Ewert Stephan D, Schubotz Wiebke, Brand Thomas, Kollmeier Birger
Medizinische Physik and Cluster of Excellence Hearing4all, Universität Oldenburg, D-26111 Oldenburg, Germany.
J Acoust Soc Am. 2017 Jul;142(1):12. doi: 10.1121/1.4990019.
Speech reception thresholds (SRTs) decrease as target and maskers are spatially separated (spatial release from masking, SRM). The current study systematically assessed how SRTs and SRM for a frontal target in a spatially symmetric masker configuration depend on spectro-temporal masker properties, the availability of short-time interaural level difference (ILD) and interaural time difference (ITD), and informational masking. Maskers ranged from stationary noise to single, interfering talkers and were modified by head-related transfer functions to provide: (i) different binaural cues (ILD, ITD, or both) and (ii) independent maskers in each ear ("infinite ILD"). Additionally, a condition was tested in which only information from short-time spectro-temporal segments of the ear with a favorable signal-to-noise ratio (better-ear glimpses) was presented. For noise-based maskers, ILD, ITD, and spectral changes related to masker location contributed similarly to SRM, while ILD cues played a larger role if temporal modulation was introduced. For speech maskers, glimpsing and perceived location contributed roughly equally and ITD contributed less. The "infinite ILD" condition might suggest better-ear glimpsing limitations resulting in a maximal SRM of 12 dB for maskers with low or absent informational masking. Comparison to binaural model predictions highlighted the importance of short-time processing and helped to clarify the contribution of the different binaural cues and mechanisms.
随着目标声源与掩蔽声在空间上分离（空间掩蔽释放，SRM），言语接受阈（SRTs）会降低。本研究系统评估了在空间对称掩蔽声配置中，针对前方目标的SRTs和SRM如何依赖于频谱-时间掩蔽声特性、短时耳间声级差（ILD）和耳间时间差（ITD）的可用性以及信息掩蔽。掩蔽声范围从稳态噪声到单个干扰说话者，并通过头相关传递函数进行修改，以提供：（i）不同的双耳线索（ILD、ITD或两者）和（ii）每只耳朵中的独立掩蔽声（“无限ILD”）。此外，还测试了一种条件，即仅呈现来自具有良好信噪比耳朵的短时频谱-时间片段的信息（较好耳瞥见）。对于基于噪声的掩蔽声，ILD、ITD以及与掩蔽声位置相关的频谱变化对SRM的贡献相似，而如果引入时间调制，ILD线索则发挥更大作用。对于言语掩蔽声，瞥见和感知位置的贡献大致相等，而ITD的贡献较小。“无限ILD”条件可能表明较好耳瞥见存在局限性，导致对于具有低信息掩蔽或无信息掩蔽的掩蔽声，最大SRM为12 dB。与双耳模型预测的比较突出了短时处理的重要性，并有助于阐明不同双耳线索和机制的贡献。
