Hi,
I'm a native Japanese speaker from Tokyo. I've noticed that there are quite a few words that don't have the right pronunciation samples. For example, the sound sample for 「欠ける」 sounds like 「書ける」; both would be 「かける」 in hiragana, but the pitches are different (pitches described at http://sp.cis.iwate-u.ac.jp/sp/lesson/j/doc/accent.html ).
There could be some improvement. Where do you get your sound samples from?