How long do the batteries last in the DS-4000?

Question: How long do the batteries last in the Olympus DS-4000 Digital Voice Recorder?
Alkaline batteries will power the recorder in the Recording Mode for aproximately 16 hours and in the Playback Mode for approximately nine hours.

NiMH batteries will run the recorder in the Recording Mode for approximately 12 hours and in the Playback Mode for approximately eight hours.
Verification Source: Olympus Website