 The babysitter (Ann) phones the husband at the shop (store) that he and his wife jointly run (I think). The wife hears the receptionist put through the call from Ann to her husband and surreptitiously picks up an extension phone. Now, this may be a goof, since this is a fairly large workshop, making jewellery, and one might suppose that they have a small PABX exchange and each phone is on a separate line. Anyway, the wife overhears that the babysitter is having a bay with the husband and it all snowballs from there... I post this because I don t, having just watched this scene, understand why the film is titled Baby Monitor: Sound of Fear. The Baby Monitor does figure in a few scenes but was not how the wife discovered her husband s infidelity...