Discussion and Conclusions

1. Speech discrimination with FM Radio Aid Systems and Cochlear Implant users: Results over distance Flynn SL, Wood EJ and Eyles JA Institute of Sound and Vibration Research, University of Southampton UK Aim To investigate speech discrimination ability and sound quality over distance with the use of FM radio aids with cochlear implants. • Results 1 • The mean score at which subjects identified 71% toys correctly was:- • 1m without FM aid = 54.8dB sd 5.2dB • 1m with FM aid = 41.0dB sd 8.9 dB • 3m with FM aid = 41.3dB sd 10.7dB • >10m with FM aid = 45.0dB sd 11.3dB • T-test Results:1m with and without FM aid t=-4.4 p<0.001 • 1m and 3m with FM aid t=-0.16 NS • 1m and 10m with FM aid t=-1.69 NS • 3m and 10m with FM aid t=-2.18 p< 0.05 • Correlation: BKB and Toy Test r=-0.76 p<0.05 Speech levels at 1m • Method • The McCormick Automated Toy Test (ATT) was used to evaluate speech discrimination over distance. The Toy Test uses an adaptive technique to obtain a result at which the subject scores 71% correct. The maximum level that speech can be delivered is 70 dB(A). • Subjects • 2 children and 8 adults aged between 8 and 76 years • 5 male, 5 female • 5 Nucleus CI22 users with Spectra processors • 5 Nucleus CI24M users; 4 with Esprit processors and 1 with a Sprint processor • All subjects had used their cochlear implants for more than 1 year • The 2 children and 1 adult had used their radio aids for at least 1 year • The latest BKB sentence scores obtained in clinic for the adults were between 57-92% key words correct in quiet • The latest Toy Test scores obtained in the clinic for the children were both 57dB(A) Toy test 71% correct score dB(A) subject • Results 2 • Sound quality results were obtained from 9 of the 10 subjects. The youngest of the children (aged 8 years) was unable to understand the sound quality questions. Sound quality scores are reported as a percentage where 100% indicates very clear and sharp sound with no muffling of the signal, hissing, buzzing or echos at all and 0% would indicate unclear sound, very muffled sound and loud hissing buzzing and echos. Sound quality assessments were as follows: • 1m without FM aid = 92% • 1m with FM aid = 87% • 3m with FM aid = 88% • >10m with FM aid = 80% Speech discrimination using FM radio aids and implants at different distances Toy Test 71% correct score dB(A) • Experimental Design • Each subject used one of 5 radio aids (Connevans 220, Senheisser, Phonic Ear, Microvox, Solaris) and acted as their own control. Each radio aid was thus used by 2 subjects.. 4 conditions were used in a balanced order. • ATT with cochlear implant only at 1m • ATT with FM radio aid and implant at 1m • ATT with FM radio aid and implant at 3m • ATT with FM radio aid and implant at >10m • After each test condition subjects were asked to rate clarity and sharpness of the sound as very clear/sharp, okay or not clear/sharp (2 questions). They were also asked to assess if sound was muffled or whether there were any hissing, buzzing or echo like sensations choosing between the answers; none at all, slight and loud (4 questions). subject • Discussion and Conclusions • 9 of the 10 subjects were able to discriminate speech better with the radio aid at 1m, 3m and 10m than with out the radio aid at 1m from the speaker. • The ATT scores for this group of subjects were the same as for children of a previous study (55.4dB(A) sd 6.2dB, Wood, Flynn and Eyles, 2000). • Using the FM radio aid at 1m gave a mean score of 41dB(A) compared with 47.9dB(A) in the previous study suggesting that the older more experienced listeners in this study were better able to discriminate words. • Sound quality was good over all distances with all FM radio aids. • The slight reduction in ATT scores and sound quality at 10m could have been influenced by not using the special FM transmitter cable with the Connevans and Phonic Ear radio aids with the Esprit processor (not recommended with these radio aids). • Cochlear implant users can listen at a comfortable level with good sound quality at least up to 10m with any of the 5 radio aids used. ATT References McCormick B (1977) The Toy Discrimination Test: An aid for screening the hearing of children above the mental age of 2 years. Public Health London 91, 67-69 Wood EJ, Flynn SL and Eyles JA (2000) The benefit of using an FM radio aid system with cochlear implant users. Poster presented at the 6th international cochlear implant conference CI 2000, Miami FM transmitter subject at 1m with and without FM receiver subject at 3m with FM receiver subject at >10m with FM receiver