Lower frequencies are Limited by the shortest dimesnion in a room (usually ceiling height). Other than that you are generally talking about room nodes (the points at which standing waves tend to cancel out). Generally this is at quarter wave locations.The most often ignored factor in how your drums sound is the room itself. If you don't have an acoustically treated space (and I mean doing it right- not a bunch of cheap foam) you've likely got locations throughout the room where certain frequencies (particularly lower frequencies) aren't present. This could be where your ears are or where the drum is.