News Release

The friendly honk

Acoustical remake of car horns alerts without jarring

Peer-Reviewed Publication

Acoustical Society of America

WASHINGTON, D.C., June 25, 2017 -- Sound permeates the human experience -- we are exposed to sounds from birth to death, and the human auditory system can distinguish and classify about 400,000 different sounds, according to some estimates. It is noise that gets our attention. Sometimes traumatically so.

Consider the car horn. It is a widespread practical application of this noise-trauma-alert principle -- and an increasing source of noise pollution worldwide as the global traffic population grows. It also is the subject of new noise pollution research to be presented during Acoustics '17 Boston, the third joint meeting of the Acoustical Society of America and the European Acoustics Association being held June 25-29, in Boston, Massachusetts.

The study, led by Myungjin Bae of Soongsil University in Seoul, Korea, and presented at the meeting by SangHwi Jee, introduces a new pedestrian-friendly car-horn sound identified through the Mean Option Score (MOS). The MOS is a simple ranking method commonly used to evaluate machine speech, sounds and noise. Test listeners used MOS to evaluate candidate horn sounds based on five different perceptual qualities such as stress and loudness. It ranks sounds on a scale from bad (1) to excellent (5).

"The sound of Klaxon heard outside the car of the driver is uncomfortable because it is too loud to the people around him," Bae 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," Bae explained.

The historic standard car horn sound is familiar: It's the trademark-named Klaxon car horn developed in 1908 -- the classic "ah-oo-gah" sounding horn.

To test the perceptual effects of their new horn sounds, researchers exposed 100 volunteers to a menu of sounds in hopes of finding those that were less irritating to the ear of pedestrians.

"For almost 100 years, the car Klaxon sound was almost invisible and its design was simple, and it had the advantage of being able to make a loud noise at low power. But the level of loudness could not be easily controlled. In this study, when a driver presses a Klaxon, a loud sound of 110dB or more is not transmitted directly to a pedestrian," Bae said.

The intended result is a calmer more peaceful environment, he said -- attributes that increase a driver's focus and rational response. The selected sound can be applied to any motor vehicle. Its advantage is that it reduces stress on drivers as well as pedestrians or bikers, thus improving the city soundscape.

"Everyone can live more comfortably without hearing any annoying noise from the streets," Bae said.

Session 1pEA3, "On designing a new sound of the car-horn" by SangHwi Jee, is at 2:00-2:20 p.m. EDT, Sunday, June 25, 2017 in Room 204 of the John B. Hynes Veterans Memorial Convention Center.


Acoustics '17 Boston, the third joint meeting of the Acoustical Society of America and the European Acoustics Association.

The meeting is being held June 25-29, 2017 at the John B. Hynes Veterans Memorial Convention Center in Boston, Massachusetts.


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The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world's leading journal on acoustics), Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. For more information about ASA, visit our website at


The European Acoustics Association (EAA) is a non-profit entity established in 1992 that includes in its membership societies predominantly in European countries interested in to promote development and progress of acoustics in its different aspects, its technologies and applications. EAA gathers 33 societies of acoustics and serves public citizens and more than 9000 individual members all over Europe with yearly events as well as scientific conferences and publications such as Acta Acustica united with Acustica and Acoustics in Practice. The European Acoustics Association (EAA) is an Affiliate Member of the International Commission for Acoustics (ICA) and of Initiative of Science in Europe ISE. Visit our website at

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