This study simulates the phoneme errors made by speech recognizers and determines the phoneme error level at which a reasonable comprehension of text can still be achieved. Finnish is written almost phonemically and Finnish-speakers have no trouble in comprehending phonemic text. Phonemically corrupted text was presented to normal-hearing, hearing-impaired as well as deaf subjects and their comprehension levels were measured. According to this study, current speech recognition methods allow for limited applications in this field.