Abstract
Background:
Open-fit domes (OFDs) coupled with behind-the-ear (BTE) hearing aids were designed
for adult listeners with moderate-to-severe bilateral high-frequency hearing loss
(BHFL) with little to no concurrent loss in the lower frequencies. Adult research
shows that BHFL degrades sound localization accuracy (SLA) and that BTE hearing aids
with conventional earmolds (CEs) make matters worse. In contrast, research has shown
that OFDs enhance spatial hearing percepts in adults with BHFL. Although the benefits
of OFDs have been studied in adults with BHFL, no published studies to date have investigated
the use of OFDs in children with the same hearing loss configuration. This study seeks
to use SLA measurements to assess efficacy of bilateral OFDs in children with BHFL.
Purpose:
To measure SLA in children with BHFL to determine the extent to which hearing loss,
age, duration of CE use, and OFDs affect localization accuracy.
Research Design:
A within-participant experimental design using repeated measures was used to determine
the effect of OFDs on localization accuracy in children with BHFL. A between-participant
experimental design was used to compare localization accuracy between children with
BHFL and age-matched controls with normal hearing (NH).
Study Sample:
Eighteen children with BHFL who used CE and 18 age-matched NH controls. Children in
both groups were divided into two age groups: older children (10–16 yr) and younger
children (6–9 yr).
Data Collection and Analysis:
All testing was done in a sound-treated booth with a horizontal array of 15 loudspeakers
(radius of 1 m). The stimulus was a spondee word, “baseball”: the level averaged 60
dB SPL and randomly roved (±8 dB). Each child was asked to identify the location of
a sound source. Localization error was calculated across the loudspeaker array for
each listening condition.
Results:
A significant interaction was found between immediate benefit from OFD and duration
of CE usage. Longer CE usage was associated with degraded localization accuracy using
OFDs. Regardless of chronological age, children who had used CEs for <6 yr showed
immediate localization benefit using OFDs, whereas children who had used CEs for >6
yr showed immediate localization interference using OFDs. Development, however, may
play a role in SLA in children with BHFL. When unaided, older children had significantly
better localization acuity than younger children with BHFL. When compared to age-matched
controls, children with BHFL of all ages showed greater localization error. Nearly
all (94% [17/18]) children with BHFL spontaneously reported immediate own-voice improvement
when using OFDs.
Conclusions:
OFDs can provide sound localization benefit to younger children with BHFL. However,
immediate benefit from OFDs is reduced by prolonged use of CEs. Although developmental
factors may play a role in improving localization abilities over time, children with
BHFL will rarely equal that of peers without early use of minimally disruptive hearing
aid technology. Also, the occlusion effect likely impacts children far more than currently
thought.
Key Words
children - hearing loss - outcomes
