The relation between tone and speech hearing in noise-induced hearing loss is argued controversely. Important publications according to which close correlations between both audiological methods are extensively supposed, are listed initially. Own research results that have already been published otherwise are introduced briefly. After that - with the help of discrimination functions on the monosyllable level - a correct order of the audibility is possible with a high hit share. The incorrect empirical adaptation of the hearing loss tables can be improved upon by quadratic optimation. Simultaneously, the polynomic functions calculated with the help of the quadratic optimation show frequency-specific characteristics. After addition of these functions one gets a virtual characteristic - tone and speech hearing - with a general character for noise-induced hearing loss. We believe that we have found by this mathematical method a new way for the solution of this difficult complex of questions. Our opinion is that the procedure mentioned above is also suitable for other types of hearing disturbances and for other languages.