A 20 Hz harmonic mask did not increase speech period accuracy on 42 later trials in one bipolar SEEG record with reported VNS artifact

We tested a 20 Hz harmonic mask for reading speech periods from public SEEG data. We used OpenNeuro ds004993 version 1.1.2, with adjacent contact subtraction and an early-to-later trial split. In W3, the source reports vagus nerve stimulation artifact. The ordinary reader, harmonic mask, and equal-bin-count control each classified all 84 windows from 42 later sentence trials correctly. The harmonic gain was zero percentage points. This is a test ceiling, not proof of equal future performance. In W2, the ordinary reader classified 63 of 68 later windows correctly. The harmonic mask classified 60 and the control classified 59. Fixed-pair checks gave the same accuracy results. The package preserves unmasked window spectra, sample windows for audit, models, all predictions, three figures, a local analysis plan, code, and a pinned retrieval recipe. Full source hashes pass. Independent signal and model checks pass. A full voltage replay matches every derived array. The test uses known sentence times during passive listening in two short records. It does not test direct brain stimulation or performance across patients.

spectral masking · speech period classification · stereoelectroencephalography · VNS artifact · ridge regression · signal processing