In Phonetic Sciences, statistical analysis from experimental data have to be carried out to confirm or disconfirm hypotheses. In this paper, a phonetic data set is considered and phonetic research questions are addressed. To answer these questions, a mixed model is built using a complex random effects structure and a non-diagonal residual variance-covariance matrix. Then, it is validated on the data. Finally, we focus on statistical tests in the final model allowing to compare the means between two groups of subjects, and a single mean to a reference value. The paper is accessible to an audience experienced with linear models. Some familiarity with the R software is also helpful.