This invention describes a method for processing pressure signals derivable from locations inside or outside a human or animal body or body cavity. A major aspect of the invention relates to a method for determining relationships between different pressure-related signals with the purpose of obtaining signals predicting pressures inside a body or body cavity from pressure signals outside said body or body cavity. According to the invented method different formula-based relationships for specific types of signals and locations and sensor types are determined, which provides for a reference that can be applied on new and individual non-invasive pressure measurements. Thereby continuous pressure-related signals from a non-invasive source may be processed in a way that makes the continuous non-invasive pressure signals highly predictable of the pressures inside the body or body cavity.
