Characterization of the acoustic signals of the explosion of hand-held fireworks

To improve the accuracy of investigating fire incidents caused by fireworks explosions, we collected and analyzed the phenomena and acoustic signal features at different stages of the explosion process. First, acoustic data were captured in a laboratory for all phases of the fireworks explosion. Next, the collected data underwent framing, windowing, and short-time Fourier transform operations, resulting in the generation of waveform and spectrogram plots of the sound signals. Finally, we extracted the frequency characteristics of the fireworks explosion at different stages , concluding that: during the ignition phase, the sound is characterized by a faint hissing noise, accompanied by a few sparks, with the frequency spectrum primarily concentrated in the low-frequency range of 0-200 Hz, particularly featuring a distinct band around 180-200 Hz. During the stagnation phase, external acoustic and optical manifestations temporarily diminish. The ejection phase produces a short and crisp ejection sound, with the acoustic signals predominantly distributed in the 0-6 kHz frequency range, displaying a waveform envelope resembling that of a bullet. In the explosion phase, the waveform envelope takes on a conical shape, with the frequency spectrum concentrated in the 0-6 kHz range, especially highlighting distinct bands around 2 kHz and 4 kHz.