Sirens: these loud noise making devices have been a part of history for a very long time and are widely used in the world today for various applications. Most of the uses of sirens are usually for emergency noise makings, such as in the case of an ambulance speeding through traffic or a hurricane warning system to inform civilians of the upcoming weather condition. No matter what the application of a siren, it can always be divided either into a pneumatic or electronic siren. A measure for civil defense, sirens are typically used for air raids, tornado/ tsunami warning systems or for emergency service vehicles such as ambulances, fire trucks or police cars.
Civil defense sirens are usually mounted at the top of community or civil defense building to alert an entire community of any impending danger such as fires, tornados or other natural disasters. If they are not mounted on the roof of the buildings, they can be located next to the building in the open to enhance the sound quality. Sirens that are used for civil defense usually have some type of coding to ensure the right message is passed across. For example if a fire station wanted to inform fire fighters where the fire was located, it could let out a slow wail three times, or in other cases three steady tones can be let out for another signal. These types of signals are usually understood by the parties that are involved due to pre-rehearsal or pre-determined set of codes that are meant to be understood by the parties involved. The local authority would inform civilians of the set of codes and what they are supposed to mean and ensure that everybody is familiar with each signal so that they know when to evacuate in case of a natural disaster. In terms of war signals, armies can have their own set of signals to indicate an air raid or an attack on the enemy or an incoming attack. This form of communication can be very effective as those involved would be able to understand what is happening and their expected task whilst the enemy would not be able to decode the signal and the opponent’s next move.
The use of sirens on emergency vehicles is very essential in times of emergency. Although most of these vehicles have flashing lights that are fixed on top of them, the siren acts as an additional feature to aid the movement of the vehicle in times of emergency. The siren is more effective than the lights as it can be heard from a distance allowing vehicles to get out of the way of the speeding emergency vehicle. The sound that these vehicles make is very distinct and cannot be confused with any other types of emergency sirens. Also the siren of these emergency vehicles can be calibrated to output a louder signal when approaching heavy traffic or an intersection. As emergency vehicles are usually exempted from some traffic rules in case of emergency, it is important for these vehicles to give out a loud signal when approaching an intersection in order to avoid an accident and give the drivers time to move out of the way.
Aside from sirens used on emergency vehicles, there are also home or vehicle safety sirens that many people now use to safeguard their home, vehicle or property. These sirens are usually called security alarms and set off when an intruder breaks the security system with unregistered means. The siren would then go off to notify the property owner. These sirens are usually not as loud as those used for emergency warning as these are normally used in neighborhoods. Though sirens are very beneficial for their various applications, there are some disadvantages that come with their use. They can cause noise pollution due to their repetitive high pitch volume that could be disturbing to some. Also if a person is constantly exposed to a siren, it could harm his or health. As for those sirens used in security alarm systems, they could be disruptive to neighborhood peace as they require an owner to turn it off before it goes off, for instance if the owner of a property happens to be away and the alarm was to go off, it could be a nuisance to those living around. This means that although sirens have benefits, they do have some disadvantages as well.