Experimental Study of the Absorption Coefficient of Acoustic Insulators for Undergraduate University Students

Abstract

Objective: This study investigates the techniques for measuring the acoustic absorption coefficient that use an impedance tube, to evaluate their use by students of scientific-technical degrees. Theoretical Framework: This topic presents the concept of absorption coefficient and how it is obtained using impedance tubes. Method: The absorption coefficient of an acoustic insulator is measured as a function of frequency, thickness and density, with an experimental system that uses the transfer function method in an impedance tube. Results and Discussion: The results reveal that the absorption coefficient varies with frequency, being lower at low frequencies. An increase in thickness and/or density produces better acoustic absorption performance. The results are compared with others obtained with an experimental system that uses the standing wave method in an impedance tube. The agreement between the two methods is quite good. Research Implications: The advantages and disadvantages of the two methods are discussed, and their use by students of scientific-technical degrees is assessed. It is recommended to use the transfer function method when students work more autonomously, for example, in final degree projects. Originality/Value: This work offers teachers information related to the experimental study of the acoustic absorption coefficient, which allows them to choose the most appropriate method for each student based on their ability to work autonomously and their knowledge.