Agarwalla Swapna, Farhadi Afagh, Carney Laurel H
Department of Biomedical Engineering, University of Rochester, Rochester, New York 14627, USA.
Department of Speech, Language and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
J Acoust Soc Am. 2025 May 1;157(5):3680-3693. doi: 10.1121/10.0036741.
In forward masking, the detection threshold for a target sound (probe) is elevated due to the presence of a preceding sound (masker). Although many factors are known to influence the probe response following a masker, the current work focused on the temporal separation (delay) between the masker and probe and the inter-trial interval (ITI). Human probe thresholds recover from forward masking within 150-300 ms, similar to neural threshold recovery in the inferior colliculus (IC) within 300 ms after tone maskers. Our study focused on the recovery of discharge rate of IC neurons in response to probe tones after narrowband Gaussian noise (GN) forward maskers, with varying time delays. Additionally, we examined how prior masker trials influenced IC rates by varying ITI. Previous masker trials affected probe-evoked discharge rates, with full recovery requiring ITIs over 1.5 s after 70 dB SPL narrowband GN maskers. Neural thresholds in the IC for probes preceded by noise maskers were in the range observed in psychoacoustical studies. Two proposed mechanisms for forward masking, persistence, and efferent gain control, were tested using rate analyses or computational modeling. A physiological model with efferent feedback gain control had responses consistent with trends in the physiological recordings.
在前向掩蔽中，由于存在先于目标声音（探测音）的声音（掩蔽音），目标声音的检测阈值会升高。尽管已知许多因素会影响掩蔽音之后的探测音响应，但当前的研究重点是掩蔽音与探测音之间的时间间隔（延迟）以及试验间隔（ITI）。人类探测音阈值在前向掩蔽后150 - 300毫秒内恢复，类似于下丘（IC）中音调掩蔽音后300毫秒内的神经阈值恢复。我们的研究重点是在具有不同时间延迟的窄带高斯噪声（GN）前向掩蔽后，IC神经元对探测音的放电率恢复情况。此外，我们通过改变ITI来研究先前的掩蔽音试验如何影响IC放电率。先前的掩蔽音试验影响探测音诱发的放电率，对于70 dB SPL窄带GN掩蔽音，完全恢复需要ITI超过1.5秒。噪声掩蔽音之前的探测音在IC中的神经阈值处于心理声学研究中观察到的范围内。使用速率分析或计算模型对前向掩蔽的两种提出的机制，即持续性和传出增益控制进行了测试。具有传出反馈增益控制的生理模型的反应与生理记录中的趋势一致。
