Figure 4.

Free-field frequency tuning and sensitivity of auditory nerve responses. A: scatterplot showing characteristic frequencies (CFs) and threshold at CF for the 117 fibers. The black line connects the most sensitive fibers at each frequency. B: distribution of CFs. C–F: response areas of four fibers showing spike rates (color scale, average of three presentations) in response to 50 ms tone bursts emitted from the 90° direction at different levels and frequencies (200–4,000 Hz in 1/6th octave steps). G: rate-level functions of seven auditory nerve fibers with different CFs, stimulated from the 90° direction. The smooth curves are three-parameter sigmoidal approximations (SigmaPlot 12.5); actual data points plotted for three of the fibers (symbols). The sigmoidal functions were used to convert measured spike rates to equivalent dBs. H: distribution of maximal slopes of all rate-level (R-L) curves, in all cases stimulated from the 90° direction. I: latency-level functions in four fibers stimulated from the 90° direction. The figure shows the measured data points (symbols) as well as power function fits calculated from the measurements (see methods for details).