Key points
  1. The sound localisation ability was disrupted both in children with UMA and stimulated UHL.
  2. 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.
  3. The non-surgical BCD provided a definite benefit on speech recognition and high participant satisfaction to children with UMA.
  4. The non-surgical BCD did not improve or deteriorate the original sound localisation ability of children with UMA.
  5. 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