Distortion product otoacoustic emissions show exceptional resistance to noise exposure in MOLF/Ei mice.

Baseline distortion-product otoacoustic emissions (DPOAEs) at several primary-tone levels were compared between naive 2- to 3-month old inbred CBA/CaJ (CBA) and wild-derived MOLF/Ei (MOLF) mice. Only minor DPOAE differences were noted between the two strains and these differences were not systematic across frequency or test levels. These emission findings were consistent with earlier results on auditory brainstem response thresholds reported by others [Zheng et al., Hear. Res. 130 (1999) 94-107] thus suggesting that both CBA and MOLF strains have normal hearing. Subsequent episodes of over-exposure to a 105-dB SPL, octave-band noise centered at 10 kHz for 8 h revealed that MOLF DPOAEs were exceptionally resistant to the adverse aftereffects of excessive noise exposure as compared to CBA mice. Unlike the noise-exposure resistant inbred 129/SvEvTac strain, which has reduced baseline DPOAE levels especially at high frequencies, MOLF mice have normal DPOAEs making the interpretation of noise-exposure effects more straightforward.