Pre-Stimulus Head Position and Its Effect on Sound Localization Metrics in Children

Background: This study investigates the impact of initial head position prior to stimulus presentation on sound localization accuracy in children. The quadratic angular root mean square error (RMSE) and the linear mean-absolute-error (MAE) have been considered for this study. Material and Methods: A total of 28 normal-hearing children (ages 6–10) participated in sound localization. The participants localized sounds presented from five speakers at the frontal semicircle. Head positions at stimulus onset were tracked using glasses with a built-in webcam. The localization results were analyzed with and without correcting for the offset from the frontal direction of the initial head position prior to stimulus presentation. Results: The initial head position prior to stimulus presentation significantly affected the RMSE but had no influence on the MAE. This effect was stronger in younger children. The MAE showed fewer changes in head position due to its linear nature, which reduces the effect of large errors. An analysis of the children’s initial head positions revealed a tendency to deviate from the frontal direction. Therefore, the initial head position prior to stimulus presentation should be considered when calculating localization measures. Conclusions: The initial head position prior to a stimulus can distort the RMSE in directional hearing tests for children, while the MAE remains robust against such deviations.