Construção e teste de um tubo de impedância para medição de isolamento

Abstract

Due to the increasing noise pollution, especially in large urban centers, the need for sound insulation in order to increase comfort and reduce noise damage has increased. To use and research for materials for this purpose, some properties must be analyzed, one of these properties is Transmission Loss (TL). The present work focuses on the design, construction and subsequent validation of a device called Impedance Tube, capable of measuring the TL property, using the Transfer Matrix Method which, because of its good repeatability, makes it possible to use only a signal pickup microphone, significantly reducing the cost of production. The prototype design is presented in detail as well as its manufacturing and validation process. The technique used is based on obtaining data using a MATLAB Toolkit, with data treatment implemented in its programming language, using the Transfer Matrix Method and the Two Loads Method. Results of measurements made with the sampled tube resulted in Transmission Loss close to zero as expected. Measurements of a sample of porous material were made to compare results with those obtained on another Impedance Tube and showed similar performance. Samples made of wood and aluminum were also measured and showed results below that obtained from an estimate based on a mathematical model.