This study examines duration sensitive neurons in the inferior colliculus (IC) of the least horseshoe bat, Rhinolophus pusillus, from China. We employed CF-FM pulses to analyze the differential effects that these two pulse components had on the duration tuning in neurons of the horseshoe bat's IC. Duration sensitive neurons found in the horseshoe bat fall into three main classes: short-pass, band-pass and long-pass. Using a CF stimulus alone, 54% (51/95) of all IC neurons showed at least one form of duration selectivity at one or more stimulus intensities. In 65 neurons tested with CF pulses, we were also able to test their duration selectivity for a combined CF-FM pulse, which increased the ratio of duration sensitive neurons to 66% (43/65). 7-15 neurons that failed to show duration tuning for CF bursts became duration sensitive for CF-FM pulses, with most of them exhibiting short-pass (depending on stimulus intensity, between 4 and 8 neurons) or band-pass tuning (1- 3 neurons). Band widths of band-pass neurons were not significantly affected by any stimulus configuration, with only a slight trend for increasing bandwidths for louder CF bursts (but not CF-FM stimuli). Best durations and cutoff durations reached higher values than in the other bat species examined so far and roughly match the longer durations of echolocation pulses emitted by horseshoe bats. Therefore, presentation of a CF-FM stimulus improved the duration tuning in IC neurons by increasing the ratio of duration tuned neurons and making them less susceptible to changes in signal intensity.