Automotive audio systems require precise spectral tuning to achieve consistent sound quality across vehicle models, trim levels, and seating positions. Cabin acoustics introduce strong resonances and seat-dependent responses, while manufacturing tolerances, loudspeaker variability, and interior materials create additional differences between vehicles. As modern infotainment platforms incorporate multi-speaker playback, active sound design, speech communication, and personalized audio processing, manual equalization becomes impractical for production environments. This paper presents an automatic parametric equalization approach for production calibration of automotive audio systems. The method estimates the minimal number and determines the parameters of a cascade of biquad filters such that the resulting frequency response matches a predefined target curve while satisfying constraints typical for embedded DSP implementations. The solution is formulated as a constrained non-linear optimization problem tailored for stable and efficient biquad coefficient estimation. The proposed approach enables automated tuning workflows in which measured acoustic responses are directly converted into equalization parameters without manual intervention. Applications include factory calibration, premium audio tuning, and speech communication optimization, resulting in improved repeatability, reduced tuning time, and consistent spectral performance across vehicles.
