An order-based structural response function was developed as a simple intermediate index that indicates the quality of transmission characteristics when taking measures regarding transmission systems in order to enhance combustion noise quality. The index is the sum of the structural response functions from each cylinder for each typical order component, taking into account the different combustion timing of each cylinder. This enables identification of frequencies at which combustion noise is likely to be generated for each order. Comparison of the actual order-based structural response function and combustion noise showed that combustion noise quality deteriorates in frequency bands with high response amplitudes across multiple order components of the function. The results demonstrated that the function can be a useful intermediate index for structural measures.