The Acoustic Nerves enter the brain stem in the Medulla where most nerves cross to the opposite side.
In order that neural transmissions can mirror high frequency sounds, neurons work in complicated units or banks and fire in volleys.
The Acoustic (VIII th) nerve from each ear enters the brain stem at the level of the top of the Medulla. Here, curiously, most of the nerve fibers cross to the opposite side and proceed up through the Pons, Midbrain and Thalamus to the Temporal Lobe of the Cerebral Cortex.
NOTES: More information on the Auditory Pathways.