TABLE 1 is taken from the above report published in May 2017.
The sirens below give 2 or 3 seconds warning at 30 mph (44 ft/second) on straight roads.
At crossroads there is less than 1 second warning that an emergency vehicle is approaching.
The sirens below give 2 or 3 seconds warning at 30 mph (44 ft/second) on straight roads.
At crossroads there is less than 1 second warning that an emergency vehicle is approaching.
These sirens are still in Worldwide use today - over 40 years later.
PERCEPTION of YELP and WAIL SIRENS
Most motorists have experienced hearing emergency vehicle sirens,
but are unable to readily locate the direction the vehicles were travelling from.
• Electronic sirens often use rising frequency sounds which change continuously.
The human psychoacoustic system has insufficient time to lock on to the sound because the frequency is constantly changing, often over a very short time.
• The high frequencies of electronic sirens bounce off walls and buildings with little perceptible change in volume or pitch.
This makes it difficult for motorists to differentiate between the original siren sound and the reflected sound.
• Current sirens have a narrow sound beam projecting mainly forward but not to the sides.
This makes them hard to detect, especially at crossroads - where the majority of accidents occur.
The human psychoacoustic system has insufficient time to lock on to the sound because the frequency is constantly changing, often over a very short time.
• The high frequencies of electronic sirens bounce off walls and buildings with little perceptible change in volume or pitch.
This makes it difficult for motorists to differentiate between the original siren sound and the reflected sound.
• Current sirens have a narrow sound beam projecting mainly forward but not to the sides.
This makes them hard to detect, especially at crossroads - where the majority of accidents occur.
ELECTRONIC SIRENS - TESTING RESULTS
YELP! and WAIL! Sirens were introduced in the mid 1970's
A USA Government Sponsored Report in 1977 tested electronic sirens.
The results showed that the Wail siren's direction was able to be judged
41 percent of the time.
The yelp siren's direction could be heard
just 17 percent of the time.
Wail and Yelp sirens continue to be used today
with detrimental effects on the health and safety
of the public and emergency services personnel.
A USA Government Sponsored Report in 1977 tested electronic sirens.
The results showed that the Wail siren's direction was able to be judged
41 percent of the time.
The yelp siren's direction could be heard
just 17 percent of the time.
Wail and Yelp sirens continue to be used today
with detrimental effects on the health and safety
of the public and emergency services personnel.
Electronic sirens are proven to have poor effectiveness.
Fit Quadrasonic ™️ Directional Siren Systems for improved efficiency and safety.
Fit Quadrasonic ™️ Directional Siren Systems for improved efficiency and safety.