Why Do Teslas Make a Noise When Backing Up?

Since mid-2019, have you noticed any strange sci-fi type sounds coming from Teslas when they’re reversing? The peculiar noise is part of a new feature that arrived in September 2019 and is going to form the main focus of today’s blog post.

Why have Teslas started making these strange noises? Does this mean that when I thought I heard that stationary Tesla farting, I wasn’t mistaken? In today’s blog, we’ll take a deeper dive into these questions concerning the interesting audio features that are defining a new generation of Tesla vehicles.

Background: What Noise Are We Talking About?

As this video will show, there is a distinctive sound being made by Teslas when they are backing up:

It’s a kind of mixture between a high-pitched humming and whining sound that sounds quite a lot like sounds made in 1950s movies and TV shows to denote the arrival of extraterrestrial beings on planet Earth.

The sound starts as a constant hum/whine, but as the car reverses faster, then the sound gets louder and more noticeable if you speed up in reverse. It activates as soon as you put the car into reverse, and will deactivate when you go back into drive.

While you may think that this noise is yet another quirk from the world’s most popular EV company, trying once again to stand out from the crowd with this unusual UFO-esque sound, the root of this sound addition is actually quite a lot more bureaucratic and dull.

September 1, 2019: The Day Teslas Got Noisier

A meme with the text When A Tesla Is Backing Up
A meme with the text When A Tesla Is Backing Up

There was a time when people were excited about electric cars because they would help to make the world a quieter place, especially for those people who live near busy roads. Those people might finally be able to start hearing the sounds of birdsong again! Alas, as it turns out when EVs are travelling at speed they are still quite noisy.

But at very slow speeds they are, of course, whisper quiet, so much so that the NHTSA in 2019 was demanding that all EV producers include some kind of noise generator to create noise when travelling under 19-mph. This, they hold, will help the visually impaired, as well as those who can see fine but are just inattentive, to be alerted to a moving EV’s presence.

This requirement came in and was implemented on all cars manufactured after September 1, 2019. This explains why it’s only relatively new Teslas at the moment that are making this sound.

The only model to have all vehicles come with this feature is the Model Y, which started production in early 2020. In true Tesla fashion, however, they couldn’t make these additions purely functional, but instead turn it into something “cool” for Tesla owners to enjoy. The NHTSA had just prompted the arrival of Tesla’s “Boombox” feature.

What is the Tesla Boombox?

The NHTSA requirements state that a car must have a noise-generating feature — invariably some kind of external speaker — that emits noise when traveling under 19-mph. When installing this speaker, Tesla’s team decided to take advantage of the new feature to add something really fun to their vehicles, and they call it “Boombox.”

Inside of a Tesla Model 3, showing the speaker grill and three mounting points for a as-yet-unfitted speaker.
Inside of a Tesla Model 3, showing the speaker grill and three mounting points for an as-yet-unfitted speaker.

There were many who were skeptical that using this legally required speaker for a feature like Boombox wouldn’t be allowed, but it seems that under current Department of Transportation rules in the US at least, there’s no issue with it. Tesla vehicles with the speaker will have received Boombox mode as part of Firmware update 2020.48.26.

The Boombox feature that people immediately liked was that it could replace the horn sound of your Tesla and use it whenever the car is stationary. Users were quick to discover in the Toxbox section of Boombox that they could change the regular horn to (among other things) a bleating goat, or a round of applause, a “tada” noise, or…in a contribution certain to have come from Musk himself, a farting sound. The last one allowed many users to change the name from “Boombox” to “Bum Box.”

The Boombox feature comes with those standard modes, but as Musk was to later confirm in a tweet, it is also possible for people to customize sounds and upload them to the system, as well as use their own music to use.

These custom sounds can be used when hitting the horn, using the Summon function on Autopilot, or when driving the car. Just imagine rolling down the street in an obsidian black Tesla with Darth Vader’s theme playing, and you’re starting to get the idea of what Boombox can do.  

Do All Tesla Vehicles Have This Feature?

The front of a parked up white Tesla
The front of a parked up white Tesla

The short answer is no, not all Teslas have the “boombox” pedestrian warning sounds. The requirement for the external speaker function only came into being for cars manufactured from September 1, 2020.

There was also no retroactive requirement for installation on older models, which means that invariably the speaker, humming reverse sound, and additional fun Boombox features are only present on Tesla vehicles made after that date.

That should explain why you’ve never heard it from your neighbors’ Tesla that they’ve owned since 2017. Beware when they get a new one, though, because as one YouTube commenter pointed out on the video we highlighted above, “…it sounds like an alien is leaving every time my neighbor leaves for work in the morning.”

The sound features were first introduced in the US market where the speaker had been mandated and therefore was necessary. Other markets like the UK didn’t have it when it was first rolled out, but by May of 2021, it was also available in European markets.

If you’re unsure if your Tesla has the feature, first check the manufacturing date: if it was made before September 1, 2019, then it doesn’t have one, simple.

If you have a post September 1, 2019 Tesla, then open up your Application Launcher icon and then tap on “Toybox.” In there you’ll see if you have the option to activate Boombox mode.

Conclusion: What Benefit Does it Bring?

The more celebrated and fun aspects of Boombox make the reversing sound feature seem somewhat frivolous. We shouldn’t lose sight of the fact, however, that in giving us Boombox, Tesla was merely trying to make a mandated requirement a little more fun and acceptable to buyers. The main function of that external speaker is to provide the sounds that help visually impaired and careless pedestrians avoid potentially getting seriously injured by even slow-moving reversing Tesla cars.

It will still be interesting to see how far Tesla takes the feature in the coming year.

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