Learning auditory space: generalization and long-term effects

Background: Previous findings have shown that humans can learn to localize with altered auditory space cues. Here
we analyze such learning processes and their effects up to one month on both localization accuracy and sound
externalization. Subjects were trained and retested, focusing on the effects of stimulus type in learning, stimulus type
in localization, stimulus position, previous experience, externalization levels, and time.
Method: We trained listeners in azimuth and elevation discrimination in two experiments. Half participated in the
azimuth experiment first and half in the elevation first. In each experiment, half were trained in speech sounds and
half in white noise. Retests were performed at several time intervals: just after training and one hour, one day, one
week and one month later. In a control condition, we tested the effect of systematic retesting over time with post-tests
only after training and either one day, one week, or one month later.
Results: With training all participants lowered their localization errors. This benefit was still present one month after
training. Participants were more accurate in the second training phase, revealing an effect of previous experience on
a different task. Training with white noise led to better results than training with speech sounds. Moreover, the
training benefit generalized to untrained stimulus-position pairs. Throughout the post-tests externalization levels
increased. In the control condition the long-term localization improvement was not lower without additional contact
with the trained sounds, but externalization levels were lower.
Conclusion: Our findings suggest that humans adapt easily to altered auditory space cues and that such adaptation
spreads to untrained positions and sound types. We propose that such learning depends on all available cues, but
each cue type might be learned and retrieved differently. The process of localization learning is global, not limited to
stimulus-position pairs, and it differs from externalization processes.
Foundation for Science and Technology
FEDER