在英语中, 尤其在美国英语中, 轻读音节 [ I ] 和   [ə] 是可以混读的, 如 believe/behind 里的 be- ; it 和 at 轻读在快速语流里常常读相同的音[ət]; effect 和 affect 也可以读相同的发音。recognize 中的字母o最经常被读做[ I ] 。 eraser 的第一个字母e 既可以读 [ I ] 也可以读   [ə]，因人而异, 读  [ə] 也许还更经常呢。

LONGMAN DICTIONARY OF AMERICAN ENGLISH 《朗文美语词典》：
Unstressed Vowels
[ I ]  and   [ə]  
Many unstressed syllables in American English are pronounced with a very short unclear vowel. This vowel is shown as [ I ] or   [ə] ; however, there is very little difference between them in normal connected speech. For example, the word affect and effect usually sound the same. The word  
rabbit is shown as /rabbit/, but it may also be pronounced /rabbət/  .

it 和 at 轻读在快速语流里常常读相同的音[ət]，这个说法见于AMERICAN ACCENT TRAINING 一书。