Threshold hypothesis and bottom-up processing in English listening of Japanese learners : High-frequency sound discrimination and categorical perception of consonants

在听力理解的加工模式中，熟练的学习者被认为具有自动的自下而上的技能，这使得他们能够有效地利用自上而下的技能。也有人说，自下而上的技能必须达到一个门槛水平，自上而下的技能才能使用。本研究主要关注听力的“高频水平”，并提出以下假设：（1）精通英语的日本人对高频纯音的辨别能力较强。(2)熟练的听者在词的层次上对辅音的辨别能力更高。(3)高频纯音的辨别能力与辅音辨别能力呈正相关。(4)对于熟练的英语听力者来说，高频纯音的辨别能力和辅音的辨别能力都存在一定的阈值水平。我们准备了2000 Hz和3000 Hz的纯音辨别测试和L-R分类测试，并分析了132名参与者的数据。L-R分类是以4种不同的速度用[轻-右] [玩-祈祷]对进行测试的。此外，控制较高/较低频率声音的条件。结果表明，高水平的参与者，如GTEC测量：（1）区分高频纯音显着更好，（2）显着更高的能力，在区分辅音。至于假设（3），相关性仅在2000 Hz声级下具有统计学显著性，尽管它被认为不是很强。结果还表明，只有高度熟练的听者可以区分L-R声音时，低于1400 Hz的区域被切断的刺激。这被认为支持假设（4）。

In the processing model of listening comprehension, proficient learners are considered to have automatic bottom-up skills, which enable them to utilize the top-down skills effectively. It is also said that the bottom-up skills must reach a threshold level for the top-down skills to be employed. The current investigation focused on the role of "high-frequency levels" of listening and posited the following hypotheses : (1) Proficient Japanese listeners of English have better discriminatory ability for high-frequency pure sounds. (2) Proficient listeners have higher ability in discriminating consonants at the word level. (3) Discriminatory ability for high-frequency pure sounds positively correlates with consonant discrimination. (4) There exist threshold levels for discriminatory ability for high-frequency pure sounds as well as consonant discrimination for proficient listeners of English. We prepared pure-sound discrimination tests for 2000Hz and 3000Hz and an L-R categorization test and analyzed 132 participants' data. L-R categorization was tested with [light-right] [play-pray] pairs at 4 different speeds. Additionally, conditions of higher/lower frequency sounds were controlled. The findings indicate that the high-proficiency participants, as measured by the GTEC : (1) discriminated high-frequency pure sounds significantly better and (2) showed significantly higher ability in discriminating consonants. As for the hypothesis (3), the correlation was statistically significant only at the 2000 Hz sound level, although it was not considered very strong. Results also indicated that only highly proficient listeners could discriminate L-R sounds when the areas lower than 1400 Hz were cut in the stimuli. This is considered to support Hypothesis (4).