Authors state that Fowler’s percentual hearing threshold fall evaluation, ingeniously based on the significance of given frequency and intensity, allows for a reasonable assessment of communication difficulties. It is a for well known fact that even minor decibelar fall in the „speech core“ may cause significant communication limitations. On the contrary even major losses situated in acoustic field periphery usually do not entrain catastrophy. In cooperation with psychologists, sociologists and educationalists, 300 patients were primarily followed up. On acount of further more than 3000 hearing losses gradually followed up on a long term, we came to conclusion, that a hearing threshold fall up to 20-25% affects in nearly no way Czech language understanding. Close attention and redundancy of the speech may successfully counterbalance losses of 20-45%. A severe limitation of speech understanding occurs when the limit 45% is being exceeded. Such losses should be compensated either using hearing aids or by surgery, functional effect of which may again be evaluated by Fowler’s percentage. Above-mentioned statements are demonstrated by documentation of a number of definite examples.

        Key words: hearing threshold, Fowler’s, percentual evaluation, speech core, speech understanding.