A back-up beeper, also known as back-up alarm or vehicle motion alarm, is a device intended to warn passers-by of a

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

moving in reverse. Some models produce

pure tone In psychoacoustics, a pure tone is a sound with a sinusoidal waveform; that is, a sine wave of constant frequency, phase-shift, and amplitude. By extension, in signal processing a single-frequency tone or pure tone is a purely sinusoidal signal ...

beeps at about 1000 Hz and 97-112

decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a Power, root-power, and field quantities, power or root-power quantity on a logarithmic scale. Two signals whos ...

s. Matsusaburo Yamaguchi of Yamaguchi Electric Company,

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, invented the back-up beeper which was first manufactured as model BA1 in 1963. In the U.S., the back-up beeper was first manufactured by Ed Peterson who sold the system to Boise engineering firm Morrison Knudsen in 1967. As of 1999, the company marketed the Bac-A-Larm and sold about one million of the backup alarms annually, more than other suppliers. ISO 6165 describes "audible travel alarms", and ISO 9533 describes how to measure the performance of the alarms.

Criticism

Back-up beepers have been criticized by the public and in scientific literature. Beepers are at or near the top of lists of complaints to government road builders about road construction noise. There is published concern that due to desensitization and the cry wolf effect people tend to disregard ever-present alarm sounds, diminishing their effectiveness. The typical 1000 Hz

beeps at 97-112

s exceed the long-term

hearing loss Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spo ...

threshold of 70 decibels. Brains do not adapt to the repetitive and persistent sound of back-up beepers, but have evolved to process natural sounds that dissipate. The sound is perceived as irritating or painful, which breaks concentration. In some countries, back-up warning systems using blasts of

white noise In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used with this or similar meanings in many scientific and technical disciplines, i ...

have become more common. White noise is more audible than monotone beeping over background noise, and one can more easily ascertain the distance and direction of the sound.

Regulations in the United States

Back-up beepers or an observer are required by

OSHA The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...

for earth-moving vehicles with an obstructed view to the rear and no one on the ground to help guide the driver.

regulation 29 CFR Part 1926.601(b)(4) requires "a reverse signal alarm audible above surrounding noise level", but only when the motor vehicle has "an obstructed view to the rear". The determination of the noise level is left to the employer.

NHTSA The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation, focused on automobile safety regulations. NHTSA is charged with writing and enforcing Feder ...

requires electric vehicle warning sounds to alert pedestrians in electric and hybrid vehicles manufactured after 2018, for both forward and reverse travel at low speeds.

References

{{Reflist Construction safety Warning systems Automotive technologies