Q - What is the sound feedback feature in RF meters?
A - The sound function of most RF meters that have it is based on turning the modulation of the signal (the number of times it starts and ends) to sound.
Every RF signal has a special sound fingerprint, which the meter can help you hear and you can identify (after some practice).
In addition the CORNET ED78S has an alarm feature which can be set to 0,-5,-10,-15 and-20 dbm. When the RF level will accede the levels set the alarm will go off.