Hearing-in-noise benefits after bilateral simultaneous cochlear implantation continue to improve 4 years after implantation

Rose J. Eapen, Emily Buss, Marcia Clark Adunka, Harold C. Pillsbury, Craig A. Buchman

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


OBJECTIVE: The purpose of this 4-year longitudinal study was to assess the stability of the binaural benefits of head shadow, summation, and squelch for bilateral cochlear implant recipients and to quantify these benefits for the understanding of speech in noise. DESIGN: This is a prospective study of 9 patients who received simultaneous bilateral insertion of MED-EL COMBI +40 cochlear implants in a single-stage operation at the University of North Carolina, Chapel Hill, NC. Each patient had postlingual deafness of short duration before insertion of the device. Each year, the patients were tested for word recognition using consonant-nucleus-consonant words in quiet and speech perception in noise using City University of New York sentences. These tests were administered using direct audio input to the implants. Head-related transfer functions were used to simulate speech in noise testing in a spatial environment. Speech was always presented at midline (0°), and the noise masker was presented at either side or midline (-90, 0, +90 degrees). RESULTS: The binaural benefits of head shadow and summation effects developed early in the postoperative period and remained stable throughout the follow-up period. Squelch developed more slowly and was first demonstrated at 12 months after implantation but continued to increase beyond the first year of follow-up. CONCLUSION: Benefits of head shadow and summation emerge early and remain stable. However, squelch has the most protracted period of development, with increasing benefit after a year or more of implant experience. These data support the idea that binaural integration continues several years after insertion of bilateral cochlear implant devices.

Original languageEnglish
Pages (from-to)153-159
Number of pages7
JournalOtology and Neurotology
Issue number2
StatePublished - Feb 2009


  • Bilateral cochlear implant
  • Binaural hearing
  • Speech discrimination


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