일상생활 속 의사소통은 다양한 소음에서 말을 이해하는 능력이 요구된다. 건청인들도 때론 소음 환경에서 말을 이해하는데 어려움을 보이기도 하지만 (Wilson & Strouse, 2002), 난청인들은 일반적으로 건청인에 비해 소음환경에서 상대방의 말을 이해하는데 더 큰 어려움을 보인다(Plomp et al., 1986). 소음 환경에서 어음인지능력의 측정은 조용한 환경에서 보다 청력손실로 인한 일상생활에서의 듣기 어려움을 좀 더 실질적으로 평가하며, 보장구에 대한 실질적인 정보를 제공하고 그 외에 의사소통 훈련에 따른 평가와 재활, 더 나아가 중추청각처리의 평가 및 재활에 대한 중요한 정보를 제공한다(Beattie, 1989; Carhart & Tillman, 1970; Dirks et al., 1982). 이렇듯 소음환경에서 어음인지검사의 중요성으로 인하여 많은 검사도구들을 개발하여 사용하고 있는데, 소음유형, 제시자극 종류, 신호대잡음비(signal-to-noise ratio, SNR) 등에 의해 검사결과가 영향을 받는 것으로 보고되고있다(Nilsson et al., 1994).
The purpose of this study was to investigate effects of noise type and signal-to-noise ratio (SNR) on word recognition performance. Word recognition scores were measured in three types of noise conditions [white noise (WN), speech noise (SN), and multi-talker babble noise (MBN)], which were applied to various signal-to-noise ratio conditions (-5, 0, +5, +10, +15, and +20 dB SNR). Twenty adults and twenty school-aged children with normal hearing sensitivity participated. The results of this study are summarized as follows: First, the adults showed significantly increased word recognition performance as SNR increased from -5 dB to +10 dB in all the noise types. The scores for SN were significantly higher than those for the other noise types and there was no significant difference between MBN and WN. At least +10 dB SNR was required to maximize their recognition abilities in the SN and MBN conditions. Second, the children also showed significantly increased word recognition performance as it changed from +10 dB SNR to +20 dB SNR in three different noise types. Performances were significantly different among three types of noise, indicating SN, MBN, and WN from greatest to least. At least +20 dB SNR was required to maximize their recognition abilities in the SN and MBN conditions. Third. when comparing the performances between adults and children at the +10 dB SNR, there were significant differences between groups and among noise types. In conclusion, the results revealed word recognition to be affected by the function of SNR and type of noise. The findings show that SN and MBN can be more useful in clinical practice than WN, since even subjects with normal hearing showed very low performance in WN. Moreover, when comparing the performances between adults and children, approximately +10 dB SNR was required for children more than adults for their best word recognition performance.
INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSIONS AND CONCLUSIONS Acknowledgements
