Key points
- The sound localisation ability was disrupted both in children with UMA
and stimulated UHL.
- In children with UMA, an inter-subject variability of the directional
hearing was observed. Some of them could use the remaining distorted
binaural cues to detect sound sources, unlike the children with
stimulated UHL.
- The
non-surgical BCD provided a definite benefit on speech recognition and
high participant satisfaction to children with UMA.
- The non-surgical BCD did not improve or deteriorate the original sound
localisation ability of children with
UMA.
- The non-surgical BCD is a valid and safe device for children with UMA
and is recommended as an interventional device from an early age.
Keywords : Unilateral; Microtia and Atresia; Conductive Hearing
Loss; Speech Perception; Sound Localisation; Adhesive Bone Conduction
Device
INTRODUCTION
Microtia and atresia,
developmental malformations of the external and middle ear, is a common
cause of congenital unilateral conductive hearing loss (UCHL)1, 2. Disability in speech recognition in noisy
backgrounds and inaccuracy of sound localisation are the two main
functional deficits experienced by these patients 3,
4.
Common treatment options for patients with unilateral microtia and
atresia (UMA) include traditional canaloplasty, active middle ear
implants, bone conduction implants, and non-surgical bone conduction
devices (BCDs). For children with UMA, who are not willing to undergo
surgery or who have not reached the age for surgery, non-surgical BCDs
represent an important transition intervention 5.
However, whether these patients
can achieve more accurate sound localisation after receiving such
interventions remains disputed, as diverse audiological results are
reported. Some studies have shown remarkable improvements in horizontal
spatial hearing in patients with UCHL using a
BCD6, 7. In contrast, other studies have suggested that
patients with congenital UCHL cannot benefit from BCDs in terms of
spatial hearing 8, 9.
These
studies suggested that patients with congenital UCHL had adapted to
their hearing impairment through the use of spectral shape cues and
ambiguous monaural head shadow effect (HSE) cues from the normal hearing
ear that they had acquired through long-term unilateral hearing
deprivation 10, 11. Using a BCD may cause such
listening cues to be distorted, thereby jeopardizing directional
hearing.
Given the uncertain benefits of hearing amplification and unesthetic
appearance, studies concerning the sound localisation ability of
children with UMA are limited by heterogeneous patient populations,
varying in study design and audiological test results. Currently, there
is no research investigating the characteristics of sound localisation
and the effects of non-surgical BCDs in school-aged children with UMA.
To
provide a theoretical basis for early hearing intervention of
non-surgical BCDs for children with UMA, two primary objectives were
addressed in this study. First, to compare characteristics of sound
localisation in children with congenital UMA and stimulated UCHL.
Second, to detect the effect of a BCD on speech perception and sound
localisation in children with congenital UMA.
METHODS