Sladen Douglas P, Nie Yingjiu, Berg Katelyn
a Mayo Clinic , Rochester , MN , USA.
b James Madison University , Harrisonburg , VA , USA.
Cochlear Implants Int. 2018 May;19(3):119-130. doi: 10.1080/14670100.2018.1424513.
The purpose of this study was to investigate speech recognition in noise and listening effort among a group of adults with cochlear implants (CIs). Two main research questions were addressed. First, what are the effects of omni versus directional microphone configuration on speech recognition and listening effort for noisy conditions? Second, what is the effect of unilateral versus bimodal or bilateral CI listening on speech recognition and listening effort in noisy conditions?
Sixteen adults (mean age 58 years) with CIs participated. Listening effort was measured using a dual-task paradigm and also using a self-reported rating of difficulty scale. In the dual-task measure, participants were asked to repeat monosyllabic words while at the same time press a button in response to a visual stimulus. Participants were tested in two baseline conditions (speech perception alone and visual task alone) and in the following experimental conditions: (1) quiet with an omnidirectional microphone, (2) noise with an omnidirectional microphone, (3) noise with a directional microphone, and (4) noise with a directional microphone and with a second sided CI or hearing aid. When present, the noise was fixed with a +5 dB signal-to-noise ratio. After each listening condition, the participants rated the degree of listening difficulty.
Changing the microphone from omni to directional mode significantly enhanced speech recognition in noise performance. There were no significant changes in speech recognition between the unilateral and bimodal/bilateral CI listening conditions. Listening effort, as measured by reaction time, increased significantly between the baseline and omnidirectional quiet listening condition though did not change significantly across the remaining listening conditions. Self-perceived listening effort revealed a greater effort for the noisy conditions, and reduced effort with the move from an omni to a directional microphone.
Directional microphones significantly improve speech in noise recognition over omnidirectional microphones and allowed for decreased self-perceived listening effort. The dual task used in this study failed to show any differences in listening effort across the experimental conditions and may not be sensitive enough to detect changes in listening effort.
本研究旨在调查一组成人人工耳蜗（CI）使用者在噪声环境中的言语识别能力和聆听努力程度。研究主要探讨了两个问题。第一，全向与定向麦克风配置对噪声环境下言语识别和聆听努力程度有何影响？第二，单侧人工耳蜗聆听与双侧或双模式人工耳蜗聆听对噪声环境下言语识别和聆听努力程度有何影响？
16名成人人工耳蜗使用者（平均年龄58岁）参与了研究。使用双任务范式以及自我报告的难度评分量表来测量聆听努力程度。在双任务测量中，要求参与者重复单音节词，同时对视觉刺激做出按键反应。参与者在两种基线条件下（单独言语感知和单独视觉任务）以及以下实验条件下接受测试：（1）使用全向麦克风的安静环境，（2）使用全向麦克风的噪声环境，（3）使用定向麦克风的噪声环境，（4）使用定向麦克风且另一侧佩戴人工耳蜗或助听器的噪声环境。当存在噪声时，将信噪比固定为 +5 dB。在每个聆听条件结束后，参与者对聆听难度进行评分。
将麦克风从全向模式切换为定向模式可显著提高噪声环境下的言语识别性能。单侧与双侧/双模式人工耳蜗聆听条件下的言语识别没有显著变化。通过反应时间测量的聆听努力程度在基线和全向安静聆听条件之间显著增加，但在其余聆听条件下没有显著变化。自我感知的聆听努力程度显示，噪声环境下的努力程度更高，而从全向麦克风切换到定向麦克风时努力程度降低。
定向麦克风在噪声环境下的言语识别方面显著优于全向麦克风，并能降低自我感知的聆听努力程度。本研究中使用的双任务未能显示出不同实验条件下聆听努力程度的差异，可能不够灵敏，无法检测到聆听努力程度的变化。
