This article analyses noise measurement on a tuning fork micro-electromechanical sensor (MEMS) gyroscope with the sense mode operated in open loop. It considers the impact of noise on drive displacement through the mechanical coupling, which to our best knowledge has only one mention in the literature. A model for this noise and its parameters estimation based on experiments is proposed. Models for other noise sources and the sensor, mainly based on literature, are developed. The expected noise power spectral density (PSD) at the sensor output is compared with experiments. It was found successful to predict the main behaviours of measured noise. Moreover, noise resulting from mechanical coupling is found to be an important contributor in low frequencies.