It is said that it takes 10,000 hours of practice to become a master of something. Practice Timer gives you a simple indication of just how far along you are.
The idea is simple, and so is the app. When you start playing your instrument, the app starts a timer. When you stop, the timer stops. Start again, and the timer picks up from where you last left it.
Unfortunately, the app picks up any audible noise present -- there's no fancy algorithm to distinguish what is a musical instrument and what is the TV. However, there is an adjustable input volume threshold to customize to the volume of what you're practicing on, so unwanted input can be accounted for.
Additionally, when looking back, there's a calender that tracks your progress on a daily and monthly basis. Simply select a range of dates to see how much time you've put in at specific points in a month. You can print, email and brag about your log to your Facebook and Twitter friends, too.
In practice (excuse the pun), Practice Timer is probably going to be beneficial to kids who need a bit of encouragement and discipline in learning the art of practicing. For everyone else, it's probably not going to be all that necessary to track your practice time in this much detail, but each to their own. Practice Timer would also benefit from some extra features to aid with practicing, like a built-in metronome.
Practice Timer is available from the iOS App Store for US$1.99. But do check out a couple of the free options on the App Store first before taking the plunge with Practice Timer.