The door response to audio excitation contributes to the overall performance of a vehicle audio system on several items: acting as a cabinet, it influences the loudspeaker response, but it also radiates unwanted sound through the inner door panel. Associated design issues are numerous, from the loudspeaker design to door structure and inner panel definition. Modeling then appears as an unavoidable tool to handle the acoustic response of the loudspeaker in its actual surrounding as well as the door inner panel radiation.
In the low frequency range (<300 Hz), the loudspeaker is conveniently modelled using the classical Thiele&Small 1 D model. The interaction with the door and the acoustic surroundings requires a more detailed Finite Element modeling considering the acoustic loads on both sides of the loudspeaker membrane and the force at the loudspeaker frame interface with the door structure.
The proposed hybrid modeling is first assessed by comparison of the computed and the measured membrane’s displacement. An update of the T&S parameters is performed in order to optimize the model. Then, the computed loudspeaker frame displacement and the acoustic loads may be checked against measurement. Finally, the computed vibrational response of the trimmed door is compared to an extensive 3D LASER measurement.
Such an analysis allows the loudspeaker membrane displacement control as well as the inner door panel’s motion that may radiate unwanted sound. Previously proposed indicators are used to quantify the door audio performance.