Silence in Advertising
Radiocentre advises no more than three seconds of silence in advertisements. It should quickly become clear from the context of the scenario that the silence forms part of an advertisement and should not sound as if the station has stopped broadcasting.
Please note that stations will have their own rules for the use of silence, so always check with them prior to using silence in ads.
Some creatives may benefit from the use of ambient background noise, rather than complete silence.