Traffic noise is a major environmental pollutant affecting public health and quality of life. Although sound level meters (SLMs) compliant with IEC 61672 and IEC 61260 provide reliable measurements, their high cost limits large-scale deployment. Digital micro-electro-mechanical systems (MEMS) microphones offer a compact and cost-effective alternative for distributed monitoring networks; however, their integrated digital architecture prevents conventional electrical testing, challenging metrological traceability and regulatory compliance. This work presents a full-acoustic verification methodology for digital MEMS microphones intended for sound level metering, inspired by IEC 61672-3. The method uses controlled playback of standardized test tones and representative traffic noise signals in an anechoic test box. Unlike established approaches for conventional SLMs verification based on both electrical and acoustic tests, the proposed methodology introduces a full-acoustic, SI-traceable verification framework tailored to digital MEMS architectures. By leveraging easily controllable pressure-field comparison techniques against a reference microphone, this method guarantees measurement accuracy and reliability while facilitating repeatability. It allows for the consistent characterization of sensitivity, frequency response, and dynamic performance under realistic conditions, resulting in a scalable, metrologically robust, and cost-effective solution for advanced traffic noise monitoring applications.