FIGURE 6.
Real and imaginary parts of the impedance of a preparation 12 mm from the round window at three radial locations: Tunnel of Corti (•), inner hair cell (○), and first-row outer hair cell (▵). The arrow indicates the characteristic frequency according to the map of Tsuji and Liberman (1997). Fitted parameters are tunnel of Corti, k = 0.375 ± 0.010; c1 = 122 ± 48; c2 = (2.41 ± 0.16) × 10−5; c3 = (2.96 ± 0.28) × 10−5; c4 = (2.22 ± 0.52) × 10−5; and c5 = (1.04 ± 0.11) × 10−5. Inner hair cell, k = 0.198 ± 0.009; c1 = 254 ± 36; c2 = (2.19 ± 0.08) × 10−5; c3 = 0; c4 is not used; and c5 = (2.37 ± 1.01) × 10−6. First-row outer hair cell, k = 0.202 ± 0.008; c1 = 0; c2 = (9.39 ± 1.15) × 10−6; c3 = (1.47 ± 0.15) × 10−5; c4 = (2.29 ± 0.68) × 10−5; and c5 = (2.68 ± 0.88) × 10−6. Stiffness of cantilever, 1.59 N/m. At frequencies below ∼2 kHz, the SNR was approximately half that for the more basal recordings in Figs. 4 and 5, because the cantilever was stiffer and, in addition, the magnetic force was 70% of that for the softer cantilever. All units are SI.