## 3 Results and Discussion  
Study of the Possibilities of the Acoustic Method for Detecting and Extinguishing Fires of Organic Substances  
The acoustic technique is currently in the testing phase. Since, as previously demonstrated by the co-authors of this paper (bibliography), both unmodulated and modulated waves can be applied to extinguishing, this paper presents results on the possibility of extinguishing flames using sinusoidal waveforms amplitude-modulated (AM) by a square waveform (M\({}_{\text{Freq}}\) = 0.125 Hz). The posted results experimentally confirmed the validity of the theory that such waves can be used successfully to extinguish flames. The results of the research and development work presented in this article are related to experimental attempts to extinguish flames using a prototype acoustic extinguisher with high and very high acoustic power, created based on the structural concept developed (the result is a product--creation) within the framework of the competition co-financed by the Ministry of Science and Higher Education of the program \"Imnovation Incubator +\" [112]. The tangible goal of the research within this program is the presentation of the results from actual attempts of extinguishing, including organic substances, as well as the explanation and description of the principle of the acoustic method, taking into account the physical apparatus of acoustics, considering the molecular point of view and the propagation of acoustic waves that effectively extinguish flames. This approach to the subject made it possible, from a conceptual point of view, to explain the phenomenon in a practical way and to use acoustic waves to control and extinguish flames (the purpose of the extinguisher is to extinguish flames from various substances). For this reason, scientific efforts within the framework of the \"Innovation Incubator +\" (InIn+) project have focused, inter alia, on considering the physical properties of propagated acoustic waves (to control the combustion process and the extinguishing of flames), the analysis of convection disturbances, and the study of the extinguishing properties of unmodulated and modulated waves. In particular, these analyses can be applied to detail the phenomena accompanying the propagation of acoustic waves in confined or enclosed spaces. Acoustic technology is effective in extinguishing organic flames. The reason why the acoustic method is in the center of interest is the many benefits of its application in fire protection, including its versatility, the possibility of multiple applications, and the adjustment of the extinguisher (waveform and modulation) to a particular flame source [82; 83; 84]. These factors significantly reduce operating costs and simplify the maintenance of the acoustic fire protection system, which, in addition to the portable version, can be permanently installed, inter alia, on the foundations of a building (such as an industrial plant). As mentioned previously, this paper presents the results on the extinguishing of flames using the acoustic method over a range of two extinguisher operating frequencies, i.e., 15 and 19 Hz, depending on a distance of the flame source from the extinguisher outlet. For the experiments, a point source of flame was used, i.e., a candle filled with a paraffin wax with a flame height of about 2 cm, whose distance from the extinguisher outlet was changed from 20 cm to 70 or 80 cm (with a step of 20 or 10 cm in the case of the last distance). Using a point source of flames, as opposed to diffuse sources, it was possible to clearly determine whether the flames were successfully extinguished. The power level required to extinguish the flames and the sound pressure level at the point where the flames were extinguished were examined. As previously indicated, all measurements were made under similar conditions with the background sound level of about 65 dB.