‘Smart’ tannoy to make rail announcements clearer

Station announcers may be heard properly thanks to the latsest software. Picture: Bill Henry
Station announcers may be heard properly thanks to the latsest software. Picture: Bill Henry
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A team from Edinburgh University is preparing to rescue generations of baffled rail commuters after devising a way of making public address (PA) system announcements intelligible.

Scientists have developed software that can alter speech before it is broadcast, making it easier to hear against background noise.

Now they hope their synthetic speech system will help make public announcements in places such as railway stations, airports, or sports venues both quieter and clearer in future.

Professor Simon King, director of the university’s centre for speech technology research, said: “A PA system is not aware of noise – it speaks the same way all the time, not doing what a human would do and wait for silence or adjust one’s speech. What we are doing is making the computer do what a human would do in modifying its speaking style to help the listener out.

“It’s something that has never been done before.”

The researchers studied how speech was perceived by listeners and carried out tests to pinpoint the components of speech that are most easily heard by people in a noisy place.

They found that in loud situations, listeners pay most attention the parts of speech that are easiest to hear, and use those to decipher what is being said.

The team then developed a mathematical computer programme to analyse spoken words and enhance the sounds that help listeners hear what is being said, to make speech better understood overall.

In tests, the manipulated speech was found to be much easier to understand than natural speech. In some cases, the improvement was the equivalent of lowering noise by five decibels.

Professor King said a lot had to do with the frequency, or timbre, of different voices.

He said: “Almost all public address systems use a female voice because the female voice tends to have a higher frequency and that has been found to cut through background noise better.”

He said the same techniques could also be used to improve other computer-generated voices, such as those in smartphones or sat-nav systems.

Dr Cassia Valentini Botinhao, of Edinburgh University’s school of informatics, added: “Noisy environments make it difficult to understand what is being said and simply making speech louder isn’t the smartest solution. Our findings could offer an alternative, by making speech more intelligible without turning up the volume.”

Network Rail barred the Evening News from asking passengers at Waverley what they thought about tannoy announcements at the station. However, a spokeswoman for ScotRail said: “We continually work to further improve our facilities and service. As such, we would be happy to learn more about Edinburgh University’s public announcement software.”


FEDERAL magistrates in Australia ruled earlier this year that train company Railcorp discriminated against blind passengers by failing to make audible station announcements.

Graeme Innes lodged more than 60 complaints about the New South Wales train network.

Magistrate Kenneth Raphael said: “It would appear startlingly obvious to the lay observer that passengers travelling upon trains need to know where to get off.”

The court ruled that Railcorp must award Mr Innes A$10,000 (£5880) in compensation along with interest and legal costs.