Effects of reduced spectral uncertainty and masker fringes with multitonal maskers

This study examined the degree to which masker spectral uncertainty contributes to the high thresholds often observed with random‐frequency, multitonal, simultaneous maskers. Masked thresholds for four normal‐hearing adults were measured for a 1000‐Hz, 200‐ms signal presented with broadband‐noise or multitonal maskers with 2 or 10 components. The multi‐tonal maskers were 70 dB SPL and had a 160‐Hz spectral gap centered at the signal. Two sets of conditions, using a 2AFC adaptive task, manipulated the degree of spectral uncertainty (masker randomized with each presentation vs fixed throughout a block of trials) and the temporal offset of the masker (masker equal to signal duration vs. masker increased to 400 ms, with a 100‐ms fringe preceding and following the signal). A third set of ‘‘molecular’’ conditions, using a yes‐no adaptive task, measured thresholds with five samples of multitonal maskers, either randomizing samples across trials or using one sample throughout trial blocks. For both large‐set and ...

本研究考察了掩蔽声频谱不确定性在多大程度上导致了在随机频率、多频、同时掩蔽声情况下经常观察到的高阈值。对四名听力正常的成年人测量了其在1000Hz、200ms信号被宽带噪声或具有2个或10个成分的多频掩蔽声掩蔽时的掩蔽阈值。多频掩蔽声为70dB声压级，在信号中心有一个160Hz的频谱间隙。两组条件采用二项迫选自适应任务，操纵频谱不确定性的程度（每次呈现时掩蔽声随机化与在一组试验中固定不变）以及掩蔽声的时间偏移（掩蔽声与信号持续时间相同与掩蔽声增加到400ms，在信号前后各有100ms的边缘）。第三组“分子”条件采用是 - 否自适应任务，用多频掩蔽声的五个样本测量阈值，要么在试验中随机选取样本，要么在整个试验组中使用一个样本。对于大样本集和……