Figure 5. An example of permanent threshold shift in the left ear (similar results were found for the right ear) of an adult male from our longitudinal study (arrows indicate significant shifts). The subject was exposed to noise from a high-powered car stereo system. (a) The audiogram shows significant threshold shifts in Year 3 at 2, 3, and 4 kHz. (b) The DPOAEs (65/45 dB SPL, averaged over ½-octave bands) show a significant emissions shift at only 2 kHz. (b) The TEOAEs (non-linear 74 dB pSPL, averaged over ½-octave bands), on the other hand, show wide-band significant emission shifts over all frequencies in Year 3.