The wave length (frequency) will effect how directional the sound is.
Low direction has longer wave lengths and is usually heard by both ears at or about the same time. It also bounces better and spreads more (lamens terms)
Higher frequncy (10 -15Khz) is more dirctional because the wavelength is smaller. In lamens terms one ear hears it ebefore or instead of the other because of the distance involved (think about it sound travels in waves and at a set speed with very few variables)
An analogy, a bass drumb is heard by many were as a horn has to be pointed somwhere.
