[autumnstwilight]

Japanese vowels are simple and consistent, for example 'e' is always the 'e' sound in 'bed', but (due to the history of the English language) English speakers are used to taking in the context of the vowels and pronouncing them in a variety of ways. When reading Japanese (in which the surrounding letters do not provide any hints as to how to pronounce the vowels), English speakers often end up guessing at random, sometimes pronouncing 'a' like in 'cat', sometimes pronouncing it like in 'father', etc.

Since Japanese has simple and consistent rules for vowel pronunciation, and Japanese people aren't used to hearing much deviation from these rules, this often means what the English speaker is saying is entirely incomprehensible to them.