Title

Recording the tympanic membrane response of the túngara frog to sound pressure in water

Poster Number

08B

Lead Author Major

Biological Sciences

Lead Author Status

Junior

Format

Poster Presentation

Faculty Mentor Name

Marcos Gridi-Papp

Faculty Mentor Email

mgridipapp@pacific.edu

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Some species of frogs have ears specialized for hearing in air, while others have ears specialized for hearing under water. The túngara frog (Engystomops pustulosus) has ears that operate effectively in both media. Their middle ear shares an expanded, disc-shaped extrastapes with anurans who specialize in underwater hearing (pipids). Previous experiments have documented, in air, a wide range of stimulus amplitudes (>60 dB) in which the vibration velocity (and amplitude) of the eardrum responds linearly to sound pressure, suggesting that hearing in air is not impeded by the expanded extrastapes. To determine the range of linear response of the eardrum under water, the vibrations of the eardrums in response to frequencies between 200 Hz and 5000 Hz were recorded using a laser Doppler vibrometer. Small patches (5x5 beads) of retroreflective tape were glued to the center of the tympanic membrane, and the bulging of the eardrum was recorded by reflection of the laser light while sound was played at various frequencies and amplitudes. Obtaining consistent recordings of vibrational frequency under water has proved challenging as the laser signal is weakened by diffraction at the boundaries between air, glass and water. Angle adjustments, as well as larger bead patches will be implemented to resolve this issue. These measurements will show if the eardrum in water, responds linearly to sound pressure, giving the animal a sense of the amplitude of a signal.

Location

DeRosa University Center, Ballroom

Start Date

29-4-2017 10:00 AM

End Date

29-4-2017 12:00 PM

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Apr 29th, 10:00 AM Apr 29th, 12:00 PM

Recording the tympanic membrane response of the túngara frog to sound pressure in water

DeRosa University Center, Ballroom

Some species of frogs have ears specialized for hearing in air, while others have ears specialized for hearing under water. The túngara frog (Engystomops pustulosus) has ears that operate effectively in both media. Their middle ear shares an expanded, disc-shaped extrastapes with anurans who specialize in underwater hearing (pipids). Previous experiments have documented, in air, a wide range of stimulus amplitudes (>60 dB) in which the vibration velocity (and amplitude) of the eardrum responds linearly to sound pressure, suggesting that hearing in air is not impeded by the expanded extrastapes. To determine the range of linear response of the eardrum under water, the vibrations of the eardrums in response to frequencies between 200 Hz and 5000 Hz were recorded using a laser Doppler vibrometer. Small patches (5x5 beads) of retroreflective tape were glued to the center of the tympanic membrane, and the bulging of the eardrum was recorded by reflection of the laser light while sound was played at various frequencies and amplitudes. Obtaining consistent recordings of vibrational frequency under water has proved challenging as the laser signal is weakened by diffraction at the boundaries between air, glass and water. Angle adjustments, as well as larger bead patches will be implemented to resolve this issue. These measurements will show if the eardrum in water, responds linearly to sound pressure, giving the animal a sense of the amplitude of a signal.