<prompt> Symbol X denotesAir conduction threshold for right earBone conduction threshold for right earAir conduction threshold for left earBone conduction threshold for left ear  <response>: .An O often is used to represent responses for the right ear and an X is used to represent responses for the left ear. A key on the audiogram, similar to one found on a map, identifies what the different symbols mean Hence, indicates air conduction test for left year Ref physiology textbook A. K Jain.. 3e 