Earlier Intervention Leads to Better Sound Localization in Children with Bilateral Cochlear Implants.

We present sound localization results from 30 children with bilateral cochlear implants. All children received their implants sequentially, at ages from 6 months to 9 years for the first implant and 1.5-12 years for the second implant, with delays of 10 months to 9 years. Localization was measured in the sound field, with a broadband bell-ring presented from 1 of 9 loudspeakers positioned in the frontal horizontal plane. The majority of the children (63%) were able to localize this signal significantly better than chance level. Mean absolute error scores varied from 9 to 51 degrees (root mean square error scores from 13 to 63 degrees ). The best scores were obtained by children who received their first implant before the age of 2 years and by children who used hearing aids prior to implantation for a period of 18 months or longer. Age at second implantation was important in the group of children who did not use a contralateral hearing aid during the unilateral implant period. Additionally, children who attended a mainstream school had significantly better localization scores than children who attended a school for the deaf. No other child or implantation variables were related to localization performance. Data of parent questionnaires derived from the Speech, Spatial and Qualities of Hearing Scale were significantly correlated with localization performance. This study shows that the sound localization ability of children with bilateral cochlear implants varies across subjects, from near-normal to chance performance, and that stimulation early in life, acoustically or electrically, is important for the development of this capacity

Earlier intervention leads to better sound localization in children with bilateral cochlear implants

We present sound localization results from 30 children with bilateral cochlear implants. All children received their implants sequentially, at ages from 6 months to 9 years for the first implant and 1.5–12 years for the second implant, with delays of 10 months to 9 years. Localization was measured in the sound field, with a broadband bell-ring presented from 1 of 9 loudspeakers positioned in the frontal horizontal plane. The majority of the children (63%) were able to localize this signal significantly better than chance level. Mean absolute error scores varied from 9 to 51° (root mean square error scores from 13 to 63°). The best scores were obtained by children who received their first implant before the age of 2 years and by children who used hearing aids prior to implantation for a period of 18 months or longer. Age at second implantation was important in the group of children who did not use a contralateral hearing aid during the unilateral implant period. Additionally, children who attended a mainstream school had significantly better localization scores than children who attended a school for the deaf. No other child or implantation variables were related to localization performance. Data of parent questionnaires derived from the Speech, Spatial and Qualities of Hearing Scale were significantly correlated with localization performance. This study shows that the sound localization ability of children with bilateral cochlear implants varies across subjects, from near-normal to chance performance, and that stimulation early in life, acoustically or electrically, is important for the development of this capacity.status: publishe

Bilateral cochlear implants in children: binaural unmasking

Bilateral cochlear implants (CIs) may offer deaf children a range of advantages compared to unilateral CIs. However, speech perception in noise is mainly facilitated by better-ear effects and much less by interaural comparisons or true 'binaural' hearing. Little is known about the development of the binaural auditory system with CIs provided at a young age. It is possible that, as with adults, binaural sensitivity exists but is not accessed due to technical limitations in electrical stimulation methods. In this paper, we present results on binaural hearing in children with bilateral CIs. Binaural masking level differences (BMLDs) were measured for a 180-degree phase shift in a 125-Hz sinusoid, presented in a 50-Hz-wide noise band and modulating a 1000-pps carrier pulse train. Stimuli were presented to a single electrode in the middle of the electrode array at both ears. Eight children between 6 and 15 years of age participated in this study. Six children had a significantly better detection threshold when the signal was out of phase (dichotic) between two ears than when it was in phase (diotic), with a mean difference (BMLD) of 6.4 dB. The present results show that children with bilateral CIs are sensitive to binaural cues in electrical stimuli, similar to adults, even when implants are provided at a later age and with a longer delay between implantations.status: publishe