Liepins Rudolfs, Kaider Alexandra, Auinger Alice Barbara, Dahm Valerie, Honeder Clemens, Riss Dominik, Arnoldner Christoph
Department of Otolaryngology-Head and Neck Surgery, Medical University of Vienna, Vienna, Austria.
Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University of Vienna, Vienna, Austria.
Ear Hear. 2023;44(1):146-154. doi: 10.1097/AUD.0000000000001262. Epub 2022 Aug 4.
Stimulation with triphasic pulses has been shown to reduce the occurrence of unwanted facial nerve stimulation (FNS) with cochlear implants (CIs). However, there is little data available on how different pulse shapes affect the hearing outcome with electrical hearing in general. The aim of the study was to evaluate the effects of different stimulation pulse shapes on speech perception in noise, as well as loudness perception and subjective sound quality.
Twenty experienced cochlear-implant users not suffering from FNS participated in a prospective single-visit study. Based on the subjects' current clinical fitting, six fitting maps with different pulse shapes (biphasic and triphasic) and different interphase gap (IPG) durations (2.1 µs, 10 µs, and 20 µs) were created. First, the loudness was balanced for each configuration by adjusting the stimulation charge amount. Then, speech perception in noise was measured with a German matrix sentence test (Oldenburg Sentence test). The perception of particular sound attributes of speech and music, as well as overall preference, was evaluated with visual analog scales.
Similar levels of speech perception were obtained with triphasic stimulation ( P = 0.891) and longer IPGs ( P = 0.361) compared to the subjects' clinical map settings. The stimulation amplitudes for equal loudness were significantly higher with triphasic stimulation compared to biphasic stimulation when keeping the IPG constant. Increasing the IPG had a significantly larger effect on perceived loudness ( P < 0.0001) and charge reduction for equal loudness with triphasic pulses compared to biphasic pulses. Triphasic configuration showed lower overall subjective sound quality ratings than biphasic for speech intelligibility, clarity, naturalness, and overall preference, as well as for music naturalness, and overall preference in the acute setting without adaptation time. Post-hoc pairwise comparisons against the clinical map revealed significantly lower speech naturalness ratings for triphasic with 2.1 µs IPG and for triphasic with 20 µs IPG only.
Although some sound quality attributes were rated lower compared to the clinical map in the acute test setting, stimulation with triphasic pulses does not affect speech perception in noise and can be considered as a valuable option in CI fitting.
已证明使用三相脉冲刺激可减少人工耳蜗（CI）引起的不必要的面神经刺激（FNS）。然而，关于不同脉冲形状如何总体影响电听觉的听力结果，现有数据很少。本研究的目的是评估不同刺激脉冲形状对噪声中言语感知、响度感知和主观音质的影响。
20名无FNS的经验丰富的人工耳蜗使用者参与了一项前瞻性单次就诊研究。根据受试者当前的临床调试情况，创建了六种具有不同脉冲形状（双相和三相）和不同相间间隙（IPG）持续时间（2.1微秒、10微秒和20微秒）的调试图谱。首先，通过调整刺激电荷量使每种配置的响度达到平衡。然后，使用德语矩阵句子测试（奥尔登堡句子测试）测量噪声中的言语感知。使用视觉模拟量表评估对语音和音乐特定声音属性的感知以及总体偏好。
与受试者的临床图谱设置相比，三相刺激（P = 0.891）和较长的IPG（P = 0.361）获得了相似水平的言语感知。在保持IPG不变的情况下，与双相刺激相比，三相刺激时同等响度的刺激幅度明显更高。与双相脉冲相比，增加IPG对三相脉冲的感知响度（P < 0.0001）和同等响度下的电荷减少有显著更大的影响。在没有适应时间的急性情况下，对于言语可懂度、清晰度、自然度和总体偏好，以及音乐自然度和总体偏好，三相配置的总体主观音质评分低于双相配置。事后与临床图谱进行的两两比较显示，仅2.1微秒IPG的三相和20微秒IPG的三相的言语自然度评分明显较低。
尽管在急性测试环境中，与临床图谱相比，某些音质属性的评分较低，但三相脉冲刺激不会影响噪声中的言语感知，可被视为人工耳蜗调试中的一个有价值的选择。
