Comparisons of complex sounds across extended retention intervals survives reading aloud

A simple experimental arrangement is designed to foil verbal rehearsal during an extended (from 5 to 30 s) retention interval across which participants attempt to discriminate two periodic complex sounds. Sounds have an abstract timbre that does not lend itself to verbal labeling, they differ across trials so that no 'standard' comparison stimulus is built up by the participants, and the spectral change to be discriminated is very slight and therefore does not shift the stimulus into a new verbal category. And, crucially, in one experimental condition, participants read aloud during most of the retention interval. Despite these precautions, performance is robust across the extended retention interval. The inference is that one form of auditory memory does not require verbal rehearsal. Nevertheless, modest forgetting occurred. Whatever form memory takes in this situation, it is not totally secure from disruption.