CarTunes

By Peter Drescher
November 18, 2009 | Comments: 25

Green Technologies and Interactive Audio are two fields not generally considered related, but a new trend may change that: "Generated Sounds for Electric Vehicles", aka "EV Audio", aka "CarTunes".

The problem is this: battery powered vehicles are dead quiet. The only external noise produced by the car's motion is "tires on road". If you're driving on clean asphalt, your green automobile will run absolutely silently.

Some consider this a feature, not a bug. Certainly, if you live next to the freeway, the prospect of replacing the constant roar of internal combustion engines with a low SPL whooshing of streamlined air displacement would seem to be a good thing.

But others think it might be a safety hazard. We humans pick up a great deal of information about our environment by listening to the sounds and echoes around us. Our incredibly sensitive auditory system has evolved over millions of years to accurately place objects within a 3-dimensional, 360° field, as a survival mechanism (i.e. those who couldn't sense the saber-tooth creeping up behind them didn't breed as much as those that could).

So the writers of the Pedestrian Safety Enhancement Act of 2009 are concerned that accidents may increase if there are no audio cues to warn those on foot about oncoming traffic. This is particularly problematic for the blind. Yet others cry "Bullshit!" since constant public cellphone/iPod headphone usage does not seem to have caused a dramatic increase in people being run over.

Personally, I'm not sure that's the point. When I'm standing next to a Prius, and it suddenly starts moving, without warning, in total silence, it can be startling. After a lifetime of standing next to car engines, I expect a whine, or rumble, or something, to accompany automotive motion. In fact, I suspect it's the anticipation of sound that will drive a trend towards EV Audio.

What Do They Do In The Movies?

People expect moving objects to make noise! That's why there's a "whoosh" when the Starship Enterprise flashes past (in the vacuum of space), or a "crescendo-BOOM" when the warp drive is engaged. You also hear the presumption of sound in the "vibrating rumble" of a lumbering Imperial Star Destroyer, or the "dopplering whine" of a TIE Fighter, or the "muscle car shudder" of Princess Amidala's chrome ship. And then there's the sound made by flying cars in Blade Runner, and the Jetsons, and many others ...

But it's not only fictional vehicles that get "sonified". Every car chase sequence, every racetrack movie, every time you see anybody driving any vehicle on any screen, the moving image is always accompanied by zoom zooming, tire screeching, engine revving, metal banging, knocking, growling, whistling, roaring, doppler pitch-shifting noises of all sorts ... NONE of which you would hear if you were actually standing next to the camera taking the shot (and in these days of CGI, there may not even BE a camera taking the shot).

One time, at the Game Developer's Conference, I listened to Oscar winner Michael Hedges of Park Road Post talk about creating the sound of the motorcycle in "The World's Fastest Indian". To make a convincing, exciting, gut-wrenching sound, he recorded 50 different audio tracks and mixed them together in various ways, depending on the demands of the narrative. At no point did he simply point a microphone at the engine, and say "There ya go!" Rather, he carefully built up layer after layer of close-miked recordings of the pistons firing, the housing vibrating, bolts rattling, tires spinning, etc etc etc ... all to create a hyper-real audio illusion that audiences accept as the sound of "old motorcycle going 200MPH down the Bonneville Salt Flats."

What Do They Do In Video Games?

Re-recording mixers may have an easier time creating car sounds than video game sound designers. In a linear medium like film, it's all about mixing and timing myriad audio tracks to match the onscreen action, and induce the desired emotional response. But an interactive application, like "Need for Speed", requires a different approach: take a large number of short audio clips, and play them in a variety of ways based on gameplay variables.

Thus, a short loop of "engine noise" can be pitched up or down based on the car's speed, a "tire squeal" can be played when accelerating around a corner, or a doppler effect can be produced when a competitor leaves you in the dust. These kinds of functions are performed by the game's audio engine (for example, Wwise), and the implementations can be quite complex. A wide range of techniques, including the use of Real Time Parameter Controls (RTPCs), blending different sounds together in varying ways, attenuation curves, environmental occlusions, and other special effects, are utilized to produce the audio illusion of authentic race car action.

And not only for realistic audio! These same techniques are used when creating the sound of any vehicle in a game, including Batmobiles, Podracers, and LightCycles. Lots of times, sound designers won't even use "real" engine noises when working up sounds for fictional vehicles. They'll start with synthesizer clips, tiger roars, fighter jet swooshes, pitch them up or down, add LFOs, mix in effects, twist and stretch, until they've crafted a noise that blows you outa your seat (or into your seat, in this case).

What Do They Do In The Real World?

Until now, non-engine external audio produced by real world vehicular motion has been fairly limited. There's that incredibly annoying BEEP---BEEP---BEEP of a truck backing up. There's the car horn, which is usually just some flavor of HONK, but can be controlled to play simple melodies, like La Cucaracha. In Europe (especially Greece) there are "gypsy trucks" with megaphones mounted on the roof, that drive through the streets blaring incredibly loud and astonishingly distorted announcements of watermelons and plastic chairs for sale (Aman! Talk about annoying audio!!) Here in the States, a more pleasant equivalent is the ice cream truck melody, which might be considered a precedent to EV Audio.

But the sound of a cool new modern electric vehicle must be cool new and modern itself. We're talking branding opportunity here, a way for marketing to set the product apart from the crowd. The sound needs to be distinctive, and convey a mood or message, but like a good movie score or game soundtrack, should be "heard but not listened to". Most importantly, the sound should be interactive, and adapt to changing conditions and environments.

SO I gotta hope that when electric automobile manufacturers start thinking about what their futuristic cars will sound like, and how that sound will be produced, they'll be looking at game audio engines (like Wwise) to produce interesting, adaptive soundtracks, rather than simply playing a looped WAV file at a standard volume. There are many good reasons to do this:

  • Generated EV Audio can be varied based on velocity, thereby fulfilling the expectation that "faster = higher pitch".

  • External speaker volume can be adjusted to be a few dB louder than the ambient noise level, so that the sound can be heard rain or shine (or wind or city or country, etc).

  • Sophisticated systems might even feature infra-red sensors and motion-detection capabilities, so that the warning's volume or tone could be intensified if "possible collision with pedestrian" seemed imminent.

  • Start, accelerate, cruise, decelerate, stop, and idle, could all be states that generate different, related, and appropriate sounds, mixed and modified on the fly.

  • By using game audio systems, there will be a large pool of sound designers available to provide content.

Vanity Plates

And make no mistake, it's the audio content that will push the idea of EV Audio towards ubiquity. The reason I think so => when I first heard that "electric cars are so quiet, manufacturers want them to make noise", I had a strong memory flashback to 1995, when I was contracted to produce my first ringtone (Fur Elise for Sprint PCS). At the time, I thought "mobile phone plays melody when it rings" was the stupidest idea I'd ever heard of; now, it's a multi-billion dollar industry.

If you think audio personalization of your cellphone is an important statement of your individuality (as many do), imagine how much more important personalizing the sound of your car will be! Hell, automobiles are already incredibly powerful expressions of who you are and what you do, and they support a HUGE and thriving customization industry.

If you think ringtones are an important statement of individuality, imagine how much more important personalizing the sound of your car will be!
Now, I'm not saying that specialized sounds for your car will ever be as popular or lucrative as Corinthian leather seats, chrome bumpers, or hydrolic shocks, but I'll bet as more cars go electric (or even hybrid), more car owners will be interested in making their rides sound like nobody else's ... or perhaps, more like something from a science fiction movie, or a superhero cartoon, or even their favorite "driving music" ...

CarTunes

Personally, I credit Jeff Essex of Audiosyncrasy with coining the term "cartune", though I've subsequently seen it used elsewhere. The word does perfectly embody the idea of using music to address the pedestrian safety issue, while simultaneously enhancing the personalization of your car's sound. In fact, it is completely analogous to a ringtone, i.e. "my song means my phone's ringing" as opposed to "my song means my car's moving".

Obviously, playing music, whether it be the latest popstar hit, or Carmina Burana, or a cool electronica groove, is a far cry from simulating engine noises, but it serves a similar function, and opens up a whole new media market. In fact, cartunes could someday be as profitable a revenue stream as ringtones are today, particularly if the function were built into Internet-savvy vehicles.

Imagine turning on your car, hitting a few buttons, and downloading a cartune from the web (or your phone) that matches your mood for the day. If you're feeling grouchy, you could play Ride Of The Valkyries to warn bystanders of your impending approach ("I love the smell of lithium ions in the morning!"). The latest Jay-Z song could show off how hip your hop is, while a Sesame Street musical number might be the audio equivalent of a "Baby On Board" sticker.

Sound effects of various sorts might also be popular, providing incongruous comedy. Imagine your car making the sound of a herd of elepants, an oncoming train, waves on the beach, a murder of crows, or the sound of applause! Other recognizable sounds might be fun, too. A friend of mine wants his car to sound like the Flintstones "dugga dugga bongos" foot-powered automobile (now that's a cartune!)

I can even imagine a voice-over market that would give your auto the personality of a British butler ("Excuse me, sir, so sorry to bother, coming through here") or an Italian cabbie ("Aye! Stupido! Idiota! Cretino!) or even [insert celebrity name here]. And if you think that sounds silly or annoying ... well, you're right, of course, but have you looked at a ringtone catalog lately? One of the more popular download categories for the T-Mobile Sidekick is the voice over section, consisting of many items in the following format: "Yo yo yo, baby, this is [insert rap artist name here], ya phone is ringing, pick it up!!"

By far, the most annoying idea is the possibility of selling your car's audio output to a marketing agency, so that when you drive down the road, your "pedestrian safety sound" is an advertisement for Pepsi. This could be considered the audio equivalent of the signs on top of taxicabs, but should be recognized a horrible dystopian evil, implemented by the Sirius Cybernetics Corporation, to be killed before it multiplies. I only mention it here to prevent its implementation.

Auto-Mobile Audio: The Wave Of The Future?

SO, will CarTunes become the ringtones of tomorrow? Will producing interactive audio applications for automobiles become a new job skill? Will a freeway full of murmuring EV sounds turn into a new kind of cacaphony, as drivers override the default volume level to show off their rides' sounds (like cranking up the stereo until the whole neighborhood is booming)?

Will EV Audio be a cool new thing, an idea that never caught on, or THE most annoying audio you've ever heard in your life (prompting another bill outlawing automated automobile audio altogether)!? Guess we'll find out ...

   - pdx

What do you want your electric vehicle to sound like? Please comment below!

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25 Comments

Peter, that was a beautifully written blog. As a former editor (many, many years ago), I appreciated that. But I still have a general disagreement with the premise, however interesting, that we can (or should) now begin to think about original sounds for electric cars. I do believe that this is very probably what will happen--lots of "personal soundtracks," etc., with inventive ways of denoting the motion status of the vehicle. But I think it misses the point. We're already surrounded by many, sometimes too many, sounds, public audio (commercial or civil), ring-tones, etc.--and the sounds of vehicles. Out of this cacophony we treat this last sound class, vehicle sounds, very differently, as we must. It's a familiar warning we immediately recognize. While someone may be amused to intelligently process, say, a dance track, a synthesized abstract sound or any other non-vehicular sound so that it changes with motion status, that's not going to give a pedestrian, a motorcyclist or even another driver the same heads-up. I think the core sound has to be an automotive sound, responding intelligently, as you propose, to motion-status. At freeway speeds and in the absence of an indication of another vehicle in proximity, perhaps that sound can be lowered or turned off, as the driver prefers. But in city traffic electric cars should sound somewhat like any other car. It's a safety issue, not an aesthetic choice.

Part of the context awareness should be the ability to harmonize with other tune-playing cars nearby...though I suppose doppler shifts would mess with that.

Another avenue (so to speak) would be to encode tunes or pitches in tire treads, with each wheel playing a different note of a chord.

Great article!

Peter, great post. As an owner of a hybrid vehicle that often goes into pure electric-vehicle mode when I enter underground carparks, I am often unaware of the near-silence of my vehicle as it approaches pedestrians who look up at me in horror when I get within peripheral vision. Modern vehicles are also insulated FROM the outside sounds as well -- so you don't hear any 'comfort tone' from the outside world which would help you empathize with pedestrians in the same way as comfort tone on the phone helps you modulate the volume of your voice. I agree with Pat, however, we need to keep the sounds 'vehicular' in nature. As for your evil advertising concept, you need to adhere to the evil advertising concept inventors oath: "I will not tell ANYONE about this evil advertising idea." Now that you have blogged about it, it is sure to happen. Thanks. Thanks a lot.

A few comments:
I completely agree that this is a safety issue first and aesthetic issue second (or 14th). I can't imagine there being no restrictions on the type of content for car sounds. The "well, people wear iPods" arguement doens't hold water. People wearing iPods (pedistripods, let's call them) put themselves at risk. Silent cars put others at risk.

If I'd worked on a game like Forza, NFS, etc, I'd be booking a ticket out to Detroit and telling them that no one on the planet can solve their problem like I can. While I don't see arbitrary sounds being legal, I could see 'cartunes' market in Ferrari, Lotus, Porsche, etc sounds. And those folks have a huge library of 'em,a long with the logic to drive them from all the cool info present in the car (RPM, Gear, Load, etc.).

One other nice thing about traditional 'car' sounds is that, unlike say "Ride of the Valkyre" it won't get as annoying w/ multiple plays. Imagine the *driver* annoyance level when stopped in city traffic and they're hearing the 92nd loop of "Ride."

Plus, all those elements say much more than just "there's a car here." they also say if it's going fast, if it's engine is idling-- the parameters of the sound help convey a lot of information to the pedestrians (pedestria?) nearby.

So.. Sounds for electric cars- yes. Arbitary sounds for electric car...err..nope.

The lowriders are already on this. They have special woofers in the back of their rides, the CDs they're playing have enhanced bass tracks; they're not trying to share their music with the world, what's coming out is no longer music at all. They want you to hear (& feel) them coming from 2 blocks away, viscerally.
This is gonna be horrible, even worse than the ringtones.

@MrGleeson: aw, gee, shucks [toes dirt] thanks! I agree that the best default EV audio would be an "adaptive engine" implementation, and that at freeway speeds, the sound of "airflow over vehicle" and "tires on road" might negate the need for a generated sound altogether (not to mention the improbability of pedestrian collision).

But I'm not convinced that pedestrian safety is actually the primary concern. I suspect it's simply a justification for the natural expectation that moving objects should make noise. Until the advent of EVs, every form of transportation has always been accompanied by sound, including the clip-clop of horses hooves, and wind in the sails. There's something ghostly and surreal about a machine moving in complete silence, and so (like ringtones) there will be as many ideas as to what constitutes a "good" electric engine sound as there are people driving electric vehicles ...

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@MrBattino: "tiretones" are a nice low-tech solution (the equivalent of "playing card in bicycle wheel") that might actually make an interesting sound, particularly if they were tuned to play nicely together. But they would make no sound when the car was idle, which is maybe the most important time for EV audio to be produced ... otherwise, how do you know your car is on? (or even more importantly, how can others tell your car is on? or perhaps even MORE importantly, how can you impress bystanders with how cool your car sounds?)

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@MrLayton: Good points! Underground garages are where I first starting thinking about this, as I was one of those horror-struck pedestrians. And I would hope that there would either be enough bleed from the external speaker, or an interior "mirror" speaker, so that drivers would hear the sound their vehicles were generating.

And if it's any consolation, there are even MORE evil ideas I did not write about :)

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@MrSchmidt: We'll have to agree to disagree on your first point, and see what actually happens in the EV marketplace over the next 5 years. But I will suggest that risk responsibility is not necessarily the pertinent issue. The fact that millions of earbud-wearing people are currently walking the streets completely oblivious to car engine noises, without a significant percentage of accidents being caused by "i didn't hear your car", serves to reinforce my suspicion that the safety issue is a kind of understandably psychological ploy to justify making silent machines noisy.

I will be interested to see if the idea of using game audio techniques to generate real world engine sounds gets any traction (yeah, i know, i'm a punster) with EV manufacturers, but I don't see how "today, I'd like my car to sound like a Ferrari" is that much different than "today, I'd like my car to play Wagner". Nor do I see a need for looping one section; you could play the entire piece, or an entire playlist of "driving music", and default to the engine sound when the music is turned off.

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Bottom Line: So far, the comments have been from esteemed colleagues, each highly respected audio professionals. They are extremely sensitive to their acoustic environments, and have dedicated their lives to producing high quality sounds of all sorts. But unless I miss my guess, they are not enthusiastic consumers of ringtones, and probably mostly use either the default ringer, or the more polite silent/buzz option, on their cellphones.

I, on the other hand, am not known as the "annoying audio" guy for no reason. I have spent a good portion of my career producing, and thinking about the consequences of, some of the MOST annoying sounds EVER ... and have concluded that in many cases, that's what people want, need, will pay handsomely for! (or as I like to say, "You say 'annoying' like it's a bad thing!") Annoying audio is a direct result of that most egregious and common mortal sin: vanity. If I can generate a sound that attracts attention, that is uniquely mine, that says something about me me me, that displays how cool I am, that annoys the crap out of everyone who is NOT the target audience ... well, that's kinda the point, isn't it.

NOW apply that principal to something as ego bolstering, image shaping, status bestowing, and class defining, as your automobile -- and the rest follows logically. Sure, in an all-EV future, my colleagues will probably prefer to use the default engine sounds exclusively (and I admit, I probably would myself, unless I was developing/testing some annoying implementation). But I'll bet there will be a market (and huge revenue streams available) for non-engine EV sounds of all sorts ...

Of course, I could be wrong ... let's find out! :)

Gotta disagree, Peter--- With something with the potential for liability including death, I think people will be necessarily cautious about "car-tunes". If I were making a product with the ability to kill someone (which cars are), I'd be VERY carful about adding a 'fun' feature that might impact safety..

It's tough to google this because so many of the sites are attorney sites, but there lots of 'hits' on pedestrians and headphones not being safe together.
Marty O'Donnell's game audio rule of "First do no annoying" perhaps should revert back to its inspiration "First do no harm."

http://www.dailymail.co.uk/news/article-1072130/Podestrians-pedestrians-iPods-trigger-rise-traffic-accidents-failing-hear-cars.html?ITO=1490

http://www.injurytriallawyer.com/blog/bicycles-and-head-phones-dont-mix.cfm

http://www.npr.org/templates/story/story.php?storyId=100980281

And this from the ca drivers manual:
http://www.dmv.ca.gov/pubs/curriculum/Unit%209.pdf

A significant cause of accidents is pedestrians walking on
roadways while intoxicated, wearing headphones, or otherwise
not paying attention to traffic.
It is dangerous wear headphones while walking on roadways
because you cannot hear approaching vehicles.

ok, that IS interesting, and I stand corrected ... being audio-oblivious to your surroundings can be hazardous to your health! Nobody's really arguing otherwise, but I don't think anybody is proposing making public use of earbuds illegal.

In fact, the "safety issue" might be an impetus to develop/deploy "augmented audio earpods", which would let users mix ambient sounds from the external mics into the output of their media player, rather than shutting out the world altogether, as when listening to music on earbuds.

And I'm certainly not going to contradict the esteemed Mr. O'Donnell, except to suggest that his admirable rule "First, Don't Be Annoying" applies to game music, sound effects, and Audio UIs (movie scores and soundtracks too) ... but not to ringtones (and by extension, cartunes as well).

This is such a terrible idea, I have been meaning to blog about it for a while. So I wrote up a post of why we don't want vanity car noises turning our streets back into the cacophony they once were.

It's better to keep to modulated bursts of white noise. They are obvious if you are close, but blend quickly into the background if you are further away. These are now replacing (slowly) the BEEP BEEP BEEP of heavy equipment (which travels for miles.)

Electric cars will not be that loud but there are better solutions than letting people try to do stuff that deliberately catches attention.

Full details here:
http://ideas.4brad.com/can-we-stop-electric-cars-playing-music-safety

I hadn't heard about using modulated white noise instead of the BEEP BEEP. That makes sense-- the harmonic nature of the BEEP BEEP is more difficult to localize in 3D space than broad spectrum noise. (ever wonder why 3D audio demos all seem to have helicopters--nice, broad spectrum sound that hits our 3D hearing centers very well!).
Of course, there's the learned effect of "BEEP BEEP".

Current car sounds are also nicely broadband which makes them easy to locate --another reason I like (from a safety, not aesthetic perspective) the idea of 'regulated' car sounds for elect vehicles.

First, let me say how much I appreciate and support the work done by the EFF, and how honored I am that the chairman is even reading (and responding to) my "annoying audio" blog. I have only the greatest respect for you and your organization.

Nonetheless, I must admit to being surprised by your attitude towards the cartunes concept, which seems to be that "EV audio is an important safety feature, but only certain kinds of sounds should be allowed". Are you really saying that, in this context, shaped noise (like adaptive engine sounds, and ocean waves) is good, but ordered sine waves (like music and voice) are bad!?

As a strong advocate for individual freedoms, I'm kinda stunned you would take that position, partly because the line between (your concept of) good audio vs. bad is so blurry. Imagine a "holiday theme" that turns my EV into a horse-drawn sleigh, complete with clip-clops, jingle bells, and the occasional Ho Ho Ho ... This implementation, containing noise, music, and voice, all in one sound set, should be illegal in your view!?

One person's "polite warning" will be "boring" to others, same as music you classify as "horrifying noise" will be considered the best thing since flavored toothpaste to somebody else. That goes both ways, and I'd say is a consequences of living in a free society, as I would think you, of all people, would understand, and defend.

Now, I not saying there should be NO restraints (same as free speech doesn't mean you can cry Fire! in a crowded theater) but I suspect current public decorum laws will cover the situation. Obviously, a "Tourette's Syndrome" cartune that shouts random obscenities and epithets would be frowned upon, as would a tasteless-but-probably-popular CarFarts program. Volume over a certain SPL would be obvious overkill, and hopefully EV manufacturers would adaptively set levels to be "audible @ one yard, inaudible @ ten", or something like that.

BUT the bottom line is this => given a system that generates sounds for electric vehicles, there will be a market for audio content of all kinds. Trying to regulate "good vs bad" EV audio seems to me to be pointless, impossible, unprofitable, restrictive, maybe even downright un-merkan!

Also please note: I am certainly not advocating that all EVs must blast Bon Jovi while driving, or that interactive music implementations (where numerous tracks fade in or out, depending on your speed) be standard required features. All I'm saying is: if you build it, they will come ...

Hi. Tim O'Reilly (who used to be on the EFF board) pointed me to your post.

It's not usually viewed as a big violation of individual freedoms to say you can't play audio which annoys people. Unlike other freedoms of speech, where I can choose not to pay attention to what you say when it offends me, sounds are a different story. I'm not concerned at all with the message of the sounds you want to play (or have others play) but simply their noise pollution aspect.

Noise pollution is, like traditional pollution, one of those things which seems innocuous when done by one person in small quantities, but quickly becomes a burden when done by many. Imagine living next to a stop sign (which I do) and having every car that stops there play a different musical tune as it slows down and starts up again.


But in particular you were talking about more than just individual choice, but one actually spurred by a proposed law to make some sort of sound mandatory.

There is a big difference between broad spectrum sounds that follow predictable patterns (like motor noise or even motor noise simulations) and sounds which are deliberately unpredictable and meant to call attention from far away. How about having your car make a child's high pitched scream each time it moves? (We have some low level programming that makes it almost impossible for us to ignore that sound, and in fact our ears are tuned to give better response in that pitch zone.)

Frankly, I am not so sure of the safety need here, and in 10 years cars will commonly have pedestrian sensors so that they can simply not hit pedestrians or at the very least only make sounds when it appears a pedestrian is ignoring the car.)

But if the world you predict comes to pass, it will become untenable to live next to a stop sign or traffic light. Sure, cars make noise starting and stopping at them, but it's the same noise and easy to tune out.

If the government is going to mandate noise for safety reasons, it makes sense for the law to require that the mandated sound be one that calls attention up close, is not audible further away, and is only used when necessary.

That's what the legally required unit built into the car would do. If people want to turn their radio up loud or install a different system they can do that (they already do this) and it would be annoying, but infrequent enough to tolerate.

We regulate people's use of the horn. When it got so bad in NYC that it destroyed the peace of the city, they cracked down. In many cases the use of ringing cell phones in peaceful environments is also regulated. I have no problem with this. (I think phones should never ring but that's another matter.)

Well, I'm certainly not foolish enough to try and argue with your comment, because what you say is obviously true ... and btw, I personally am in complete agreement with you. As an "audio guy", I am extraordinarily aware of my sonic environment, and usually work in very quiet, noise-controlled rooms. Thus you will get no argument from me that subdued adaptive "engine noise" implementations should be the EV audio default, which covers both the safety and the polite society concerns.

However, there is an even better solution than trying to produce non-annoying EV audio, which I've been hesitant to talk about: "hypersonic directional speaker technology", along the lines of systems sold by Holosonics, Inc. These flat panel speakers create sound by projecting ultrahigh frequencies, and manipulating the interference patterns to produce a "collimated" audio beam. Point it at me from across the room, and only I can hear it. The guy standing next to me doesn't even know sound is being projected.

Mount one of these to the front grill of your EV, and project any annoying sound you want, white noise, crying babies, "Get The Hell Out The Way!" V/O, Phasers At Maximum, whatever ... only the guy standing in front of your car will hear it. At low power, the sound doesn't even travel that far (Note: at extreme high power, the military has been experimenting with the technology as a stun [or even fry-your-brain death-ray] weapon).

There are 2 reasons I've been avoiding discussing "laser audio" in this context. First, it's reeeally pricey. Maybe that would change if EVs become more common, and this tech were required for all of them.

But more importantly, it negates the owner's "i want my car to sound cool" sentiment ... and by preventing the innocent bystander from hearing any sound at all, does nothing to mitigate the "startling silent machine motion" issue. It also diminishes the driver's ability to show off his ride and attract attention (preferably from the hotties).

Now, I know you think that's a feature, not a bug, and that a quiet car is a good car. But to the EV manufacturer, trying to make a buck, CarTunes might be a fabulously lucrative revenue stream, created as a direct result of marketing requirements, and customer demand.

It's quite analogous to the ringtone market. You may think "phones should never ring", but millions of consumers disagree (with their wallets). In fact, I'm sorry to say, but since you are obviously a highly intelligent, well informed, socially concerned and considerate humanitarian, your impassioned opposition to the idea of cartunes only strengthens my conviction that this shit's gonna happen ...

Again, I'm not advocating "annoying cartune" adoption, nor judging its moral value, I'm just calling it like I see it, based on my experience with ringtones ...

Sure to happen? That's hard to say. If there is a law demanding the cars make artificial noise, if it throws in a clause requiring efforts to make sure the noise is not obtrusive to those not likely to contact the vehicle, this would make cartunes quite rare, because no factory noise system would have them. People could of course put in gear on their cars to make noises and play music, and they already do -- some you can hear from blocks away -- but it is done rarely.

They question is not whether people might want to do it, but whether it is institutionalized, either from a law or from the thought of it being a marketplace. (Ringtones do make lots of money but it's small compared even to the cellular market and tiny compared to the car market.)

If it's something that comes with your car, and you just have to order a cartone on a web site, we'll have our streets a constant blare of cartones. If it's something you have to go out of your way to add to your car, it will remain minor I think.

I've been trying to figure out what's got me viscerally reacting negatively to the arbitrary cartunes concept. I think it comes down to this:

The sound created by a 2-ton moving hunk of metal currently has tremendous utilitarian value which is tightly coupled to valuable information about a potentially dangerous environment. As sound (and only sound) seems to be able to do, it takes multiple input parameters (distance, velocity of car, RPM, and numerous other real-world paramaters--perhaps even driver mood--hear them revving the engine in impatiance, for example--) and creates a single input stream (sound) to our ear/brain system. That system hears the sound and can instantly analyze and decode it, providing us with a wealth of information about world around us, in this case the status of the numerous 2-ton chunks of metal hurling around us.

Arbitrary "Cartunes" eliminates all but the most basic piece of information from the equation. As a result, we lose a LOT of valuble information that can make us safer and more aware-- an important advantage when the cars outweigh us by thousands of pounds.

Worse yet, completely arbitrary cartunes may even go so far as to cause misleading audio cues-- imagine you happen to be near a car just as a quiet part of the "cartune" comes up. Or a section that, for whatever reason, appears more 'distant' than the car actually is. Or that pitches down (emulating doppler) when in fact the car is speeding up.

So while cartunes is a very cool concept, and has lots of very fun and interesting things about it, I remain somewhat skeptical...

I'd say a cartune that gives false signals to pedestrians would seem to be the definition of a "bad cartune", i.e. one that doesn't function well in context, like a ringtone consisting of a beep followed by 30" of silence. Hopefully, a well designed EV audio system would maintain a fairly constant, dynamic range compressed, audible stream, possibly even mixing in the default engine noise if the volume level dropped too low for too long.

I've decided i'd like to use a recording of the Flight of the Valkyries, (AKA "Kill the Wabbit" as performed by by Elmer Fud.) I'm changing the lyrics a bit...

Wook owut fo' da Pweeeus

Here come da Pweeeus

I'm dwivin da Pweeus

I'm savin' fuwel

LOL!!!

Especially on my bicycle I have been caught completely off guard by electric vehicles. I depend on my ears a LOT when I'm on my bike. Perhaps, rather than a sound, some kind of sensor would light up on my handlebars when I'm coming up on a blind intersection where an EV is approaching.

So should the new term for highway noise pollution should be "carcophony"?

Love it!

Dave, explain this one to me.... how are we audio guys gonna deal with ground loops on a vehicle resting on four rubber tires? Will we be back to using ground lifters when we plug in our plug-in hybrids? Use a hum-reducing EQ? Perhaps we should get started on plug-in plug-ins?

Follow Up:

There was an article in the New York Times yesterday about the 2011 Chrevrolet Volt, an EV featuring a gas-powered generator that kicks in to charge the batteries if they drop below a certain level. The car's drive is completely electric, so when the generator turns on ... it's on, baby, like a lawn mower, a constant drone unrelated to the speed of the car.

The thing I found most interesting about the piece is the number of times the author discusses the sound of the vehicle. The audio experience seemed disconcerting when it varied from the "faster = more noise" paradigm of the internal combustion engine ... which serves to reinforce my belief that "adaptive engine" cartunes will be more about providing sonic familiarity and feedback for customers, than pedestrian safety.

...if you live next to the freeway, the prospect of replacing the constant roar of internal combustion engines with a low SPL whooshing of streamlined air displacement would seem to be a good thing...

The sound of vehicles on a freeway is primarily road noise, not engine noise. The one notable exception is engine breaking used by semi trucks on a steep decent.

2nd Follow Up

When Conan O'Brien makes fun of your idea on the Tonight Show (monologue @ 9'40"), ya gotta figure you're onto something :)

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