Subjective Estimation of Airborne Sound Insulation

This study explores airborne sound insulation as an objective and subjective measure.
The concept of this study starts with a hypothesis that there is a need to assess airborne sound insulation in terms of a hearing related measure. Firstly, this study examines how the airborne sound insulation is determined in current standards and how it is affected using different sound signals. To quantify the sound insulation effect of different sound signals and to allow investigating the results numerically, a series of measurements have been carried out. To assess the differences in the evaluation of source signals, electronic filters were generated as well as subjective tests were conducted. The overall results for each research topic can be summarised as follows: Airborne sound insulation determined according to current standards, does not reflect the subjectively perceived sound insulation. It was proven that sound pressure level difference as well as loudness level difference does not relate well to subjectively assessed sound insulation. The introduced loudness level based model correctly depicts the experimental results of the loudest and quietest sound samples as well as the individual frequency dips in the airborne sound insulation. Results of field measurements show that subjectively assessed airborne sound insulation differ from objectively judged airborne sound insulation using descriptors of current standards. Measurements made with different sound signals indicate that the subjectively judged sound insulation is depending on the type of source signal. The model correctly identifies dif-ferent sound signals relating a measure of “reliable” and “not reliable” in terms of a subjective assessed measure with respect to the predicted value. Thus, the model describes the probability that a measured or computed airborne sound insulation corresponds to the subjectively assessed airborne sound insulation.