In the article, we consider the model of pulse signal distortion in the computer sound card channel. The use of such a model allows expanding the possibilities of using computers in the researches of the wood properties in the form of various dielectric characteristics analysis, in particular using the computer sound card channel. This makes it possible to verify the state of the signal propagation channel during the experiment. This experiment researches samples of wood for the presence of defects. Also is proposed an approach to constructing the distortion model. It allows to expand the possibilities of investigating the parameters of the pulse signal and to verification the state of the channel during the research of the dielectric properties of wood. To research, a sample of wood using a computer sound card is developed a structured scheme that allows you to analyze the characteristics of pulse signals during the measurement process. To determine the dielectric parameters of different types of industrial wood is developed the software in the MATLAB environment. Using it is analyzed complex pulse signals that used during the research. In particular, were taken into account different currents of wood polarization and dielectric characteristics.