Abstract: The calibration of the measurement error of the sound absorption coefficient, using the impedance tube (transfer function method), employs the standard sample method. The excitation of a plane wave is produced by the broadband sound source within the tube. By measuring the transfer function of the response signals of two transducers, the sound absorption coefficient of the standard sample is determined. The measurement error of the sound absorption coefficient is then deduced by comparing this with the standard value of the standard sample. As the operating frequency range of the impedance tube under calibration may not correspond with the calibration frequency range mentioned in the certificate of the standard sample, it is essential to determine the impedance tube's working frequency range prior to calibration. This further aids in establishing the calibration frequency range, thereby avoiding calibration result inaccuracies. This study encompasses a theoretical analysis and simulation of the cut-off frequency of the plane wave sound field generated within the impedance tube, and a simulation of the sound absorption coefficient of two impedance tubes with distinct diameters (or side lengths) and varied transducer spacing. A mathematical model that establishes a relationship between the tube diameter (or side length), transducer spacing, and frequency range has been derived from these simulations. This model serves as a useful tool providing guidance for the calibration of the measurement error of the impedance tube's sound absorption coefficient.