Lopez-Poveda Enrique A, Eustaquio-Martín Almudena, Fumero Milagros J, Gorospe José M, Polo López Rubén, Gutiérrez Revilla M Auxiliadora, Schatzer Reinhold, Nopp Peter, Stohl Joshua S
Laboratorio de Audición Computacional y Psicoacústica, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain.
Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain.
Ear Hear. 2020 Nov/Dec;41(6):1492-1510. doi: 10.1097/AUD.0000000000000880.
OBJECTIVES: Cochlear implant (CI) users continue to struggle understanding speech in noisy environments with current clinical devices. We have previously shown that this outcome can be improved by using binaural sound processors inspired by the medial olivocochlear (MOC) reflex, which involve dynamic (contralaterally controlled) rather than fixed compressive acoustic-to-electric maps. The present study aimed at investigating the potential additional benefits of using more realistic implementations of MOC processing. DESIGN: Eight users of bilateral CIs and two users of unilateral CIs participated in the study. Speech reception thresholds (SRTs) for sentences in competition with steady state noise were measured in unilateral and bilateral listening modes. Stimuli were processed through two independently functioning sound processors (one per ear) with fixed compression, the current clinical standard (STD); the originally proposed MOC strategy with fast contralateral control of compression (MOC1); a MOC strategy with slower control of compression (MOC2); and a slower MOC strategy with comparatively greater contralateral inhibition in the lower-frequency than in the higher-frequency channels (MOC3). Performance with the four strategies was compared for multiple simulated spatial configurations of the speech and noise sources. Based on a previously published technical evaluation of these strategies, we hypothesized that SRTs would be overall better (lower) with the MOC3 strategy than with any of the other tested strategies. In addition, we hypothesized that the MOC3 strategy would be advantageous over the STD strategy in listening conditions and spatial configurations where the MOC1 strategy was not. RESULTS: In unilateral listening and when the implant ear had the worse acoustic signal-to-noise ratio, the mean SRT was 4 dB worse for the MOC1 than for the STD strategy (as expected), but it became equal or better for the MOC2 or MOC3 strategies than for the STD strategy. In bilateral listening, mean SRTs were 1.6 dB better for the MOC3 strategy than for the STD strategy across all spatial configurations tested, including a condition with speech and noise sources colocated at front where the MOC1 strategy was slightly disadvantageous relative to the STD strategy. All strategies produced significantly better SRTs for spatially separated than for colocated speech and noise sources. A statistically significant binaural advantage (i.e., better mean SRTs across spatial configurations and participants in bilateral than in unilateral listening) was found for the MOC2 and MOC3 strategies but not for the STD or MOC1 strategies. CONCLUSIONS: Overall, performance was best with the MOC3 strategy, which maintained the benefits of the originally proposed MOC1 strategy over the STD strategy for spatially separated speech and noise sources and extended those benefits to additional spatial configurations. In addition, the MOC3 strategy provided a significant binaural advantage, which did not occur with the STD or the original MOC1 strategies.
目的:目前的临床设备仍使人工耳蜗(CI)使用者在嘈杂环境中理解言语存在困难。我们之前已经表明,通过使用受内侧橄榄耳蜗(MOC)反射启发的双耳声音处理器可以改善这一结果,这种处理器涉及动态(对侧控制)而非固定的压缩声电映射。本研究旨在探究使用更逼真的MOC处理实现方式可能带来的额外益处。 设计:8名双侧CI使用者和2名单侧CI使用者参与了本研究。在单侧和双侧聆听模式下,测量了与稳态噪声竞争时句子的言语接受阈值(SRT)。刺激信号通过两个独立运行的声音处理器(每只耳朵一个)进行处理,分别采用固定压缩,即当前的临床标准(STD);最初提出的具有快速对侧压缩控制的MOC策略(MOC1);具有较慢压缩控制的MOC策略(MOC2);以及在低频通道比高频通道具有相对更大对侧抑制的较慢MOC策略(MOC3)。针对言语和噪声源的多种模拟空间配置,比较了这四种策略的性能。基于之前发表的对这些策略的技术评估,我们假设MOC3策略的SRT总体上会比其他任何测试策略更好(更低)。此外,我们假设在MOC1策略不占优势的聆听条件和空间配置下,MOC3策略将优于STD策略。 结果:在单侧聆听且植入耳的声信噪比更差时,MOC1的平均SRT比STD策略差4 dB(如预期),但MOC2或MOC3策略的平均SRT与STD策略相当或更好。在双侧聆听中,在所有测试的空间配置下,MOC3策略的平均SRT比STD策略好1.6 dB,包括言语和噪声源位于前方同一位置的情况,此时MOC1策略相对于STD策略略有劣势。对于空间分离的言语和噪声源,所有策略产生的SRT都显著优于位于同一位置的情况。发现MOC2和MOC3策略具有统计学上显著的双耳优势(即,在空间配置和参与者中,双侧聆听的平均SRT比单侧聆听更好),而STD或MOC1策略则没有。 结论:总体而言,MOC3策略的性能最佳,它保持了最初提出的MOC1策略相对于STD策略在空间分离的言语和噪声源方面的优势,并将这些优势扩展到其他空间配置。此外,MOC3策略提供了显著的双耳优势,而STD或原始MOC1策略则没有。
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