Factors Affecting Siren Loudness & Sound

Siren is an important part of the alarm system to warn and notify others of dangers, whether it is fire, intrusion or other accidents. Below we list some of the factors that can affect the siren sound’s loudness:

Obstruction & Barriers

Various barriers can impede the sound. Some commonly used materials for absorbing sound include: wood, plastic, concrete and composites. Obstruction such as earphones or hearing protection gears can also reduce the effectiveness of siren.

Placement
How the alarm siren is placed can also have an effect on sound projection. For example, an alarm siren placed in a directed funnel could have an amplifying effect on sound. While a siren placed in front of reflective material, can have sounds quickly dissipated or reflected.

Distance

As with what you observe in real life, when a person is farther away, it is harder to hear the sound. This can also be applied to sirens. As the alarm sounder distance doubles, the sound level pressure also decreases logarithmically.

Ambient Noises
When the environment has loud ambient noises, the siren’s effectiveness could be diminished. This is due to the complex effect of sound particles interacting with one another and impeding the sound propagation. Significant ambient noise also affects how our brain processes the sound. For the siren sound to be perceived, we suggest to make your device 5 decibels louder than the environment.

Recipient’s State of Consciousness
For above factors we are considering the sounder device or environment, but there is also difference between an awake or asleep person. For an awake individual, it is recommended that the siren sound is at least 65dB. For a sleeping person, it is suggested that the siren sound is at least 75dB.

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