A new method for analyzing auditory brain-stem response waveforms using a moving-minimum subtraction procedure of digitized analog recordings

Figures & data

Figure 1 Principles of the moving-minimum subtraction method.

Notes: The table shows arbitrary data points (raw data) representing a simple wave form in the graph (filled line). The raw data value at time point 1 was subtracted by the minimum (min) value of the following four data points (time points 2–5) equal to −2 (subtracted). The raw data value at time point 2 was subtracted by the minimum value of the following three data points (time points 3–6), equal to −2, etc. The column labeled “Subtracted” shows all subtracted values corresponding to the data points (dotted line in the graph). Baseline (BL) alignment to zero was achieved by setting the min value in the “Subtracted” column (−3) to 0 (dashed curve in the graph). All computations were done using Microsoft Excel.

Figure 2 Application of the moving-minimum subtraction method on authentic auditory brain-stem responses (ABRs) from four subjects (subjects A–D) with highly variable waveforms.

Notes: The digitized ABR waveforms comprise 1,540 data points/10 ms, ie, 154 data points/ms. The minimum values within three different windows (W=136, W=68, W=34 data points, corresponding to 0.88, 0.44, and 0.22 ms) following each unprocessed data point were selected for processing baseline alignment using the moving-minimum subtraction method. Roman numerals I, III, V, and VI indicate the conventional ABR waves: I, II–III, and IV–V, which are often fused into one wave, and VI.

Figure 3 Median auditory brain-stem response (ABR) waveforms of ten healthy volunteers (gray curve) compared with ten patients with schizophrenia (black curve, left panels) and with ten patients with adult attention deficit/hyperactivity disorder (ADHD) (dotted curve, middle panels), respectively. The schizophrenia and ADHD groups are directly compared in the right panels. The authentic analog waveforms were digitized to allow baseline alignments according to the moving-minimum subtraction method using three windows (W=136, W=68, W=34 data points), and to allow descriptive statistics of groups and statistical analyses of group differences.