In the field of noise control and monitoring, a new generation of small and low-cost microelectro-mechanical system (MEMS) microphones is nowadays widely adopted. MEMS microphones, after recognition as traceable measurement instruments, could open up promising measurements based on wireless sensor networks. Current standards do not apply specifically to digital microphones. In this work, a pressure calibration procedure by comparison is carried out for a digital MEMS microphone and a sensitivity parameter suitable for metrological purposes is proposed. Measurement procedure and results between 20 Hz and 20 kHz are presented along with uncertainty contributions.