Summary: Sober & Brainard (2009)

Humans use vocal imitation from auditory feedback when learning to talk. Similarly, during the process of imprinting, young birds learn to imitate the songs of adults (tutors) through a reliance on auditory feedback. Initially discordant vocalizations are crystallized into mature song similar to their demonstrator's. During adulthood, humans continue to rely on auditory feedback to correct vocal errors. However, it is unclear whether parallel processes drive the stability of adult vocal behaviour. Sober & Brainard (2009) tested the hypothesis that adult Bengalese finches maintain vocal output by disturbing the pitch (fundamental frequency) of auditory feedback (using custom-designed headphones) and monitoring any resulting vocalization modifications. They predicted that shifts in auditory feedback pitch would cause birds to change their own song pitch in the direction opposite to the imposed feedback. They found that birds use auditory feedback and maintain their song vocalizations through a continual process of error correction. The birds adjusted their song pitch, thereby compensating for the auditory error imposed. Sober & Brainard's (2009) result show that error correction, even in adulthood, is a general principle of learned vocal behaviour.