Towards a Reference Spectrum for Façade Sound Insulation: on average Spectra representing temporally varying Sounds

Excessive noise has an adverse outcome on the quality of life of humans. Sound insulation serves to reduce the exposure to environmental sounds intruding into living spaces. The performance of buildings and elements is described by single-number quantifiers, which, for façade sound insulation, weighs the frequency-dependent attenuation according to noise exposure at the façade in an averaged spectrum of road traffic noise. This paper presents a preliminary investigation in the evaluation of the perceptual relevance of average spectra to represent temporally varying sounds relevant to façade sound insulation. It evaluates if the overall loudness of a temporally varying sound corresponds to that of noise with the same average spectrum. This is done in a listening test where the participants adjust the level of noise to equal-loudness of the time-varying sound as the reference. Moreover, methodological aspects regarding the stimuli preparation and response collection method are also explored. The results indicate that the average spectrum of a temporally variable stimulus does not capture the loudness perception of the stimulus, although with stimuli-dependent deviations of less than 2 dB. Impacts of spectrum resolution and shape were negligible; however, the responses were greatly influenced by the direction of the adjustment.