Why Does Our Yearlong 2025 Honda Civic Hybrid Make That Humming Sound?

We know you know what sound we’re talking about: that pitchy, futuristic whir-whine that hybrids and EVs make when backing up or traveling at low speeds. It sounds like the rapture is coming for us all whenever one of these things drives by.

Of course, the sound isn’t just for fun. It’s a federally mandated pedestrian alert because hybrids and EVs are either much quieter than other cars or completely silent. When operating on battery power, they don’t produce the noise that’s a natural byproduct of an internal combustion engine at work. So automakers had to come up with new alerts, also known as an acoustic vehicle alerting system (AVAS), in order to be compliant.

If you pay attention, the alerts actually do vary across automakers. Below, you can see and hear what our long-term 2025 Honda Civic Hybrid sedan sounds like while it’s reversing or driving forward slowly:

It’s a very choral noise that sounds as though it’s formed of at least G and B notes, so it’s almost definitely a G chord of some kind. It also seems much louder during reverse than in drive—mostly likely for backing out of parking spots.

By comparison, here are some sounds from Hyundai and Toyota. They’re all slightly different, which indicates that while the alert itself is required, what key it’s in is not.

The regulation that requires a minimum sound requirement for hybrid and EVs is Federal Motor Vehicle Safety Standard—or FMVSS—No. 141. The National Highway Traffic Safety Administration announced its intent to implement it at the end of 2016, reasoning that it would help all pedestrians, especially those who are visually impaired, be able to detect where these vehicles are when they’re traveling at low speeds.

“[It] will help prevent about 2,400 pedestrian injuries each year once all hybrids in the fleet are properly equipped,” the agency said via a release. “Under the new rule, all hybrid and electric light vehicles with four wheels and a gross vehicle weight rating of 10,000 pounds or less will be required to make audible noise when traveling in reverse or forward at speeds up to 30 kilometers per hour (about 19 miles per hour).”

FMVSS No. 141 became effective in April of 2018 and mandated all newly manufactured hybrids and EVs to be compliant starting on September 1, 2020.

A spokesperson for NHTSA provided us with a real-world sound comparison of FMVSS 141, which we’ve re-created as a chart here so you can see what the requirements are.

*This means the sound in multiple frequency bands must be 40, preventing “bass-heavy but quiet-sounding” EV warning tones.

NHTSA also notes three things:

1. These values represent the approximate minimum A-weighted sound pressure levels in required frequency bands, not a single overall maximum vehicle loudness.
2. The alert sound is designed to be: (a) detectable by pedestrians (especially visually impaired individuals), (b) tonally distinctive from background noise, and (c) not excessively loud.
3. Above 30 kph (19 mph), no artificial sound is required because tire and wind noise exceed these levels naturally.

In an email, a Honda spokesperson confirmed the Civic Hybrid is compliant in all regards, at all speeds, and at all decibels levels. (Not that we doubted it.) The car’s AVAS speaker is located at its front.

We were hoping for some fascinating insight into how the Civic Hybrid produces its unique pedestrian alert. Why was this the pitch and chord Honda decided on? What were some of the other options that engineers ultimately rejected? Yet a company rep merely said, “FMVSS 141 specifies requirements for frequency bands. Based on these requirements, Honda determines the characteristics of its pedestrian alert sound.”

Ah, well.

But if you’ve ever heard the spectral hum of a hybrid or EV approaching you from behind, you now know why it’s exactly as loud as it is.

More on Our Long-Term 2025 Honda Civic Hybrid Sedan:

• An Incredible Win for the Masses?​
• We Took Our 2025 Honda Civic Hybrid Sedan on a 3,000-Mile Road Trip Back Home​
• Five Months In, the Cabin of Our 2025 Honda Civic Hybrid Still Wins​
• Our Honda Civic Hybrid Turns Regenerative Braking Deceleration Into a Game​
• Honda Civic Hybrid vs. NYC: We Put 50 City MPG to the Test!​
• We Hosted a Tailgate Party Out of Our Honda Civic Hybrid Sedan. It Went Great​
• Winter Tried to Break Our Civic Hybrid. It (Mostly) Failed.​