from http://american-hearing.org/disorders/noise-induced-hearing-loss/ "An example of a noise induced hearing loss is shown in Figure 1. There is a “notch” at 3000 Hz, with better hearing at both lower and higher frequencies. When noise is too loud, it begins to kill cells in the inner ear. As the exposure time to loud noise increases, more and more hair cells are destroyed. As the number of hair cells decreases, so does your hearing. Currently, there is no way to restore life to dead hair cells; the damage is permanent." I'll admit, I have no idea how credible this source is, just the first thing google turned up. Seems to me it's talking about "loudness" though.