HSC Section 8_April 2017

QuickSIN was administered at 50 dB HL in soundfield. Again,

two listening conditions were assessed and counterbalanced

across participants: the S0Npe (sentences at 0 degree azimuth,

noise at 90 degrees azimuth to poor ear) and the S0Nbe (sen-

tences at 0 degree azimuth, noise at 90 degrees azimuth to the

better ear) condition. For each condition, two different lists

were presented and the scores averaged.

CROS Hearing Aid Fitting

Participants were randomly assigned to be fitted with the

CROS hearing aid either at the end of the first visit or at the end

of the second visit. They were given a 2-week trial with the

CROS and asked to refrain from wearing their BAHD during

that time. At the end of the first visit, four participants were

fitted with the CROS hearing aid and were subsequently tested

with this device on their second visit, at which time they were

instructed to use the BAHD for the next 2 weeks. This protocol

was reversed in the other four participants, with testing after

each device experience.

CROS hearing aids were fitted with a retainer earhook on the

poorer ear and a slim tube with an open dome on the better ear.

The hearing aid’s response was verified with real-ear measures

(Audioscan Verifit) using Dillon’s (26) recommended approach

for probe microphone verification of CROS hearing aids. Dur-

ing real-ear verification, the hearing aid’s response was fine-

tuned as needed. Adaptive directional microphone and noise

reduction algorithm were active.

Aided Measures With CROS and BAHD

Participants were tested with either the CROS or BAHD,

depending on which device they had been instructed to use

during the previous 2 weeks. Similar to the baseline measures,

aided soundfield thresholds were obtained with warble tones

delivered at 90 degrees azimuth to the better ear in one condition

and at 90 degrees azimuth to the poorer ear in the other condi-

tion. Aided word recognition testing and aided QuickSIN were

administered using the same protocol as for unaided measures.

Moreover, two self-assessment questionnaires, the Bern Benefit

in Single-Sided Deafness Questionnaire (BBSS) and the Speech

Spatial Qualities Questionnaire (SSQ), were given to assess the

self-perceived benefits provided by the device that was worn

the previous 2 weeks. The BBSS (27) is a 10-item questionnaire

where participants rate the benefit derived from their device in

different situations, with ratings that range from

5 (‘‘Much

Easier Without the Aid’’) to +5 (‘‘Much Easier With the Aid’’).

The SSQ (28) requires participants to rate their perceived hear-

ing ability for 49 scenarios using a 10-point scale, ranging from

‘‘Not at all’’ to ‘‘Perfectly.’’

Participants were asked to fill out a diary during the 2-week

period for the CROS and for the BAHD; they were instructed to

indicate the date the device was worn, hours of device use per

day, and specific situations in which the device was worn. Fi-

nally, at the end of the study, the researcher verbally asked

participants whether the CROS or BAHD was preferred and

questioned them on the specific reasons for their choice.

Statistical Analyses

Statistical analyses were conducted in R (29). An alpha of 0.05

was assumed for all analyses. Shapiro-Wilks tests were used to

assess normality and Mauchly’s test was used to assess sphericity

in all repeated measures analyses. No violations of sphericity

were detected. Repeated measures ANOVAs were used to com-

pare conditions for normally distributed data, otherwise statistical

analysis was performed using Friedman’s non-parametric test.

All reported

values for parametric post hoc measures were

adjusted using Bonferroni corrections. Confidence intervals (CI)

were adjusted for within-subjects testing using the Cousineau-

Morey method with Baguley’s corrections (30).

RESULTS

Head Shadow

Figure 1 shows mean head-shadow values (i.e., thresh-

old increases for sounds presented to the poorer ear) at

each frequency in all three conditions, with error bars

showing 95% confidence intervals. Significant devia-

tions from normality were detected for the unaided con-

dition (W = 0.912,

= 0.013) and the CROS condition

(W = 0.896,

= 0.005), so a Friedman’s nonparametric

ANOVA was used to test for within-subject device-

dependent differences in head shadow across all fre-

quencies. There was a significant main effect of device

(

(2) = 21.769,

= 0.00002). Post hoc analyses con-

ducted using the Friedman post hoc analysis (31) showed

significant reductions in head shadow for both the BAHD

(mean reduction of 25 dB) and the CROS (mean reduc-

tion of 32 dB), relative to the unaided condition. The 7-dB

advantage for the CROS over the BAHD did not exceed

the critical difference (19.15 dB) required for significance.

Word Recognition Scores

The mean word recognition percentages for each de-

vice condition are displayed in Figure 2. Error bars show

95% confidence intervals. Note that the scores for the

quiet condition are close to 100%, suggesting a ceiling

effect. This observation was indeed the case, as 10 of

the scores (42%) were perfect. The quiet condition was

therefore excluded from further statistical analysis. Data

in the remaining conditions were normally distributed and

were analyzed with a repeated measures ANOVA. The

ear to which the noise was presented (better or poorer)

had a significant effect on word recognition scores (F(1,7) =

32.82,

= 0.0007,

= 0.329), but there was no signifi-

cant main effect of device (

0.05). The interaction of

FIG. 1.

Mean head shadow in the three device conditions.

Error

bars

denote 95% confidence intervals.

CROS VS BAHD FOR SINGLE-SIDED DEAFNESS

Otology & Neurotology, Vol. 36, No. 5, 2015

150