This dissertation investigates two unique phenomena, neurotransmitter co-release and neural oscillations, in early auditory regions where they have not been observed before. Co-release and oscillations are common processes in other brain regions, where they are thought to expand the computational capacity of local circuits. Co-release is the release of two neurotransmitter types packaged into the same presynaptic vesicles within a neuron and oscillations are rhythmic electrical fluctuations observed in single neurons, brain regions, and even spanning brain regions (Vaaga et al., 2014). How they contribute to early auditory processing, however, is not understood. We investigated co-release of two inhibitory neurotransmitters in the inferior colliculus, the midbrain hub for auditory processing. We also established the presence of slow oscillations in the principal neurons of the dorsal cochlear nucleus (DCN), a key brainstem nucleus that integrates auditory input from the ear with multisensory information. Both lines of research utilized patch-clamp electrophysiological recordings from in vitro slices of mouse brainstem and midbrain. This dissertation reveals new mechanisms for how auditory information is processed by local brainstem and midbrain circuits.