本SAE推荐实施规程规定了用于确定车辆总质量（重量）额定值小于等于4540 kg（10 000 lb）的乘用车、多用途车辆和轻型卡车最大外部声级的试验程序、环境和仪器。本文件旨在用于测量任何适用车辆的最大发声能力。与SAE标准J986 NOV81《乘用车和轻型卡车声级》中的程序相比，该试验程序的特点是具有固定的终端条件（在试验现场的固定端点处达到额定发动机转速），该程序具有固定的初始条件（在试验现场的固定加速点处规定的初始车速）。 这两个程序都包括车辆的节气门全开加速和节气门关闭减速。对于具有相同特性的车辆系列，根据本推荐规程确定的声级基本上独立于变速器和终传动比。因此，本推荐规程特别适用于车辆系列的开发测试，或将车辆性能差异降至最低的测试开发。

This SAE Recommended Practice establishes the test procedures, environment, and instrumentation for determining the maximum exterior sound level of passenger cars, multipurpose vehicles, and light trucks having a gross vehicle mass (weight) rating of 4540 kg (10 000 lb) or less.This document is intended for use when the maximum sound generating capability of any applicable vehicle is to be measured. The test procedure is characterized by having fixed terminal conditions (attainment of rated engine speed at a fixed end point on the test site) in contrast to the procedure of SAE Standard J986 NOV81, Sound level for passenger Cars and Light Trucks, which has fixed initial conditions (specified initial vehicle speed at a fixed acceleration point on the test site). Full-throttle acceleration and closed-throttle deceleration of the vehicle are included in both procedures.Sound levels determined in accordance with this recommended practice are essentially independent of transmission and final-drive ratios for a vehicle family having otherwise identical characteristics. Thus, this recommended practice is particularly applicable to development testing of vehicle families or to test development where vehicle performance differences are to be minimized.