Complex sounds including speech can be represented as a sum of amplitude- and frequency- modulated (AM and FM) sinusoids. For most communication sounds, AM and FM rates typically range between 1 and about 100-500 Hz (the most salient rates ranging between about 1 and 20 Hz). Each AM-FM sinusoid elicits a complex pattern of “sensory excitation” at the output of cochlear filters. This pattern shows slow fluctuations in level as a function of time (the temporal envelope) and faster oscillations close to the center frequency of the filter (the temporal fine structure). At the level of auditory nerve and low brainstem, the temporal envelope is transformed into slow (< 100-500 Hz) fluctuations in mean firing rate (neural temporal-envelope cues) and the temporal fine structure is transformed into a spike train phase locked to temporal fine structure (for oscillations below about 1-4 kHz in humans). While the role and coding mechanisms for temporal-envelope cues are relatively well understood, the role and coding mechanisms for temporal fine structure cues is still a matter a debate. The effects of aging and cochlear damage on temporal-envelope and temporal fine-structure coding are also heavily debated.