Pichora-Fuller M K, Schneider B A
Department of Psychology, University of Toronto, Mississauga, Ontario.
J Speech Hear Res. 1991 Dec;34(6):1410-22. doi: 10.1044/jshr.3406.1410.
Four dichotic thresholds (S pi N0, S0 N pi, S0 N tau, and S pi N pi tau) were measured for young and old subjects using both burst and continuous broadband maskers. Masking-level differences (MLDs) were determined by subtracting dichotic thresholds from homophasic thresholds (S0 N0 or S pi N pi). The S0 N0 thresholds for the old subjects did not differ significantly from those for the young subjects in either the continuous or the burst masking noise conditions. The S pi N pi thresholds for the old subjects did not differ significantly from those for the young subjects in the continuous masking noise condition, but there was a significant age effect (3 dB) when burst masking noise was used. Both young and old subjects obtained larger MLDs in continuous masking noise than in burst masking noise. MLDs for old subjects were smaller than MLDs for young subjects by 4.3, 5.0, 2.7, and 1.6 dB in burst masking noise and by 4.9, 3.5, 2.5, and 1.4 dB in continuous masking noise, respectively in the S pi N0, S pi N pi tau, S0 N tau, and S0 N pi conditions. Four young subjects there was a hierarchy in the size of the MLD obtained in the four dichotic conditions, with the MLD being significantly larger in the S pi N0 and S pi N pi tau conditions; however, the size of the MLD was the same in all four conditions for the old subjects. Compared to young subjects, the performance of the old subjects was characterized by decreased ability to use homophasic cues in burst masking noise and decreased ability to use interaural difference cues. These findings were observed at four signal frequencies.
使用突发和连续宽带掩蔽器，测量了年轻和老年受试者的四个双耳阈值（SπN0、S0Nπ、S0Nτ和SπNπτ）。通过从同相阈值（S0N0或SπNπ）中减去双耳阈值来确定掩蔽级差（MLD）。在连续或突发掩蔽噪声条件下，老年受试者的S0N0阈值与年轻受试者的S0N0阈值没有显著差异。在连续掩蔽噪声条件下，老年受试者的SπNπ阈值与年轻受试者的SπNπ阈值没有显著差异，但在使用突发掩蔽噪声时，存在显著的年龄效应（3dB）。年轻和老年受试者在连续掩蔽噪声中获得的MLD都比在突发掩蔽噪声中更大。在突发掩蔽噪声中，老年受试者在SπN0、SπNπτ、S0Nτ和S0Nπ条件下的MLD分别比年轻受试者小4.3、5.0、2.7和1.6dB；在连续掩蔽噪声中，分别小4.9、3.5、2.5和1.4dB。对于四名年轻受试者，在四种双耳条件下获得的MLD大小存在层次结构，在SπN0和SπNπτ条件下MLD显著更大；然而，老年受试者在所有四种条件下的MLD大小相同。与年轻受试者相比，老年受试者的表现特点是在突发掩蔽噪声中使用同相线索的能力下降，以及使用双耳差异线索的能力下降。在四个信号频率上都观察到了这些结果。
