NAQ has been proposed as the 4th prosodic dimension of expressive speech. This paper aims at testing the consistency, for characterizing emotional expressions in voice, of the Normalized Amplitude Quotient (NAQ) vs. the estimated Open Quotient (OQ) parameter vs. the direct EGG measurement of glottal parameters. Those parameters were tested on an authentic expressive speech corpus. The phonemic influence of the NAQ parameter was first evaluated by matching measure locations with an expert phonetic labeling. Estimations of F0 and OQ calculated on the one hand by inverse filtering and on the other hand from electroglottography (EGG), were then systematically compared. Results show a speaker-dependent phoneme effect on NAQ, and seem moreover to indicate a systematic overestimation of NAQ on [n] segments. In parallel, the comparison between inverse filtering and EGG parameters shows an underestimation of F0 used for the calculation of amplitude-based parameters. No correlation could be found between the OQ values calculated from both methods.