In this paper, the author discusses what he calls ‘perceptual foreign accent’, a phenomenon much less focused upon in second language acquisition research than foreign accent in production. McAllister shows that even highly proficient second language users, who perform perceptually on a par with native speakers in situations with normal acoustic conditions, have significantly greater difficulties when the signal to be perceived is masked with noise. It is claimed that if simultaneous interpreters behave like second language users in general, they must be strongly affected by disturbances in the particular speech situation that simultaneous interpreting represents.