identical, indistinguishable -- (exactly alike; incapable of being perceived as different; "rows of identical houses"; "cars identical except for their license plates"; "they wore indistinguishable hats")
indistinguishable, undistinguishable -- (not capable of being distinguished or differentiated; "the two specimens are actually different from each other but the differences are almost indistinguishable"; "the twins were indistinguishable"; "a colorless person quite indistinguishable from the colorless mass of humanity")
(Sound)
