title: Sound Localization and Speech Perception in Noise of Pediatric Cochlear Implant Recipients: Bimodal Fitting Versus Bilateral Cochlear Implants.
abstract: The aim of this study was to compare binaural performance of auditory localization task and speech perception in babble measure between children who use a cochlear implant (CI) in one ear and a hearing aid (HA) in the other (bimodal fitting) and those who use bilateral CIs.
  
  
  
  Thirteen children (mean age ± SD = 10 ± 2.9 years) with bilateral CIs and 19 children with bimodal fitting were recruited to participate. Sound localization was assessed using a 13-loudspeaker array in a quiet sound-treated booth. Speakers were placed in an arc from -90° azimuth to +90° azimuth (15° interval) in horizontal plane. To assess the accuracy of sound location identification, we calculated the absolute error in degrees between the target speaker and the response speaker during each trial. The mean absolute error was computed by dividing the sum of absolute errors by the total number of trials. We also calculated the hemifield identification score to reflect the accuracy of right/left discrimination. Speech-in-babble perception was also measured in the sound field using target speech presented from the front speaker. Eight-talker babble was presented in the following four different listening conditions: from the front speaker (0°), from one of the two side speakers (+90° or -90°), from both side speakers (±90°). Speech, spatial, and quality questionnaire was administered.
  
  
  
  When the two groups of children were directly compared with each other, there was no significant difference in localization accuracy ability or hemifield identification score under binaural condition. Performance in speech perception test was also similar to each other under most babble conditions. However, when the babble was from the first device side (CI side for children with bimodal stimulation or first CI side for children with bilateral CIs), speech understanding in babble by bilateral CI users was significantly better than that by bimodal listeners. Speech, spatial, and quality scores were comparable with each other between the two groups.
  
  
  
  Overall, the binaural performance was similar to each other between children who are fit with two CIs (CI + CI) and those who use bimodal stimulation (HA + CI) in most conditions. However, the bilateral CI group showed better speech perception than the bimodal CI group when babble was from the first device side (first CI side for bilateral CI users or CI side for bimodal listeners). Therefore, if bimodal performance is significantly below the mean bilateral CI performance on speech perception in babble, these results suggest that a child should be considered to transit from bimodal stimulation to bilateral CIs.
authors.affiliation: 1Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; 2Department of Speech and Language Pathology, Myongji University Graduate School, Seoul, Korea; 3Department of Speech Pathology and Audiology, University of Iowa, Iowa City, Iowa, USA; and 4Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Choi
authors.forename: Il Joon
authors.initials: IJ
authors.lastname: Moon
authors.forename: Eun Yeon
authors.initials: EY
authors.lastname: Kim
authors.forename: Hee-Sung
authors.initials: HS
authors.lastname: Park
authors.forename: Byung Kil
authors.initials: BK
authors.lastname: Kim
authors.forename: Won-Ho
authors.initials: WH
authors.lastname: Chung
authors.forename: Yang-Sun
authors.initials: YS
authors.lastname: Cho
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Brown
authors.forename: Sung Hwa
authors.initials: SH
authors.lastname: Hong
mesh_terms: D000293:Adolescent; D002648:Child; D019929:Cochlear Implantation; D003054:Cochlear Implants; D003638:Deafness / Q000534:rehabilitation*; D005260:Female; D006310:Hearing Aids; D006312:Hearing Loss, Bilateral / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D009622:Noise; D013017:Sound Localization; D013067:Speech Perception