Engineered audio in cars




If you could hack those little mp3 files and change them, you could have endless fun with your friend's car!


Note that the sound outside a car is also engineered. One of the concerns with early hybrids was that they might be too quiet and thus be a threat to pedestrians who were used to using ears as well as eyes to scan for oncoming traffic. I don't know whether the solution was electronic or mechanical, but they were redesigned to be somewhat noisier.

(If it's electronic, I hope hybrid police cars have a "run silent" mode... just because they could.)


Always a fun topic.

Previously on BoingBoing:

The world is full of fake sounds


In praise of skeuomorphs


Motorbikes here in Victoria, Australia are required to have their headlights wired on, but I noticed one day that police motorbikes have a crude switch installed to switch the lights off.

I have my doubts about this article.
The telltale clicking of a turn signal was once an artifact of the mechanical process that turned the light on and off. But that mechanism has long since been replaced by an electronic circuit that operates silently.
"Long since," they say, but I'm pretty sure my 2007 Toyota still has electromechanical relays for the hazards and turn signals. Easy enough to peek under the dash and see. I'll let you know. And then there was this bit:
But as you reduce the speed that the drive shaft is rotating, you lower the frequency of the sound it’s making. There comes a lower limit where the engine is making what Gordon calls “groan-y and moan-y” noises which people find unpleasant. The car sounds broken. So cars had to keep the engine’s RPM above a certain level, hurting their fuel efficiency, or risk alienating customers.

Trouble is, the speed of the driveshaft is a direct function of how fast the vehicle is traveling, not how fast the engine is spinning. There's a transmission in between, you see. I have no doubt that there's some active noise cancellation at play these days, but the engine speed is gonna be what it needs to be to enable a smooth idle, prompt throttle response, and maximum power output for minimum emissions and fuel consumption. Engine noise isn't really going to dictate how fast or slow they let the engine spin.

I have no doubt Kara Gordon knows what she's talking about. I do have doubts about Tim Maly, however.


I definitely noticed how my directional sound would mute when my seatbelt alert sounded. Is there another speaker though? What if I replace the stock radio? Would I no longer hear all the audio clues?


You can no longer replace your stock radio. It's part of the car now.


Little men come and sprinkle sand on the sidewalk so your shoes make a satisfying "whootch" as they strike the pavement. your keys are secretly tuned while you are asleep to keep them jangling harmonically. Your newspaper is starched so that it will crinkle with authority when shook into shape.

Such is the life of the affluent in a global mega-boom.


Woah, really? I guess I haven't bothered to consider it for my latest car (2008 Aura) but replacing the factory radio in my Saturns used to be part of the process. Auto makers are definitely installing better audio systems these days (external audio jacks was all I ever asked for) so whatever.


I thought they just engineered the brakes to dissipate energy as high-frequency pain instead of just heat.


Citation needed for one than one model or one with an upgraded stereo system.

If this is the case companies like Crutchfield will be out of business soon.


I wish car companies would give me to option of what I wanted to hear.

Frankly even if I was driving an Impala I'd want to hear the engine when I pushed it. Ever car I've owned I have installed some sort of open/short air intake, quiet when I'm cruising and noticeable when I push it.


Valid points.


I doubt MOST modern cars go to the extent of using an mp3 to simulate the turn signal noise. Car engineers change things at a relatively slow (compared to other technologies) pace. One reason is almost everything they do has to be DOT certified. Also, someone correct me if I'm wrong, I think they have to keep producing replacement parts for a certain number of years after initial production, much like airplane manufacturers. Most cars still use a relay for the turn signal flash, because it's simple and reliable. Or maybe the silicon equivalent of a relay, and they just add a tiny piezo beeper to the circuit board to make the noise. Again, self contained and simple. The new Impala might be cool with all this wrapped into the sound system, but what happens when (as mentioned above) someone wants an aftermarket stereo? Or there are bugs in the software? When your noise canceling system craps out, so does every other audible feedback in your car? Bad design.


All the noises on my 2005 are real save for the radio, and I love them all. It's not really a surprise on my car though, considering it's riding on a platform designed in 1979 and has (relatively) barely been changed since then. Hacking new car software to make different noises (Like the BMW with completely fake cabin engine noise. So many possibilities) is cool, but I'd much rather physically change my intake, exhaust, etc. to change my engine noise.


It depends on the car. My Jeep Wrangler's radio can be replaced, it just requires installing a CAN bus adapter to adapt it to the steering wheel controls. If it's important to you to be able to replace the radio, check whether an adapter exists for the car you're planning to buy before you buy it.


All cars with LED turn signals use electronic flashers because LED's don't pull enough power for traditional turn signal relays. All cars with the "push to flash" feature (where you push the turn signal stalk halfway down to get three or four flashes of the left turn signal for example) use electronic flashers.On my 2012 Jeep Wrangler, which has an electronic flasher controlled by a computer under the hood (as are the headlights and fog lights, the switches on the turn signal stalk merely send a signal over the CAM bus to the computer), the sound for the turn signal "flasher" comes out of a tiny almost undetectable speaker on the steering column near my right knee, not from the sound system. BTW, this Jeep has a large amount of engineering in it intended to make it sound like a "traditional" Jeep, which causes problems when people lift the heavy sound baffle over the engine and think the engine is disintegrating. It isn't. It's just a lightweight overhead-cam aluminum engine, which sounds entirely different from ancient cast-iron engines that Jeep owners are accustomed to (lots more clattering from the top end for one thing due to no heavy cast iron manifolds to absorb the sound of the valves opening and closing), and which they thus had to put baffling and padding around to keep Jeep owners (mostly) happy.


Well, I may be biased because we have a couple Prii, an older one and a newer one. They have the radio integrated tightly into the console display unit. I sure haven't seen any cars made in the last five years with modular DIN stereos, that's for sure.


The van I rented last year, a new but old-school Ford E-350, had the musical turn signal thing. It really disturbed me. I could tell that it was a musical version of the clicky relay present in my 1958 Chevy. The sound took me deep into the Uncanny Valley.