If the particle model is selected as calculation procedure and the option "generate particles per octave" (see chapter 9.1.3.1, „Particle Model“ tab) is not enabled (default setting), the scattering coefficient and the transmission factor is averaged from all values in octave bands and this average value is displayed on the button. Spectra of the sound reduction index are first converted to transmission factors, averaged, converted back to the sound reduction index and displayed as a single value on the button.