Philips VTR5500 Manual page 56

the following picture:
Note: This function should only be used in noisy environment. It
records in WAV format with bit rate of 384 kbps .
(3) Voice-activated Setting
A practical function of recording, no button operation is needed.
When the function is enabled, in the course of recording, if no
voice is detected, the device will automatically pause recording
after 3 seconds; if voice is detected again, the device resumes
recording. See the below related reference picture:
(4) The listen in function
After activating the Listen in function, you can plug in an
earphone to listen to the sound which is to be recorded. See the
Listen in function setting interface picture as follows:
56