声压校准(sound press level calibration)的含义

下面列出B&K公司在噪声测量中对声压级校准的描述:
Calibration
Sound level meters should be calibrated in order to provide precise and accurate results. This is best done by placing a portable acoustic calibrator, such as a sound level calibrator or a pistonphone, directly over the microphone. These calibrators provide a precisely defined sound pressure level to which the sound level meter can be adjusted. It is good measurement practice to calibrate sound level meters immediately before and after each measurement session. If recordings are to be made of noise measurements, then the calibration signal should also be recorded to provide a reference level on playback.,
在某一频率下产生标准声压:



将一个称为校准块的单一频率的标准发声器套到传声器上,以校准声学测量系统.不同厂家的校准块的频率不尽相同.例如L&D噪声分析仪是250Hz上114dBA.B&K噪声分析仪是1000Hz上114dBA.不论是哪种单一频率,效果都是一样的,只要被校准的噪声测量系统显示与标准块的频率与声级值相同就 OK了.

校准是精确测量中的必要步骤。校准程序将传声器的声压输入和的电输出建立精确的关联。校准可在250Hz或1kHz的频率下进行。两种频率各有其优缺点
  在250Hz的频率范围,几乎所有传声器的频率响应都非常平坦,因而可得到最精确的校准。但如果传声器是与计权滤波器连接并作为测量设备使用时,例如带A计权的声级计,则250Hz处的信号便会被计权网络衰减。此时用1kHz的校准频率就有其优势。
 计权滤波器在1kHz的衰减为0dB,故不会对校准构成影响。但是当传声器的频率响应不平坦时,可能会出现细微的误差
 活塞发声器是校准传声器的精密声源。
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