We hypothesize that the effectivity of sirens as warning signals has been enhanced by natural sensory predisposition of humans to get alerted by howling of wolves; wolves reply to technical sirens with howling too

Wolf Howling and Emergency Sirens: A Hypothesis of Natural and Technical Convergence of Aposematic Signals. Diana Kořanová, Lucie Němcová, Richard Policht, Vlastimil Hart, Sabine Begall & Hynek Burda. Acta Biotheoretica (2020). Sep 2 2020. https://link.springer.com/article/10.1007/s10441-020-09389-6

Abstract: Acoustic signals serving intraspecific communication by predators are perceived by potential prey as warning signals. We analysed the acoustic characteristics of howling of wolves and found a striking similarity to the warning sounds of technical sirens. We hypothesize that the effectivity of sirens as warning signals has been enhanced by natural sensory predisposition of humans to get alerted by howling of wolves, with which they have a long history of coexistence. Psychoacoustic similarity of both stimuli seems to be supported by the fact that wolves and dogs perceive the sound of technical sirens as a relevant releasing supernormal stimulus and reply to it with howling. Inspiration by naturally occurring acoustic aposematic signals might become an interesting example of biomimetics in designing new warning sound systems.