It is TRUE that years of exposure to loud sounds may cause hearing loss. However, the frequency of the sound is a factor too, not just the volume. I recall that while running tests inside an aircraft, we needed to wear hearing protection because the frequency of the sound was harmful to the human ear, even though the volume was not high. A high volume of sound at any frequency can be bad, but at some frequencies, even a low volume can be bad. This is a significant issue in industrial safety, especially in aviation environments.