Summary
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1.
Female green treefrogs (Hyla cinerea) are attracted to a sound source which broadcasts appropriate synthetic mating calls. Continuous noise (broad-band or band-passed) was added to these signals in order to determine masked auditory thresholds at frequencies within the two bands that are typically emphasized in the natural mating call.
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2.
Signal-to-noise-ratios for total masking at 900 Hz were determined in a one-speaker situation at three signal levels (55, 65, and 75 dB SPL re 20 μPa), and critical ratios (CR-bands) were calculated (Tables 1,2).
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3.
The most reliable averaged CR-bandwidth at 900 Hz was 158 Hz (≙22 dB). CR-bands at 3,000 Hz, measured in a two-choice situation at a signal level of 65 dB, were 141 Hz (≙21.5 dB).
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4.
Thus sounds processed by both auditory organs in the treefrog (the amphibian papilla for f<1,500 Hz and the basilar papilla for higher frequencies) can be analyzed in CR-bands that are sufficiently narrow to resolve the harmonic structure of a typical mating call.
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5.
A super-optimal stimulus consisted of a continuous low-frequency noise (100–1,000 Hz band-pass, spectrum level=40 dB) superimposed on 3,000 Hz tone bursts (at 65 dB) with temporal properties typical of the natural mating call.
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Abbreviations
- SPL :
-
sound pressure level
- CR-band :
-
critical ratio band
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This study was supported by grants of the Deutsche Forschungsgemeinschaft to G.E. (Eh 53/4), of the NSF (BNS 7300795) and a NIH career development award (NS 00217-02) to H.C.G., and of the NIH (NS 09244) to Dr. R.R. Capranica, who provided part of the apparatus. We wish to thank Dr. Capranica for helpful discussions and comments.
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Ehret, G., Gerhardt, H.C. Auditory masking and effects of noise on responses of the green treefrog (Hyla cinerea) to synthetic mating calls. J. Comp. Physiol. 141, 13–18 (1980). https://doi.org/10.1007/BF00611873
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DOI: https://doi.org/10.1007/BF00611873