2.3 Device and listening conditions
An adhesive BCD (DHEAR, MED-EL, Innsbruck, Austria) was used in the current study. For all experimental conditions, the devices were set to omnidirectional mode, and the volume was adjusted according to patients’ preferences.
Children with UMA were tested with the BCD off (unaided condition) and on (aided condition) (Supplementary Fig. 1b). Children with NH were measured with both ears unplugged (UP condition) as normal controls. When measuring the sound localisation, control listeners were tested with plugging (P condition) to stimulate an acquired UCHL to reveal the characteristics of directional hearing of acquired UCHL. Plugging was performed by covering an ear with an earmuff (Peltor X5A; 3M Company, MN, USA), along with a foam earplug (E-A-R soft; 3M Company) inserted into the external auditory canal. For the UMA group, unaided audiological tests were performed on the day when receiving the BCD and aided audiological tests were measured after a mean period of 9.27 ± 1.85 weeks. For the NH group, all tests were performed in one visit.
2.4 Subject satisfaction
The Chinese version of the international outcome inventory for hearing aids (IOI-HA) (IOI-HA) 13 was handed out to all patients at the end of the follow-up. The IOI-HA consists of seven items: daily use, benefit, residual activity limitations, satisfaction, residual participation restrictions, impact on others, and quality of life. Each item has a five-point rating scale, with higher ratings reflecting better outcomes (or fewer residual difficulties).