Fig. 1

BAER tracings. a: right ear, normal waveform recorded at the age of 12 years using alternating stimulus polarity and an intensity of 90 dB NHL. b: left ear, waveforms recorded at the age of 8 months using rarefaction (R) and condensation (C) stimulus polarity. c: left ear, waveforms recorded at the age of 12 years using alternating (A) stimulus polarity. Using high stimulus intensities a V-shaped negative potential with a latency of approximately 2 ms (ASNR; arrows) is recorded in the left ear. The ASNR is not recorded in the same ear at 80 dB NHL. The ASNR is affected by click polarity but without phase reversal. Peaks V (arrowheads) and VI (star) are produced in the left ear by unwanted stimulation of the contralateral ear (crossover effect). Vertex-ipsilateral mastoid montage. a, c: 1 ms/Div; 0.31 μV/Div. b: 1 ms/Div; 0.62 μV/Div