The neurons of the DCN and VCN are the second order neurons of the auditory pathway. A majority of the axons from these neurons cross over before making their way up through the brainstem while a small number of fibers continue upward ipsilaterally. Most of the crossed fibers synapse with the neurons in the superior olive . The superior olive receives fibers from both the ipsilateral and contralateral ventral and dorsal cochlear nuclei. Some crossed fibers skip the superior olive to go directly to the inferior colliculus in the brainstem.
Superior olive is believed to be prominently involved in the spatial localization of sound.
The horizontal localization of sound appears to be based on the differences in arrival time and intensity of auditory input from the two ears. The ear closest to the sound source receives sound a fraction of a second earlier and the sound signal also has greater intensity at that ear. In addition, as with all other parts of the auditory pathway, the superior olive is also tonotopically organized. The medial superior olive processes low frequency sounds and the lateral superior olive receives high frequency sounds. The stapedial reflex , in which the stapedial muscle in the middle ear contracts in response to loud sounds, is mediated by the superior olive.