## 3 Results and Discussion
It should be noted that in an environment with high noise levels, acoustic waves, depending on the frequency used, can be more or less susceptible to ambient sounds (generally in the range of about 15 to 60 Hz). For this paper, the results of the experimental attempts on the possibility of extinguishing flames using modulated acoustic waves are presented (this technique has not yet been fully discovered, so there was a need to fill the literature gap in this area). In the experimental part, amplitude modulation (AM) was applied--a sinusoidal waveform modulated by a rectangular waveform (M\({}_{\text{Freq}}\) = 0.125 Hz). These experimental results have potential application in the testing of the acoustic extinguisher with a high and very high acoustic power and in clarifying the principle of its operation. Below are presented the results for the necessary electrical power that had to be delivered to the acoustic extinguisher to extinguish the flames and the recorded sound pressure level at the point where the flames were successfully extinguished, as a function of a distance from the waveguide outlet (20, 40, 60, and 70 or 80 cm), for the carrier wave frequencies analyzed (15 and 19 Hz). Figure 7 shows the results for the required power to extinguish the flames at 15 Hz as a function of distance from the device outlet. The minimum sound pressure level at which the flames were completely extinguished as a function of a distance from the device outlet is presented in Figure 8.  
Figure 8: Minimal Sound Pressure Level (SPL) at which complete extinguishment of flames was recorded depending on a distance (L) from the fire extinguisher outlet (a case of the carrier wave of 15 Hz). Figure 7: Minimum electrical power (P) that must be delivered to the extinguisher to extinguish the flames depending on a distance (L) from the fire extinguisher outlet (a case of the carrier wave of 15 Hz). Correspondingly, Figures 9 and 10 present the analogous measurement results obtained for the higher frequency of the acoustic wave analyzed, i.e., 19 Hz. The results of the sound pressure level obtained for the second of the acoustic wave frequencies analyzed, i.e., 19 Hz, seem interesting against this background (Figure 10). The conducted research shows that the extinguishing effect depends on a frequency. A correlation can be observed between an increase in power and an increase in frequency, with differences due to the operating point of the acoustic extinguisher. Taking into account the identification of the fire extinguisher parameters, the closer to the frequency at which the minimum impedance was recorded, the lower power required to extinguish the flames. For both frequencies analyzed, as the distance between the waveguide outlet and the flame source gradually increased (with a step of 20 or 10 cm in the case of the last distance), more and more electrical power had to be delivered to the sound source to observe the phenomenon of the complete extinguishment of the flames (this regularity applied to all analyzed distances from the flame source). The recorded necessary powers to extinguish the flames were generally higher for the second of the analyzed frequencies, i.e., 19 Hz (except for the data obtained for the smallest of the distances at which similar results were noted). By comparing these two frequencies, for a distance of the flame source from the extinguisher outlet equal to 20 cm, a power difference of 50 W was recorded, for a distance equal to 40 cm--145 W, for a distance equal to 60 cm--203 W, and for the last  
Figure 10: Minimal Sound Pressure Level (SPL) at which complete extinguishment of flames was recorded depending on a distance (L) from the fire extinguisher outlet (a case of the carrier wave of 19 Hz). Figure 9: Minimum electrical power (P) that must be delivered to the extinguisher to extinguish the flames depending on a distance (L) from the fire extinguisher outlet (a case of the carrier wave of 19 Hz).