[Is there noise-induced hearing loss in the low and middle tone frequencies?].

Statistical material was collected on over 1000 patients with noise-induced hearing loss (expert opinions on these patients). All those patients were excluded who showed any other cause for their hearing loss i.e. head trauma, mumps, ototoxic medication, family history of hearing disease, or other causes. 200 patients showed loss of hearing at 250 Hz and 500 Hz of 20 dB or more and at 1000 Hz a hearing loss of at least 30 dB. Several matched-pair investigations with great variability of hearing loss are given. There is substantial evidence to prove that noise may damage the lower and medium frequencies as well as the higher frequencies.