## 3 Materials and Methods
### Formal Formulation of the Evaluation Problem
Such fluctuations can increase cognitive load and cause irritability. This is particularly important in the aviation environment, where varying noise levels can affect attention stability and fatigue levels [15; 16]. \(ve_{3}\): Roughness is a psychoacoustic parameter that defines the subjective perception of rapid amplitude modulations of sound, creating a sensation of \"roughness\" or unpleasantness in the sound. It is most noticeable at modulation frequencies from 20 to 300 Hz and depends on the frequency of the main signal, the modulation depth, and the spectral composition. The unit 'asper' is used to measure the roughness of sound and defines the subjective perception of rapid amplitude modifications of sound that create a sensation of 'roughness' or unpleasantness. One asper corresponds to a sinusoidal signal with a frequency of 1 kHz and 100% modulation at 70 Hz [20]. It is known that sound with a high level of roughness contributes to increased nervous tension and stress response in the body, which are critical for flight instructors in situations of increased workload [16; 21]. \(ve_{4}\): Sharpness is a psychoacoustic parameter that defines the subjective perception of high-frequency components of sound, becoming sharper as the energy increases in the frequency range above 3 kHz. It is measured in acum units. High sharpness of sound is associated with increased sensory tension, which can lead to cognitive overload and fatigue. Research in psychoacoustics suggests that sharp high-frequency noises are more irritating than low-frequency ones and can significantly affect the psychophysiological state [15; 20]. \(ve_{5}\): The tonality of sound according to the harmonic masking signal (HMS) is a psychoacoustic parameter that determines the level of prominence of the harmonic (tonal) component in a sound relative to its noise component. It indicates how much the sound is perceived as a pure tone or how much noise it contains, and it is measured in tonal units (tu). According to the evaluation criteria, the flight instructor is surveyed via questions before each flight. The HMS method assesses the degree to which the harmonic components of a sound are masked by surrounding noise, thereby determining the prominence of tonal features. This makes this parameter important for analyzing pleasure in the subjective perception of sound. However, it should be noted that in this version of the platform, only acoustic parameters are considered tension or discomfort according to the \"Device for measuring individual psychophysiological load\" [24]. A complex psychoacoustic signal contains both tonal and noise components, where the tonal component stands out distinctly against the background noise. The clearer and more isolated the tonal element is from the noise, the higher the perceived tonality. It is known that a high level of tonality can either facilitate or complicate cognitive perception of information, depending on the conditions. Conditions in which noise has a pronounced tonal component can place additional load on the auditory analyzer and affect the stability of attention [15; 16]. These five parameters were recorded in real time during flight using a Head Acoustic measuring device, with a sampling frequency ranging from 59 to 1848 times per second, and the results were subsequently processed using Artemis software Suite 11.0 for Head Acoustic [21]. Thus, the selection of these parameters is justified by their proven impact on cognitive processes, stress levels, and physiological state, which are critical for flight instructors when performing their professional duties. To measure the noise level, the device provides data that simulates the perception of sounds by human hearing, distributing them between the right \(\left\{ve(R)\right\}_{1};ve(R)_{2};\ldots;ve(R)_{5}\) and the left \(\left\{ve(L)\right\}_{1};ve(L)_{2};\ldots;ve(L)_{5}\) ear. This allows a more accurate assessment of the sound characteristics in relation to the physiology of the human auditory system.