Selective auditory attention modulates cortical responses to sound location change in younger and older adults.

The present study measured scalp potentials in response to low-frequency, narrowband noise bursts changing location in the front, azimuthal plane. At question was whether selective auditory attention has a modulatory effect on the cortical encoding of spatial change and whether older listeners with normal-hearing thresholds would show depressed cortical representation for spatial changes relative to younger listeners. Young and older normal-hearing listeners were instructed to either passively listen to the stimulus presentation or actively attend to a single location (either 30° left or right of midline) and detect when a noise stream moved to the attended location. Prominent peaks of the electroencephalographic scalp waveforms were compared across groups, locations, and attention conditions. In addition, an opponent-channel model of spatial coding was performed to capture the effect of attention on spatial-change tuning. Younger listeners showed not only larger responses overall but a greater dynamic range in their response to location changes. Results suggest that younger listeners were acquiring and encoding key spatial cues at early cortical processing areas. On the other hand, each group exhibited modulatory effects of attention to spatial-change tuning, indicating that both younger and older listeners selectively attend to space in a manner that amplifies the available signal. [ABSTRACT FROM AUTHOR]