It's on the penultimate syllable unless there is a written accent. So, it's the second one. The Duolingo audio is wrong.
You can hear the correct pronunciations by clicking the speaker button at these links:
Seems like since April (2014) people have been complaining about the audio or questioning the pronunciation of the only two words in this sample phrase. I wish native speakers would confirm that audio is indeed terrible; I'd hate to add to the complaints, but it DOES sound very, very strange to me, too. In fact, it sounds "wrong" and, yes, awful :(. And it's now October 15, 2014!
Duo's translation box shows that "personales" can also translate to the English word "personnel", which is a noun. Would the phrase structure be different if i wanted the phrase to mean "PERSONNEL objects"? Ex. Objetos DE personales. "Personal" is an adjective while "Personnel" is a noun. Hope somebody understands what i mean. Thanks
Warren, In real life, probably, but on Duolingo the best I can reply is perhaps. Try "items" the next time you encounter this phrase. I think I'm in the beta phase, so if I get one wrong I just have to answer more before the session is over; it's a better system than three strikes and you're out. Buena suerte!