On the auditory and cognitive functions that may explain an individual's elevation of the speech reception threshold in noise.

It is generally recognized that poor results of speech-in-noise tests by hearing-impaired persons cannot be fully explained by the elevated pure-tone hearing threshold. Plomp has shown, among others, that an additional factor has to be taken into account, often referred to in general terms as distortion. In an attempt to specify auditory and cognitive functions which may underlie this distortion, various studies on this topic originating from Plomp's research group are reviewed, as well as other relevant studies which provide quantitative data on the correlations between various types of auditory or cognitive tests (the predictor tests) and speech-in-noise tests. The predictor variables considered include, besides the pure-tone audiogram, measures of spectral and temporal resolution, intensity difference limen, age, and some cognitive aspects. The results indicate that, by and large, these variables fall short in fully explaining the variance observed in the speech-in-noise tests. This strongly suggests that the predictor variables considered so far do not cover all sources of variance relevant for speech reception in noise.