Electro-neurophysiological and brain imaging studies have revealed that there is correlation between stimulus presentation rate (PR) and acoustical responses features of central auditory neurons as well as auditory related neural activity.On the other hand, clinical observations show that one of the major symptoms on the presbyacusia is in the defect of ability to process rapid sound signal.Hence, the question we address here is whether the alteration in temporal representation induced by the increment of sound load is correlated with the ages.In our experiments, under free field stimulation conditions we recorded neural responses from the inferior collicular (IC) neurons by presented the characteristic frequency (CF) tones with different durations (10、 40 and 120 ms), and intensities (10 dB SPL above minimal threshold) at different PRs (0.5, 1.0, 3.3, 5.0, 6.7, 10.0 and 20.0 Hz) to pentobarbital anesthetized mice (Mus musculus, Km).