Analýza vybraných predikčních metod výpočtu vzduchové neprůzvučnosti dvojitých lehkých stěnových konstrukcí

Abstract

Procedures for an approximation of an air sound reduction of building structures have been developing since the second half of the 20 th century. The simplified procedures, which are also called the numerically graphical methods, serve for the approximation of a single number value of the weighted sound reduction index Rw [dB] The complex models allow a calculation of the sound reduction index R [dB] depending on the frequency. There is some special software for some methods, but the most of predictions is presented in the form of manual calculation. Methods and result : There were chosen three simplified predictive procedures and two complex models for the analysis of the predictive methods. The mutual comparison of prediction was done by the calculation of the weighted sound reduction index Rw [dB] from input parameters of samples of laboratory measurements and calculation of weighted apparent sound reduction index R´w [dB] with measurement in-situ. Because of the reduced calculation effort, the chosen predictions were processed using MS Excel spreadsheet. The most effective method for calculation Rw [dB] a R´w [dB] of double light wall construction. The most suitable Rw [dB] calculation method is the operating method (Čechura).The criterion of applicability has been fulfilled. This method seems to be the best of all from assessed methods because of approximation accuracy and when MS Excel spreadsheet is used, the calculation is easy. The manual index method (Vaverka) was chosen for making adjustments to improve accuracy approximation. Predictive method adjustment complied well with the criterion of accuracy approximation, but it requires a new elaboration of higher amount of dates for final blanket using, which were not available. The complex model Ellefsen is universally suitable allowing the sound reduction index R [dB] calculation depending on frequency. The method is undemanding for evaluation using MS Excel application. The prediction with modification is immediately applicable to calculate this weighted apparent sound reduction index R´w [dB]. The technical method (Čechura) seems to be suitable directly for calculation of weighted apparent sound reduction index R´w [dB] because of approximation accuracy, without correction value k1 [dB] consideration which depends on side ways of sound spread. Conclusions: Using computationally demanding predictive procedures in MS Excel simplified computation and calculation. It has increased the possibility to use a prediction in a real life. Further development of this branch of science can concentrate on a correction of predictive methods. They do not often respond to the real values because of approximate accuracy like the manual index method (Vaverka) and material parameter accuracy. Material parameter often do not correspond to the actual values.