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Occasional posts on subjects including field recording, London history and literature, other websites worth looking at, articles in the press, and news of sound-related events.

29 September 2009

Birds and police whistles

THE OMNIPRESENT GROWL of city traffic is mostly made up of low-frequency sounds. In response, some birds living in built-up areas have begun adapting their behaviour by putting more effort into the higher-frequency parts of their songs, so they can make themselves heard better. I wondered whether any human noise-making technologies had undergone similar changes in response to traffic noise.

So I emailed Acme Whistles of Birmingham. How could you not want to know more about a firm with a great name like that? They began making whistles in the mid-1880s, with the Metropolitan Police as their first customers. London policemen had been using whistles in a haphazard way since the 1820s as an alternative to cumbersome wooden rattles, but whistle-tootling tests on Clapham Common were carried out in the 1880s, and the Acme product became standard issue. Were whistles back then lower in pitch than those made today? Simon Topman replied:

The original whistles were hand made by different workers and varied considerably. Some were deeper than others. Some were higher pitched than today and some had a very unusual and cheerful note that had a real warble to it. Today the note is consistent at 2200 Hertz.

The only real effect of traffic noise on police whistles was that it contributed to them being abandoned nearly altogether by the 1970s. This Daily Mail article from May 2009 reports on their modest comeback in Falmouth. But they also persisted in one specialised corner of London policing.

Motorbike riders of the Metropolitan Police’s Special Escort Group use whistles to clear the way ahead as they escort the Royal Family and visiting heads of state around London. The Wikipedia entry for them states that whistles are used to “reduce the level of noise that precedes an escort and reduces the environmental impact on the escorted person and general public.”

All well and good, but if you’ve ever seen and heard the Royal motorcade heading through London, the blowing of the whistles somehow adds to the impression of sleek and understated prestige, and that probably isn’t accidental either.