7.4. Contours and Confidence

The key contour changes how frequency evidence contributes to detection and harmonic-detail ranking. None is calibrated-flat, ECMA-418 is the release default, and the two ISO 226 profiles vary with reference SPL.

The selected profile can change a derived key without rescanning because Harmonic DJ retains the underlying calibrated harmonic evidence. Gain analysis is separate and remains fixed so changing the key contour cannot move previously copied gain recommendations.

Key confidence is an uncalibrated separation heuristic: it describes how strongly the selected category separated from nearby alternatives inside the current model. It is useful context, not a promise of musical certainty and not a rejection threshold.