Contributing Factors to Improved Speech Perception in Children Using the Nucleus 22-Channel Cochlear Prosthesis

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1 Honjo I, Takahashi H (eds): Cochlear Implant and Related Sciences Update. Adv Otorhinolaryngol. Basel, Karger, 1997, vol 52, pp Contributing Factors to Improved Speech Perception in Children Using the Nucleus 22-Channel Cochlear Prosthesis Robert S.C Cowan a,c, e, Karyn L. Calvina, d, Sharon Klieve a, Elizabeth 1. Barker a. e, Julia Z. Sarant a,d, Shani Dettman a, e, Rod Hollow a, e" Cary Rance a, d, Richard C. Dowel/a, c, e, Brian Pymana,C,e, Craeme M. Clarka- d "Cooperative Research Centre for Cochlear Implant, Speech and Hearing Research; bhuman Communication Research Centre; cthe Department of Otolaryngology, University of Melbourne; d The Bionic Ear Institute, and e The Royal Victorian Eye and Ear Hospital, Cochlear Implant Clinic, Melbourne, Vic., Australia Introduction It has been established that use of multiple-channel intracochlear implants can significantly improve speech perception for postlinguistically deafened adults [1]. In the development of the Nucleus 22-channel cochlear implant, there have been significant developments in speech processing strategies, providing additional benefits to speech perception for users [2]. This has recently culminated in the release of the Speak speech processing strategy, developed from research at the University of Melbourne [3]. The Speak strategy employs 20 programmable bandpass filters which are scanned at an adaptive rate, with the largest outputs of these filters presented to up to ten stimulation channels along the electrode array. Comparative studies of the Speak processing strategy (in the Nucleus Spectra-22 speech processor), with the previously-used Multipeak (Multipeak) speech processing strategy (in the Minisystem-22 speech processor), with profoundly deaf adult cochlear implant users have shown that the Speak processing strategy provides a significant benefit to adult users both in quiet situations and particularly in the presence of background noise (4]. Since the first implantation of the Nucleus device in a profoundly hearingimpaired child in Melbourne in 1985, there has been a rapid growth in the Advances in Oto-Rhino-laryngology Editor: w. Arnold, Miinchen Reprint Publishers: S.Karger, Basel Printed in Switzerland

2 number of children using this device. Studies of cochlear implant benefits for children using the Nucleus 22-channel cochlear implant have also shown that children can obtain significant benefits to speech perception, speech production and language, including open-set understanding of words and sentences using the cochlear implant alone [5-9]. In evaluating contributing factors to speech perception benefits available for children, four specific factors are important to investigate: (1) earlier implantation - resulting from earlier detection of deafness; (2) improved hardware and surgical techniques - allowing implantation in infants; (3) improved speech processing, and (4) improved habilitation techniques. Results reported previously have been recorded primarily for children using the Multipeak strategy implemented in the MSP speech processor. While it is important to evaluate the factors which might contribute to improvements in speech perception benefits, an important question is the effect of improved speech processing strategy, since this will determine what is perceived through the device. Given that adult patients changing to the Spectra speech processor had also shown improved perception in noisy situations, and the fact that children are in general in noisy environments in the classroom setting for a large proportion of their day, it was of obvious interest to evaluate the potential for benefit in poor signal-to-noise ratios from use of the Speak processing strategy and from specific training in the ability to perceive in background noise. The study was aimed at evaluating whether children who were experienced in use of the Multipeak speech processing strategy would be able to changeover to the new Speak processing strategy, which provides a subjectively different output. Secondly, the study aimed to evaluate the benefits which might accrue to children from use of controlled habilitation in background noise. Methods Seven children participated in the study. These children were all patients of the University of Melbourne/Royal Victorian Eye and Ear Hospital Cochlear Implant Clinic. All of the children had more than 1 year of experience with the Multipeak processor, and had achieved implant-alone scores on open-set word and sentence materials. In addition, all of the children were in the age range of 6-14 years. No other specific selection criteria were applied, and the children varied in etiology, length of profound deafness preimplant, residual hearing thresholds, age at onset, and experience with the device. These children represented a reasonable crosssection of the pediatric population. The children were evaluated with open-set Speech Intelligibility Test (SIT) sentences. scored by key words (50 per list). In all cases, testing was live-voice, using a consistent speaker throughout the test procedures for each child. Children wrote their response to each test item. or if this was not possible, the responses were videotaped and indepen Cowan/Gal vin/klievelbarkerisarantidettman/hollow/rance/doweilipymaniclark 194

3 % 100 Speak 18 m o Speak 12 m 90 ~ Speak 6 m 80 rul Mpeak * 40 * -* 30 ~ ~l I 20 m. 10 o * * L * 1 ~ ~ jut] lli ~ ~ ~ MA EB CG DH SE RW SN Mean Child * Fig. 1. Implant-alone scores on SIT sentences for 7 children using the Multipeak and Speak processing strategies in background noise (+15 db SIN ratio). *p = dently scored by two experienced clinicians. Each list was only used once for each child, and the use of lists and order of presentation was balanced between processors and across sessions. Each child had four assessments with Multipeak at 2 weekly intervals. The children were switched to Speak, and were subsequently evaluated after 6,12 and 18 months' experience with Speak. In the second study, 4 children participated in a pilot study, during which they received habilitation in background noise for 15 minsession, 2 sessions/week. The signal-tonoise varied for each child, across the range of +5 to +15 db SPL. The children were assessed on perception of CNC words in background noise before and after 6 months of habilitation. Results Figure 1 shows speech perception scores on the SIT sentences in background noise for the 7 children. As shown, 6 of the 7 children showed significant improvements in speech perception scores when using the Speak speech processing strategy as compared with Multipeak. Only 1 child did not show an improved speech perception ability with Speak. It was also evident that improvements for a number of the children continued to increase with additional Improved Speech Perception for Children Using Cochlear Implants 195

4 % 1001J ~ Pretraining Posttraining JA RW SE SN Child Fig. 2. Implant-alone scores on CNC words in background noise for 4 children following controlled habiliation in background noise (+15 db SIN ratio). experience. Mean scores for the group were also significantly higher with Speak as compared to Multipeak. Figure 2 shows results on CNC words in background noise for the 4 children who participated in the controlled habilitation in background noise study. As shown, all 4 children showed improved perception scores following habilitation in background noise. Discussion The results suggest that children who have previously used the Multipeak speech processing strategy in the Nucleus Mini-22 multichannel cochlear implant are able to change to the new Speak processing strategy implemented in the Spectra-22 speech proeessor, and that speech perception benefits may be improved through use of the advanced strategy. As indicated in the data presented in figure 1, and as presented in more detail elsewhere [10], the Speak processing strategy would be of benefit to a large proportion of the children currently using the Multipeak strategy, as benefits were available in both quiet and in the presence of baekground noise, which is more representative of the communication environment experienced by children at school It is also of note that following completion of the study all of the 12 children chose to re- Cowan/Galvin/Klieve/BarkerlSarant/Dettman/Hollow/RancelDoweII/Pyman/Clark 196

5 tain the Speak processor. This included the child who did not score at a higher level with Speak, who was adamant in preferring the Speak processing strategy. Follow-up testing showed that 5 of the children continued to show improvements in speech perception benefits following additional experience with the Speak processing strategy. The results for the habilitation in background noise study suggest that children might benefit from a specific program of habilitation which is focused on improving the children's listening skills in noisy environments. The results also suggest that children, using the Speak processing strategy, will be able to show improved perception in background noise. References Dowell RC, Mecklenburg Dl, Clark GM: Speech recognition for 40 patients receiving multichannel cochlear implants. Arch OtoI1986;112: Clark GM: The development of speech processing strategies for the University of Melbourne/Cochlear multiple channel implantable hearing prosthesis. 1 S L P A 1992;16: McDermott H: An advanced multiple channel cochlear implant. IEEE Trans Biomed Eng 1989:36: Skinner MW, Clark GM, Whitford LA, Seligman PM, Staller SI, Shipp DB, Shallop lk, Everingham C, Menapace CM, Arndt PL, Antognelli T, Brimacombe la, Pijl S, Daniels P, George CR, McDermott HI, Beiter AL: Evaluation of a new spectral peak coding strategy for the Nucleus 22 channel cochlear implant system. Am 1 Otol 1994;15: Cowan RSC, Dowell RC, Pyman BC, Dcttman SJ, Dawson PW, Rance G. Barker EJ, Sarant lz, Clark GM: Preliminary speech perception results for children with the 22-electrode Melbourne/Cochlear hearing prosthesis. Adv OtorhinolaryngoI1993;48: Dawson PW, Blarney PI, Rowland LC, Dettman SI, Clark GM, Busby PA, Brown AM, Dowell RC. Rickards FW: Cochlear implants in children, adolescents, and prelinguistically deafened adults: Speech perception. J Speech Hear Res 1992;35: Osberger MJ, Maso M, Sam LK: Speech intelligibility of children with cochlear implants, tactile aids or hearing aids. J Speech Hear Res 1993;36: Tye-Murray N, Spencer L, Gilbert-Bedia E: Relationships between speech production and speech perception skills in young cochlear implant users. J Acoust Soc Am 1995;98: Cochlear Implants in Adults and Children: NIH Consensus Statement, May , No 13, pp Cowan RSC, Brown C, Whitford LA, Galvin KL, Sarant lz, Barker EJ, Shaw S, King A, Skok M, Seligman PM, Dowell RC. Gibson WPR, Clark GM: Comparative evaluation of Multipeak and Speak speech processing strategies in children using the Nucleus multichannel cochlear implant. Ear Hear, in review. Robert Cowan, Department of Otolaryngology, University of Melbourne, Albert Street, East Melbourne, Vic 3002 (Australia) Improved Speech Perception for Children Using Cochlear Implants 197

6 Minerva Access is the Institutional Repository of The University of Melbourne Author/s: Cowan, Robert S. C.; Galvin, Karyn L.; KLIEVE, SHARON; Barker, Elizabeth J.; Sarant, Julia Z.; DETTMAN, SHANI; Hollow, Rod; RANCE, GARY; Dowell, Richard C.; PYMAN, BRIAN; Clark, Graeme M. Title: Contributing factors to improved speech perception in children using the nucleus 22-channel cochlear prosthesis Date: 1997 Citation: Cowan, R. S. C., Galvin, K. L., Klieve, S., Barker, E. J., Sarant, J. Z., Dettman, S., et al. (1997). Contributing factors to improved speech perception in children using the nucleus 22- channel cochlear prosthesis. In I. Honjo, & H. Takahashi (Eds.), Cochlear implant and related sciences update (Advances in Oto-Rhino-Laryngology), 52, Persistent Link: File Description: Contributing factors to improved speech perception in children using the nucleus 22-channel cochlear prosthesis Terms and Conditions: Terms and Conditions: Copyright in works deposited in Minerva Access is retained by the copyright owner. The work may not be altered without permission from the copyright owner. Readers may only download, print and save electronic copies of whole works for their own personal non-commercial use. Any use that exceeds these limits requires permission from the copyright owner. Attribution is essential when quoting or paraphrasing from these works.