A team of Ford engineers spend their days dreaming up sounds and subjecting them to a battery of tests to determine which warnings help drivers best react to possible dangers and work in harmony with other sounds in the vehicle. This grueling process involves complex scientific theory, listening clinics and on-road simulations to whittle down numerous sounds to the few that prove most effective.
“Ford engineers spend a tremendous amount of time finding just the right sound for just the right situation to help customers react to potential dangers,” said Paul Mascarenas, Ford vice president of engineering, Global Product Development. “We also listen to our customers so they listen to the car when needed – we don’t want them to be annoyed and tune out important warnings.”
Composing the right safety symphony
In developing its safety sound cues, Ford relies on principles of music theory, mathematical analysis and psychoacoustics – the study of sound perception – to research properties such as pleasantness, loudness and sharpness. As a musical composer might select from different types of sound to cast a specific mood, Ford sound technicians choose from a palette of psychoacoustic parameters to create the ideal acoustical and vibrational environment based on the following measures:
- Appropriate character for sounds and the response they evoke, such as the difference between a courtesy seat belt chime and a cross-traffic alert to prompt immediate action
- Correct balance between road noise, engine noise and wind noise
- Minimal disturbing sound components such as whines, squeaks and rattles
- Mitigated sensory overload to reduce driver distraction
Ford’s preliminary research shows certain types of alerts work better in certain situations, and that sound frequencies and rhythms play an important role. For instance, in studies designed to see how proactive safety features can best alert drivers to potential accidents, drivers responded faster to audible alerts that sound more authoritative and are emitted in a rapid, staccato rhythm.
Drivers also indicated a preference for a combination of warnings – audio alerts backed up by a visual warning. As a result, Ford pairs audible alerts with visual cues for scenarios requiring a more urgent driver response, such as its collision warning with brake support system, now standard in Ford Taurus, Explorer and Edge.
Another important consideration is the presence of other sounds, including the radio or other in-car signals that compete for the driver’s attention. For proactive safety features that require the driver’s immediate response, such as Ford’s cross-traffic alert, the system actually silences the radio in order to guarantee instant communication with the driver.
Passing the audio-visual exam
Ford uses a variety of methods to test the effectiveness of audio and visual components. To re-create the driving experience, Ford pumps wind and road noise into cars isolated in a soundproof chamber with mannequins equipped with precise microphones that capoEre high-fidelity recordings of the alerts as a driver would hear them.
Ford also conducts subjective evaluations at customer clinics with volunteers who provide immediate feedback through “paired comparison,” in which jurors are asked to pick their favorites. In other “semantic differential” exercises, a sound is presented to a juror and that juror is asked to rate the sound between two polar opposite adjectives, such as “Does it sound expensive or cheap?”
Many of the prevailing sounds incorporate a series of notes along the major scales, with intervals that are pleasing to the ear, yet discernible enough to break through the ambient background of the car and other sounds competing for the driver’s attention. Some sounds that do well in the consumer preference testing do not meet the standard for eliciting the proper driver response, such as the soft, electronic beat sound “Techno01,” si[ lar tn club music around the world, which did well in the subjective studies but was not audible enough to cut through the car’s background sounds.
As Ford draws inspiration from many sources, it considers a wide array of sod options, many of which don’t make the final cut. Some sounds that were considered but not adopted, such as a sound that mimicked the chirping of crickets, were too literal to be effective. Others couldn’t overcome a generational divide, such as the “Youth Scratch” sound, created in the likeness of a DJ scratching a vinyl record. That appealed to younger drivers, but not to an older driver population.
Finding the right universal sound that works for all drivers is a challenging objective and one that transcends geographic boundaries. Because sensory perception and preference varies around the globe, Ford also tests some sounds in different regions to develop uniform cues that work in its various consumer markets.
For example, Ford tested 24 sound options for its new global turn signal for Europe, North America, South America and Asia. Leveraging the company’s global resources, sound engineers were able to determine in one week the new variation of a modern-day version of the “tick-tock” customers have grown accustomed to based on older electromechanical systems that relay the beating sound of their turn signal.
“There are both creative and technical elements in fine-tuning our sounds to get them exactly right,” said Petniunas. “A key objective is identifying the kinds of warnings drivers will find both more effective and easier to understand so that safety features are used correctly and more frequently.”
The sights and sounds of Ford safety
Sight and sound alerts are incorporated into many of Ford’s innovative safety features, including:
- BLIS® (Blind Spot Information System) with cross-traffic alert: Identifies when a vehicle enters the defined blind spot zone and illuminates an indicator light on the corresponding sideview mirror, providing a warning that a vehicle is approaching. An audible alert is sounded as well
- Collision warning with brake support: This technology is designed to help drivers avoid rear-end collisions. Using long-range radar hidden in the front of the vehicle, collision warning detects moving vehicles ahead and alerts the driver of a collision risk with an alarm and warning light
- MyKey®: Allows parents to limit vehicle’s top speed and radio volume to encourage teens to drive safer and improve fuel efficiency. The audio controls are important to maintaining a volume level that ensures drivers can hear outside warnings, such as emergency response vehicles and traffic hazard signals. It also encourages seat belt use, provides earlier low-fuel warnings and can be programmed to sound chimes at 45, 55 or 65 mph
- Belt-Minder®: A seat belt reminder technology for the front occupants that takes over after the initial seat belt reminder stops chiming. If the occupants remain unbuckled, the system chimes and flashes a warning lamp periodically for five minutes, or until the driver buckles up, whichever comes first