The choice of stimulation strategy affects the ability to detect pure tone inter-aural time differences in children with early bilateral cochlear implantation.
OBJECTIVES
To investigate if the interaural time difference (ITD) ability is dependent of stimulation strategy. To examine the correlation between ITD, interaural level differences (ILD) and the ability to localize different sounds.


METHODS
Thirty subjects aged 8-13 who were implanted bilaterally before 3 years of age were tested. Twenty of the subjects used processors programmed with fine structure (FS) strategy on both sides. ITD and ILD just noticeable difference (JND) of a 250 Hz pure tone was measured using their clinical processors. Furthermore, their ability to localize sound in the horizontal plane was measured using eye tracking.


RESULTS
Ten of the 20 subjects with FS obtained an ITD threshold compared to none in the group without FS (0/10). ILD JND was correlated to localization ability of the broadband (BB) sound. Mean absolute error of the localization of a low-frequency (LF) sound was larger than that of a BB sound.


CONCLUSIONS
The ability to detect ITD was present only when the cochlear implant stimulation had FS. The LF sound was more difficult to localize than the BB sound and ITD ability of FS strategies did not affect the localization ability of either sound. A low ILD seems necessary to improve the localization ability.
['Eklöf|Martin|M|http://orcid.org/0000-0002-2196-9780', 'Tideholm|Bo|B|http://orcid.org/0000-0002-5530-7662']
D000293:Adolescent D001301:Audiometry, Pure-Tone D002648:Child D019929:Cochlear Implantation D005500:Follow-Up Studies D006801:Humans D007223:Infant D013017:Sound Localization
children Bilateral cochlear implant interaural time difference ITD localization fine structure CI