Ilmankestoisuusääneneristysindeksi

Ilmankestoisuusääneneristysindeksi, often abbreviated as R'w, is a standardized measurement used to quantify the sound insulation performance of building elements against airborne sound. It is a single-number index derived from the sound reduction index (Rw) curve, which represents the sound insulation of a building element across a range of frequencies. The R'w value provides a simplified way to compare the acoustic performance of different walls, windows, doors, and other building components.

The measurement is determined in laboratory conditions using standardized procedures. The sound reduction index (Rw) is measured at various one-third octave bands of frequency, typically from 100 Hz to 3150 Hz. The R'w value is then calculated by comparing this measured curve to a reference curve, using a specific weighting method defined in international standards such as ISO 717-1. This weighting accounts for the differing sensitivity of the human ear to various frequencies, giving more importance to frequencies where humans are more sensitive to noise.

A higher R'w value indicates better sound insulation, meaning the building element is more effective at blocking airborne sound from passing through. This index is crucial for architects, builders, and regulators to ensure that buildings meet specified acoustic requirements for comfort, privacy, and compliance with noise regulations. While R'w provides a useful single-figure assessment, it's important to note that it's a simplified representation and the detailed frequency-dependent sound reduction index (Rw) curve provides a more complete picture of a building element's acoustic performance.