Invisible Clock is a small System 7-only Apple Macintosh utility that
audibly announces the time between the hours you choose every hour,
half-hour, or quarter-hour as you prefer at the volume you decide.

Actually, it's a pair of applications: "Invisible Clock" and
"Invisible Clockwork." Invisible Clockwork does the announcing.
Whenever it's running, it sits quietly in the background except to
announce the time every so often. You use Invisible Clock to tell
Invisible Clockwork when, how often, and how loud to announce.

? From the "About Invisible Clock 2.0.1" ReadMe

First DL is v2.0.1
Second DL is v2.0

Compatibility
Architecture: 68k

Only tested on an LC III+ running Mac OS 7.5.5. Should work with
emulators.