Espinoza-Varas B, Watson C S
J Acoust Soc Am. 1986 Dec;80(6):1685-94. doi: 10.1121/1.394281.
This paper extends previous research on listeners' abilities to discriminate the details of brief tonal components occurring within sequential auditory patterns (Watson et al., 1975, 1976). Specifically, the ability to discriminate increments in the duration delta t of tonal components was examined. Stimuli consisted of sequences of ten sinusoidal tones: a 40-ms test tone to which delta t was added, plus nine context tones with individual durations fixed at 40 ms or varying between 20 and 140 ms. The level of stimulus uncertainty was varied from high (any of 20 test tones occurring in any of nine factorial contexts), through medium (any of 20 test tones occurring in ten contexts), to minimal levels (one test tone occurring in a single context). The ability to discriminate delta t depended strongly on the level of stimulus uncertainty, and on the listener's experience with the tonal context. Asymptotic thresholds under minimal uncertainty approached 4-6 ms, or 15% of the duration of the test tones; under high uncertainty, they approached 40 ms, or 10% of the total duration of the tonal sequence. Initial thresholds exhibited by inexperienced listeners are two-to-four times greater than the asymptotic thresholds achieved after considerable training (20,000-30,000 trials). Isochronous sequences, with context tones of uniform, 40-ms duration, yield lower thresholds than those with components of varying duration. The frequency and temporal position of the test tones had only minor effects on temporal discrimination. It is proposed that a major determinant of the ability to discriminate the duration of components of sequential patterns is the listener's knowledge about "what to listen for and where." Reduced stimulus uncertainty and extensive practice increase the precision of this knowledge, and result in high-resolution discrimination performance. Increased uncertainty, limited practice, or both, would allow only discrimination of gross changes in the temporal or spectral structure of the sequential patterns.
本文扩展了先前关于听众辨别连续听觉模式中短暂音调成分细节能力的研究（沃森等人，1975年，1976年）。具体而言，研究了辨别音调成分持续时间增量Δt的能力。刺激由十个正弦音调序列组成：一个添加了Δt的40毫秒测试音，加上九个上下文音调，其各自的持续时间固定为40毫秒或在20至140毫秒之间变化。刺激的不确定性水平从高（20个测试音中的任何一个出现在九个因子上下文中的任何一个），到中（20个测试音中的任何一个出现在十个上下文中），再到最低水平（一个测试音出现在单个上下文中）。辨别Δt的能力在很大程度上取决于刺激的不确定性水平以及听众对音调上下文的经验。在最小不确定性下的渐近阈值接近4 - 6毫秒，即测试音持续时间的15%；在高不确定性下，它们接近40毫秒，即音调序列总持续时间的10%。没有经验的听众最初表现出的阈值比经过大量训练（20000 - 30000次试验）后达到的渐近阈值大两到四倍。具有均匀40毫秒持续时间上下文音的等时序列产生的阈值低于具有不同持续时间成分的序列。测试音的频率和时间位置对时间辨别只有轻微影响。有人提出，辨别连续模式成分持续时间能力的一个主要决定因素是听众关于“听什么以及在哪里听”的知识。降低刺激的不确定性和广泛的练习会提高这种知识的精度，并导致高分辨率的辨别性能。增加的不确定性、有限的练习或两者兼而有之，只会允许辨别连续模式在时间或频谱结构上的大致变化。
