Summary
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1.
We used laser vibrometry and free field sound stimulation to study the frequency responses of the eardrum and the lateral body wall of awake male Eleutherodactylus coqui.
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2.
The eardrum snowed one of two distinct frequency responses depending on whether the glottis was open (GO response) or closed (GC response) during the measurement.
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3.
The lateral body wall vibrated with a maximum amplitude close to that of the eardrum and in the same frequency range.
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4.
Covering the frog's body wall with vaseline reduced the vibration amplitude of the GC response by up to 15 dB.
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5.
When a closed sound delivery system was used to stimulate a local area of the body wall the eardrum also showed one of two types of responses.
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6.
These results suggest that sound is transmitted via the lung cavity to the internal surface of the eardrum. This lung input has a significant influence on the vibrations of the eardrum even when the glottis is closed.
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7.
The vibration amplitude of the eardrum changed with the angle of sound incidence. The directionality was most pronounced in a narrow frequency range between the two main frequencies of the conspecific advertisement call.
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Abbreviations
- GC :
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glottis closed
- GO :
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glottis open
- IVAD :
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interaural vibration amplitude difference
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Jørgensen, M.B., Schmitz, B. & Christensen-Dalsgaard, J. Biophysics of directional hearing in the frog Eleutherodactylus coqui . J Comp Physiol A 168, 223–232 (1991). https://doi.org/10.1007/BF00218414
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DOI: https://doi.org/10.1007/BF00218414