Press the play button on the app's opening page, and you'll hear the two-syllable word mama with one of the 20 unique tone combinations for two-syllable words in Chinese. By doing it this way, it accustoms you to the way tones changes when used together with another tone, something Chinese learners usually tend to overlook.
You then must select the tones for each syllable by simply tapping on a graphical representation of the tones. Each test goes through all 20 tone combinations in a random order, only taking a couple minutes.
You get 2 points for each correct tone and 1 point for each answer provided in less than 3 seconds (you also get 1 point off for each answer provided in more than 6 seconds).
Despite all these years of using Chinese, I still view tones as one of my weak spots. That's largely because I had teachers who didn't care about tones; since I needed to care about my grades that left me ignoring tones at the time as well. Thus my use of tones is largely instinctual, just picking things up from what I heard.
Well, it seems I didn't do too bad, because I consistently score in the "good" range. My high score was an 88. My low score of 70 came when I was doing this while a train pulled into the station I was at, which is pretty much real-life accurate; with loud noises around you, you're gonna have a harder time hearing (shocking!).
What I love about this app is that it's just so quick to use. Because it takes so little time to run through the drills, you can do it anytime at a moment's notice. And it does seem to be effective; just after using it for a few days, my average score seems to be going up from close to 80 to the mid 80s.
The scoring system could probably be improved. As is, you can game the system to some degree just by answering fast. I tend to answer quickly, meaning I get the full 20 point speedy-answer bonus every time. That's enough to cover 10 mistaken tones, or a full 25% of all the tones tested. For instance, if I get 30/40 tones correct (60 points) and get the full 20-point bonus, that I'm "good" even though I messed up a full quarter of the tones.
One way to remedy this would simply be to only give the time bonus if the answer's correct A time bonus is given if you answer quickly and at least one of the two tones is correct, but I'd probably suggest some kind of split system. The user would start without worrying about timing, and would thus be able to repeatedly listen to the words as much as he or she likes. The app would monitor accuracy and how many times the user presses the replay button and, once the user stops using the button and reaches a certain threshold accuracy, the app could add in the timing aspect.
Down the line, the app is looking to incorporate speaking the tones as well as listening to the tones, and I very much look forward to that feature.
For the time being, however, Laokang Tone Test is a great, simple way to improve your ability to distinguish Chinese tones through quick bursts of listening practice, and I'd recommend it strongly to any Chinese learner.
This post was updated on 30 November 2011 to reflect some clarifications from the developer in the comments below.