Tuning of the middle ear in túngara frogs ( Engystomops pustulosus)
To effectively communicate using sound, animals have to hear well in the frequency range of their calls. In frogs, body size is a major predictor of both the dominant frequency of the mating call, and the frequency of best sensitivity of the ear, which tend to match each other. Various pathways are known to receive sound in frogs. Eardrums receive high-frequency sound, lungs receive low-frequency sound and forelegs, via the opercularis system, receive seismic frequencies. Túngara frogs are an anomaly among amphibians for having a low frequency mate-identification call, relative to their body size, but they also do not appear to fit the pattern of sound reception pathways described above. Using laser vibrometry, I evaluated the vibration response of the eardrum and body wall to airborne sound. The results revealed a clear mismatch between the tuning of both middle ear and lungs, and that of the brain, with the eardrums and lungs tuned to approximately 2500 Hz and the brain tuned to 500 Hz. Both eardrums and lungs are well tuned to receive chucks, an ornamental part of the call. However, a pathway that is tuned to the whine, which is the mate-identification call where the brain is tuned, has yet to be found.
Zoology, Animal sciences, Biological sciences, Acoustic, Anuran, Auditory, Hearing, Middle ear, Túngara frogs, Biology
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