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Wind noise is becoming a higher priority in the automotive industry. Several past studies investigated whether Statistical Energy Analysis (SEA) can be utilized to predict wind noise. Because wind noise analysis requires both radiation and transmission modeling in a wide frequency band, turbulent-structure-acoustic-coupled-SEA is being used. Past research investigated coupled-SEA’s benefit, but the model is usually simplified to enable easier consideration on the input side. However, the vehicle is composed of multiple interior parts and possible interior countermeasure consideration is needed. To enable this, at first, a more detailed coupled-SEA model is built from the acoustic-SEA model which has a larger number of degrees of freedom for the interior side. Then, the model is modified to account for sound radiation effects induced by turbulent and acoustic pressure.

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.

Automotive OEMs are required to meet applicable regulations for exterior noise for vehicles they produce. Acceleration noise (typically called pass-by noise) regulations impose an upper limit for noise emission. In addition, vehicles which can operate without a combustion engine must comply with regulations for minimum noise emitted during low speed driving. In order to make regulation-compliant measurements for global destinations, a test track meeting requirements of ISO 10844 may be necessary. However, strictly meeting this requirement doesn’t guarantee a usable facility for efficient measurements. This paper describes design goals, challenges and construction of a regulation compliant facility in Arizona. The intent was to build a facility with a long usable life before requiring repaving, sufficient isolation from nearby test roads, 24-hour usability and onsite amenities to accommodate technical staffs and vehicle retrofits.

Vehicle interior wind noise is typically managed through the overall exterior geometry of the vehicle, mirror shape and mounting location, sealing features and glass thickness and damping. Prior research has distinguished between contribution of fluctuating pressure due to air turbulence as compared to acoustic pressure to a passenger vehicles exterior at highway speeds. Because of the large difference in propagation speed between turbulent and acoustic pressure for on-road passenger vehicles, the structural response of the glass to turbulent versus acoustic pressure is not the same. The acoustic coincidence frequency of door glass is typically in the 2-3 kHz range. Turbulent coincidence frequency is much lower, and the effective transmission loss (TL) of the glass depends on the mix of turbulent and acoustic pressure on the exterior surface of the glass.

Test standards are essential for evaluating the performance of a product properly and for developing a data base for the product. This paper discusses various standards that are available for determining the acoustical performance of sound package materials. The paper emphasizes various SAE standards that are available in this area, the reasons why these standards are important to the researchers working in the mobility industry, the history behind the development of these standards, and how they are different from standards that are available from other standards organization on similar topics.

In-vehicle reverberation time as a function of frequency can be used as one indicator of the quality of a vehicle interior as an acoustic space. Typically, however, reverberation times in passenger vehicles are so short that they can be extremely difficult to measure using interrupted noise or impulse excitations. This paper investigates a steady state method of determining reverberation times by adapting the power injection method, which is typically used to determine composite damping loss factors of panels. The results of using this method will be compared with those of other methods. Theoretical and practical advantages and disadvantages will be discussed. Application of this method to absorption measurement will be discussed as well.

The transmission of turbulent flow pressures through panels to the interior noise depends on the spatial matching of the pressure and vibration fields. Since the exterior pressure field on a moving vehicle includes both turbulent pressure and acoustic pressure, both need to be factored into a noise transmission loss calculation. However, these two exterior pressure fields have very different spatial patterns. This is further complicated when the exterior flow is separated from the surface due to an obstruction. This study uses wind tunnel and road tests to measure and model the wind noise transmission loss through the side glass of a vehicle. The results are seen to be very different from the traditional sound transmission loss curves for an acoustic pressure source.