How Much Noise Is Enough? Automakers, Legislators Wrestle with Artificial Sound in EVs
For the last 30 years or so, automakers have worked hard to reduce the amount of noise car engines — and cars in general — emit when they’re in motion. Engine-powered vehicles are so much quieter than they used to be, and noise pollution has been greatly reduced.
And when hybrid and then electric-powered cars came along, noise was almost completely eliminated. Gone was the belching of smoke from the tailpipe and the loud “hum” of a gas-powered engine; now, with electric vehicles (EVs), you can barely hear when a car is near you at all.
Great, right? Well, not for everyone. Specifically, not great for the National Federation of the Blind and the American Council of the Blind, lobbying groups for sight-impaired people in the U.S. The two organizations were very concerned that with these new extremely quiet cars becoming more popular, there was a much greater risk that blind pedestrians would be in danger, since obviously when crossing the street they rely heavily on hearing a car’s noise to determine how safe they are.
And so, three years ago Congress passed the Pedestrian Safety Enhancement Act of 2010, with a specific requirement that new electric or hybrid vehicles are “to provide an alert sound conforming to the requirements of the motor vehicle safety standard.”
Now, the bill itself didn’t stipulate what type of sound, how loud, or at what speeds it must be made, but the National Highway Transportation Safety Administration (NHTSA) was charged with coming up with the requirements, and in January of this year, made its recommendations.
The NHTSA issued guidelines that, among other things, EVs would be required to emit a sound when traveling below 18 miles per hour; the NHTSA said that any speed above that wouldn’t be necessary due to “tire-on-road” noise becoming the dominant sound of an oncoming vehicle.
The law says that “noise generators” will be phased in, starting in Sept. 2014.
Jay Joseph is a senior manager in the Product Regulatory Office at Honda USA, and he’s also been a committee member dealing with artificial sound devices at SAE International, a global association of more than 128,000 engineers and related technical experts in the aerospace, automotive and commercial-vehicle industries.
SAE has been working on the artificial sound problem for years, and Joseph said one of the challenges has been dealing in uncharted waters.
“The typical pattern for something like this is the effort to address the problem is made when the data shows there’s a problem,” Joseph said. “Here, the (Federation for the Blind) is saying we don’t want to wait until the bodies to start to pile up, we see this could be a problem, let’s take care of it now. ”So this is an unusual situation, in that we’re proceeding with situations that haven’t yet manifested themselves.”
But Honda, Nissan, Fisker, and others have dived right in and begun creating these artificial systems, and Joseph took me through Honda’s new Acoustic Vehicle Alerting System.
The system begins with a small speaker being placed under the hood of the vehicle (the first Honda vehicles with the AVAS are the fuel-cell FCX Clarity). The speaker, roughly the size of a small iPod speaker, is attached to an amplifier. Inside the speaker/amplifier part is a small computer-like processor, which determines the vehicle speed and then emanates a low-frequency sound from the car when the speed is less than 15 miles per hour.
“We’re taking signals from the car as to when and how loud the sound should be,” Joseph explained. “And we want the sound to be emanating forward and moving from left to right.”
One possible problem with the AVAS, and other systems like it, is they need to be adapted for each vehicle. So what may work in one Honda car might not work in another, due to different specs under the hood.
“We have a system for that FCX vehicle that we have applied to some of them on the road, but it would have to be adapted for each car to make sure the sound is even,” Joseph said.
A few other facts to keep in mind about the EV artificial sound devices: The costs to car manufacturers is “not anything substantial,” Joseph said. “It’s manageable when you consider what the other expenses of building a car are. Basically, we’re using energy to produce sound.”
Second, the devices would have a negligible effect of the weight of the car; the Honda AVAS weighs just a few ounces, Joseph said.
“These devices aren’t huge, it’s not like carrying a cinder block in your car,” he added. “We’re fighting tooth and nail to reduce the mass of the cars to improve their efficiency, so with this we’re adding mass that’s only used occasionally at low speeds.”
The other thing to remember is that now that NHTSA has issued guidelines, these artificial sound devices will be mandatory for all EV and hybrid cars; the phase-in period begins in 2015, with 30 percent of a manufacturer’s vehicles produced between Sept. 2015 and Sept. 2016 required to have artificial sound, and progressively more each year until 2017, when every EV or hybrid will require them.
And while the carmakers have little choice now but to comply, they have raised objections in the past few months. The Association of Global Automakers, a lobbying group representing vehicle manufacturers and suppliers, is worried the artificial noisemakers will be too, well, noisy.
“While we support the intent of the regulation to assist pedestrians, we have concerns that the current proposal may lead to alert sounds that are excessively and unnecessarily noisy to others inside and outside of the vehicle,” said AGA director of safety Michael Cammissa. “As hybrid and electric cars have become more widespread, some of our members have already added noise alerts to these vehicles.”
Then there are the complaints from the noise pollution folks; a group called Noises Off has been complaining about EV artificial sound. “The advantage of hybrid and electric vehicles is that they’re quiet,” Richard Tur, the founder of NoiseOff.org, has been quoted as saying. “There’s a lot of scaremongering in the media portraying these cars as some kind of shark in the water, but I don’t see people getting run over left and right by them.”
Obviously, this is an issue that won’t be going away, but it’s clear that automakers and the government are trying to do the right thing; surely a little extra noise in the world is a fair tradeoff for safe pedestrian transport for all.