With hybrids startling pedestrians in parking lots because of their silent running, there has been some talk of putting synthetic sound-emitting devices in the vehicles--to put a bell on the cat, as it were. Beyond the talk, nothing has actually been done, until now. Nissan announced a pedestrian safety sound system for its upcoming Leaf electric car.
The sound system includes a speaker under the hood and a synthesizer in the dash. The driver will be able to turn it off, but it comes on by default at start up. At speeds above 18 mph (30 kph), the system turns off as natural road noise heightens.
The sound, a sine wave sweeping from 2.5kHz to 600Hz, was designed to be audible to all age groups. At start-up, the sound comes on at its loudest to warn the visually impaired and other pedestrians that a car is about to enter their vicinity. When the Leaf is reversing, the system produces an intermittent sound, similar to the back-up warning systems on trucks.
According to Nissan, the sound was designed to meet guidelines for an audible pedestrian warning system set forth by Japan's Ministry of Land, Infrastructure and Transport.
The Nissan Leaf goes on sale this December in the United States, Japan, Portugal, and the Netherlands, and will be the first production vehicle to incorporate this type of system.