Audiovisual training rapidly reduces potentially hazardous perceptual errors caused by earplugs.

Our ears capture sound from all directions but do not encode directional information explicitly. Instead, subtle acoustic features associated with unique sound source locations must be learned through experience. Surprisingly, aspects of this mapping process remain highly plastic throughout adulthood: Adult human listeners can accommodate acutely modified acoustic inputs ("new ears") over a period of a few weeks to recover near-normal sound localization, and this process can be accelerated with explicit training. Here we evaluated the extent of such plasticity given only transient exposure to distorted inputs. Distortions were produced via earplugs, which severely degrade sound localization performance, constraining their usability in real-world settings that require accurate directional hearing. Localization was measured over a period of ten weeks. Provision of feedback via simple paired auditory and visual stimuli led to a rapid decrease in the occurrence of large errors (responses >|±30°| from target) despite only once-weekly exposure to the altered inputs. Moreover, training effects generalized to untrained sound source locations. Lesser but qualitatively similar improvements were observed in a group of subjects that did not receive explicit feedback. In total, data demonstrate that even transient exposure to altered spatial acoustic information is sufficient for meaningful perceptual improvement (i.e., chronic exposure is not required), offering insight on the nature and time course of perceptual learning in the context of spatial hearing. Data also suggest that the large and potentially hazardous errors in localization caused by earplugs can be mitigated with appropriate training, offering a practical means to increase their usability.