Kimberley Chan

CI Programming Day 2: Finding Thresholds and Volumes

Wednesday, February 3 – Programming, day 2. As I was heading to the hospital early in the morning, I tried to make out what the GPS was saying. It sounded like a chipmunk, and I couldn’t understand a thing. I could make out a few words when people talked, but it still sounded high pitched, and I had to look at them to understand everything.

Joanie greeted me and explained that we were going to finish “setting up” my CI for programing. She started it the day before, but didn’t want to do too much other than regulate the volume of each electrode. She was right; since I haven’t heard sounds that loud in a few months, some sounds sounded louder to me than they actually were.

Now that we have found the most comfortable volume of loudness, the next step was to determine the lowest volume that each electrode should be programmed at.

We also needed to find the maximum Electrical Compound Action Potential (ECAP) threshold level of each electrode – how we can reach the highest level of comfortable loudness in the safest way – without causing problems like dizziness or facial nerve stimulation.

For this, we performed a Neural Response Telemetry test, which determines the point which the auditory nerve responds to stimulation. This test didn’t require any collaboration from me. She hooked my processor to the computer and sent sounds from each electrode to my ear. Each time, the sound got louder, until my nerve responded to the simulation. When the test was over, she showed me the results on her computer. I don’t have the exact picture of my mapping, but it looked something like this:


The red level shows the max threshold level that we eventually want to reach. Green is where it is currently mapped at, and now we needed to find the blue levels – the lowest volume I can hear at for each electrode.

First, we wanted to make sure all the electrodes are indeed at the same volume level. Hence, we begin with a difficult volume-level comparison test. She would generate one high-pitched sound, and one low-pitched sound, and I had to determine whether they were the same in terms of volume. This was hard, because sometimes the higher-pitched sounds seem louder just because they are high-pitched.

After comparing a lot of electrode sounds to each other and determining that they were all at the same volume level, we did the opposite of what we did yesterday; she sent sounds from each electrode to my implant. Very very very soft sounds. So soft that at the beginning, you don’t hear anything. Then she slowly increased the volume, as soon as I heard something (or thought I heard something), I stopped her.

After we went through all the electrodes, it was time to test whether I could actually hear at these really low levels..

This time, she sent a series of multiple beeps to my CI and I had to indicate how many beeps I heard. She said I would either hear 2, 3, 4 or 5 beeps at a time. It was a really interesting test as I would at times be off by one, but when when she put it only a tiny bit louder, I heard all of them.

She then increased the threshold a little bit – brought the “green level” up on the chart above higher. This made it a bit louder, and for the first few minutes, my ear had to adjust to it. It’s like when someone turns the light on after you’ve been in complete darkness for awhile. Voices were not a bit lower-pitched – no more chipmunks! But high-pitched voices, particularly women voices, sounded very croaky and witch-like.

Zephyr dryer with disposable moisture-absorbing desiccant
Zephyr dryer with disposable moisture-absorbing desiccant

She then showed me how the dryer/de-humidifier that I would have to use every night works. Moisture and humidity affects the sound quality of the CI. All I have to do is remove the battery and place the CI in the dryer. When the lid is closed, and the power button is pressed, warm, dry air is circulated around, and a capsule filled with silica gel captures the moisture. When the gel becomes dark, it has to be reset by putting in the oven for an hour. I was relieved to know that there are also disposable drying capsules and portable drying cases that don’t need to be plugged in.

Next: Day 3 and first sound detection test

Leave a Reply