This option specifies the conditions in which sound-activated recording starts and stops. It's only applicable when the record activation type is "Sound". Start and stop each have their own condition, consisting of an input level threshold in decibels, and a minimum duration in seconds. Recording begins if the input level (on any channel) reaches or exceeds the start threshold, for at least the start duration. Once started, recording continues until the input level (on all channels) falls below the stop threshold, for at least the stop duration.
The start condition defines "activity" or "signal", while the stop condition defines "inactivity" or "quiet". The stop duration is especially important because it determines how inconsistent input is handled. If the input contains quiet pauses, and the pauses are longer than the stop duration, the recording may be split into multiple files. To avoid this, increase the stop duration.