## 1 Introduction
showed attempt results based on various parameters of acoustic signals (including waveform shape, modulation techniques, frequencies) and powers delivered to the sound source, depending on the distance from the extinguisher output. In the course of the research, they observed, among other things, an inverse relationship between the decrease in sound pressure level and the distance from the device output (within a limited range), and they also analyzed the sound pressure level and the power necessary to be delivered to the sound source to completely extinguish the flames [19; 28; 29; 31; 46; 48; 52]. As demonstrated in the work [48], to extinguish flames, waves with a changing frequency can also be applied, which is possible with the frequency sweeping technique. In this case, it was shown for sinusoidal waves with frequencies from 16 to 18 Hz (lower and upper limits), with a tuning time not exceeding 750 ms. In the course of the research, the necessary electrical power that had to be delivered to the extinguisher was determined so that, depending on the selected parameters (i.e., frequency and tuning time), the phenomenon of complete extinguishing of the flames was observed. This experimental research confirmed that sweeping frequency acoustic waves can be effectively applied to extinguish flames [48]. In fact, the intended use of acoustic technology is to extinguish flames from the combustion of various substances. Currently, with the acoustic extinguisher, it is possible to extinguish flames from burning organic substances, among other things [29; 32]. In practice, such waves may be useful for extinguishing flames from the combustion of fuels that would be difficult to extinguish by traditional methods. Moreover, it is expected to be applied to the extinguishment of flames from materials that are impossible to extinguish by classical means. However, this requires further research. A separate group of research is the analysis of new materials that are non-combustible or resistant to high temperatures. These can be used, for example, to build components of an acoustic fire extinguisher [57]. In this sense, new developments in nanotechnology and materials engineering play an important role [18; 58; 59; 60; 61; 62; 63; 64; 65]. This is even more important because there is ongoing research around the world that aims to find flame-retardant materials that can be used in many applications. In the case of data transmission from hard-to-reach places, wireless communication can be applied, which is also applicable in the event of natural disasters [66; 67; 68; 69; 70; 71]. In addition to the use of reliable teletransmission techniques, including VSAT (Very Small Aperture Terminal), satellite communication, which is influenced by many factors, is crucial to quickly capture data from a specific location [72; 73; 74]. In practice, using unmodulated and modulated waves to extinguish flames, different-shaped waves can be applied for this purpose [28; 31; 46; 48; 52; 75]. In particular, extending the research presented in [48], this paper will present the results of attempts to extinguish flames originating from organic substances in the field of the influence of sinusoidal harmonics by low-frequency acoustic waves. This will make it possible to determine experimentally whether waves with modified signal components (containing frequencies that are integer multiples of the fundamental frequency) are capable of extinguishing flames, and if so, how the order of the harmonics influences the extinguishing effect.