Spatial attention relatively increases the power of neural alpha oscillations in the hemisphere ipsilateral to the focus of attention. For auditory spatial attention, the functional roles of lateralized alpha versus gamma oscillations are unclear. In a dichotic listening task, n = 20 participants were cued to attend to a stream of four spoken numbers presented to one ear, while ignoring a distracting stream of numbers presented to the other ear. Each participant performed the task during sham, under alpha (10 Hz) transcranial alternating current stimulation (tACS), as well as at under gamma (47 Hz) tACS, targeting a temporo–parietal cortical region in the left hemisphere. As predicted, alpha-tACS contralateral to the attended ear decreased recall of attended targets, while the opposite was observed for gamma-tACS. These data pose a proof of concept that externally amplified alpha oscillations can enhance lateralized spatial attention and facilitate attentional selection of speech. Furthermore, the opposite effects of alpha vs gamma oscillations support the view that, across sensory modalities, states of relatively high alpha are incommensurate with active neural processing as reflected by states of high gamma. Malte Wöstmann Institut für Psychologie I Universität zu Lübeck Tel.: +49 451 3101 3621 Mail: malte.woestmann@uni-luebeck.de <mailto:malte.woestmann@uni-luebeck.de>