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

In this study, the just noticeable difference (JND) of loudness with respect to sound transmission through walls corresponding to a weighted noise reduction index R_w of 43 dB is investigated. Two types of walls typically used in Argentina are evaluated. One is masonry composed of solid autoclaved aerated concrete bricks with a thickness of 25 cm, and the other is a drywall composed of two 12.5 mm plasterboards with a 25 cm air chamber in between them, filled with glass wool. The JND is determined using the method of constant stimuli for both ascending and descending variations. The source signals used are two types of vacuum-cleaner sounds and two music signals. Online tests are conducted owing to restrictions imposed by the COVID-19, and the presentation level of the stimuli is adjusted based on the sensation level of each individual. Responses from 148 different listeners show no significant difference in the subjective responses among the source signals. Regarding the masonry, the JND values are 3.02 and 1.62 cm for the ascending and descending variations, respectively (corresponding R_w difference of 2 and 1 dB), whereas they are 4.55 and 1.26 cm for the drywall, respectively (1 dB for both).