SAE J2521程序适用于额定车辆总重低于4540 kg的公路客车和轻型卡车的高频尖叫噪声。该程序包含高温和低温测试矩阵，但未充分考虑环境对制动器啸叫的影响。 对于本试验程序，当使用全悬挂角或全轴总成进行试验时，1.25 kHz和16 kHz之间的峰值噪声级至少为70 dB（A），或不使用全悬挂转角的制动器时，峰值噪声级在2 kHz和16 Hz之间时，会出现尖叫声。 在使用本推荐的底盘测功机试验规程之前，应详细审查至少与（a）仪表相关的细节，包括- 座舱麦克风，（b）噪声检测阈值水平，（c）前轴和后轴之间的温度控制优先级，（d）车辆负载和负载分配，（e）冷却空气和环境调节，以及（f）通道和传感器的详细命名和标签。

The SAE J2521 procedure applies to high-frequency squeal noise occurrences for on-road passenger cars and light trucks below 4540 kg of GVWR. The procedure incorporates high-temperature and low-temperature test matrixes but does not fully account for the effects of the environment on brake squeal. For this test procedure, squeal occurs when the peak noise level is at least 70 dB(A) between 1.25 kHz and 16 kHz for tests using full suspension corners or full axle assemblies or between 2 kHz and 16 kHz for brakes not using a full suspension corner. Before using this recommended practice for chassis dynamometer testing, review in detail the specifics related to at least (a) instrumentation, including in-cabin microphones, (b) threshold levels for noise detection, (c) temperature control priority between the front and rear axles, (d) vehicle loading and load distribution, (e) cooling air and environmental conditioning, and (f) detailed nomenclature and labeling of channels and sensors.