What should electric cars sound like?

Vroom chicka chicka

Electric vehicles (EVs) are so quiet that safety experts think pedestrians are likely to be killed or injured by EVs that they don't hear or can't see. The solution? Have EVs produce an artificial sound to alert pedestrians to their presence. But what sound?

Here are some proposed sounds for the Ford Focus.

http://www.fastcompany.com/1769225/what-sound-should-electric-cars-make

So this begs several questions:

- Is this really needed?

- What is the ideal sound a car should make to alert pedestrians?

- Can I make up my own sound and load it into my car? Will car sounds be the new ringtones?  Will this be a shot in the arm for the recording industry?

But seriously, noise pollution from automobiles is awful. I live in a suburb more than a mile from the nearest freeway and if I step outside I hear a constant roar from cars that becomes ridiculous during rush hours.

The industry may be tempted to reproduce the familiar sounds of automobiles. The most satisfying motor sounds have strong low frequency components that are felt as much as heard. But the lows propagate farther than they need to and are intrusive. You don't need to hear a car inside your house. I can't imagine they're planning to mount woofers under the front grill so it makes sense to me to use a sound that is directed in the path of travel and that human hearing is highly sensitive to...maybe something in the range of the female voice. But would the market accept it?

Tires rolling on pavement generate their own noise. Maybe that would be sufficient when the masking noise of all the internal combustion engines is gone?

Anyway, I want my car to sound like a 70s wah wah pedal... like the intro from "Shaft."

What do you want your car to sound like?

This had come up a few years back...when electric cars first made it to public roads (or rather, commercial electric cars). It's really a non-problem. There are cars out there now that, when light footing it around town, make little to no engine noise. All you actually hear is the fan or ac running, or the tires.

How about one of these?

http://www.youtube.com/watch?v=b9XAC-BvUyo

Best,
Bruno2000

Old news... but they should sound like those cycles in TRON...  or maybe like when we clipped playing card to slap up against the spokes on our bicycles  (anybody here remember bicycles? )

JR

What if all electric cars just have to crank Geto Boys on the stereo with the windows open?
Shouldn't they be personal?  Download or make a car sound just like a ringtone.  One person wants Tron, and someone else wants Mr. Magoo.  I would definitely mine the WB cartoon catalog if I ever get one of those clown cars.  Boinnng!
Maybe Jetsons. . . . or pipeless vtwin. . . so many choices. 
Mike
PS: If the sound output is anything like those wireless doorbells, any source will sound like a$$.  Actually, a transducer that can do the job will be a bigger design concern than the sound it transmits.

Mine makes the Pac Man wakka wakka sound.

kato said:

Mine makes the Pac Man wakka wakka sound.

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yesssssss!

The U.S. Department of Transportation issued this notice in July 2011 to request public comment on the PEDSAFE sound system standards for electric vehicles. 

http://www.nhtsa.gov/staticfiles/rulemaking/pdf/QuietCar-noi-draft.pdf


I find this fascinating. Obviously there are a number of industrial audio engineers, psychoacoustic researchers, and marketing experts working on this. At the end there is an interesting description of a special DSP-created sound.

Excerpts from the pdf:

"The purpose of the rulemaking mandated by the Pedestrian Safety Act is to require EVs and HVs, which tend to be quieter than the ICE vehicles, to be equipped with a pedestrian alert sound system that would activate in certain vehicle operating conditions to aid visually-impaired and other pedestrians in detecting the presence, direction, location, and operation of those vehicles. Taking this action is expected to reduce the number of incidents in which EVs and HVs strike pedestrians."


"The Pedestrian Safety Act requires NHTSA to conduct a rulemaking to establish a Federal motor vehicle safety standard requiring an alert sound for pedestrians to be emitted by all types of motor vehicles8 that are electric vehicles or hybrid vehicles (EVs and HVs). Thus, the covered types of vehicles include not only light vehicles (passenger cars, vans, sport utility vehicles and pickup trucks), but also low speed vehicles, motorcycles, medium and heavy trucks and buses.
The rulemaking must be initiated not later than 18 months after the date of enactment of the Pedestrian Safety Act. Given that the date of enactment was January 4, 2011, rulemaking must be initiated by July 4, 2012."

"Under the Act, NHTSA must publish a final rule establishing the standard requiring an alert sound for EVs and HVs by January 4, 2014. The Pedestrian Safety Act requires that the agency provide a phase-in period, as determined by NHTSA. However, full compliance with the standard must be achieved for all vehicles manufactured on or after September 1st of the calendar year beginning three years after the date of publication of the final rule."

"Automotive equipment manufacturers have begun developing speaker systems designed to produce alert sounds to install on EVs and HVs. Most of the systems have a single speaker that projects sound forward."

Several alternatives for alert sounds are being considered:
- a recording of an actual internal combustion engine (ICE)
- a synthesized ICE
- or a specially DSP-created sound

"The sounds produced by an ICE vehicle would be recorded when the vehicle is operating at constant speeds, forward from 0 potentially up to 32 km/h (0 to 20 mph) and in reverse potentially up to 10 km/h (6 mph). Other components of a vehicle's noise output such as tire noise, aerodynamic noise, and air conditioning fan noise would not be included in the recording used for the alert sound because these sounds are also emitted by EVs and HVs. The sound system would be programmed so that the pedestrian alert sound would vary based on the speed and operating mode of the vehicle in which the system was installed."

"...simulated ICE vehicle sounds would be synthesized directly by a digital-signal processor programmed to create ICE vehicle-like alert sounds that would vary pitch and loudness in relation to the speed and operating mode of the vehicle. The synthetic sounds would be based on actual ICE vehicle sounds."

"...a pedestrian alert sound combining some of the acoustic characteristics of sounds produced by ICE vehicles and some characteristics of non-ICE vehicle sounds engineered for enhanced detectability."

"...pedestrian alert sounds would be created based on psychoacoustic principles using a digital-signal processor. Some characteristics common to these non-ICE vehicle sounds would include:
§ Pitch shifting denoting vehicle speed change (in order to replicate a vehicle accelerating from 0 to 32 km/h (0 to 20 mph), a linear pitch change of approximately 40% is necessary, based on changes in vehicle speed);
§ Pulsating quality, with pulse widths of 100 to 200 msec and about three to ten pulses per second interval;
§ Inter-pulse intervals of no more than 150 msec;
§ A fundamental tonal component in the 150 to 1000 Hz frequency range;
§ At least three prominent harmonics in the 1 to 4 kHz frequency range;
§ Four or more frequencies with average sound pressure exceeding 50 dB(A).
Sounds having the characteristics listed above might not resemble the sound of an ICE vehicle, although recordings of ICE vehicle noise can be processed through a digital signal processor to conform to the characteristics above while retaining a quality that would allow pedestrians to identify the sound as coming from a motor vehicle. Although the alert sound would not sound like an ICE vehicle, it would still vary pitch and loudness in relation to the speed and operating mode of the vehicle, which would enable pedestrians to identify the sound as that of a motor vehicle in operation."

My nearly-stock 1968 Cougar (medium V-8) could sneak-up behind pedestrians on a quiet street. Note this is totally explosion-driven, and was one of the fastest cars on the road in 1990.

Tires make noise above 10MPH-30MPH. It is, on most cars, the loudest sound at these speeds.

I'm guessing the problem is at lower speed. Then the loudest sound on a conventional car is the engine wind-up to stir the automatic transmission into motion (or rarely, manual rev-up and clutch-drop). Electric get-go is spooky silent.

Maybe a loose part on the motor to vibrate with the LARGE slow AC current at get-go? Buzzzz. Once rolling at speed the higher pulse-rate and lower current would not shake the loose part so well.

PRR said:

My nearly-stock 1968 Cougar (medium V-8) could sneak-up behind pedestrians on a quiet street. Note this is totally explosion-driven, and was one of the fastest cars on the road in 1990.

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I rarely quibble with PRR but .. that must have been a lonely road...  8)

Tires make noise above 10MPH-30MPH. It is, on most cars, the loudest sound at these speeds.

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Yup  as a runner I have a lot of experience listening for cars coming from behind... Tires make noise, and cheap tires make more noise, because some of that noise is waste energy. 

I'm guessing the problem is at lower speed. Then the loudest sound on a conventional car is the engine wind-up to stir the automatic transmission into motion (or rarely, manual rev-up and clutch-drop). Electric get-go is spooky silent.

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Yup problem is blind people crossing the street, but it might be cheaper to give them car detecting canes or dogs. 

It seems like a great opportunity to sell car ringtones... or earn money with advertiements

JR