Berenstein Carlo K, Mens Lucas H M, Mulder Jef J S, Vanpoucke Filiep J
KNO/Audiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Ear Hear. 2008 Apr;29(2):250-60. doi: 10.1097/aud.0b013e3181645336.
To compare the effects of Monopole (Mono), Tripole (Tri), and "Virtual channel" (Vchan) electrode configurations on spectral resolution and speech perception in a crossover design.
Nine experienced adults who received an Advanced Bionics CII/90K cochlear implant participated in a crossover design using three experimental strategies for 2 wk each. Three strategies were compared: (1) Mono; (2) Tri with current partly returning to adjacent electrodes and partly (25 or 75%) to the extracochlear reference; and (3) a monopolar "Vchan" strategy creating seven intermediate channels between two contacts. Each strategy was a variant of the standard "HiRes" processing strategy using 14 channels and 1105 pulses/sec/ channel, and a pulse duration of 32 microsec/phase. Spectral resolution was measured using broadband noise with a sinusoidally rippled spectral envelope with peaks evenly spaced on a logarithmic frequency scale. Speech perception was measured for monosyllables in quiet and in steady-state and fluctuating noises. Subjective comments on music experience and preferences in everyday use were assessed through questionnaires.
Thresholds and most comfortable levels with Mono and Vchan were both significantly lower than levels with Tri. Spectral resolution was significantly higher with Tri than with Mono; spectral resolution with Vchan did not differ significantly from the other configurations. Moderate but significant correlations between word recognition and spectral resolution were found in speech in quiet and fluctuating noise. For speech in quiet, word recognition was best with Mono and worst with Vchan; Tri did not significantly differ from the other configurations. Pooled across the noise conditions, word recognition was best with Tri and worst with Vchan (Mono did not significantly differ from the other configurations). These differences were small and insufficient to result in a clear increase in performance across subjects if the result from the best configuration per subject was compared with the result from Mono. Across all subjects, music appreciation and satisfaction in everyday use did not clearly differ between configurations.
(1) Although spectral resolution was improved with the tripolar configuration, differences in speech performance were too small in this limited group of subjects to justify clinical introduction. (2) Overall spectral resolution remained extremely poor compared with normal hearing; it remains to be seen whether further manipulations of the electrical field will be more effective.
在交叉设计中比较单极（Mono）、三极（Tri）和“虚拟通道”（Vchan）电极配置对频谱分辨率和言语感知的影响。
九名接受先进仿生学公司CII/90K人工耳蜗植入的有经验的成年人参与交叉设计，每种实验策略各使用两周。比较了三种策略：（1）单极；（2）三极，电流部分返回相邻电极，部分（25%或75%）返回蜗外参考电极；（3）一种单极“虚拟通道”策略，在两个触点之间创建七个中间通道。每种策略都是标准“高分辨率”处理策略的变体，使用14个通道，每个通道1105个脉冲/秒，脉冲持续时间为每个相位32微秒。使用具有正弦波纹频谱包络且峰值在对数频率尺度上均匀间隔的宽带噪声测量频谱分辨率。在安静环境以及稳态和波动噪声中测量单音节词的言语感知。通过问卷调查评估对音乐体验和日常使用偏好的主观评价。
单极和虚拟通道配置下的阈值和最舒适水平均显著低于三极配置下的水平。三极配置的频谱分辨率显著高于单极配置；虚拟通道配置的频谱分辨率与其他配置无显著差异。在安静和波动噪声环境下的言语中，单词识别与频谱分辨率之间存在中度但显著的相关性。在安静环境下的言语中，单极配置的单词识别最佳，虚拟通道配置最差；三极配置与其他配置无显著差异。综合所有噪声条件，三极配置的单词识别最佳，虚拟通道配置最差（单极配置与其他配置无显著差异）。如果将每个受试者最佳配置的结果与单极配置的结果进行比较，这些差异很小，不足以使所有受试者的表现明显提高。在所有受试者中，不同配置之间在日常使用中的音乐欣赏和满意度没有明显差异。
（1）尽管三极配置提高了频谱分辨率，但在这一有限的受试者群体中，言语表现的差异太小，不足以证明可在临床上引入。（2）与正常听力相比，整体频谱分辨率仍然极差；电场的进一步操控是否会更有效仍有待观察。
