Improving pitch discrimination

28 02 2012

I’ve been taking part in a clinical study over the last few months on factors affecting audio-perception in patients with cochlear implants.

This study was conducted to determine if cochlear implant sound processors can be adapted to improve speech perception.  My processor program on my older processor (now two years old!) was changed to improve pitch discrimination, based on my discrimination abilities during testing, and evaluated with speech perception tests.

During initial testing, the Hearing In Noise Test (HINT) was used. Two lists of ten common, simple sentences (such as “The weather looks good today”) were used in quiet and noise with sentences administered at +10 signal to noise ratio, to give a baseline level of my ability to discriminate.

During the first session I undertook a pitch discrimination task. Two sounds (beeps) were played, and I was asked to say which sound is higher in pitch. Each sound is a separate electrode on my implant being stimulated, and this was continued for all electrodes to work out which ones give the clearest pitch, and if there are electrodes which sound the same.  This went on for 2-3 hours … uggg! I had a new program added to my sound processor to try out, based on the pitch task, and I used this all the time. This meant I had about 6 electrodes switched off and a simpler map.

During session 2, one month later, I underwent the same speech perception tests with the new program and then was given a different program to try based on the results of another pitch discrimination task.

During session 3, one month later, I underwent the same speech perception tests with the latest program and then asked which program I preferred out of the two new programs and the original one that I started with.  I couldn’t tell that there were any major differences between them, they were slightly different in the quality of the sound but I could have lived with any of them. However, the speech discrimination tests told a different story …

HINT testing in quiet :

Bilateral % Left ear only (older CI) %
Nov 2011 57 Dec 2011 48
Dec 2011 84 Feb 2012 70

Out of 26 in this clinical trial group, 4 saw an increase in their speech perception scores. It is likely that a simpler map allowed my brain to ‘sit back’ for a while, take the time to absorb sounds through a simpler map, then start again refreshed. 🙂

Now, it’s onwards and upwards with more auditory verbal therapy, as I’ve purchased a course of AVT from Pindrop Hearing on Harley Street. This course is ideal for hearing aid users but not quite as effective for cochlear implant users. This new version of LACE training has British accents but the regular testing is done with US accents, as the comparative data is pulled from the US database of other LACE users.

I’m willing to try anything to increase my speech perception scores, so watch this space. I wonder if I will ever be able to hit 100%?