As Long as It’s the Right Sound
Lawrence Rosenblum on the hazards of ultra-quiet hybrid cars:
This finding is consistent with a fact many of us have suspected all along: the quietness of slow moving hybrid cars is a danger to all of us—blind and sighted alike. Our auditory systems often work at an implicit level in warning of nearby dangers, allowing us to concentrate on more conscious tasks. Our ability to safely cross a parking lot while we talk to a friend, manage our children, or simply look for where we’ve parked, is aided by our implicit auditory warning system.
In fact, there’s evidence that our brains are exceedingly sensitive to approaching sounds. Research shows that when we hear a sound approach—vs. recede or remain stationary—brain regions associated with attention and motor action are quickly recruited. The auditory brain also possesses a disproportionately large number of cells sensitive to increasing sound loudness: one of the primary cues for perceiving approaching sounds. These brain findings jibe well with perceptual research showing that we consistently over-anticipate the location of approaching sounds. It’s likely that our auditory systems have been designed to use approaching sounds to avoid hazards. If there’s too little sound to effectively engage the system, as is the case with hybrids at low speeds, then any normal distraction becomes hazardous.
But our hyper-sensitivity to approaching sounds can also be part of the solution. It means that only a subtle enhancement of sound should be needed. Hybrids and electric cars won’t need to beep, chirp, or produce an alarm to be audible. Beeps and chirps are likely more distracting than they are perceptually useful. The enhancing sound, needed only at slow speeds, could be either the simulated sounds of a very quiet engine (think cooling fan), or of rolling tires. For purposes of both auditory utility and simple familiarity, the safest sounds are car sounds. And these sounds would be barely noticeable for most of us. Not much sound is needed for the auditory system to warn us about hazards, as long as it’s the right sound.
This entry was posted on Friday, October 9th, 2009 at 6:17 am and is filed under Traffic safety. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.