Re-visiting Al Feng's contributions toward understanding the peripheral basis of acoustic communication in frogs

Abstract

Al has made substantial contributions toward understanding the peripheral auditory mechanisms underlying acoustic communication in frogs. Al was the first to demonstrate that the basilar papilla is innervated by high-frequency auditory nerve fibers, while the amphibian papilla gives rise to low- and mid-frequency fibers. Subsequent work from Al's lab showed that the tuning of these end organs changes during post-metamorphic development. Al developed a dorsal surgical approach to the auditory nerve, which allowed the coupling between the ears to be studied, and then demonstrated that both the monaural directivity patterns and the coupling between ears are frequency dependent. In a follow-up study, the coupling between ears was manipulated and it was concluded that the frog's ear functions as a combination pressure/pressure gradient receiver. In this talk, the frequency-dependent crosstalk between the ears first described by Al in 1980 is re-visited. The crosstalk function is analyzed using an acoustic model of a tube with a side branch. This analysis shows the mouth cavity combined in parallel with the nares as the side branch yields a bandpass function for sound transmission that accounts for Al's empirical crosstalk data.