Background: Disrupted binaural hearing is thought to contribute in part to the academic, social,
and communication problems often associated with unilateral hearing loss (UHL) in
childhood. It is not known, however, if putting a hearing aid in the impaired ear
of a child with UHL will lead to bilateral or binaural benefit. This study seeks to
utilize sound localization acuity measurements to assess hearing aid amplification
efficacy in children with UHL.
Purpose: To measure sound localization ability in children with UHL who use a hearing aid
in the impaired ear to determine the extent to which amplification, age, early intervention,
and degree of hearing loss affects localization acuity.
Research Design: A within-subjects experimental design using repeated measures is used to determine
the effect of amplification on localization acuity in children with UHL. A between-subjects
experimental design is used to compare localization acuity between children with UHL
and age-matched controls with normal hearing.
Study Sample: Twelve children with UHL who used a hearing aid in the impaired ear and 12 age-matched
controls with normal hearing. Children with UHL were divided into two groups based
on degree of hearing loss. Children in both groups were divided into two age groups:
older children (10–14 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.
Results: In the experimental study a significant interaction was found between hearing aid
amplification and child age. A hearing aid significantly improved localization acuity
in younger children with UHL and significantly impaired localization acuity in older
children. A significant correlation was found between age at intervention and localization
bilateral benefit. Children who were fit earlier showed bilateral benefit whereas
children who were fit later showed bilateral interference. Development, however, may
play a role in sound localization acuity. When unaided, older children had significantly
better localization acuity than younger children with UHL.
Conclusions: A hearing aid can provide bilateral localization benefit to some children with UHL.
Early intervention may increase the likelihood of bilateral benefit. However, developmental
factors appear to play a role in improving localization abilities over time for children
with UHL. Nonetheless, without a means of establishing bilateral benefit with hearing
aid amplification, localization performance in children with UHL will rarely equal
that of peers.
Key Words
Children - hearing aid - localization - unilateral hearing loss
