Semin Hear 2011; 32(1): 003-031
DOI: 10.1055/s-0031-1271945
© Thieme Medical Publishers

Bimodal Hearing or Bilateral Cochlear Implants: A Review of the Research Literature

Carol A. Sammeth1 , 2 , Sean M. Bundy1 , Douglas A. Miller3
  • 1Cochlear Americas, Centennial, Colorado
  • 2Division of Speech, Language, and Hearing Sciences, University of Colorado, Boulder, Colorado
  • 3Department of Electrical and Computer Engineering, University of Denver, Denver, Colorado
Further Information

Publication History

Publication Date:
16 February 2011 (online)

ABSTRACT

Over the past 10 years, there have been an increasing number of patients fitted with either bimodal hearing devices (unilateral cochlear implant [CI], and hearing aid on the other ear) or bilateral cochlear implants. Concurrently, there has been an increasing interest in and number of publications on these topics. This article reviews the now fairly voluminous research literature on bimodal hearing and bilateral cochlear implantation in both children and adults. The emphasis of this review is on more recent clinical studies that represent current technology and that evaluated speech recognition in quiet and noise, localization ability, and perceived benefit. A vast majority of bilaterally deaf subjects in these studies showed benefit in one or more areas from bilateral CIs compared with listening with only a unilateral CI. For patients who have sufficient residual low-frequency hearing sensitivity for the provision of amplification in the nonimplanted ear, bimodal hearing appears to provide a good nonsurgical alternative to bilateral CIs or to unilateral listening for many patients.

REFERENCES

  • 1 Balkany T, Hodges A, Menapace C et al. Nucleus Freedom North American clinical trial.  Otolaryngol Head Neck Surg. 2007;  136 (5) 757-762
  • 2 Krueger B, Joseph G, Rost U, Strauss-Schier A, Lenarz T, Buechner A. Performance groups in adult cochlear implant users: speech perception results from 1984 until today.  Otol Neurotol. 2008;  29 (4) 509-512
  • 3 Durlach N, Colburn H. Binaural phenomena. In:, Carterette E C, Friedman M P, eds. Handbook of Perception, Volume IV. New York, NY: Academic Press; 1978: 365-466
  • 4 Zurek P. Binaural advantages and direction effects in speech intelligibility. In:, Studebaker G A, Hochberg I, eds. Acoustical Factors Affecting Hearing Aid Performance, 2nd ed. Boston, MA: Allyn & Bacon; 1993: 255-276
  • 5 Yost W, Dye R. Fundamentals of directional hearing.  Semin Hear. 1997;  18 321-344
  • 6 Ross M. Binaural versus monaural hearing aid amplification for hearing impaired individuals. In: Libby E R, ed. Binaural Hearing and Amplification II. Chicago, IL: Zenetron; 1980: 1-21
  • 7 Byrne D. Clinical issues and options in binaural hearing aid fitting.  Ear Hear. 1981;  2 (5) 187-193
  • 8 Gelfand S A, Silman S. Apparent auditory deprivation in children: implications of monaural versus binaural amplification.  J Am Acad Audiol. 1993;  4 (5) 313-318
  • 9 Shaw E A. Transformation of sound pressure level from the free field to the eardrum in the horizontal plane.  J Acoust Soc Am. 1974;  56 (6) 1848-1861
  • 10 Gatehouse S. The time course and magnitude of perceptual acclimatization to frequency responses: evidence from monaural fitting of hearing aids.  J Acoust Soc Am. 1992;  92 (3) 1258-1268
  • 11 Green K M, Bhatt Y M, Mawman D J et al. Predictors of audiological outcome following cochlear implantation in adults.  Cochlear Implants Int. 2007;  8 (1) 1-11
  • 12 Sharma A, Dorman M F, Kral A. The influence of a sensitive period on central auditory development in children with unilateral and bilateral cochlear implants.  Hear Res. 2005;  203 (1–2) 134-143
  • 13 Portmann D, Felix F, Negrevergne M et al. Bilateral cochlear implantation in a patient with long-term deafness.  Rev Laryngol Otol Rhinol (Bord). 2007;  128 (1–2) 65-68
  • 14 Waltzman S B, Cohen N L, Shapiro W H. Sensory aids in conjunction with cochlear implants.  Am J Otol. 1992;  13 (4) 308-312
  • 15 Shallop J K, Arndt P L, Turnacliff K A. Expanded indications for cochlear implantation: perceptual results in seven adults with residual hearing.  J Spoken Language Pathology Audiology. 1992;  16 141-148
  • 16 Blamey P, Armstrong M, James J. Cochlear implants, hearing aids, or both together?. In:, Clark G M, ed. Cochlear Implants. Bologna, Italy: Monduzzi Editore; 1997: 273-277
  • 17 Dunn C C, Tyler R S, Witt S A. Benefit of wearing a hearing aid on the unimplanted ear in adult users of a cochlear implant.  J Speech Lang Hear Res. 2005;  48 (3) 668-680
  • 18 Mok M, Grayden D, Dowell R C, Lawrence D. Speech perception for adults who use hearing aids in conjunction with cochlear implants in opposite ears.  J Speech Lang Hear Res. 2006;  49 (2) 338-351
  • 19 Blamey P J, Dooley G J, Parisi E S, Clark G M. Pitch comparisons of acoustically and electrically evoked auditory sensations.  Hear Res. 1996;  99 (1–2) 139-150
  • 20 Blamey P J, Dooley G J, James C J, Parisi E S. Monaural and binaural loudness measures in cochlear implant users with contralateral residual hearing.  Ear Hear. 2000;  21 (1) 6-17
  • 21 Ching T Y, van Wanrooy E, Hill M, Incerti P. Performance in children with hearing aids or cochlear implants: bilateral stimulation and binaural hearing.  Int J Audiol. 2006;  45 (Suppl 1) S108-S112
  • 22 Cowan R, Chin-Lenn J. Pattern and prevalence of hearing aid use post-implantation in adult cochlear implant users.  Aust N Z J Audiol. 2004;  (Suppl) 48
  • 23 Ching T Y, Incerti P, Hill M, van Wanrooy E. An overview of binaural advantages for children and adults who use binaural/bimodal hearing devices.  Audiol Neurootol. 2006;  11 (Suppl 1) 6-11
  • 24 Gifford R H, Dorman M F, McKarns S A, Spahr A J. Combined electric and contralateral acoustic hearing: word and sentence recognition with bimodal hearing.  J Speech Lang Hear Res. 2007;  50 (4) 835-843
  • 25 Luntz M, Yehudai N, Shpak T. Hearing progress and fluctuations in bimodal-binaural hearing users (unilateral cochlear implants and contralateral hearing aid).  Acta Otolaryngol. 2007;  127 (10) 1045-1050
  • 26 Beijen J W, Mylanus E A, Leeuw A R, Snik A F. Should a hearing aid in the contralateral ear be recommended for children with a unilateral cochlear implant?.  Ann Otol Rhinol Laryngol. 2008;  117 (6) 397-403
  • 27 Lee S H, Lee K Y, Huh M J, Jang H S. Effect of bimodal hearing in Korean children with profound hearing loss.  Acta Otolaryngol. 2008;  128 (11) 1227-1232
  • 28 Berrettini S, Passetti S, Giannarelli M, Forli F. Benefit from bimodal hearing in a group of prelingually deafened adult cochlear implant users.  Am J Otolaryngol. 2010;  31 (5) 332-338 Epub ahead of print
  • 29 Potts L G, Skinner M W, Litovsky R A, Strube M J, Kuk F. Recognition and localization of speech by adult cochlear implant recipients wearing a digital hearing aid in the nonimplanted ear (bimodal hearing).  J Am Acad Audiol. 2009;  20 (6) 353-373
  • 30 Yuen K C, Cao K L, Wei C G, Luan L, Li H, Zhang Z Y. Lexical tone and word recognition in noise of Mandarin-speaking children who use cochlear implants and hearing aids in opposite ears.  Cochlear Implants Int. 2009;  10 (Suppl 1) 120-129
  • 31 Beijen J, Snik A F, Straatman L V, Mylanus E A, Mens L H. Sound localization and binaural hearing in children with a hearing aid and a cochlear implant.  Audiol Neurootol. 2010;  15 (1) 36-43
  • 32 Fitzpatrick E M, Séguin C, Schramm D, Chenier J, Armstrong S. Users' experience of a cochlear implant combined with a hearing aid.  Int J Audiol. 2009;  48 (4) 172-182
  • 33 Sucher C M, McDermott H J. Bimodal stimulation: benefits for music perception and sound quality.  Cochlear Implants Int. 2009;  10 (Suppl 1) 96-99
  • 34 Ching T YC, Hill M, Dillon H et al. Fitting and evaluating a hearing aid for recipients of a unilateral cochlear implant: the NAL approach Part 1.  Hear Rev. 2004;  11 (7) 14-22
  • 35 Ching T Y, van Wanrooy E, Dillon H. Binaural-bimodal fitting or bilateral implantation for managing severe to profound deafness: a review.  Trends Amplif. 2007;  11 (3) 161-192
  • 36 Olson A D, Shinn J B. A systematic review to determine the effectiveness of using amplification in conjunction with cochlear implantation.  J Am Acad Audiol. 2008;  19 (9) 657-671
  • 37 Huart S, Sammeth C. Hearing aids plus cochler implants: Optimizing the bimodal pediatric fitting.  Hear J. 2008;  61 (11) 54, 56-58
  • 38 Green Jr J D, Mills D M, Bell B A, Luxford W M, Tonokawa L L. Binaural cochlear implants.  Am J Otol. 1992;  13 (6) 502-506
  • 39 Balkany T, Boggess W, Dinner B. Binaural cochlear implantation: comparison of 3M/House and Nucleus 22 devices with evidence of sensory integration.  Laryngoscope. 1988;  98 (10) 1040-1043
  • 40 Müller J, Schön F, Helms J. Speech understanding in quiet and noise in bilateral users of the MED-EL COMBI 40/40 + cochlear implant system.  Ear Hear. 2002;  23 (3) 198-206
  • 41 Vermiere K, Brokz J P, Van de Heyning P et al. Bilateral cochlear implantation in children.  Int J Pediatr Otorhinolaryngol. 2002;  67 (1) 67-70
  • 42 Brown K D, Balkany T J. Benefits of bilateral cochlear implantation: a review.  Curr Opin Otolaryngol Head Neck Surg. 2007;  15 (5) 315-318
  • 43 Papsin B C, Gordon K A. Bilateral cochlear implants should be the standard for children with bilateral sensorineural deafness.  Curr Opin Otolaryngol Head Neck Surg. 2008;  16 (1) 69-74
  • 44 Litovsky R Y, Parkinson A, Arcaroli J, Sammeth C. Simultaneous bilateral cochlear implantation in adults: a multicenter clinical study.  Ear Hear. 2006;  27 (6) 714-731
  • 45 Ricketts T A, Grantham D W, Ashmead D H, Haynes D S, Labadie R F. Speech recognition for unilateral and bilateral cochlear implant modes in the presence of uncorrelated noise sources.  Ear Hear. 2006;  27 (6) 763-773
  • 46 Galvin K L, Mok M, Dowell R C. Perceptual benefit and functional outcomes for children using sequential bilateral cochlear implants.  Ear Hear. 2007;  28 (4) 470-482
  • 47 Manrique M, Huarte A, Valdivieso A, Pérez B. Bilateral sequential implantation in children.  Audiol Med. 2007;  5 224-231
  • 48 Peters B R, Litovsky R, Parkinson A, Lake J. Importance of age and postimplantation experience on speech perception measures in children with sequential bilateral cochlear implants.  Otol Neurotol. 2007;  28 (5) 649-657
  • 49 Scherf F, van Deun L, van Wieringen A et al. Hearing benefits of second-side cochlear implantation in two groups of children.  Int J Pediatr Otorhinolaryngol. 2007;  71 (12) 1855-1863
  • 50 Tyler R S, Dunn C C, Witt S A, Noble W G. Speech perception and localization with adults with bilateral sequential cochlear implants.  Ear Hear. 2007;  28 (2 Suppl) 86S-90S
  • 51 Wackym P A, Runge-Samuelson C L, Firszt J B, Alkaf F M, Burg L S. More challenging speech-perception tasks demonstrate binaural benefit in bilateral cochlear implant users.  Ear Hear. 2007;  28 (2 Suppl) 80S-85S
  • 52 Wolfe J, Baker S, Caraway T et al. 1-year postactivation results for sequentially implanted bilateral cochlear implant users.  Otol Neurotol. 2007;  28 (5) 589-596
  • 53 Buss E, Pillsbury H C, Buchman C A et al. Multicenter U.S. bilateral MED-EL cochlear implantation study: speech perception over the first year of use.  Ear Hear. 2008;  29 (1) 20-32
  • 54 Chan J C, Freed D J, Vermiglio A J, Soli S D. Evaluation of binaural functions in bilateral cochlear implant users.  Int J Audiol. 2008;  47 (6) 296-310
  • 55 Dunn C C, Tyler R S, Oakley S, Gantz B J, Noble W. Comparison of speech recognition and localization performance in bilateral and unilateral cochlear implant users matched on duration of deafness and age at implantation.  Ear Hear. 2008;  29 (3) 352-359
  • 56 Galvin K L, Mok M, Dowell R C, Briggs R J. Speech detection and localization results and clinical outcomes for children receiving sequential bilateral cochlear implants before four years of age.  Int J Audiol. 2008;  47 (10) 636-646
  • 57 Steffens T, Lesinski-Schiedat A, Strutz J et al. The benefits of sequential bilateral cochlear implantation for hearing-impaired children.  Acta Otolaryngol. 2008;  128 (2) 164-176
  • 58 Zeitler D M, Kessler M A, Terushkin V et al. Speech perception benefits of sequential bilateral cochlear implantation in children and adults: a retrospective analysis.  Otol Neurotol. 2008;  29 (3) 314-325
  • 59 Budenz C L, Roland Jr J T, Babb J, Baxter P, Waltzman S B. Effect of cochlear implant technology in sequentially bilaterally implanted adults.  Otol Neurotol. 2009;  30 (6) 731-735
  • 60 Eapen R J, Buss E, Adunka M C, Pillsbury III H C, Buchman C A. Hearing-in-noise benefits after bilateral simultaneous cochlear implantation continue to improve 4 years after implantation.  Otol Neurotol. 2009;  30 (2) 153-159
  • 61 Gordon K A, Papsin B C. Benefits of short interimplant delays in children receiving bilateral cochlear implants.  Otol Neurotol. 2009;  30 (3) 319-331
  • 62 Kim L S, Jang Y S, Choi A H et al. Bilateral cochlear implants in children.  Cochlear Implants Int. 2009;  10 (Suppl 1) 74-77
  • 63 Koch D B, Soli S D, Downing M, Osberger M J. Simultaneous bilateral cochlear implantation: prospective study in adults.  Cochlear Implants Int. 2009;  Epub ahead of print
  • 64 Laske R D, Veraguth D, Dillier N, Binkert A, Holzmann D, Huber A M. Subjective and objective results after bilateral cochlear implantation in adults.  Otol Neurotol. 2009;  30 (3) 313-318
  • 65 Litovsky R Y, Parkinson A, Arcaroli J. Spatial hearing and speech intelligibility in bilateral cochlear implant users.  Ear Hear. 2009;  30 (4) 419-431
  • 66 Loizou P C, Hu Y, Litovsky R et al. Speech recognition by bilateral cochlear implant users in a cocktail-party setting.  J Acoust Soc Am. 2009;  125 (1) 372-383
  • 67 Mosnier I, Sterkers O, Bebear J P et al. Speech performance and sound localization in a complex noisy environment in bilaterally implanted adult patients.  Audiol Neurootol. 2009;  14 (2) 106-114
  • 68 Ramsden J D, Papsin B C, Leung R, James A, Gordon K A. Bilateral simultaneous cochlear implantation in children: our first 50 cases.  Laryngoscope. 2009;  119 (12) 2444-2448
  • 69 Scherf F, Van Deun L, van Wieringen A et al. Three-year postimplantation auditory outcomes in children with sequential bilateral cochlear implantation.  Ann Otol Rhinol Laryngol. 2009;  118 (5) 336-344
  • 70 Van Deun L, van Wieringen A, Francart T et al. Bilateral cochlear implants in children: binaural unmasking.  Audiol Neurootol. 2009;  14 (4) 240-247
  • 71 Chang S-A, Tyler R S, Dunn C C et al. Performance over time on adults with simultaneous bilateral cochlear implants.  J Am Acad Audiol. 2010;  21 (1) 35-43
  • 72 Galvin K L, Hughes K C, Mok M. Can adolescents and young adults with prelingual hearing loss benefit from a second, sequential cochlear implant?.  Int J Audiol. 2010;  49 (5) 368-377
  • 73 Lovett R E, Kitterick P T, Hewitt C E, Summerfield A Q. Bilateral or unilateral cochlear implantation for deaf children: an observational study.  Arch Dis Child. 2010;  95 (2) 107-112
  • 74 van Hoesel R JM, Tong Y C, Hollow R D, Clark G M. Psychophysical and speech perception studies: a case report on a binaural cochlear implant subject.  J Acoust Soc Am. 1993;  94 (6) 3178-3189
  • 75 van Hoesel R JM, Clark G M. Fusion and lateralization study with two binaural cochlear implant patients.  Ann Otol Rhinol Laryngol Suppl. 1995;  166 (Suppl 166) 233-235
  • 76 Verschuur C A, Lutman M E, Ramsden R, Greenham P, O'Driscoll M. Auditory localization abilities in bilateral cochlear implant recipients.  Otol Neurotol. 2005;  26 (5) 965-971
  • 77 Beijen J W, Snik A F, Mylanus E A. Sound localization ability of young children with bilateral cochlear implants.  Otol Neurotol. 2007;  28 (4) 479-485
  • 78 Grantham D W, Ashmead D H, Ricketts T A, Labadie R F, Haynes D S. Horizontal-plane localization of noise and speech signals by postlingually deafened adults fitted with bilateral cochlear implants.  Ear Hear. 2007;  28 (4) 524-541
  • 79 Neuman A C, Haravon A, Sislian N, Waltzman S B. Sound-direction identification with bilateral cochlear implants.  Ear Hear. 2007;  28 (1) 73-82
  • 80 Seeber B U, Fastl H. Localization cues with bilateral cochlear implants.  J Acoust Soc Am. 2008;  123 (2) 1030-1042
  • 81 Grieco-Calub T M, Litovsky R Y, Werner L A. Using the observer-based psychophysical procedure to assess localization acuity in toddlers who use bilateral cochlear implants.  Otol Neurotol. 2008;  29 (2) 235-239
  • 82 Nava E, Bottari D, Portioli G et al. Hearing again with two ears: recovery of spatial hearing after bilateral cochlear implantation.  Neuropsychologia. 2009;  47 (3) 928-932
  • 83 Van Deun L, van Wieringen A, Scherf F et al. Earlier intervention leads to better sound localization in children with bilateral cochlear implants.  Audiol Neurootol. 2010;  15 (1) 7-17
  • 84 Salloum C A, Valero J, Wong D D, Papsin B C, van Hoesel R, Gordon K A. Lateralization of interimplant timing and level differences in children who use bilateral cochlear implants.  Ear Hear. 2010;  31 (4) 441-456
  • 85 Grantham D W, Ashmead D H, Ricketts T A, Haynes D S, Labadie R F. Interaural time and level difference thresholds for acoustically presented signals in post-lingually deafened adults fitted with bilateral cochlear implants using CIS + processing.  Ear Hear. 2008;  29 (1) 33-44
  • 86 Summerfield A Q, Barton G R, Toner J et al. Self-reported benefits from successive bilateral cochlear implantation in post-lingually deafened adults: randomised controlled trial.  Int J Audiol. 2006;  45 (Suppl 1) S99-S107
  • 87 Bichey B G, Miyamoto R T. Outcomes in bilateral cochlear implantation.  Otolaryngol Head Neck Surg. 2008;  138 (5) 655-661
  • 88 Veekmans K, Ressel L, Mueller J, Vischer M, Brockmeier S J. Comparison of music perception in bilateral and unilateral cochlear implant users and normal-hearing subjects.  Audiol Neurootol. 2009;  14 (5) 315-326
  • 89 Dorman M F, Dahlstrom L. Speech understanding by cochlear-implant patients with different left- and right-ear electrode arrays.  Ear Hear. 2004;  25 (2) 191-194
  • 90 Litovsky R Y, Johnstone P M, Godar S et al. Bilateral cochlear implants in children: localization acuity measured with minimum audible angle.  Ear Hear. 2006;  27 (1) 43-59
  • 91 Litovsky R Y, Johnstone P M, Godar S P. Benefits of bilateral cochlear implants and/or hearing aids in children.  Int J Audiol. 2006;  45 (Suppl 1) S78-S91
  • 92 Schafer E C, Thibodeau L M. Speech recognition in noise in children with cochlear implants while listening in bilateral, bimodal, and FM-system arrangements.  Am J Audiol. 2006;  15 (2) 114-126
  • 93 Mok M, Galvin K L, Dowell R C, McKay C M. Spatial unmasking and binaural advantage for children with normal hearing, a cochlear implant and a hearing aid, and bilateral implants.  Audiol Neurootol. 2007;  12 (5) 295-306
  • 94 Mok M, Galvin K L, Dowell R C, McKay C M. Speech perception benefit for children with a cochlear implant and a hearing aid in opposite ears and children with bilateral cochlear implants.  Audiol Neurootol. 2010;  15 (1) 44-56
  • 95 Noble W, Tyler R, Dunn C, Bhullar N. Hearing handicap ratings among different profiles of adult cochlear implant users.  Ear Hear. 2008;  29 (1) 112-120
  • 96 Noble W, Tyler R, Dunn C, Bhullar N. Unilateral and bilateral cochlear implants and the implant-plus-hearing-aid profile: comparing self-assessed and measured abilities.  Int J Audiol. 2008;  47 (8) 505-514
  • 97 Noble W, Tyler R S, Dunn C C, Bhullar N. Younger- and older-age adults with unilateral and bilateral cochlear implants: speech and spatial hearing self-ratings and performance.  Otol Neurotol. 2009;  30 (7) 921-929
  • 98 Firszt J B, Reeder R M, Skinner M W. Restoring hearing symmetry with two cochlear implants or one cochlear implant and a contralateral hearing aid.  J Rehabil Res Dev. 2008;  45 (5) 749-767
  • 99 Schafer E C, Amlani A M, Seibold A, Shattuck P L. A meta-analytic comparison of binaural benefits between bilateral cochlear implants and bimodal stimulation.  J Am Acad Audiol. 2007;  18 (9) 760-776
  • 100 Ching T Y, Massie R, Van Wanrooy E, Rushbrooke E, Psarros C. Bimodal fitting or bilateral implantation?.  Cochlear Implants Int. 2009;  10 (Suppl 1) 23-27
  • 101 Offeciers E, Morera C, Müller J, Huarte A, Shallop J, Cavallé L. International consensus on bilateral cochlear implants and bimodal stimulation.  Acta Otolaryngol. 2005;  125 (9) 918-919
  • 102 Balkany T, Hodges A, Telischi F William House Cochlear Implant Study Group et al. William House Cochlear Implant Study Group: position statement on bilateral cochlear implantation.  Otol Neurotol. 2008;  29 (2) 107-108
  • 103 Craddock L, Brinton J, Saeed S R, Balkany T J. Editorial. Bilateral cochlear implantation: the British Cochlear Implant Group position.  Cochlear Implants Int. 2008;  9 (2) 65-69
  • 104 Tyler R S, Dunn C C, Witt S A, Preece J P. Update on bilateral cochlear implantation.  Curr Opin Otolaryngol Head Neck Surg. 2003;  11 (5) 388-393
  • 105 Murphy J, O'Donoghue G. Bilateral cochlear implantation: an evidence-based medicine evaluation.  Laryngoscope. 2007;  117 (8) 1412-1418

1 However, Christopher Long, Ph.D., of Cochlear Americas, notes that such binaural effects are not necessarily indicative of particular mechanisms (personal communication, 2009). For example, dichotic speech cue summation (i.e., processors using interleaved frequency bands on the two sides) would not be expected to give binaural decorrelation benefit, but could still give benefits beyond head shadow and binaural redundancy effects. Also, a listener with patchy nerve survival may hear different cues in each ear across SNRs, but this would not be detected by a simple binaural redundancy test. Thus, it is still debatable whether “true” binaural processing effects are being measured with today's CIs, especially because ITD (interaural timing difference) sensitivity is likely the source of binaural “unmasking” yet these cues are often blurred by the sound processing. Although this is an important academic discussion, for purposes of this article, the focus will not be on the source of bilateral benefits, but simply whether or not they are reported using traditional measurements.

2 Although occasionally authors have referred to the bimodal hearing configuration as “electric-acoustic hearing,” that term will not be used herein because it can also mean stimulation with investigational hybrid devices currently in development but not yet approved for marketing. In hybrid devices, like in bimodal hearing, both electric (CI) and acoustic (HA) hearing are provided; however, in the case of hybrid devices, both are provided to the same ear, rather than opposite ears as in bimodal hearing.

3 Note that studies that directly compared performance of a group of subjects with bimodal hearing with a group subjects with bilateral CIs are reviewed later in this article.

4 Internal Cochlear estimates are that, of the more than 140,000 recipients of Nucleus CIs worldwide, less than 10% are currently implanted bilaterally.

5 Although from a future research perspective, it will be important to determine what cues provide benefits and which are lost, to assist in improving future outcomes with new sound processing approaches.

6 Nevertheless, these researchers recommended an intersurgery interval in postlingual adults of no more than 12 years and noted that in children a longer interval may result in the need for additional rehabilitation to avoid refusal of the second implant. The value of 12 years may be arguable based on research showing benefit with even longer periods of auditory deprivation.

Carol A SammethPh.D. 

Senior Regulatory/Clinical Specialist, Cochlear Americas

13059 East Peakview Avenue, Centennial, CO 80111

Email: csammeth@cochlear.com

    >