Recovery of otoacoustic emissions after high-level noise exposure in the American bullfrog

Abstract

There was an error published in J. Exp. Biol. 217, pp. 1626-1636 In Fig. 3, panel A has a duplicated line graph and the keys in panels B and D are incorrect. The correct figure is printed below. The cubic distortion product (DP) 2f 1 -f 2 recorded from the bullfrog ear with primary f 1 and secondary f 2 frequencies as shown. In this example, secondary levels are 10 dB lower than primary levels. (B) Plot of cubic distortion product otoacoustic emission (DPOAE) levels from the right ear (ipsilateral) versus secondary frequency (f 2 ). DPOAE levels are in decibels relative to 1 V rms (dBV). The plot depicts DPOAE levels recorded before (solid symbols) and 24 h after (open symbols) 150 dB SPL broad-band noise exposure. Filled and open squares represent corresponding pre-and post-noise levels, respectively. At each frequency, the primary stimulus was held constant at 80 dB SPL and the secondary stimulus level was presented at equal strength (solid squares, L 1 =L 2 ) and then with secondary levels 10 dB lower than primary levels (solid circles, L 1 >L 2 ). Noise level measurements were taken and averaged on either side of the peak DPOAE level immediately before and after noise exposure, with each ear tested and averaged over three presentations. Dashed lines represent noise floor. (C) Cubic DPOAEs (L 1 >L 2 ) from the right ear were tested before (day 0) and 1, 2, 5, 6, 7 and 8 days after noise exposure. Dashed lines represent noise floor. (D) Plot of the DPOAE shifts at each frequency tested before (0 days) and following (1, 2, 5, 6, 7 and 8 days) a 20 h noise exposure. The DPOAE shift was calculated as the difference in pre-exposure and post-exposure DPOAE levels.We apologise to the authors and readers for this omission. DP level (dBV) day 0 DP level (dBV) day 1 DP level (dBV) day 2 DP level (dBV) day 5 DP level (dBV) day 6 DP level (dBV) day 7 DP level (dBV) day 8Pre-exposure, L1>L2 Pre-exposure, L1=L2 Post-exposure, L1>L2 Post-exposure, L1=L2 DP level (dBV) day 0 DP level (dBV) day 1 DP level (dBV) day 2 DP level (dBV) day 5 DP level (dBV) day 7 DP level (dBV) day 8 BThe ABSTRACTThe American bullfrog (Rana catesbeiana) has an amphibian papilla (AP) that senses airborne, low-frequency sound and generates distortion product otoacoustic emissions (DPOAEs) similar to other vertebrate species. Although ranid frogs are typically found in noisy environments, the effects of noise on the AP have not been studied. First, we determined the noise levels that diminished DPOAE at 2f 1 -f 2 using an f 2 stimulus level at 80 dB SPL and that also produced morphological damage of the sensory epithelium. Second, we compared DPOAE (2f 1 -f 2 ) responses with histopathologic changes occurring in bullfrogs after noise exposure. Consistent morphological damage, such as fragmented hair cells and missing bundles, as well as elimination of DPOAE responses were seen only after very highlevel (>150 dB SPL) sound exposures. The morphological response of hair cells to noise differed along the mediolateral AP axis: medial hair cells were sens...