Our Resident Pilot can chime in anytime BoeingBoy, but correct me if I'm wrong...

Probably the APD

The GPWS (Ground Proximity Warning System) will chime Terrain, Terrain whereas it may also say Whoop, Whoop Pull Up, Pull Up ...

Then there are sounds when an Aircraft flies over a VORTAC or certain NAVAIDS as well...

Pilots will also have a Cabin Chime to let the FAs know right when they're about to land over the Middle Marker which is literally 30 seconds or less...