An easy method to determine crucial AMEI performance parameters from clinical routine data in individuals – Part 2: dynamic range

Figures & data

Figure 1. Schematic overview of the hearing range of subjects with hearing loss compared to subjects with normal hearing and the maximum output (MO). The covered dynamic range reflects the part of the dynamic range accessible to the patient by using an implant. The dynamic range is determined as the difference between MO of the implant system and the hearing threshold of the patient.

Table 1. Band importance function as reported in ANSI S3 5-1997/Table 4 and rescaled for four (4F) and five frequencies (5F), respectively. Please note that the band importance function for 8 kHz was applied to 6 kHz instead.

Frequency	Band importance I(f)
[kHz]	SII	rescaled 5F	rescaled 4F
0.25	0.0534
0.5	0.1671	0.1781	0.1892
1	0.2373	0.2529	0.2686
2	0.2648	0.2822	0.2998
4	0.2142	0.2283	0.2425
6 (8)^1	0.0549	0.0585

1 SII values for 8 kHz used for 6 kHz.

Figure 2. Scatterplot of word recognition scores (WRS, empty circles) as a function of dynamic range (A DR PTA4; B DR PTA8) and weighted dynamic range (C WDR PTA4; D WDR PTA5). The boxplot for each 10-dB dynamic range group shows the median (solid line), the 25th and 75th percentiles (box) and the 10^th and 90^th percentile (whiskers) the mean value (dashed line) and outliers (black circles). Significant differences between adjacent 10-dB dynamic range groups are marked by an asterisks (*p < 0.05; ** p < 0.01). The sigmoidal function was fitted based on the single data points using the Chapman equation with three parameters.

Table 2. Descriptive statistics of word recognition score (WRS) for each 10-dB dynamic range group 1 to 7 presenting the mean values, standard deviation (SD), the median and the 25^th and 75^th percentile and the sample size of each group for all four dynamic range variables.

		Word recognition score [%]
	DR group	1 0–10 dB	2 > 10–20 dB	3 > 20–30 dB	4 > 30–40 dB	5 > 40–50 dB	6 > 50–60 dB	7 > 60–70 dB
DRPTA4	Mean	18.8	55.0	78.5	81.9	87.9	93.8	90.0
	SD	30.9	19.7	15.7	10.0	5.6	4.8	–
	Median	5.0	55.0	80.0	82.5	90.0	92.5	90.0
	25^th percentile	3.8	40.0	65.0	75.0	85.0	90.0	90.0
	75^th percentile	20.0	60.0	95.0	90.0	90.0	96.3	90.0
	N	4	5	17	18	17	4	1
DRPTA8	Mean	18.8	47.5	77.0	81.9	89.1	95.0	90,0
	SD	30.9	11.9	15.6	9.7	5.4	5.0	0.0
	Median	5.0	47.5	80.0	80.0	90.0	95.0	90.0
	25^th percentile	3.8	38.8	62.5	75.0	85.0	92.5	90.0
	75^th percentile	20.0	56.3	87.5	90.0	90.0	97.5	90.0
	N	4	4	15	21	17	3	2
WDRPTA4	Mean	18.8	55.0	77.4	81.6	87.9	90.6	90.0
	SD	30.9	22.7	16.7	9.9	5.8	5.8	–
	Median	5.0	50.0	80.0	80.0	90.0	90.0	90.0
	25^th percentile	3.8	38.8	60.0	75.0	85.0	90.0	90.0
	75^th percentile	20.0	66.3	95.0	90.0	90.0	95.0	90.0
	N	4	4	17	19	12	9	1
WDRPTA5	Mean	18.8	55.0	77.7	83.0	87.3	92.5	90.0
	SD	30.9	19.7	16.1	9.8	6.3	4.2	–
	Median	5.0	55.0	80.0	85.0	85.0	90.0	90.0
	25^th percentile	3.8	40.0	62.5	75.0	85.0	90.0	90.0
	75^th percentile	20.0	60.0	92.5	90.0	90.0	93.8	90.0
	N	4	5	15	22	13	6	1

Table 3. Statistic results of the pairwise testing of word recognition scores (WRS) of neighbouring dynamic range groups 1 to 6 only for all dynamic range variables (DR_PTA4, DR_PTA8, WDR_PTA4, WDR_PTA5). Group 7 was not included in the pairwise testing because the sample size was too small.

Bin	Word recognition score [%]
	DRPTA4	DRPTA8	WDRPTA4	WDRPTA5
1-2: 0-10 dB vs. >10-20 dB	U = 4.000^a p = 0.190	U = 4.000^a p = 0.343	U = 3.000^a p = 0.200	U = 4.000^a p = 0.190
2-3: >10-20 dB vs. >20-30 dB	t = −2.792^b p = 0.011	t = −3.499^b p = 0.003	t = −2.262^b p = 0.036	t = −2.792^b p = 0.011
3-4: >20-30 dB vs. >30-40 dB	t = −0.763^c p = 0.452	t = −1.081^c p = 0.292	t = −0.911^c p = 0.371	t = −1.134^c p = 0.270
4-5: >30-40 dB vs. >40-50 dB	t = −2.167^b p = 0.038	t = −2.745^b p = 0.009	t = −2.248^c p = 0.032	t = −1.426^b p = 0.163
5-6: >40-50 dB vs. >50-60 dB	t = −1.906^b p = 0.072	U = 10.000^a p = 0.095	t = −1.027^b p = 0.038	t = −2.120^c p = 0.052
6-7: >50-60 dB vs. >60-70 dB	dnt	dnt	dnt	dnt

^a Mann-Whitney rank sum test.

^b Student’s t-test.

^c Welch’s t-test, dnt – did not test (sample size is too small for statistical testing).

Figure 3. Comparison of different measures characterising the DR, weighting the importance of different sets of frequencies equally or according to their importance for speech cues (SII): (A) DR PTA4 vs. DR PTA8); (B) DR PTA4 vs. WDR PTA4; (C) DR PTA4 vs. WDR PTA5; (D) WDR PTA4 vs. WDR PTA5.

Table 4. Comparison of different dynamic range approaches used for determining the relationship between the dynamic range of an implanted patient and their ability for word recognition (n = 66).

Deviation	(A) DR PTA4/DR PTA8	(B) DR PTA4/WDR PTA4	(C) DR PTA4/WDR PTA5	(D) WDR PTA4/WDR PTA5
Mean	0.6 dB	1.2 dB	0.4 dB	−0.8 dB
SD	2.3 dB	0.8 dB	1.1 dB	0.8 dB
Min	−5.8 dB	−1.1 dB	−2.8 dB	−2.6 dB
Max	6.6 dB	3.2 dB	2.7 dB	1.0 dB
Median	0.9 dB	1.2 dB	0.3 dB	−0.8 dB
25^th percentile	−0.9 dB	0.7 dB	−0.4 dB	−1.4 dB
75^th percentile	1.7 dB	1.7 dB	1.0 dB	−0.2 dB

Table 5. Results of the nonlinear regression model with dynamic fitting based on the sigmoidal Chapman function with unknown parameters a, b and c and the overall model fit.

		Coefficient	Std. Error	t	p	R²
DR PTA4	a	93.5077	5.7785	16.1820	<0.0001	0.6371
	b	0.0629	0.0234	2.6935	0.0090
	c	0.9607	0.3420	2.8088	0.0066
DR PTA8	a	91.7983	4.4299	20.7225	<0.0001	0.6360
	b	0.0848	0.0257	3.2955	0.0016
	c	1.7364	0.7563	2.2959	0.0250
WDR PTA4	a	93.7589	5.7890	16.1961	<0.0001	0.6403
	b	0.0618	0.0223	2.7709	0.0073
	c	1.0244	0.3680	2.7836	0.0071
WDR PTA5	a	93.9300	5.7612	16.3039	<0.0001	0.6417
	b	0.0631	0.0227	2.7857	0.0070
	c	1.0294	0.3703	2.7800	0.0072

Data availability statement

The clinical data that support the findings of this study are available from the corresponding author, SB, upon reasonable request. The technical data that support the findings of this study are available in the accompanying manuscript from the co-author, H.M., entitled “An easy method to determine crucial AMEI performance parameters from clinical routine data in individuals – Part 1: maximum output”.