Volume Booster - At first glance it may seem that this application does not need, but do not rush. Many smartphone users, there is the problem that the maximum volume of sound is not enough, and even when it was included in full, their sound was pretty quiet. So this app will help to circumvent this barrier, and increase your max sound for another 20 - 30%. Yes, this sound quality gets a little worse, but this is an essential feature if you want to customize the sound of call to your grandparents who may not hear the usual signal. Or if you need to make the alarm louder, that would not sleep through something important.