Automotive audio systems rely on complex signal-processing algorithms. Technologies such as noise reduction, acoustic echo cancellation, beamforming, and in-car communication processing must be meticulously tuned across vehicle platforms and their unique microphone and loudspeaker layouts. This optimization process requires constant evaluation of where and how specific algorithm parameters alter the output. Pinpointing these deviations remains a major challenge, as no existing tool is designed for such granular comparison. We introduce a comparison methodology that adapts the blink comparator — an instrument invented in astronomy over a century ago and used to discover Pluto — to the analysis of spectrograms of automotive audio signals. This technique rapidly alternates between aligned spectrograms of different processing variants in a flicker-free display, making differences in time, frequency, and intensity immediately visible, even when scalar metrics such as Echo Return Loss Enhancement or wideband Signal to Noise ratio improvement indicate similar performance. To further expose subtle changes that might otherwise remain hidden, the method incorporates spectral difference masking, which highlights local spectral deviations between processing variants. We also extend the classical visual blink comparator with synchronized audio playback switching, enabling the engineer to see and hear the difference simultaneously. We demonstrate its effectiveness through automotive case studies involving noise reduction tuning, echo cancellation artifacts, and beamformer comparisons.
