Noteworthy Characteristics of Lift Truck Noise Test Standards

Several test standards exist for measuring lift truck sound levels, both for operator's ear sound levels and exterior (sound power) levels. All of the test standards result in the reporting of a single-number sound level that is a weighted average of the measured sound levels in various operating modes.

This paper presents the results of calculations based on actual measured data that clarify the sensitivity of the reported sound levels to the sound levels in the individual modes. The results show that for both of the common operator's ear noise test standards, the reported sound levels are typically very insensitive to the idle sound level even though the idle sound level is given a much higher weighting factor than the other modes.

Also of interest are the lift truck sound power test standards. The test procedures include a driving test mode that is derived from the ISO 6395 earthmoving machinery test standard. Measured data and calculations are included that illustrate some unique aspects of this test mode.