The References and the Derivations of the ABR Topography

Techniques in ABR topography were studied in five normal adults. 1. Noise potentials between a vertex exploring electrode and 6 non-cephalic references were measured and evaluated by time-series and spectrum analyses. A laryngeal prominence reference had the least ECG contamination. 2. To reduce ECG and EMG noises, an aluminum foil strip was wound round the neck. It was effective in reducing the noise. 3. Simultaneous 16chs ABR recordings were obtained by binaural acoustic click stimuli. Exploring electrodes were located according to the 10-20 system. A non-cephalic reference was placed at the laryngeal prominence. A set of peak-to-peak amplitude values of Jewett wave V was employed in computation to obtain amplitude topograms of laryngeal prominence reference, average potential reference and source derivation. The latter two were reference invariant. The test-retest stability of the records were satisfactory. 4. Wave V peak latency distribution topograms were obtained with the same technique as described above. We concluded that the laryngeal prominence reference with metal neck belt was one of the best techniques for multichannel ABR recording; the source derivation topogram may have advantages in clinical neurophysiological investigation.