162 



Lawrence S. Frishkopf and Walter A. Rosenblith 



in Fig. 11. Consider the ratio of the response amplitude ^R^ to a second click 

 and the response amphtude R^ to the same click presented alone. In Fig. 12 

 this ratio is plotted, for a fixed second-click intensity, as a function of the inten- 

 sity of the first click. The parameter is the interval between clicks, At. If 



STIMULUS INTENSITY 



IN DB 



(RE 1.29 VOLTS) 



•90 



•40 



-80 



-30 



■70 



•20 



-60 



■10 



■60 



3 msec 



3 msec 



DB RELATIVE GAIN -12 DB 



Fig. 9. Ink tracings of responses obtained from an anesthetized cat to clicks over 

 a 90-dB range. The electrode was located near the round window. Note that the 

 voltage gain of the recording equipment was reduced by 12 dB (factor of i) for 

 stimulus intensities above —40 dB. The first peak represents the summated 

 activity of first-order auditory neurons. With this calibration, click threshold for 

 humans (verbal report) is about —95 dB. 



we assume a one-population model, we obtain the result that the ratio 1R2IR2 

 is Hnearly related to the intensity function for the first click, provided that 

 the second-click intensity (S^) and At are held constant. Specifically, we obtain 



rR. , ^^^^\l - giS„ Ar)] (1) 



R, 



1 - 



Rr 



Determination of a single intensity function therefore permits us to predict 

 the dependence of this ratio on S^ for any value of 5*2 and of At. We may 



