Directional sounder shows the safe way out

A new directional sounder technology is paving the way for more efficient building evacuations.

A new directional sounder technology, manufactured by Klaxon Signals, is paving the way for more efficient building evacuations.

Localizer directional sound evacuation beacons can guide the occupants of a building to the emergency exits, essential to a successful escape when smoke limits vision, or when those in danger are visually impaired.

Traditional aids such as emergency lighting and luminous guidance strips are often of little use in these situations.

The directional sounder has been developed by Sound Alert Technology, a company led by a research team from Leeds University, and manufactured by Klaxon Signals.

Existing fire alarms operate over a small portion of the human hearing range, generally from 800Hz-3kHz, which, although most effective in terms of perceived volume, will not allow the hearer to localise the sound.

For the human brain to perform this feat the sounds supplied must cover a very broad range of frequencies, ideally as much as possible from the audible frequency range of 20Hz-20kHz.

The Localizer directional sounder emits pulses of broadband noise, as well as a series of rising or falling tones to indicate when an emergency route leads up or down.

In trials designed to test the efficiency of the device, sighted and visually impaired subjects were required to escape from a building filled with artificial smoke.

The complex escape route included staircases and multiple alternatives to the correct path.

The subjects had no idea of the intended route or the meaning of the alarm beacon signals.

None of the subjects took a wrong turning, and all intuitively understood the meaning of the rising and descending tones and the pulserate of the beacons.

The closer a beacon was to the exit, the faster the pulserate was set.

Evacuation times were close to those expected of people who knew the building and who were able to see.

The Localizer proved so effective that when the building was cleared of the smoke and devices, some subjects who were asked to go through it again lost their way on a route they had successfully travelled earlier.

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