One of the selling points for electric and hybrid vehicles is that electric motors are much quieter than combustion engines. Unfortunately, that quietude creates a potential safety problem for pedestrians, particularly those who have impaired vision, who often rely on the sound of an approaching car or truck to know to stay out of its way. For that reason, as of September, a new federal motor vehicle standard now requires makers of hybrid-electric vehicles to incorporate a warning sound to alert pedestrians that the vehicle is approaching. To meet that standard, Ford has worked with both audio engineers and advocates for the visually impaired to come up with what the automaker internally refers to as “O-29,” a “melodic and futuristic” audio warning for pedestrians. The system will initially be introduced on the hybrid Explorer hybrid, the hybrid Escape, and the Escape PHEV.
O-29 has a volume and pitch similar to the sounds made by a gasoline-powered combustion engine but the automaker deliberately did not recreate the sounds of a conventional motor vehicle. After the federal guidelines for loudness and frequencies were finalized, Ford NVH engineer Brian Brassow started designing what Ford hopes will be a brand-identifying signature sound in concert with music producers at Ozone Music and Sound of Royal Oak, Michigan. Besides protecting pedestrians, this is an opportunity to give a brand’s cars a distinguishing sound, similar to what the industry is doing with the shape of LED running lights.
“For the Escape and the Explorer, we were originally envisioning something technical, mechanical, but O-29 is a different approach,” said Brassow. “It’s fluid, more chord-like than what you hear across the industry. We zeroed in on ensuring it’s not too overpowering, because one key feature electric-powered owners like best about their cars is that they’re quiet.”
That last bit is a point of contention for Tesla chief Elon Musk. This writer witnessed Musk lobbying a team of U.S. Department of Transportation officials visiting the Detroit auto show a few years back, and his primary complaint seemed to be about pedestrian warnings making Teslas noisier.
The sounds for O-29 are generated by two street-facing loudspeakers hidden behind the vehicles’ front and rear ends. When the SUV is powered up and the transmission is out of Park, the system is active up to 19 miles per hour, with volume and frequency increasing as speed does. When sitting still, the volume modulates as though it was breathing.
Scott Amman, Ford technical expert for voice and audio technologies, worked with vision advocacy groups like Leader Dogs for the Blind and their clients to optimize the alert so people would recognize it as coming from an approaching vehicle. “People need to quickly recognize sounds that pose a potential threat and they need to establish which direction it’s coming from and where it’s headed,” said Amman. “We took traditional internal combustion vehicles and early electric vehicles with different sounds to see how both sighted pedestrians who were blindfolded and pedestrians with vision impairments detected the presence and direction of an oncoming vehicle.”
According to the National Institutes of Health, the number of Americans who are blind or otherwise visually impaired is expected to double to more than eight million people in the next 30 years. Jeff Hawkins is a retired paramedic who is legally blind and uses a support animal provided by Leader Dogs. “When I first heard electric cars were coming, it honestly scared the heck out of me,” he said. “I’m really glad to hear Ford is addressing this issue because it will benefit not only blind pedestrians, but everyone.”