U.S. Department of Transport - report on effectiveness of sirens -1977. Most detectable signal (6) Pulsed sinusoidal then (5) Sinusoidal; (1) Wail; (3) Electronic Hi-Lo; (4)Electromechanical. Least detectable signal Yelp (2) - one of the main sirens still in use today World wide.
|
Note how signal (6) pulsed sinusoidal - is 3 to 4 times more detectable than signal (2) - yelp.
Subjects aged over 64 scored significantly higher with most signals. Older people lose the ability to hear higher frequencies, the high frequency components of some sirens are a distraction and add confusion to the listeners' perception of the direction of the source signal. |
Registered office:
DIRECTIONAL SIRENS Ltd 21 Wyndcote Rd Merseyside L18 2EB |
phone +44 (0)151 234 9887
mobile +44 (0)796 426 9350 |