Supplementary Information for Quantifying nonlinear electric-acoustic mixing in lead zirconium titanate with a vector network analyzer

Information on how we measured the speed of sound in our sample and an error analysis for calculated values reported here. More detailed information on the experiment we conducted to determine the propagation delay time of the acoustic signal in our sample is also contained here as well as the results of our
background noise measurement. Lastly we provide a thermodynamic argument for attributing the mixing signal to
electrostriction.