The research presented regards the study of D4 using experimental speed of sound measurements to obtain the ideal gas isobaric heat capacity. The isobaric heat capacity is not a useful property for the generation of equations of state, in the presented research it is used for the validation of thermodynamic models. However, due to the observed sensitivity of the conventional method used for the analysis of the speed of sound data, an effort is undertaken to develop a new analysis method. The aim of this newly developed method is to determine the same properties as the conventional method, albeit less sensitive towards a fluctuation in speed of sound.