What is the standard of review applied to a motion to suppress a statement under Miranda?

"An appellate court applies the independent or de novo standard of review, which by its nature is nondeferential, to a trial court's granting or denial of a motion to suppress a statement under Miranda insofar as the trial court's underlying decision entails a measurement of the facts against the law. [Citations.] As for each of the subordinate determinations, it employs the test appropriate thereto. That is to say, it examines independently the resolution of a pure question of law; it scrutinizes for substantial evidence the resolution of a pure question of fact; it examines independently the resolution of a mixed question of law and fact that is predominantly legal; and it scrutinizes for substantial evidence the resolution of a mixed question of law and fact that is predominantly factual." (People v. Waidla (2000) 22 Cal.4th 690, 730.)