Auditory stream segregation in cochlear implant listeners: Measures based on temporal discrimination and interleaved melody recognition
Auditory stream segregation in cochlear implant listeners: Measures based on temporal discrimination and interleaved melody recognition
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DOI：
10.1121/1.3203210
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发表时间：
2009-10-01
影响因子：
2.4
通讯作者：
Roberts, Brian
中科院分区：
文献类型：
--
作者：
Cooper, Huw R.;Roberts, Brian
人工耳蜗者经常经历流分离的证据是有限的和模棱两可的。使用与植入物的22个电极的中心频率相匹配的音调序列来探索这些听者的心流。实验一测量了短序列(ABA三联体)和长序列(12个AB周期)(音调/静音持续时间=60/40ms)的时间辨别能力。A音刺激电极11个，B音刺激14个电极中的1个。在每一次试验中，一个序列保持同步，而另一个序列B调延迟；听者必须识别不同步间隔。延迟是在较长序列的后半部分引入的。随着电极间距的增加，预先建立的流动应该会导致阈值更陡峭地上升，但没有发现与序列长度的相互作用。实验2要求听者在交织干扰物(音调/静音持续时间=120/80ms)时识别出两个目标序列中的哪一个存在。对于孤立的目标，准确率很高，但大多数听众在添加响度匹配的干扰物时表现得近乎成功，即使是在远离目标的情况下。只有显著降低分心物水平才能改善表现，而且这种影响不会与目标-分心物分离相互作用。这些结果表明，即使在相对不具挑战性的任务中，植入者通常也无法实现流分离。(C)2009年美国声学学会。[DOI：10.1121/1.3203210]
The evidence that cochlear implant listeners routinely experience stream segregation is limited and equivocal. Streaming in these listeners was explored using tone sequences matched to the center frequencies of the implant's 22 electrodes. Experiment I measured temporal discrimination for short (ABA triplet) and longer (12 AB cycles) sequences (tone/silence durations = 60/40 ms). Tone A stimulated electrode 11; tone B stimulated one of 14 electrodes. On each trial, one sequence remained isochronous, and tone B was delayed in the other; listeners had, to identify the anisochronous interval. The delay was introduced in the second half of the longer sequences. Prior build-up of streaming should cause thresholds to rise more steeply with increasing electrode separation, but no interaction with sequence length was found. Experiment 2 required listeners to identify which of two target sequences was present when interleaved with distractors (tone/silence durations = 120/80 ms). Accuracy was high for isolated targets, but most listeners performed near chance when loudness-matched distractors were added, even when remote from the target. Only a substantial reduction in distractor level improved performance, and this effect did not interact with target-distractor separation. These results indicate that implantees often do not achieve stream segregation, even in relatively unchallenging tasks. (C) 2009 Acoustical Society of America. [DOI: 10.1121/1.3203210]