(a–e) BM displacement threshold (0.2 nm criterion) as a function of stimulus frequency measured from the basal turn of the cochlea. Strain and genetic state of individual mice identified in the wording and colour of the captions at the top of each figure (CD-1Cx30A88V/A88V (black), CD-1Cx30WT/WT (blue), CD-1Cx30A88V/WT (green), CD-1 (orange) CBA/J (red)). Curves with solid symbols in b–d are post-mortem measurements from the same preparations. Inset to d: Q10 dB as a function of threshold at the tuning curve tip for CD-1Cx30A88V/A88V mice. (e) Inset to e: mean±s.d., n=5 of the 10–40 kHz region of tuning curves for CBA/J and CD-1Cx30A88V/A88V. For clarity, the curves are displaced downwards by 30 dB SPL. Asterisks: significantly different (unpaired t-test, **0.01, *0.05 two-tailed p value). (f) Phase of BM responses (measured at 70 dB SPL) (open symbols) as a function of frequency for tuning curves shown in e. Solid symbols, mean±s.d. of phase (10–45 kHz) from five each of CD-1Cx30A88V/A88V and CBA/J mice. Inset to f: linear plots of expanded section of curves between 45 and 55 Hz. The slopes of regression reveal that the phase of BM responses from the CBA/J mouse decreases by −0.232±s.e. 0.014 cycles per kHz and that from the CD-1Cx30A88V/A88V mouse decreases by −0.335±s.e. 0.011 cycles per kHz.