Title

The acoustic performance of the middle ear in túngara frogs, Engymostops pustulosus

Poster Number

16

Lead Author Major

Pre-Dentistry and Biological Sciences

Format

Poster Presentation

Faculty Mentor Name

Marcos Gridi-Papp

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Thin eardrums and air filled middle ears are crucial for airborne hearing in vertebrates because they match the low impedance of air with the high impedance of body fluids. These specializations are unnecessary underwater where sound can transfer directly from the medium to the body tissues. The eardrums of frogs tend to be thin in species that communicate in air and thick in subaquatic species. A cartilaginous disk is commonly found deep to the skin of the ear in subaquatic species. Túngara frogs communicate with sound both in air and underwater. Their eardrums are thick and undifferentiated from the rest of the skin, and a preliminary examination revealed a cartilaginous disk in the middle ear We examined the hearing performance of túngara frogs in air, looking for biases caused by the expanded middle ear cartilage. We recorded the bulging of the eardrums in response to sound using a laser Doppler vibrometer. The eardrums vibrated the most within 1.5 – 6 kHz reaching velocities of 1.0 mm/s, being well within the range observed for small terrestrial frogs. The vibration response was impressively linear within a range > 70 dB, which is beyond the hearing sensitivity range recorded from the brain of this animal. The slope of the response to sound pressure was nearly constant within 1.5-6 kHz. Male túngara frog calls may contain a "whine" at 700 Hz and a "chuck" at 2500 Hz. The chuck is within the range of most linear response and highest sensitivity of the eardrums, whereas the whine is not. The expanded middle ear cartilage of túngara frogs does not hinder its eardrum sensitivity in comparison with other frogs. Our data indicates that their eardrums are tuned to the chuck but not the whine in air, although this could be modified underwater.

Location

DeRosa University Center, Ballroom

Start Date

30-4-2016 1:30 AM

End Date

30-4-2016 3:30 PM

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Apr 30th, 1:30 AM Apr 30th, 3:30 PM

The acoustic performance of the middle ear in túngara frogs, Engymostops pustulosus

DeRosa University Center, Ballroom

Thin eardrums and air filled middle ears are crucial for airborne hearing in vertebrates because they match the low impedance of air with the high impedance of body fluids. These specializations are unnecessary underwater where sound can transfer directly from the medium to the body tissues. The eardrums of frogs tend to be thin in species that communicate in air and thick in subaquatic species. A cartilaginous disk is commonly found deep to the skin of the ear in subaquatic species. Túngara frogs communicate with sound both in air and underwater. Their eardrums are thick and undifferentiated from the rest of the skin, and a preliminary examination revealed a cartilaginous disk in the middle ear We examined the hearing performance of túngara frogs in air, looking for biases caused by the expanded middle ear cartilage. We recorded the bulging of the eardrums in response to sound using a laser Doppler vibrometer. The eardrums vibrated the most within 1.5 – 6 kHz reaching velocities of 1.0 mm/s, being well within the range observed for small terrestrial frogs. The vibration response was impressively linear within a range > 70 dB, which is beyond the hearing sensitivity range recorded from the brain of this animal. The slope of the response to sound pressure was nearly constant within 1.5-6 kHz. Male túngara frog calls may contain a "whine" at 700 Hz and a "chuck" at 2500 Hz. The chuck is within the range of most linear response and highest sensitivity of the eardrums, whereas the whine is not. The expanded middle ear cartilage of túngara frogs does not hinder its eardrum sensitivity in comparison with other frogs. Our data indicates that their eardrums are tuned to the chuck but not the whine in air, although this could be modified underwater.