Wednesday, October 21, 2009

Cochlear implants give performance similar to HAs with 80db HL

This study shows CI matches HA with 80db HL

Comprehensive study that demonstrates medium-gain HAs with only 40db gain was able to match the average CI result except in HINT+5 where HAs were significantly ahead!
The average HA was 78db PTA unaided, 38db aided. For CI it was 110db HL aided down to 36db.

My comments: With a 110db HL, even high-gain HAs with 70db gain would aid you down to only 40db. Speech scores with such a profound loss would be far below the scores of CI and those with severe losses because there's extensive cochlear dead regions associated with a 110db loss. Also the surviving hair cells would be of very low quality and contribute little to acoustic information.

CI matches HA with 90db HL

Ive been doing my research on comparing CI vs. HA and I found this! I will keep looking for more articles that compare the two. But from what ive researched, CI today usually gives better hearing than what HAs can give for a profound loss. But CI appears to match the performance of HAs for a severe loss.

I also learned that those with severe losses generally score at least 70% speech on a difficult monosyllable test. I will do more research on speech scores for different degrees of hearing loss. But that article does show that those with profound losses generally scored below 50%. It's that group who with CI could hear comparable to those with severe losses and HAs. Speech would improve from perhaps 40% to perhaps 80% which is significent.

HAs come out way ahead of CIs in most tests

Results: The aided pure-tone hearing thresholds of the hearing aid users were better at low frequencies. In contrast, the cochlear implant group’s thresholds were better at high frequencies. with a statistically significant difference at 250 and 6000 Hz.. The hearing aid users had similar scores to the normal hearing group in vowel identification and pattern perception. In addition, the hearing aid group performed better than did the cochlear implant group in vowel identification, pattern perception, and daily sentences tasks (P = .001, P = .02, P = .0001, respectively). No significant differences were found between the hearing aid and cochlear implant groups in multi-syllabic, phonetically balanced words, and consonant identification tasks. Although similar performances were obtained for three groups in music perception tasks, there was a positive and significant correlation was found between pattern perception and rhythmic perception ability of the cochlear implant group, whereas the hearing aid group, who had better performance in multisyllabic word discrimination, also performed better in tonal and rhythmic tasks.
My comments: Hearing aids are great, no need to say any more!

FIGURE 3. Advances in technology and signal processing in cochlear implants have resulted in improved performance outcomes over time. Shown are group mean percent correct scores for CUNY and HINT sentences in quiet, and for CNC monosyllabic words. Source: Internal data from Cochlear Americas clinical trials.
My comments: CI performance improvement has peaked and leveled off since the early 2000s. Future technologies won't even be CI based as CI has physical limitations due to physics and principle.

Results of Pediatric Cochlear Implantation Compared with Results Obtained with Hearing Aids

Profoundly deaf children with 110db HL and 22% speech improved to 72% speech after CI and they hear with CI comparable to those with a severe hearing loss(70-85db) younger children did better with CI, the performance of children implanted between age 2 and 4 was equivalent to the mean performance of children with hearing loss of 70-85 dB wearing hearing aids.

Image got cut off, to view in full, click here

My comments: The HI group had only 55db PTA HL while the NH group had 5db PTA HL. Properly amplified, a moderate HL(60db max) which involves only the OHC and not IHC can give you near normal hearing except in the most challenging situations. Even with a channel simulator, the NH and HI did far better than CI. CIs do a great job in quiet but not so well in noise. It should be known that CIs aren't a cure and they won't give you anywhere near normal hearing, but they can be great for the profoundly deaf.

I found a recent CI study that shows the average performance for CI speech scores. Different studies show slightly different scores. The concensus is that CI can match HAs for someone with a severe hearing loss. CI is usually better than HAs for those who are profoundly deaf so it's no surprise many become CI candidates.