Centre for Applied Hearing Research, Department of Electrical Engineering, Technical University of Denmark, Orsteds Plads, Building 352, DK-2800 Kgs Lyngby, Denmark.
J Acoust Soc Am. 2013 Sep;134(3):2197-204. doi: 10.1121/1.4816409.
Masking release (MR) is the improvement in speech intelligibility for a fluctuating interferer compared to stationary noise. Reduction in MR due to vocoder processing is usually linked to distortions in the temporal fine structure of the stimuli and a corresponding reduction in the fundamental frequency (F0) cues. However, it is unclear if envelope periodicity related to F0, produced by the interaction between unresolved harmonics, contributes to MR. In the present study, MR was determined from speech reception thresholds measured in the presence of stationary speech-shaped noise and a competing talker. Two types of processing were applied to the stimuli: (1) An amplitude- and frequency-modulated vocoder attenuated the envelope periodicity and (2) high-pass (HP) filtering (cutoff = 500 Hz) reduced the influence of F0-related information from low-order resolved harmonics. When applied individually, MR was unaffected by HP filtering, but slightly reduced when envelope periodicity was attenuated. When both were applied, MR was strongly reduced. Thus, the results indicate that F0-related information is crucial for MR, but that it is less important whether the F0-related information is conveyed by low-order resolved harmonics or by envelope periodicity as a result of unresolved harmonics. Further, envelope periodicity contributes substantially to MR.
掩蔽释放（MR）是指与固定噪声相比，波动干扰者的语音可懂度的提高。由于声码器处理导致的 MR 减少通常与刺激的时间精细结构的失真以及基频（F0）线索的相应减少有关。然而，目前尚不清楚由未解析谐波相互作用产生的与 F0 相关的包络周期性是否有助于 MR。在本研究中，通过在存在固定语音噪声和竞争说话者的情况下测量语音接收阈值来确定 MR。对刺激应用了两种类型的处理：（1）幅度和频率调制声码器衰减了包络周期性，（2）高通（HP）滤波（截止频率= 500 Hz）降低了来自低阶解析谐波的 F0 相关信息的影响。当单独应用时，HP 滤波对 MR 没有影响，但当衰减包络周期性时，MR 略有降低。当两者都应用时，MR 则大大降低。因此，结果表明，F0 相关信息对 MR 至关重要，但 F0 相关信息是通过低阶解析谐波还是通过未解析谐波的包络周期性来传递则不太重要。此外，包络周期性对 MR 有很大贡献。
