因为两个字的发音完全一样，所以听见没有法子分别。 在日常会话中我们要免生误解，长用其他字词。

You could work it out easily from the context: if the topic is about listening, then you can be sure that word is "aural". I'm not sure how it's written in your dictionary, but if I wanted to be completely clear in speech, I'd make the "au" in "aural" longer, and keep the word "oral" as short syllables.