During the acoustical characterization of a component of a building, machine or vehicle, the normal incidence sound transmission loss is a major factor. Transmission loss simulation is also crucial in designing intake or exhaust elements, such as reflective mufflers. However, there is not enough information in the open literature about the applicable frequency ranges of experimental and 1- and 3D simulation methods. Therefore, the main purpose of this paper is to evaluate the frequency limits of computational and experimental transmission loss analyses of various reflective mufflers. For the validation two in-house impedance tube test benches were designed and multiple measurement setups were investigated. The combination of the four-pole matrix and the two-load methods was used during the experimental part of the study. In order to obtain appropriate transfer function results, distinct setups were evaluated, such as a low-frequency sound source with bigger tube diameter and a high-frequency sound source with smaller tube diameter. The low-frequency setup is suitable for the investigation of the system in the range of 30-500 Hz. The high-frequency setup is capable of measuring from 300 Hz to 2000 Hz, which is the upper frequency limit of the range of interest. Consequently, the in-house system is suitable for measuring the transmission loss in the 30-2000 Hz frequency range. 1D simulations were performed using Ricardo Wave software and 3D simulations were carried out in the STAR-CCM+ software. The upper cutoff frequency of 1D simulation method was determined to be 1500 Hz according to the correlation with the measurements. The frequency range of simulation could be extended up to 2000 Hz by employing 3D simulation for transmission loss calculations. This paper gives insights into the transmission loss measurements with the in-house system and the correlation analysis with different simulation methods.