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Microphone array-based Panel Contribution Analysis (PCA) is a new technique used for Sound Package design optimization for commercial vehicles. The technique allows for noise control performance and cost optimization. This technique ranks the contribution of fully trimmed structural panels (e.g. floor, roof, etc.) and leaks in a vehicle cabin to the noise levels experienced by a driver while the vehicle is in cruising operation. Often the noise and vibration sources (engine, transmission, exhaust, aerodynamic noise, tires, etc) cannot be easily modified, thus the only practical action to solve noise problems is to design the noise control treatments applied to the vehicle panels. Panels that have a large contribution to the noise levels at the driver's ear are heavily treated with noise control materials, whereas panels with low contribution get little to no treatment.

The new Acoustic Technology Center (ATC) at E-A-R™ Thermal/Acoustic Systems is a purpose-built facility to serve the commercial vehicle, automotive, aircraft, industrial and electronics markets supplied by this company. The design was driven by test versatility and rigorous facility performance specifications, enabling simultaneous testing of heavy duty vehicles and high performance noise reduction materials and systems in adjacent but uncoupled chambers. The intent of the facility layout is to utilize space efficiently while allowing a wide variety of vehicle, subsystem, component and material tests. Working closely with E-A-R, Acoustical Consulting Services established critical facility parameters to achieve intended functional attributes and Affiliated Construction Services constructed the facility to these specifications.

This paper describes a general noise control system design process. The methodology is applied to heavy duty trucks. The paper describes the benefits, for optimization purposes, of a systems approach versus a component approach. The role of both experimental and predictive approaches on the design process is outlined. Available noise control materials are briefly described, and lastly, an example of the results of the development of a noise control system by the experimental systems approach is provided.

This paper describes a pilot benchmarking study of polyether foams for acoustical applications. The study investigates the differences in sound absorption performance that result from two different foam manufacturing methods: thin sheet casting and bun manufacturing. A basic conjecture that is examined in this work is that thin sheet cast foams have the following advantages over bun stock manufacturing: higher sound absorption performance and lower variability of the physical properties that determine acoustical performance. It is shown that the sound absorption performance of thin sheet cast urethane foam is 40% and 67% higher than the best performance of bun stock foam when evaluated by the Average Normal Sound Absorption Coefficient (ANSAC) and the noise reduction coefficient (NRC) respectively. In general, the computed variabilities for the properties of thin sheet cast urethane foam are lower than those for the bun stock foams.

In the United States, an intercity long-haul truck averages approximately 1,800 hrs per year for idling, primarily for sleeper cab hotel loads, consuming 838 million gallons of diesel fuel across the entire long-haul fleet [1]. Including workday idling, over 2 billion gallons of fuel are used annually for truck idling [2]. The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) is working on solutions to reduce idling fuel use through the CoolCab project. The objective of the CoolCab project is to work closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining the cab occupant comfort. NREL conducted an experimental test program at their Vehicle Testing and Integration Facility in collaboration with Volvo Trucks, Aearo Technologies LLC / E-A-R Thermal Acoustic Systems - a 3M company, 3M Corporation, and Dometic Environmental Corporation.