Figure 1

Auditory brainstem responses. (A) ABR thresholds in dB SPL for 32 kHz pure tone stimuli in the parental and second-generation (N2 and F2) populations. (B-D) Threshold distributions for (B) C3H-N2, (C) CBA-F2, and (D) C57-F2 populations. (B) The C3H-N2 frequency distribution was produced using data presented previously [10] and is reproduced here for clarification and presentation purposes. This distribution is best fit by the sum of two Gaussian distributions (Goodness-of-fit R² = 0.96, n = 306). (C) The CBA-F2 frequency distribution was fitted using a Gaussian distribution (Goodness-of fit R² = 0.96, n = 294). (D) The C57-F2 frequency distribution appears to be bi-modal but only the first peak of the curve could be fitted initially (Goodness-of-fit R² = 0.76, n = 320). When the data from individuals with 32 kHz ABR thresholds 60 dB SPL or greater was analyzed separately, the second peak fit a Gaussian distribution (Goodness-of-fit R² = 0.85, n = 82).