Just noticeable difference of loudness through building wall of masonry and drywall.

This study investigates the just noticeable difference (JND) of loudness related to sound transmission through two types of walls commonly used in Argentina—masonry walls made of 25 cm thick autoclaved aerated concrete bricks and drywall composed of two 12.5 mm plasterboards separated by a 25 cm glass wool-filled air chamber—both having a weighted noise reduction index (Rw) of 43 dB. Using the method of constant stimuli and online listening tests with 148 participants, the study found no significant difference in subjective loudness perception among four sound stimuli (two vacuum cleaner sounds and two music signals). The JND values for masonry walls corresponded to thickness changes of approximately 3.02 cm (ascending) and 1.62 cm (descending), equating to Rw differences of 2 and 1 dB, respectively, while drywall required larger thickness changes of 4.55 cm (ascending) and 1.26 cm (descending) for a 1 dB Rw difference. The findings suggest that the complexity of wall construction affects perceptible changes in sound insulation, with masonry walls showing smaller JNDs compared to drywall, and highlight the relevance of psychoacoustic evaluation in assessing acoustic insulation beyond standardized indices.