<prompt> This tympanogram is seen in:OMEOtosclerosisCSOMOsssicular chain discontinuity  <response>: Flat line is seen on tympanometry in patient with a perforation in tympanic membrane. It is not indicated in cases with a diagnosis of perforation of tympanic membrane. However it can be of help in cases with a suspicion of very small perforation in TM not clearly visible on otoscopy. Flat line confirms a perforation in Tympanic membrane. 