Acoustic Shock Caused By Alarms or Sirens

How do we measure sound? And how loud is an alarm? What happens when we take a call where an alarm or siren is ringing at the other end?

What is a Decibel Scale?

The Decibel scale is used to measure the intensity of sound. It is based on a logarithmic scale with multiples of 10. Human perception of sound has a roughly logarithmic response to the intensity of sound. This means that when a sound increases by 10 decibels, it is 10 times louder. This is different from what the ear perceives. The ear will perceive 80 dB twice as loud as 70 dB.


How loud is an alarm?

A fire alarm standard minimum dB is 65dB but can reach up to 120dB and more. 120dB is 37 times louder than 70dB! While 65dB is equivalent to a noisy office, 120dB is the sound of an airplane taking off. Researchers studying hearing loss in the workplace found that people being exposed to noise levels at 85db or higher for prolonged periods of time are at risk of hearing loss.

What is Acoustic Shock?

Acoustic shock is an incident caused by an unexpected loud, high frequency, sound. These sounds include alarms, sirens, fax machine tones or malicious calls. Operators react to the sound with an instinctive startle reflex, symptoms include injuries such as hearing loss, tinnitus and pain to the ear, neck and head. Furthermore fear of sound, as well as hypersensitivity to sound can be experienced.

Have you been affected by an acoustic shock incident? Would you share your experience for the benefit of other readers? Please tell us your story.

Follow the link to learn more about Acoustic Safety:

Contact Us:

Tel: 0844 477 1622

[email protected]

5 Myths about Acoustic Shock


Myth 1: I cannot get Acoustic Shock from sounds below 118 dB

Wrong! Research from Australia and Denmark suggest that the current recommended safeguard limit of 118dB will not prevent all instances of acoustic shock damage. The research suggested that an acoustic incident triggering an acoustic shock is frequently a tone at the level of 82 to 110 dB and in the frequency range of 2.3 to 3.4 kHz (Ref.Westcott*1). Thus, the 118db safeguard limit will not protect you from acoustic shock.


Myth 2: My headset protects me from Acoustic Shock

Wrong! The reality is that acoustic incidents happen at noise levels below 118dB so even if your headset is compliant with typical telecoms headset standards, it will not protect you from acoustic shock. The average human pain threshold stands at 110dB, making any noise above 110dB painful for the person subjected to them. Levels up to 118dB are allowed by headset noise limiters making you and your staff susceptible to acoustic shock incidents.

Myth 3: Noise at Work Amplifiers protect you from Acoustic Shock

Wrong! Noise At Work amplifiers will only ensure you comply with the average 85dB sound exposure over an 8 hour working day. Most amplifiers will let sounds up to 118dB through, meaning you could be subjected to an Acoustic Shock incident.

Myth 4: Acoustic Shock will not have long lasting effects on the sufferer.

Wrong! Acoustic shock is a very serious issue. Symptoms not only vary from temporary impairment such as pain, muffled hearing, nausea and loss of balance but can lead to more serious and long term issues such as tinnitus. While permanent hearing loss is difficult to measure, people often suffer the symptoms of hearing loss. This typically means that they cannot tolerate loud noises such as a crying child or the ping of a microwave. Sufferers frequently also experience depression and anxiety making it difficult for them to continue to do their job.

Myth 5: The Noise at work regulation protects me from Acoustic Shock

Wrong! Not all USB and PC headsets have the same 118dB cut off as telecom headsets do. PC headsets are outside of the standard telecom legislation used for traditional contact centre headsets. Some PC headsets comply with the 118dB upper limit. Some do not. This can be harmful for you and your staff’s hearing. If you are using USB headsets it is vital that you check the equipment that you are using  to safeguard your hearing long term.

For more information on acoustic shock and how to prevent: