Subjective impression of auditory danger signals in different countries

A study was designed to examine the effects of frequency components and temporal components and temporal factors on the impression of dangerousness with systematically controlled synthetic sounds, which were applied for stimuli. The frequency was transferred from the low octave to the high in two octaves. Six kinds of frequency components and four kinds of off-time were applied during the experiment. It was observed that when the signal consisted of a wide frequency range and the frequency sweeps from low to high, it would be hard to be masked in noisy situations and can be detected by the people who have some usable hearing to identify the signal in some frequency region. It was proposed that the signal, whose frequency shifts from low to high over a wide range, provides the impression of dangerousness and that the impression becomes more unsafe as the off-time becomes shorter.