Smithsonian Report. 1961. — Roeder and Treat 



PLATE 3 



1. Tympanic ner\"e responses (lower traces) of Noctua {=^ Amathes) c-nigrum to a 70-kc. 

 sound pulse recorded simultaneously by a Granith microphone (upper traces). The 

 numbers indicate the intensity of the sound pulse in decibels above a reference level (0). 

 The threshold of the sensitive A cell lies between and 5 db. The large spikes appearing 

 in some of the records are from the B cell. The less sensitive A cell responds in the 

 25 db recording. \'ertical lines, 4 msec, apart. 



The cry of a flying bat (Myotis) recorded b\' a Granith microphone (upper trace) and 

 the A cells (lower trace) of a noctuid moth {Agroperina dubitans). The A spikes shown in 

 the lower trace have been distorted in form by the recording technique. Time line, 

 10 msec. Made in collaboration with Dr. Fred Webster in his laboratorv. 



