4.3 Spatial Release from Masking
Several studies regarding SRM in adults and children with NH have been published [13,14]. The results were highly diverse due to numerous factors, including task setting, master stimuli type, number of competing sounds, and similarity in voices producing target and competing speech [15]. In addition, the age at which SRM fully develops is undefined. Some researchers indicated that SRM became stable earlier in childhood (4–6 years) [16,17], while others have reported that SRM was adult-like at 12 years of age [18]. This study suggests that for NH children aged 7 to 12 years, SRM continued to change, as a significant relationship was observed between age and SRM. However, the specific age at which SRM plateaus was not defined due to the narrow age range of participants.
BCDs facilitate the alleviation of HSE to improve speech perception ability, especially when the speech signal is presented from the hearing field of the poor ear [6]; however, during this process, real binaural hearing cannot be restored because the device could not provide real auditory stimulus to the deaf ear [15]. This explained why the average aided SRM for SSD group was statistically improved neither in SeparatedS0NNH condition nor the SeparatedS0NNH condition. When being unaided in the SeparatedS0NNH condition, SRMs were not detected in most SSD patients. This was the most challenging hearing condition for patients with SSD, as the SSN presented from the NH ear interfered with the fronted speech signals. When the SSN was presented in the hearing-impaired ear in the SeparatedS0NSSD condition, all paediatric SSD patients showed SRMs. This hearing condition was historically considered the optimal listening condition for SSD, as the HSE prevented the SSN located at the SSD side from disturbing the speech recognition ability of the NH ear. Theoretically, it was assumed that BCDs would increase SSN interference with the healthy ear. Fortunately, there was no difference between the unaided and aided SRMs, demonstrating their hearing adaptation to the newly aided BCDs.