Auditory stimuli and averaged EEG responses. a, b, Speech stimulus (syllable: /da/, 98 Hz fundamental frequency) in the time and frequency domain (top) and the corresponding averaged responses isolated from the EEG recordings (bottom). c, d, Tone stimulus (piano “G2,” 98 Hz fundamental frequency) in the time and frequency domain (top) and the EEG responses (bottom). The prestimulus baseline (−50 to 0 ms) and the FFR periods (20–110 ms after sound onset) are marked in gray and blue, respectively.