Sonic doesn't really fit into electormagnetic frequencies.. The reason sonic waves can somewhat pass through walls is that they are vibrations in the air, so if there's any spaces where air can pass, or even if the wall itself is made to vibrate and then passes it on to air on the other side, that's how it can pass through walls. Generally speaking, nothing below UV radiation damages DNA, hense why people aren't dropping dead from visible light or radio waves. (Which by the way have been occuring naturally for billions of years). The exception we may see is a specific frequency of microwaves (as used in microwave ovens, which do interact with matter even though they're fairly low energy. This is because the wavelength is the same as the length of atomic bonds in water, and it makes water molecules vibrate, creating heat.
Cell phones typically use somewhere in the range of shorter radio waves up to the longer frequencies of microwaves. This is still FAR below even visible light, and much much weaker than the really dangerous stuff, like x-rays. So the only thing a cellphone may do is create a bit of heat, not DNA damage. However, if you look at the power of you're phone's output, compared to a microwave oven, and also account for the fact that your body will regulate the temperature of tissues by circulation, sweating, etc, any tiny amounts of heat the phone may create will be easily handled by your body. Your brain will not cook.