Is it just me or are some of the words' (not characters') audio pronunciations non-standard? One example I just came across was 协作, xie2 zuo4, which when I hit 'a' sounds like 'jie2 suo4' to me. This is one example, but I know there have been other words which threw me off also when I heard the prerecorded sound.
So, is it just my ears or what? Some descriptions of words overlap somewhat and I use the audio to clarify those situations before writing, but in these cases it makes things harder, not easier!