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The interior noise exposure level within the state of California for new residential dwellings is 45 dBA community noise equivalent level (CNEL). Achieving this standard can be a challenge at locations of high ambient conditions where the home would be exposed to noise from a busy freeway and an active freight and passenger railroad line. In addition, select clients or specific uses may require interior noise levels well below the state standard. The goal of this custom home design project was to exceed the state standard by as much as 10 dBA. Achieving this ambitious goal required more than the typical mitigation strategies. An exterior-to-interior noise analysis was conducted to determine the necessary architectural and acoustical requirements to achieve interior noise levels of 45 dBA, 40 dBA, and 35 dBA CNEL within five rooms of this home. In each case, sound transmission calculations were conducted that resulted in reduction ratings required by the windows, doors, roof and wall assemblies to meet the desired interior levels. Specific building elements were then developed to meet the noise ratings and ultimately the desired interior noise levels. [ABSTRACT FROM AUTHOR]