Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Speech and Hearing Science


Hearing Science

Research Advisor

Patti M. Johnstone, Ph.D.


Daniela M. Corbetta, Ashley W. Harkrider, Mark S. Hedrick


children, localization accuracy, motor response, normal hearing, root-mean-square error, verbal responses


Rationale. Sound localization is the ability to pinpoint the origin of a sound source within an auditory space. This ability is essential for safety, orientation, and communication. Poor sound localization abilities, especially in young children, can have a negative impact on academics and safety. This issue is exacerbated when there is a hearing loss. Young children do not localize as well as adults until age 6 or older. Data regarding sound localization accuracy in preschoolers and young children have been sparse. Recently, with the increasing numbers of cochlear implantation (especially in children) there have been more studies investigating sound localization in children. However, these studies mainly focused on children with hearing impairments. Most of them included children with normal hearing only as a reference or for comparison. Similarities and/or differences in sound source localization accuracy between children who are hearing impaired and those with normal hearing were investigated but the mode(s) of response were not regulated or examined. The literature presents localization accuracy ranges for young children with normal hearing but does not offer any knowledge regarding the effect of various response modes on sound localization accuracy. Younger children with normal hearing show greater localization error than older children with normal hearing. This suggests that the auditory system in younger children is still maturing. There is a need to investigate sound source localization accuracy in young children with normal hearing in order to identify factors that may facilitate this skill. This study explored the effect of a motor (movement) response on sound source localization accuracy compared to the traditional verbal response. The purpose was to identify any actors that could enhance sound source localization accuracy in children who have normal hearing in order to gain insight regarding possible auditory training strategies that could be effective in building sound source localization skills especially in children with hearing impairments and/or less mature auditory systems. It was proposed that embodiment, the incorporation of the body through motor movements within the auditory environment, could facilitate auditory spatial mapping and thus yield better sound localization accuracy." Methods. Sound localization accuracy was examined in young children, aged 3 and 5 years old, with normal hearing. Each participant in both age groups was randomly divided into two groups by response modes (verbal or motor) and asked to localize a sound source using that mode. The sound localization task was then repeated using only the verbal response mode. Testing occurred in a sound booth containing a semi-circular array of 15 loudspeakers placed at 10o intervals along the frontal horizontal plane from - 70o (left) to +70o (right) azimuth. There was a small child-friendly picture attached underneath each loudspeaker for sound source identification purposes. The stimulus was the speech spondee “baseball”. Participants either sat in a chair and verbally stated the location of the origin of the sound by naming the picture underneath the corresponding loudspeaker (verbal response) or by walking over and touching/pointing to the loudspeaker/picture from which the sound originated (motor response). There were seven (7) sound source (target) locations, with a total of five (5) trials randomly presented from" "each target loudspeaker for a total of 35 trials per task. There were two blocks of trials (tasks)." "Results. Sound localization accuracy was quantified using the root-mean-square error measure. Data was analyzed using the Generalized Estimating Equations – Robust Estimator statistical method. There was a statistically significant main effect for age, with the 5-year-olds showing better performance overall. There was not a significant main effect for mode of response or task order. There was however a significant interaction for age*mode*order. The 3-year-old Verbal 1st Group showed significantly better accuracy for the second sound localization task. The 5-year-old Motor 1st Group showed significantly worse accuracy for the second sound localization task in which they had to provide a verbal response." "Conclusions. Performance improved when the same response mode was used for both sound localization tasks but was degraded when the sound localization task was repeated using a different response mode. The initial motor responses did not facilitate auditory spatial mapping. This could be due to immature auditory pathway development and/or the increased cognitive strain of trying to break the memory pattern formed by the initial motor responses in order to transition to the verbal responses required during the second task. The results showed that children do not perform well when asked to change their mode of response when learning a new skill. Using the same mode of response twice emphasized the benefit of practice and repetition. Practice and repetition may be a more effective training technique than response mode for skill building especially for those who have difficulty with sound localization."

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.





2019-010-Martin-DOA.pdf (379 kB)
Declaration of Authorship