Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, Washington 98195, USA.
J Acoust Soc Am. 2011 Jul;130(1):376-88. doi: 10.1121/1.3592521.
The goals of the present study were to measure acoustic temporal modulation transfer functions (TMTFs) in cochlear implant listeners and examine the relationship between modulation detection and speech recognition abilities. The effects of automatic gain control, presentation level and number of channels on modulation detection thresholds (MDTs) were examined using the listeners' clinical sound processor. The general form of the TMTF was low-pass, consistent with previous studies. The operation of automatic gain control had no effect on MDTs when the stimuli were presented at 65 dBA. MDTs were not dependent on the presentation levels (ranging from 50 to 75 dBA) nor on the number of channels. Significant correlations were found between MDTs and speech recognition scores. The rates of decay of the TMTFs were predictive of speech recognition abilities. Spectral-ripple discrimination was evaluated to examine the relationship between temporal and spectral envelope sensitivities. No correlations were found between the two measures, and 56% of the variance in speech recognition was predicted jointly by the two tasks. The present study suggests that temporal modulation detection measured with the sound processor can serve as a useful measure of the ability of clinical sound processing strategies to deliver clinically pertinent temporal information.
本研究的目的是测量人工耳蜗使用者的声音时域调制传递函数（TMTF），并探讨调制检测与言语识别能力之间的关系。使用受话器的临床声音处理器，研究了自动增益控制、呈现水平和通道数对调制检测阈值（MDT）的影响。TMTF 的一般形式为低通，与之前的研究一致。当刺激在 65 dBA 呈现时，自动增益控制的操作对 MDT 没有影响。MDT 不依赖于呈现水平（范围为 50 至 75 dBA），也不依赖于通道数。在 MDT 和言语识别得分之间发现了显著的相关性。TMTF 的衰减率可预测言语识别能力。评估了频谱波纹辨别力，以检验时域和频谱包络敏感性之间的关系。这两个测量值之间没有相关性，两个任务共同预测了言语识别能力的 56%的方差。本研究表明，使用声音处理器测量的时域调制检测可以作为评估临床声音处理策略传递临床相关时间信息能力的有用指标。
