For a series of applications no requirements and tests are given in the standards of the series DIN EN 61672 "Sound level meters". No specifications are contained for maximum noise levels within definite periods of noise described in the TA Lärm (German Technical Guidelines for noise reduction). Also, no specifications for the formation of characteristic values of the level frequency distribution nor exceedance levels are included. Furthermore, DIN EN 61672-1 contains no specifications for time weighting I which is required for some standards, however. Information for frequency weighting AU for ultrasound measurement in the presence of audible sound. This standard contains these specifications as optional additional requirements for sound level meters. This standard applies for sound level meters for special measuring tasks. These measuring tasks include - measurement of level frequency distribution or exceedance levels, - measurement of level frequency distribution and impulse noise with time weighting I, - measurement of ultrasound in the presence of audible sound with frequency weighting AU. The application of each special additional requirement shall be agreed upon separately. The maximum values of the expanded uncertainty of the inspection body that shall be met are given for the measurands of this standard. The tests and acceptance limits follow the specifications in DIN EN 61672. The following modifications have been made with respect to DIN 45657:2005-03: a) concept of the acceptance limits has been adopted; b) requirements for and test of time weighting I have been added; c) information for frequency weighting AU has been added; d) cited standards have been updated. This standard has been prepared by Joint Committee NA 001-01-03 GA (NALS/DKE A 3) "Schallmessgeräte" ("Sound measuring instruments") under NALS chairmanship.