IPhone 5. No problems so far.
This app is *exactly* what I was looking for. Each section offers a short audio passage, spoken at (I assume) natural speed (fast). You, the listener, are then expected to answer a short question about what you just heard.
This app is definitely a wake-up all for me. I've been studying off and on for several years but have never attepted the JLPT. Listening (and speaking) are my biggest hurdles and this app showed me just how high the listening hurdle is. I'm doing good to determine the topic of the passage -- I have no clue about the details! I have a lot of work to do. Right now, the app is on the back page, but I'll keep coming back to it to monitor my progress.