Photo credit: Q K from Pixabay

by Jeanine Botta, MPH, Co-founder, The Quiet Coalition

When a reader sent a question about sound to The Conversation’s Curious Kids column, editors turned to environmental epidemiologist Erica D. Walker, PhD, to serve as an expert. Ten-year-old Joseph of Chatham, New Jersey, asked, “If all the vehicles in the world were to convert to electric, would it be quieter?”

Walker, Assistant Professor of Epidemiology at Brown University, developer of the NoiseScore smartphone app, and a Quiet Communities Scientific Advisory Council member, responded that the world might sound different under certain conditions but there was no guarantee it would be quieter.

There are differences in sound levels among electric, hybrid, and internal combustion engine, or ICE, vehicles under different circumstances. At highway speeds, where tire and road surface noise contribute to overall sound levels, differences are not significant. Today’s ICE cars are significantly quieter than ICE cars manufactured 30 years ago–less than 20% as noisy according to one estimate. At the same time, efforts over many decades to reduce tire and road surface noise have reduced sound levels at higher speeds.

Electric vehicles traveling at 30 mph or less would create significantly lower sound levels than older ICE vehicles. But many ICE vehicles are quiet at low speeds and while idling, and minimum sound requirements to protect pedestrians will add sound from external speakers when electric cars are driven up to 18.6 mph.

The overall result? Sound level differences between electric and ICE vehicles will not be considered significant.

Credit should be given where due, but credit is due all around. Design and engineering over decades have resulted in quiet ICE and electric cars, and quieter tires and road surfaces. Questions like that of Curious Kids reader Joseph are common, and some are quick to predict that electric vehicles and other machinery alone will create a quieter world. But with so many sources contributing to ambient sound levels, that prediction is unrealistic. Some of those sources are created by vehicles, and others are created by human activity

As we enter the fifth decade of factory installed audible car alarms, distracting alerts abound. ICE and electric cars still create horn-based lock and remote start alerts, false alarms, piercing backup beeps, sound effects that recreate “lost sounds” of classic cars, and other sound effects. Vehicle owner manuals list more than a dozen horn-based sound alerts in 2023 electric cars. Automakers and regulatory agencies like NHTSA and US EPA, as well as organizations like SAE could change that, but have elected not to act.

At the same time, some drivers create vehicle noise from modified mufflers and exhaust systems, straight piping, loud sound systems, drag racing, off-road vehicles, and dirt bikes.

Predictions that electric vehicles will contribute significantly to a quieter world are unlikely to be met. Automotive product developers should eliminate preventable sounds from alert systems that have silent alternatives. We already have enough to deal with in terms of noise that is beyond our control.