Paragraph 1.8 of Approved Document E specifies that sound insulation testing should not be carried out between living spaces and: corridors, stairwells or hallways. This is because sound insulation testing between such spaces may give unreliable results due to the possible complex shape of circulation spaces, and the possible difficulty of establishing the volume of a circulation space.
There can also be reduced accuracy when sound test measurements are made in small rooms, and guidance on this is given in paragraph B2.11 in Annex B.
Where separating walls or floors are subject to requirement E1 they should always be designed and constructed to provide reasonable resistance to sound even if they are not going to be subjected to testing.