Testing and validation are essential steps in the development of software platforms designed to emulate hardware components. Since modern sound level meters rely heavily on digital signal processing for sound analysis, it seems reasonable to expect that results of equal or greater accuracy can be obtained on computing platforms. The requirements for precision measuring instruments are specified in the international standard IEC 61672-2003 – Electroacoustics – Sound level meters. The standard is applicable to stand-alone or multi-component analog and digital hardware systems, only briefly mentioning computer software as an interim part of the instrument for displaying results and limited data manipulation. On the other hand, modern multi-channel digital systems provide means for storing recorded waveforms on a PC hard drive, thus being completely dependent on dedicated software for all subsequent processing and analysis. Once integrated with the hardware into a complete sound measurement instrument, such software becomes subject to compliance with international standards requiring model evaluation tests and periodic testing. The measurement tool includes several components used for acquisition, data manipulation and analysis. The acoustic transducer (typically a condenser microphone), the signal conditioner and the analog-to-digital converter are used to first convert the sampled analog signal into an electrical voltage and then into its binary representation. Shelton [ ] recognizes this part of the tool as the real-time layer where the tool's resources are dedicated to particular functions 100% of the time. Once the signal has been sampled in real time, it is passed to the ... ... middle of the paper ... were observed during most tests. This was not the case for other common wave file sampling frequencies (44.1 kHz, 51.2 kHz) because the nominal frequencies of the test signal did not satisfy the periodicity condition. This problem is recognized in the field of audio measurement and documented in the works of Lund and in the IEC/TR 602680-18 Audio System Equipment - Peak Program Level Meters - Guide to the Digital Audio Level Meter standard. However, the topic has not been covered in detail since level monitoring in the audio and music domains typically involves broadband signals as audio input. Recommendations are provided to exclude problematic "exceptional" test frequencies from the overall results. This approach cannot be translated into model evaluation tests for sound measurement instruments as these critical frequencies provide the starting point for most electrical tests.