[Transmission of speech sounds by hearing aids (author's transl)].

Oscillograms and sonagrams demonstrate some changes of speech sounds due to transmission by hearing aids. Most important are: cut off at low and high frequencies, internal noise of the hearing aid and variations of transients. The influence on speech discrimination and subjective satisfaction is discussed. A consequence of low frequency cut off is the loss of the first vocal formants and the loss of most important parts of oral occlusives /m/ and /n/; the cut off at high frequencies diminishes the information of some fricatives. The internal noise of the hearing aid may have a masking effect on important components of fricatives, Observed temporal variations in transients are too small to deteriorate phonem identification.