Proefschrift_vd_Beek

TABLE 1. Demographics of cochlear implant users involved in this study

Results of standard clinical tests

Duration of severe deafness (yr) Duration of severe deafness (yr) 0.5 4 37 36

Duration of CI-use for clinical test data in quiet surroundings Duration of CI-use for clinical test data in quiet surroundings 3 mo 1 yr 1 yr 1 yr

TABLE 1. Demographics of cochlear implant users involved in this study

Age at implantation

CI-use (mo at moment of study)

Phoneme score in quiet (65 dB SPL)

Subject

Etiology

Results of standard clinical tests

A B C D E A F C D G H E B J F K G H L M I I

23 62 38 39 49 23 62 38 39 14 43 59 52 59 50 67 49 4 14 43 59 52 59 50 67 49

4

Meningitis Progressive

93 84 67 98 71 87 89 96 83 88 82 96 98 7 9

21 20 19 12 13 10 14 18 21 20 9 9 2 12 10 18 1 9 4 3 5 4

Age at implantation

CI-use (mo at moment of study)

Phoneme score in quiet (65 dB SPL)

Hereditary progressive Aminoglycosides Left unknown, Etiology Meningitis Meningitis Hereditary Progressive Aminoglycosides Left unknown, Sudden deafness Right glomustumor Hereditary progressive Right glomustumor Unknown Menie`re’s disease ingitis

Subject

2 0.5

6 mo 3 o 1 yr 1 yr 1 yr 1 yr 1 yr 6 mo 1 yr 3 mo 3 mo 1 yr 1 yr 1 yr 1 yr 1 yr

93 84

4

0.2

39 37 6

6

98 71

1 2

23

1 0.2

20 20 15 39 1 23

Unknown Hereditary

Noise induced Sudden eafness

Progressive Unknown

1 yr

83 88

1 yr 1 yr

J

1

Menie`re’s disease

subject were fitted with a psychometric curve. The group scores at SNR with fewer data points could be calculated using these psychometric curves. For the fitting, a x 2 function with three degrees of freedom was used as described by Schön et al. (2002). This function is equal to: The table gives the age at implantation, durations of severe deafness, CI-use and etiology. The last two columns give the average phoneme score in quiet surroundings obtained prior to the study, and the experience with the CI device at the time of the clinical test. All subjects were implanted with one cochlear implant. No hearing aid device was used in the contralateral ear. The table gives the age at implantation, durations of severe deafness, CI-use and etiology. The last two columns give the average phoneme score in quiet surroundings obtained prior to the study, and the experience with the CI device at the time of the clinical test. All subjects were implanted with one cochlear implant. No hearin aid device was used in the contralateral ear. The table gives the age at implantation, durations of severe deafness, CI-use and etiology. The last two columns give the average phoneme score in quiet surroundings obtained prior to the study, and the experience with the CI device at the time of the clinical test. All subjects were implanted with one cochlear implant. No hearing aid device was used in the contralateral ear. K 20 3 Unknown 82 3 mo L 20 15 5 Noise induced 96 98 3 mo M 12 Progressive 1 yr

u ( x ) = u q x x 2 [ 2.37 + k × ( x - x 0.5)]

where u is the speech reception score (in %) and u q the fitted score in quiet surroundings. The constant k is proportional to the gradient of the curve at 0.5 X u q , x is the signal-to-noise ratio, and x 0.5 is the signal-to- noise ratio at 0.5 X u q . The parameters u q , k and x 0.5 were used to fit the curve to the data.

RESULTS Figure 4 shows the individual results (phoneme scores) for the CVC tests as obtained for all subjects with normal hearing and the cochlear implant users with the three different microphones. All cochlear TABLE 2. Clinical results of 13 cochlear implant users, using their standard program

Phoneme scores at SNR (%) in a standard set-up with speech and noise from one loudspeaker

Word scores (%) 0 dB

Headpiece Quiet

10 dB

5 dB

0 dB

5 dB

10 dB

15 dB

TABLE 2. Clinical results of 13 cochlear implant users, using their standard program

36 [8]

Average

88

74 17

64 14

47 18

— —

— —

26 14

Phoneme scores at SNR (%) in a standard set-up with speech and noise from one loudspeaker

SD

9

8

Word scores (%) 0 dB

H adpiece Quiet

10 dB

5 dB

0 dB

5 dB

10 dB

15 dB

The mean phoneme scores on the CVC word test in a standard set-up with speech and noise from the same loudspeaker (speech at a fixed level of 65 dB SPL, free field, 11 words per data point) in quiet surroundings and in background noise with SNRs of 10, 5, 0, 5, 10 and 15 dB. The mean values are given per SNR for the results of the standard listening tests done prior to this experiment. The numbers between the brackets denote the number of cochlear implant users tested at 5 dB. The last column gives the word-score at SNR 0 dB as a comparison. Average 88 74 64 47 36 [8] — — 26 SD 9 17 14 18 8 — — 14 The mean phoneme scores on the CVC word test in a standard set-up with speech and noise from the same loudspeaker (speech at a fixed level of 65 dB SPL, free field, 11 words per data point) in quiet surroundings and in background noise with SNRs of 10, 5, 0, 5, 10 and 15 dB. The mean values are given per SNR for the results of the standard listening tests done prior to this experiment. The numbers between the brackets denote the number of cochlear implant users tested at 5 dB. The last column gives the word-score at SNR 0 dB as a comparison. The mean phoneme scores on the CVC word test in a standard set-up with speech and noise from the same loudspeaker (speech at a fixed level of 65 dB SPL, free field, 11 words per data point) in quiet surroundings and in background noise with NRs of 10, 5, 0, 5, 10 and 15 dB. The mean values are given per SNR for the results of the standard listening tests done prior to this experiment. The numbers between the brackets denote the number of cochlear implant users tested at 5 dB. The last column gives the word- score at SNR 0dBasa comparison.

28 | Chapter 2