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Most Effective Hearing Frequency - What You NEED to Know

BS 5839-6:2019 Clause 13.1.3

The British standard on Domestic Fire Alarms says 'Research has shown that the most effective alarm signal to rouse hard of hearing people, children and intoxicated young adults from sleep is a 520 Hz square wave signal'.

Further, it explains 'Age and damage to hearing reduce the sensitivity of the ear, particularly to frequencies above 2 000 Hz' and that 'the integral sounder of most smoke alarms produces a sound with a frequency in excess of 2 000 Hz.'

1 in 6 people in UK suffer from hearing loss.

The alarm sounder of most Grade D and F smoke and heat alarms operate at a frequency between 2000Hz and 3500 Hz, which is far in excess of the the most effective frequency range described in BS5839-6 clause 13.1.3.

Industry Responsibility

Stakeholders to a new or existing building have a duty to consider the occupants in a building. For example, specialist housing projects are designed to accommodate persons over the age of 55, the initial design and fire strategy will be aware of the type of occupant for these projects.

Despite BBC watchdog finding only one out of the eight children showing any sign of being woken by these particular domestic fire alarms and the British Standard itself drawing attention to this problem, we are still surrounded by large construction and social housing projects continuing to install and replace with devices falling outside the most effective frequency.


Fortunately there are systems operating inside this most effective frequency range on the market now. Solid State are leading the installation of one such solution. And in many circumstances, especially those where we find young and elderly persons, is more cost effective than the typical domestic fire alarms currently favoured.

We have an in-house technical and design team available should you want to involve us in your projects.


If you have any domestic fire alarm requirements please get in touch on 01257 463018 or email


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