[chryuop]

I admit that the "g" sound puzzles me alot in Japanese. I watch alot of Japanese TV and listen to alot of Japanese music and many times the particle I know it is "ga" coz it marks the subject sounds way too close to "na"...and that my misunderstanding of the "g" messes me up also with regular words.
Another particle that used to mess me up is the direct object one (o). Depending on the final sound of the word before it, it can sound like a wo.

But when it is not you language it is easy to hear wrong sounds trust me. I have a guy who is trying to learn Italian asking me for some help. He can't hear the sound of vowels ending a word when the next word starts with a vowel...while I (being Italian) can hear them pretty clear.