Picou Erin M, Ricketts Todd A
The Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennesse, USA.
Ear Hear. 2014 Nov-Dec;35(6):611-22. doi: 10.1097/AUD.0000000000000055.
The purpose of this study was to evaluate the effect of changing the secondary task in dual-task paradigms that measure listening effort. Specifically, the effects of increasing the secondary task complexity or the depth of processing on a paradigm's sensitivity to changes in listening effort were quantified in a series of two experiments. Specific factors investigated within each experiment were background noise and visual cues.
Participants in Experiment 1 were adults with normal hearing (mean age 23 years) and participants in Experiment 2 were adults with mild sloping to moderately severe sensorineural hearing loss (mean age 60.1 years). In both experiments, participants were tested using three dual-task paradigms. These paradigms had identical primary tasks, which were always monosyllable word recognition. The secondary tasks were all physical reaction time measures. The stimulus for the secondary task varied by paradigm and was a (1) simple visual probe, (2) a complex visual probe, or (3) the category of word presented. In this way, the secondary tasks mainly varied from the simple paradigm by either complexity or depth of speech processing. Using all three paradigms, participants were tested in four conditions, (1) auditory-only stimuli in quiet, (2) auditory-only stimuli in noise, (3) auditory-visual stimuli in quiet, and (4) auditory-visual stimuli in noise. During auditory-visual conditions, the talker's face was visible. Signal-to-noise ratios used during conditions with background noise were set individually so word recognition performance was matched in auditory-only and auditory-visual conditions. In noise, word recognition performance was approximately 80% and 65% for Experiments 1 and 2, respectively.
For both experiments, word recognition performance was stable across the three paradigms, confirming that none of the secondary tasks interfered with the primary task. In Experiment 1 (listeners with normal hearing), analysis of median reaction times revealed a significant main effect of background noise on listening effort only with the paradigm that required deep processing. Visual cues did not change listening effort as measured with any of the three dual-task paradigms. In Experiment 2 (listeners with hearing loss), analysis of median reaction times revealed expected significant effects of background noise using all three paradigms, but no significant effects of visual cues.
None of the dual-task paradigms were sensitive to the effects of visual cues. Furthermore, changing the complexity of the secondary task did not change dual-task paradigm sensitivity to the effects of background noise on listening effort for either group of listeners. However, the paradigm whose secondary task involved deeper processing was more sensitive to the effects of background noise for both groups of listeners. While this paradigm differed from the others in several respects, depth of processing may be partially responsible for the increased sensitivity. Therefore, this paradigm may be a valuable tool for evaluating other factors that affect listening effort.
本研究旨在评估在测量听觉努力的双任务范式中改变次要任务的效果。具体而言，在一系列两个实验中，量化了增加次要任务复杂性或加工深度对范式对听觉努力变化的敏感性的影响。每个实验中研究的具体因素是背景噪声和视觉线索。
实验1的参与者为听力正常的成年人（平均年龄23岁），实验2的参与者为轻度倾斜至中度重度感音神经性听力损失的成年人（平均年龄60.1岁）。在两个实验中，参与者均使用三种双任务范式进行测试。这些范式具有相同的主要任务，始终是单音节词识别。次要任务均为身体反应时间测量。次要任务的刺激因范式而异，分别为（1）简单视觉探针，（2）复杂视觉探针，或（3）呈现的单词类别。通过这种方式，次要任务主要在复杂性或言语加工深度方面与简单范式有所不同。使用所有三种范式，参与者在四种条件下进行测试：（1）安静环境中的纯听觉刺激，（2）噪声环境中的纯听觉刺激，（3）安静环境中的视听刺激，以及（4）噪声环境中的视听刺激。在视听条件下，可以看到说话者的脸。有背景噪声条件下使用的信噪比是单独设定的，以便在纯听觉和视听条件下单词识别性能相匹配。在噪声环境中，实验1和实验2的单词识别性能分别约为80%和65%。
对于两个实验，单词识别性能在三种范式中均保持稳定，证实没有一个次要任务干扰主要任务。在实验1（听力正常的听众）中，对中位反应时间的分析表明，仅在需要深度加工的范式中，背景噪声对听觉努力有显著的主效应。视觉线索并未改变使用任何一种双任务范式所测量的听觉努力。在实验2（听力损失的听众）中，对中位反应时间的分析表明，使用所有三种范式背景噪声都有预期的显著效应，但视觉线索没有显著效应。
没有一种双任务范式对视觉线索的影响敏感。此外，改变次要任务的复杂性并没有改变双任务范式对两组听众中背景噪声对听觉努力影响的敏感性。然而，次要任务涉及更深加工的范式对两组听众中背景噪声的影响更敏感。虽然这种范式在几个方面与其他范式不同，但加工深度可能部分导致了敏感性的提高。因此，这种范式可能是评估影响听觉努力的其他因素的有价值工具。
