Engine orders are a major source of tonal noise in vehicle cabins. In production engine order cancellation (EOC), good performance is not only high attenuation, but also stable behavior in real conditions. After successful cancellation, the target order can become masked by broadband noise (low SNR). In addition, uncorrelated in-band intrusions may occur in the same frequency region. In these cases, observation-based on/off rules that rely on the current visibility of the tone can cause false deactivation and mode chattering. This paper presents a multi-channel EOC method for an in-cabin audio system. Orders are modeled in real time using a quadrature sin–cos basis synchronized with rotational-speed information. The main contribution is an order-level state logic that uses a reconstructed estimate of the current control contribution through secondary-path models. This enables a practical distinction between “absent/irrelevant” and “suppressed but masked,” and supports stable operation by scheduling the adaptation step size and the accumulation length in order periods. The method also accounts for fast RPM changes by shortening the accumulation window while keeping a moderate adaptation rate for tracking. A second contribution is a dynamic order-management layer that periodically evaluates residual-based order salience (accounting for current cancellation) and selects a bounded top-K set for control. The layer includes optional fade-in/out transitions for switching and a lightweight safeguard that de-rates poorly controllable orders to reduce the risk of noise amplification. The method is evaluated on a low-reverberation bench and in a vehicle under steady-speed and run-up conditions, including background noise and audio playback.
