Patients who had undergone unilateral anterior temporal lobectomy or had temporal lobe seizures with EEG confirmation of a unilateral temporal lobe focus were audiometrically studied by means of speech discrimination at various signal-to-noise ratios. With noise the ear contralateral to the abnormal temporal lobe was found to have a poorer discrimination score than the ipsilateral ear. This defect was found to be more significant in patients who had undergone temporal lobectomy than in patients with unilateral tem poral lobe seizures. The effect appears to be related to a defect in selective attention or filtering and not to language mechanisms. © 1973 American Academy of Neurology.