This paper describes a battery of tests used to clinically assess the hearing performance of experienced cochlear implant users upgraded to a new fine structure coding strategy. The tests provide guidance for both CI users and candidates and doctors to choose different technologies as well as to steer their clinical rehabilitation. Prepare the participants for the experiment by positioning them a meter from the loudspeaker at a 45 degree angle to the cochlear implant side in the sound booth.
Remove any hearing aids from the contralateral ear and make sure the earplug or muff masking is effective for participants with residual hearing. Inform the participants that practice test sessions will be conducted followed by formal testing. Take the participants and their guardians to the mapping room.
Seat the participants in the room. Enter the password to unlock the mapping software. Remove the speech processor and connect it to the max box with a programming cable.
Choose the participant's name on the software and then click on the impedance option. Test the electrode impedance to ensure it is within the normal range of 2.2-12 kiloohm. Ensure the coding strategy is FS4 and a standard pulse rate of 12 pulses per second is used.
Set the single electrode stimulation to dynamic with three sweeps. Let the participants distinguish the volume of each electrode by pointing to the appropriate image on a loud comfort pictorial scale. Using up and down testing methods, perform the same results as the final electrical stimulation result.
To set the maximum comfortable level, activate the map by pressing the Live button. Activate the shift and tilt function to return the participants to the fitting mode. Press Strategy to set the stimulation rate at 1, 274 pulses per second and the channel specific sampling sequence to 4.
Set the biphasic pulse interface gap at 2.1 microseconds. Finally set the compression ratio to 3:1 and sensitivity to 75%Check that the threshold value for each channel is the frequency range of 70-8, 500 hertz. Test the speech perception in this order.
Once the participants are seated, as demonstrated previously, launch the speech software. Ask the participants to clearly repeat the content they hear. Turn on the audiometer and select the hearing options.
Set the sound loudness to 70 decibels hearing level above the average pure threshold of 500, 1, 000, 2, 000, and 4, 000 hertz. For the formal testing, present the participants with practice tests. Ask the participants to repeat the words and sentences for each testing.
Keeping the order of contents random and playing it once. To test sentence recognition in noisy conditions, perform a tone test with the software set at 60 decibels and set the signal to noise ratio to 10 decibels using four-talker babble. Then in the same booth, interpret the results carefully.
After confirming that all the participants are familiar with the testing vocabulary, present the practice tests simultaneously with the formal test. Direct the participants to say what they have heard once. Press Test followed by ToneID to choose the tone in which the participants repeat the content, keeping the order random.
To perform the music test, click on the music software and choose the Pitch selection in the same booth. After presenting both practice and formal tests, instruct the participants to listen to the sequentially presented stimuli and determine which of the two has a falling or rising pitch contour. Record the participant answers and repeat.
Spondee recognition in quiet conditions significantly improved from pre-upgrade to three months post-upgrade. The improvement was insignificant from pre-upgrade to six weeks post-upgrade or from pre-upgrade to immediate post-upgrade. Significant improvement in monosyllable recognition under quiet conditions was seen from pre-upgrade to immediately post-upgrade subjects.
Improvement from 59.6%at pre-upgrade to 71.4%at six weeks post-upgrade was observed, while an increase to 82.1%was observed at three months post-upgrade. Sentence recognition in quiet conditions significantly improved from pre-upgrade to three months post-upgrade. The other groups did not show any significant improvements.
In noisy conditions, sentence recognition increased from pre-upgrade to three months post-upgrade. Significant improvement was seen in tone recognition from pre-upgrade to six weeks post-upgrade and three months post-upgrade, whereas no significant improvement was observed immediately post-upgrade. Non-significant improvement was seen in musical pitch perception from 16.5 limen at pre-upgrade to 23.7 limen.
This procedure provides effective evaluation methods for clinical rehabilitation and will be used in the next stage of related research to evaluate the clinical effects in CI patients.
