## 2 Materials and Methods  
### Preparation of the Dataset  
To train the algorithm properly, we need to create a large set of data samples, avoiding to record all RIRs as this would be time-consuming, but trying to maintain the authenticity of the RIR impulses. To achieve these goals, we decided to create a dataset of synthetic impulses, but based on the recorded RIRs. First, measurements were made in a university laboratory, choosing a small number of fixed measurement positions. Subsequently, an identical room was designed and imported into the \"Odeon\" acoustic design software. The acoustic parameters of the measured and modeled RIRs were compared and the absorption coefficients of the modeled room surfaces were changed accordingly. This allowed the creation of new synthetic RIRs that are authentic and correspond not only to several measured room positions but also to any selected point in the virtual room. Measurements were taken in a small rectangular room. The main purpose of the room was to test the VR software, so it was almost empty; only three wooden tables remained after the computer screens were removed. The room has a floor area of 31.35 m\({}^{2}\) and a ceiling height of 2.86 m. Three walls of the room are covered with large porous bricks, one wall is concrete and painted, and the ceiling is made up of small square plasterboards with aluminium gaps between them. The floor of the room is linoleum floored and access to the room is through a wide glass door. Authentic room pulses were recorded according to ISO 3382-1 [11]. It is recommended to select and test at least two different sound source positions in the room (with a height of 1.5 m from the ground), as well as at least three to four microphone positions, which should be spaced at least 2 m (half the measured wavelength of the lowest frequency) apart, and at least 1 metre (a quarter of the wavelength of the lowest frequency) away from any reflecting surface. The different microphone positions should be chosen in such a way that the results take into account the reflections produced by all walls covered with different materials, and the height of the measuring microphone should be adjustable to 1.2 m, which corresponds to the typical height of the ear position of a seated listener. To maintain the distances specified in the standard, two positions of the sound source and three positions of the microphones were selected and tested, resulting in a total of six different combinations. The sound source and microphone positions are shown in Figure 1, as well as the grid of microphone positions used in the virtual version of this room. The standard also specifies that the sound source should be omnidirectional and should reproduce all frequencies uniformly between 125 Hz and 4000 Hz. However, to analyze the effect of room acoustics on human voice, these measurements were carried out using a directional loudspeaker, Genelec 8010A, whose directivity is compared to that of human speech in Figure 2[22]. A sonarworks XREF 20 omnidirectional microphone and RME Fireface UC sound card were used as receiver and recorder. We also used the Measure impulse response tool offered by Odeon 16, which allows us to generate and transmit an exponential sweep signal and record the impulse. The same room was then modeled in SketchUp and imported into Odeon. With the same positions for the sound sources and microphones, as well as the assumed absorption coefficients for the surfaces, the RIR simulation was performed. Odeon allows the technical characteristics of a real loudspeaker--directivity, frequency response, dynamic range, etc.--to be assigned to a virtual sound source. The user has to import and activate a CLF (common loudspeaker format) file, which can be downloaded for each specific model of almost all popular loudspeaker manufacturers. Figure 1: Left image shows the locations of the sound source and the measurement microphone in a real room, the different combinations of which were recorded as separate RIR impulses.