Dubno J R, Ahlstrom J B
Department of Otolaryngology and Communicative Sciences, Medical University of South Carolina, Charleston 29425, USA.
J Acoust Soc Am. 1995 Apr;97(4):2430-41. doi: 10.1121/1.411964.
Thresholds and consonant recognition were measured in six low-pass maskers as a function of masker bandwidth for hearing-impaired subjects and for normal-hearing subjects listening in spectrally shaped broadband noise (SSBB). SSBB was adjusted such that thresholds in that masker for a normal-hearing listener were equal to a hearing-impaired listener's absolute thresholds. Thresholds measured in low-pass maskers were higher for hearing-impaired than for normal-hearing subjects for signal frequencies both within and outside masker passbands, although threshold differences were larger for signal frequencies outside masker passbands. Slopes of functions relating consonant recognition to speech level were not significantly different between groups, due to the presence of SSBB for the normal-hearing listeners. However, 25% of observed scores for hearing-impaired listeners, compared to only 5% of observed scores for normal-hearing listeners, were significantly poorer than predicted by the articulation index (AI), when AIs were computed using subjects' absolute thresholds. Better correspondence between observed and predicted scores in low-pass maskers was achieved when AIs were derived empirically from thresholds measured in each low-pass masker. Hence poorer-than-predicted consonant recognition scores in low-pass maskers were accounted for by higher-than-normal thresholds in those maskers.
针对听力受损受试者以及在频谱成形宽带噪声（SSBB）中聆听的正常听力受试者，在六种低通掩蔽器中测量了阈值和辅音识别能力，作为掩蔽器带宽的函数。调整SSBB，使正常听力听众在该掩蔽器中的阈值等于听力受损听众的绝对阈值。对于掩蔽器通带内和通带外的信号频率，听力受损受试者在低通掩蔽器中测量的阈值高于正常听力受试者，尽管对于掩蔽器通带外的信号频率，阈值差异更大。由于正常听力听众存在SSBB，两组之间辅音识别与语音水平关系函数的斜率没有显著差异。然而，当使用受试者的绝对阈值计算清晰度指数（AI）时，听力受损听众25%的观察分数显著低于AI预测值，而正常听力听众只有5%的观察分数显著低于预测值。当根据在每个低通掩蔽器中测量的阈值凭经验得出AI时，低通掩蔽器中观察分数与预测分数之间的对应性更好。因此，低通掩蔽器中辅音识别分数低于预测值是由这些掩蔽器中高于正常的阈值所致。
