This paper describes the effect of site of lesion on auditory detection, discrimination and speech processing. Three groups of ten patients with confirmed pathology of the eighth nerve and right and left temporal cortex and two normal-hearing control groups, differing with respect to hospitalization, participated. In each of the fifty subjects, measurements were made of detection thresholds, and difference limens for frequency and duration for 50 and 300 ms pure tones of 500 Hz and 2000 Hz. Consonant discrimination was assessed using the Four Alternative Auditory Feature Test (Foster & Haggard, 1979), presented in quiet. Subjects with left temporal pathology had the largest frequency and duration difference limens. Those with either left temporal or eighth nerve pathology had significantly lower speech intelligibility scores that were correlated with the duration difference limen for short stimuli and detection thresholds, respectively. These findings challenge traditional views of cortical processing and highlight differences between peripheral and central mediators of speech processing.