SPEECH-INTELLIGIBILITY IN NOISE WITH FAST COMPRESSION HEARING-AIDS

The effect of fast (syllabic) compression with overshoot reduction was studied in moderately hearing-impaired and in severely hearing-impair ed listeners in quiet and in noisy situations. A test battery of daily masking noises was selected using multidimensional scaling techniques . Four relevant noises were selected: a multi-talker babble, the noise in an industrial plant, in a printing office and a city-noise backgro und. The speech measurements show that only selected patients benefit from syllabic compression, i.e. listeners with a poor speech discrimin ation score. The effect in noisy surroundings was tested at the critic al signal-to-noise ratio of each patient, showing whether they benefit ed from compression in the most critical condition or not. It turns ou t that the effect depends largely on the speech discrimination score a nd the modulation of the noise signal. When the speech discrimination score is good, compression tends to impair the results. When the speec h discrimination score is poor, compression helps if the noise is modu lated.