Figure 4. An example of temporary threshold shift and sub-clinical damage in the right ear of an adult female from our longitudinal study (arrows indicate significant shifts). The subject was exposed to noise from a wood-chipper and chain saw. (a) The audiogram indicates a significant threshold shift at 4 kHz in Year 3, which recovers to baseline in Year 4. (b) The DPOAEs (65/45 dB SPL, averaged over ½-octave bands) reflect the audiogram with a significant emission shift at 4 kHz in Year 3, recovering to baseline in Year 4. (c) The TEOAEs (non-linear 74 dB pSPL, averaged over ½-octave bands) show significant emission shifts at 1.4, 2.8, and 4 kHz in Year 3, which, unlike the audiogram, do not recover in Year 4.