In 2002, Berman’s company PDI Products developed a special sound wave that was used in remote controlled, locatable audible guidance beacons for blind people, following a two-year feasibility study funded by the UK’s Department for Trade and Industry. The Sonic Wayfinder is used by blind people to find their way to chosen locations.  Objects such as bags and coats are also easily found by following the sounds emitted by the beacon when triggered by a remote control.

Today, Berman is finalising a special technology for use on emergency vehicles and – potentially – on exit points at industrial facilities. Indeed, PDI Product’s work has gained sufficient academic interest for the University of Liverpool to provide the company with premises at the University, as well as substantial funding towards equipment.

Berman is careful when discussing his new technology – its name is currently being trademarked and he is wary that even mentioning it will give a clue as to how it works.

 But he is clear on one thing: little research and development has been done on siren technology in the last 25 years. “There are few people with acoustic knowledge in the market, and wherever you go in the world you will hear about five standard sounds used. My aim is to have the same sound on all emergency systems, whether on vehicles or beacons, because at the end of the day everyone is expected to react in a similar way on hearing the sirens. You need sound signals which will alert you and stimulate you into taking appropriate action, without panicking”

Berman’s new technology, he explains, is formed of a number of specific frequencies (or sounds). “When the human brain hears a single frequency, it automatically tries to block it out and you can end up not hearing it. The human senses work on the principle of change, and we notice change. When there is only one tone the brain loses interest. If there are two tones, the brain is stimulated because it notices the differences between the two.”

And that is why, he adds, two-tone sounds (like those used on door bells) are considered to be better alerting signals than single tone sounds. Berman has added a new dimension to the two-tone siren, and his solution involves a second tone that is sent from a different physical location. The effect, he says, adds to the spatial awareness ingredient; “So the brain senses that it is receiving even more information. You end up with the amount of audible information being squared. It is like the difference between listening to mono or stereo.  The positioning of the sounders is also critical and this aspect forms part of PDI’s  knowledge base.”

At the heart of the technology, however, is the fact that Berman has developed a new sound wave profile. Sound waves, he explains, come in different shapes – some resemble triangles, others squares. Each wave has different characteristics both in how it is perceived by the brain (psychoacoustic reaction) and how it interacts with outside surfaces.

“Many current sounders and sirens bounce off surfaces without perceptively changing pitch or volume.  This means that people cannot tell if the source of the sound is coming from the sounder, or from the wall it is bouncing off.”  The sounds that Berman has designed change in volume and pitch as they reflect off surfaces, making it easier to perceive the location of the original source.

Neither does the new wave provoke an involuntary extreme reaction such as making the body jump.  “It is not like the standard high pitched siren, which is quite piercing.  It is the siren itself which many people tell me often induces panic.

“My sound can literally guide you through a series of smoke filled rooms, so that when you reach one beacon you’ll then hear the next, and so on.”

PDI Products is now at the stage of building computer simulations of the system using loudspeakers to demonstrate effectively the differences between a non-locatable and easily locatable sound signals.  “One of the demonstrations we will set up will show sound waves coming straight at you, and then disappearing behind you. In another demonstration we aim to have the sounds coming at you, and then bending around you before going off into the distance”

Berman is currently looking for additional funding and commercial partners, and adds that Liverpool University has already offered £20,000 to match any external funding to develop working prototypes for testing by the Emergency Services and in industrial applications.

You can contact Jeff on: j.berman@pdiproducts.co.uk

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