In contrast, the audio watermarks are not readily perceptible to casual listeners, though they are what in watermarking parlance is known as “overt.” That means the fact that they are embedded is easily discerned by meeting participants: When a Zoom meeting has the audio watermark, or what Zoom also calls the “audio signature,” feature enabled, the meeting will have a green circular icon with a sound wave and a padlock at the top left of the frame next to the encryption icon.