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Infants' localization of sounds in the horizontal plane: effects of auditory and visual cues
Insights
Infants improve sound localization with age, especially when only hearing sounds. By 18 months, infants accurately locate sounds with or without visual cues, demonstrating developmental progress in auditory perception.
Area of Science:
- Developmental Psychology
- Auditory Neuroscience
- Human Infant Studies
Background:
- Auditory spatial perception is crucial for infant development.
- Understanding how infants localize sound sources informs developmental milestones.
Purpose of the Study:
- To investigate age-related changes in auditory spatial localization in infants.
- To compare infant sound localization accuracy with and without visual cues.
Main Methods:
- Infants aged 6-18 months participated in auditory-alone and auditory-visual trials.
- Head turn azimuth error was measured relative to loudspeaker locations.
- Sound localization accuracy was assessed across different ages and loudspeaker positions.
Main Results:
- Infants accurately localized sounds with visual cues, irrespective of age.
- Auditory-alone localization showed significant improvement with increasing age.
- By 18 months, infants demonstrated mature sound localization abilities, unaffected by the presence or absence of visual cues.
Conclusions:
- Infant auditory spatial perception undergoes significant development between 6 and 18 months.
- Visual cues facilitate sound localization in younger infants.
- Mature auditory spatial skills are established by 18 months of age.
Abstract:
Infants 6, 9, 12, 15, and 18 months were seated in a dark room facing a semicircular array comprising 10 loudspeakers, 5 to their right and left at 18 degrees, 36 degrees, 54 degrees, 72 degrees, and 90 degrees from midline. Each infant received 2 types of trials: auditory-alone trials (only a sequence of 8 clicks played), and auditory-visual trials (following the first 4 clicks, a light display at the location of the loudspeaker was activated and remained on for the remaining 4 clicks). Calibration markers on the infant's head were used to measure azimuth error (i.e., the discrepancy between the angle of head turn and loudspeaker location). For auditory-visual trials, all infants turned their head within 4 degrees-6 degrees of the sound source; there was no effect of age or loudspeaker location. For auditory-alone trials, there were significant age differences in performance, with a systematic decrease in discrepancy angle with increasing age. By 18 months there was no difference in performance as a function of localization cue.