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The process of developing a vehicle for optimal interior noise levels is an enormous effort on the part of a large team of individuals. Since any given vehicle program will continually evolve during the development process, an effective and robust noise control strategy and process must be implemented to ensure that vehicle performance targets are realized in production. However, robust does not mean “performance overkill” to provide for all possible contingencies, since this approach would be prohibitively expensive and massive. This paper outlines a process by which vehicle development allows for managing performance tradeoffs with other packaging and performance concerns, while continually monitoring performance, cost and mass to target.

During a vehicle development program, the sensitivity of a single sound package item or group of items is often described by its dB impact on the full vehicle response. This is often communicated between different vehicle platform teams even though the results may not be valid. Depending on the current state of the entire sound package, i.e., the initial conditions, the sensitivity of one particular item can be greatly variable. A general set of rules is proposed to help identify when a single item's sensitivity may be significantly altered due to a change in the initial conditions of the complete sound package.

Typical Statistical Energy Analysis (SEA) plate/shell subsystems usually assume that the panel is impervious to airflow. However, they are not capable of modeling a trim element or similar component that allows air to pass through it, e.g., a headliner or package tray. The theory of a simplified porous panel is presented for the coupling loss factors of a cavity-panel-cavity connection and the theoretical prediction is compared to measurements for various airflow resistance values. A discussion on the use of the porous panel subsystem for automotive SEA modeling is presented.

The acoustic performance requirements of vehicle interior trim elements and sound package elements have increased significantly in recent years. Additionally, the burden of developing these products has been shifted from the Original Equipment Manufacturers (OEMs) to suppliers. To aid in developing lightweight, low cost, and high performance parts, a flexible acoustic testing facility was designed for use in many different applications. Specific, purpose-built chambers for only one type of measurement are typically not cost effective facilities.

Setting accurate acoustic performance targets for trim components early in a vehicle program is essential to develop the vehicle on-time, with appropriate acoustical performance, at lowest weight, and at lowest cost. The laboratory measurement of acoustic absorption (ASTM C 423 and ISO 354) of flat stock trim parts is used to obtain these targets or the specific trim part is measured in a vehicle to obtain the acoustic absorption. However, the in situ measurement often does not agree with the laboratory measurement even if the variations between formed parts and flat stock materials are accounted for. A statistical energy analysis model is used to illustrate the problems with in situ absorption measurements. An approach to correct the in situ test method to obtain an approximation of the laboratory result is discussed.

Wavenumber domain methods have been developed to experimentally determine the flexural group speeds and loss factors in beam elements and the flexural power transmission and reflection coefficients of joints in a structure. These techniques are used in this paper to measure uncertain information for an Energy Finite Element Method (EFEM) model of a ladder frame structure. The loss factors and group speeds in each element in the structure were measured and found to compare well with the analytical predictions. However, the flexural power transmission and reflection coefficients of the joints in the structure were found to be significantly different from analytically predicted values. EFEM predictions and measured velocities for several components are compared.