Equivalence evaluation results indicated good psychophysical equivalence between the 10 lists except for list 2. List 9 has a reused item. After the elimination of lists 2 and 9, multivariate ANOVA revealed a good equivalence between the remaining eight lists (p = 0.136). The mean threshold of eight equivalent lists was 10.32 ± 0.38 dB HL, while the mean slope was 5.00 ± 0.29%/dB.

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Background: The SCN11A gene, encoded Nav1.9 TTX resistant sodium channels, is a main effector in peripheral inflammation related pain in nociceptive neurons. The role of SCN11A gene in the auditory system has not been well characterized. We therefore examined the expression of SCN11A in the murine cochlea, the morphological and physiological features of Nav1.9 knockout (KO) ICR mice. Results: Nav1.9 expression was found in the primary afferent endings beneath the inner hair cells (IHCs). The relative quantitative expression of Nav1.9 mRNA in modiolus of wild-type (WT) mice remains unchanged from P0 to P60. The number of presynaptic CtBP2 puncta in Nav1.9 KO mice was significantly lower than WT. In addition, the number of SGNs in Nav1.9 KO mice in the basal turn was also lower than WT, but not in the apical and middle turns. There was no lesion in the somas and stereocilia of hair cells in Nav1.9 KO mice. Nav1.9 KO mice showed higher and progressive ABR threshold at 16 kHz, a significant increase in CAP thresholds, while no changes in cochlear microphonics (CM). Conclusions: These data suggest a role of Nav1.9 in regulating the function of ribbon synapses and the auditory nerves. The impairment induced by Nav1.9 gene deletion mimics the characters of cochlear synaptopathy.