Question: What is the VCVA feature on an Olympus DS-4000 digital voice recorder?

Variable Control Voice Actuator (VCVA) is a function that sets up the recorder to record automatically only when sound is detected at a pre-set level, and stop when the sound drops below the threshold level. The purpose of the function is to eliminatedead air” during recordings, thereby conserving memory and shortening file times.

VCVA is enabled via the recorder menu.
Verification Source: Olympus Website