Cochlear Implants and Psychophysics Laboratory, Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA.
J Acoust Soc Am. 2011 Sep;130(3):1567-80. doi: 10.1121/1.3621445.
Three experiments were designed to examine temporal envelope processing by cochlear implant (CI) listeners. In experiment 1, the hypothesis that listeners' modulation sensitivity would in part determine their ability to discriminate between temporal modulation rates was examined. Temporal modulation transfer functions (TMTFs) obtained in an amplitude modulation detection (AMD) task were compared to threshold functions obtained in an amplitude modulation rate discrimination (AMRD) task. Statistically significant nonlinear correlations were observed between the two measures. In experiment 2, results of loudness-balancing showed small increases in the loudness of modulated over unmodulated stimuli beyond a modulation depth of 16%. Results of experiment 3 indicated small but statistically significant effects of level-roving on the overall gain of the TMTF, but no impact of level-roving on the average shape of the TMTF across subjects. This suggested that level-roving simply increased the task difficulty for most listeners, but did not indicate increased use of intensity cues under more challenging conditions. Data obtained with one subject, however, suggested that the most sensitive listeners may derive some benefit from intensity cues in these tasks. Overall, results indicated that intensity cues did not play an important role in temporal envelope processing by the average CI listener.
三项实验旨在研究人工耳蜗（CI）使用者对时间包络的处理能力。在实验 1 中，检验了调制敏感性部分决定 CI 使用者对调制率的辨别能力的假设。在幅度调制检测（AMD）任务中获得的时间调制传递函数（TMTF）与在幅度调制率辨别（AMRD）任务中获得的阈函数进行了比较。这两个测量值之间存在显著的非线性相关关系。在实验 2 中，响度平衡的结果表明，在调制深度超过 16%的情况下，调制刺激的响度会略有增加。实验 3 的结果表明，调制度游移对 TMTF 的整体增益有较小但显著的影响，但调制度游移对跨受试者 TMTF 的平均形状没有影响。这表明调制度游移只是增加了大多数听众的任务难度，但并没有表明在更具挑战性的条件下增加了对强度线索的利用。然而，对一位受试者的数据表明，最敏感的听众可能会从这些任务中的强度线索中获得一些好处。总体而言，结果表明，强度线索在平均 CI 使用者的时间包络处理中并没有起到重要作用。
