Time to wind up the cochlear implant posts, or at least time to wind up the regular reports on progress. I’ve just gone past the six month milestone and been effectively discharged (no more appointments with the audiologist for another year, unless something unexpected happens). Time to move on.
The six month appointment was quite relaxed. I was happy with the last programme I’d been given, so no changes there. My hearing thresholds were tested again (the quietest sounds I can hear). My ability to hear sounds at one of the frequencies is still below the theoretically optimal point. Research shows that cochlear implant users who can hear sounds quieter than 35 decibels (25 to 35 decibels being the ideal range) tend to do better at speech comprehension, so the audiologist is aiming to boost the signal from the electrodes in the implant until that point is reached for each frequency. In my case, however, boosting that one frequency any more than it already is results in worse speech comprehension, rather than better, so we mutually decided to let things stay as they were. I am hearing just fine in so many situations; let’s leave it at that.
Here’s the point I’ve reached, on an audiogram, before and after implant.
The diamond shapes are what I can hear in my implanted ear now. The crosses, connected by a dotted line, represent my hearing before the operation.
For those of you not used to reading audiograms the left side axis on the graph represents volume, with quiet sounds at the top and loud ones at the bottom. The bottom axis represents frequencies, with low pitched sounds on the left and high pitched ones on the right. The shapes on the graph represent the quietest sounds I can hear at each of the tested frequencies.
I’ve marked lines representing commonly used definitions of the different levels of hearing loss. People who can hear sounds that are quieter than 20 decibels are reckoned to have normal hearing. A threshold of between 20 and 40db represents a mild hearing loss; 40 to 70db a moderate loss and 70 to 90db a severe loss. Not being able to hear sounds of 90db represents a profound hearing loss.
You can see that before the implant I had quite a bit of low pitched hearing remaining but that the higher pitched sounds had just about gone, with about half the tested frequencies well within the profound hearing loss category. This is why hearing aids were failing to help; they operate by boosting the sounds you can hear, but are useless if there is little or no hearing left to boost.
Looking at the diamonds on the graph you can see why I’m doing so well. I can hear! The graph proves it!! It also gives me a very good answer when people ask me how good my hearing is now. I have the equivalent of a mild hearing loss in my implanted ear and I’m severely/profoundly deaf except for low frequencies in my left ear (or, as they say in the trade, I have a “mild to profound ski-slope loss”).
The other proof of how well I’m doing, if one was needed, is that we repeated the Bamford Kowal Bench (BKB) test. In this test you listen to a tape of short sentences being read out, first by a man and then by a woman, in quiet and then through background noise. The sentences might be very short (“shut the door”) or a bit longer (“we had roast beef, jacket potatoes and cauliflower cheese for Sunday lunch”). You have to repeat them back. Before the operation I managed a success rate of 30%. Six months later I understood 98%.
I’ve had to explain to a couple of people that this doesn’t mean my hearing is approaching normal, it just means that I have a radically improved score on a test used for assessing cochlear implant candidates. Still, I was delighted.
You may recall that BKB is a very controversial test. A long time ago (April 2017) I posted about a review of the cochlear implant assessment criteria, highlighting the fact that the BKB test is “credited” with being one of the main factors why so comparatively few adults with severe to profound hearing loss have an implant (7%), compared to teenagers (94%). You can read what I said here, but essentially my point was that a test conducted in a soundproof room, with only one person speaking at a time and longish pauses between the sentences to give your brain time to decipher (or, as I said in 2017 “shuffle some options about and come up with a plausible candidate for the translation”) in no way replicates living in the real world. I wrote then that NICE were expecting to conclude their review of the cochlear implant assessment process in the summer of 2017. In fact, it is still going on. They’ve said that the BKB test is one thing they are looking at, but so far no decision. I’ll break my self-imposed cochlear implant news blackout when an announcement is made and I really, really hope something changes.
So there you go, implant news over. I’ll let you know when the film is finished (sometime this autumn) but otherwise the plan is to move back to more general deafness topics (and not so often).
Bye for now then. Speak to you again later in the summer.
Image copyright: sputanski / 123RF Stock Photo