Fig. 1.

Schematic showing stimulus presentation during a single trial of the visual-attention condition without spoken distractors. Two series of seven digits were presented simultaneously to two adjacent locations on a computer screen, and the subject was instructed to attend to that set of digits surrounded by the pink border (shown here as a grey border). Following the last pair of digits on each trial, there was a 2000-ms response interval, during which two adjacent, static arrays of five digits each were shown, and the subject pressed one of two response keys to indicate which array was the middle five digits in the attended series. After the response, visual feedback was provided about the correct choice. The dotted, transparent frames mark the 330-ms interstimulus intervals that separated consecutive pairs of digits. During these intervals the digits were removed from the computer screen, and the nSFOAE-evoking stimuli (tone-alone followed by tone-plus-noise) were presented to the two ears diotically. No acoustic stimulation was presented during the final 30 ms of each 330-ms nSFOAE-evoking interval; those silent periods are shown on the right side as open rectangles. It is the physiological noise responses during those silent periods that are the focus of this report. For the visual-attention conditions with spoken distractors, those speech stimuli were presented separately to the ears at the same time (dichotic presentation), and for the same duration, as the digits used for the visual-attention condition were presented on the computer screen. The digits presented to the ears were unrelated to those presented visually, and could not be used to perform the behavioral task.