist on editing by sound and not just the visuals of the waveform. I got addicted to it way back in 1997 on my trusty old Roland VS-880 digital 8 track recorder, which couldn’t even display a waveform, so no visual editing at all. I used scrub all the time to find specific start points on Soundtrack Pro. Once you start using it, it’s hard to use a program without it.