A numerical study of the role of the noseleaf in the Egyptian slit-faced bat

Abstract

Around 300 bat species are known to emit their ultrasonic biosonar pulses through the nostrils. This nasal emission coincides with the presence of intricately shaped baffle structures surrounding the nostrils. Some prior experimental evidence indicates that these “noseleaves” have an effect on the shape of the animals' radiation patterns. Here, a numerical acoustical analysis of the noseleaf of a slit-faced bat species is presented to show that all three distinctive parts of its noseleaf (“pit”, “upper leaf”, “lower leaf”) have an effect on the acoustic near field as well as on the directivity pattern. In their effects on the near field, the noseleaf parts showed a tendency toward spatial partitioning with the effects due to each part dominating a certain region. However, interactions between the acoustic effects of the parts were also evident, most notably, a synergism between the frequency-dependent effects of two parts of the noseleaf (“pit”, “lower leaf”) to produce an even stronger frequency selectiv...