§  10.520   Common Audio Attention Signal.

   A Participating CMS Provider and equipment manufacturers may only
   market devices for public use under part 10 that include an audio
   attention signal that meets the requirements of this section.

   (a) The audio attention signal must have a temporal pattern of one long
   tone of two (2) seconds, followed by two short tones of one (1) second
   each, with a half (0.5) second interval between each tone. The entire
   sequence must be repeated twice with a half (0.5) second interval
   between each repetition.

   (b) For devices that have polyphonic capabilities, the audio attention
   signal must consist of the fundamental frequencies of 853 Hz and 960 Hz
   transmitted simultaneously.

   (c) For devices with only a monophonic capability, the audio attention
   signal must be 960 Hz.

   (d) The audio attention signal must be restricted to use for Alert
   Messages under part 10.

   (e) A device may include the capability to mute the audio attention
   signal.