On February 7th, I was on a UA 4694 from DEN to SAF, upon approach the landing was aborted; the pilot did not come on to inform passengers for the aborted landing; upon second approach, we heard the landing gear come down, which we did not hear on the first approach; the rest was uneventful. I just reviewed the "Live ATC" recording for that period, and there is 90 sec. period of complete silence on the ATC recording, between the Tower giving permission at 16:05:02 to land and at 16:07:07 instructing UA3649 to 'turn left at Delta 1, and contact ground". It appears that there is no recording of the aborted landing, second approach, nor any other communications from the tower during this approximately 90 second period. Would the ATC recording include communication related to an aborted landing? Or would someone have the ability to erase this from the recording?