To limit the probability that occupants in one part of a house will be exposed to excessive levels of airborne noise from other parts of the house, which could lead to negative effects on the psychological well-being of persons.
To exempt houses with a secondary suite from the more stringent requirements for sound transmission class ratings in Sentence 9.11.1.1.(1), on the basis that it may be cost-prohibitive where the secondary suite would be constructed as a retrofit and that the occupants of the house containing a secondary suite would be affected only by the sound from one other unit.