Part 1 of the standard shall apply to any source -receiver configuration where the receiver mobility is 10 dB below the source mobility (see definition of mobility in Clause 3 below). However, part 1 is restricted for the moment to whirlpool baths since only this type of building equipment has been experimentally studied so far; for other types of building equipment, the principle of the method is still valid, but some details in the standard might not be relevant. Therefore, this first part: - specifies methods for the measurement under laboratory conditions of airborne and structure borne sound produced by whirlpool baths connected to low mobility structures; for the case of whirlpool baths, building structures of mass per unit area equal or greater than 220 kg/m2, hollow elements excluded, are considered as low mobility elements; - defines the expression of the results, including data for comparison between products (single value descriptors) and input data for the prediction method (link to standard prEN 12354-5 explained in Annex B).