A quacking car horn designed to alert people to danger while reducing the cacophony of noise on city streets has been developed by sound experts.
The device, sounding a little like a synthesised duck, was developed to get attention in a less stressful way than the traditional angry honk.
Scientists returned to the early days of motoring and re-modelled the classic Klaxon "ah-oo-gah" car horn introduced in 1908.
Different sound variations were tested on 100 volunteers before deciding on the pedestrian-friendly "quack".
Lead researcher Professor Myung-Jin Bae, from Soongsil University in Seoul, South Korea, said: "In our study we used the existing historic Klaxon sound source, but made some modification concerning its volume and rhythm with duration time by adding a power controller.
"Our new Klaxon sound can immediately alert the pedestrians of the danger while also reducing the unpleasantness and stress of the sound."
The aim was to find a sound that could be noticed without being too irritating.
Test listeners were asked to evaluate candidate car horn sounds for perceptual qualities such as stress and loudness.
Their answers resulted in a "mean option score" (MOS) ranking sounds on from bad to excellent on a five-point scale.
The Klaxon had the advantage of making a loud noise at low power, but its volume could not be easily controlled, said Bae.
He added: "In this study, when a driver presses a Klaxon, a loud sound of 110dB or more is not transmitted directly to a pedestrian."
A less startling car horn could also contribute to road safety by being less distracting to drivers, said the researchers, who presented their findings at the Acoustincs '17 meeting taking place in Boston, US.