Applicability of measurement method according to ISO 16283 in small rooms at low frequencies

In a research project the robustness of the new measurement method for the sound pressure level in small rooms at low frequencies was investigated recently introduced in the ISO16283 series on sound insulation measurements in buildings. Annoyance due to low frequency sound, like from home theatres, became a problem in multi-family buildings. In many countries a discussion to include frequencies from 50Hz to 80Hz in building acoustic requirements started. In this range the sound field is dominated by single room modes instead of being diffuse. The introduced measurement method considers in addition to the average sound pressure level in the center area of the room also the maximum level in the corners to obtain a better estimate at low frequencies in small rooms with less than 25m3 room volume. The experimental results of the standardized methods were compared to non-standardized methods with microphone positions on the room diagonal and to the "real" average sound pressure level of the room volume in a dens grid. Further, investigations on the influence of source position, selected corner, microphone position in the corner, and of furniture in the vicinity of the corner are presented and implications on the final results are discussed.