The high-pitched "chirp, chirp" of a small bird is falling silent at busy intersections across Canada.
But naturalists need not worry.
The sound is actually an electronic signal that lets visually impaired pedestrians know when they have the right-of-way to cross east-west streets.
It is being phased out across the country because it sounds too much like the song of a real bird: the northern cardinal.
"It also sounded like the backup beeper on some trucks and some motorcycle turn signals and therefore could be confusing," says Hart Solomon, manager of traffic engineering with the City of Hamilton and an adviser to the Transportation Association of Canada.
The association, which has drafted national guidelines for Accessible Pedestrian Signals, is recommending municipalities replace the bird-like sound with a four-note tune known as the Canadian Melody.
The newer signal was first used in Montreal, where the musical tones were originally dubbed the Montreal Melody. The name was changed in 2008 when the national guidelines were updated.
"Montreal had developed that melody and found that it was easy to hear, clear and could be heard at a good distance," Solomon says.
Studies suggest the chirp sound "is not as easily discerned ... nor can it be easily found by users," the association said in a 2007 document, suggesting visually impaired people were veering off course when walking toward the weaker chirp signal.
"This leads to higher rates or lateral deviation in the pedestrian walking path. ... Representatives of people with vision loss broadly advocate a change away from the use of the chirp."
Meanwhile, the audible crosswalk signal for north-south streets will continue to be a digitized sound of the common cuckoo.
Shelley Adams, a visually impaired person who uses a guide dog to get around Halifax, says the melody is better than the chirp.
"The chirp, chirp didn't really bother me, but I'm getting used to the melody and I really like it," says Adams, a registration and referral co-ordinator with the Canadian National Institute for the Blind.
"It's really easy to hear and just makes it a little bit easier, especially when you're at a loud intersection, I find it a little bit easier to hear than the chirp, chirp."
Catherine Kieran, a spokeswoman for the institute's Atlantic chapter, says most of the visually impaired people she's talked to have welcomed the change.
"They were delighted when the Canadian Melody was implemented," she says, noting that one senior called when she first heard the melody.
"She was thrilled. She said she loved it because it made crossing the street much easier for her because the sound is so different."
Peter Parsons, an orientation and mobility specialist with the institute, says some visually impaired people don't like the new signal.
"Teaching my clients to cross these intersections, I've had a lot of mixed signals from people," says Parsons, who is also visually impaired. "The people who don't seem to like it, I think it's just because it's a change."
Parsons says some Canadian cities have been slow to adopt the new standards.
"It's really important to have all of the signals the same so that people aren't confused," he says. "Consistency is good, not only locally, but nationally as well."
In Halifax, all crosswalks using the audible signals - about two dozen in all - will be switched over to the Canadian Melody by next spring, says Taso Koutroulakis, acting manager for traffic and right-of-way services.
The upgrades can cost between $5,000 and $10,000 per intersection, he says.
The signals, which are often programmed to adjust to the level of ambient traffic noise, are typically installed at intersections near public buildings, hospitals, universities and libraries.
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