Because the decibel scale mirrors the function of the ear more accurately than a linear scale, it has several advantages in practical use these are discussed in Hearing, below.Ī fundamental feature of this type of logarithmic scale is that each unit of increase in the decibel scale corresponds to an increase in absolute intensity by a constant multiplicative factor. The reference intensity I 0, corresponding to a level of 0 decibels, is approximately the intensity of a wave of 1,000 hertz frequency at the threshold of hearing-about 10 -12 watt per square metre. Here L represents decibels, which correspond to an arbitrary sound wave of intensity I, measured in watts per square metre. Such a scale is provided by the sound intensity level, or decibel level, of a sound wave, which is defined by the equation Because of the enormous nonlinearity of the ear in sensing pressure waves, a nonlinear scale is convenient in describing the intensity of sound waves. The ear mechanism is able to respond to both very small and very large pressure waves by virtue of being nonlinear that is, it responds much more efficiently to sounds of very small amplitude than to sounds of very large amplitude. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians. COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.For instance, a jet airplane produces a sound intensity of 120 dB(A) during take-off, a heavily used urban road intersection 80 dB, and 70 dB is a common noise level near a highway. a sound barrier) or where residential land uses are restricted. Legal limits usually range between 50 dB and 65 dB, above which some abatement measures must be provided (e.g. It is often measured for the 6h00-22h00 period, which corresponds to the period of the day when most people are awake. The Leq is the average of noise exposure, often in dB(A), over a time period. Measures are often given in dB(A) or Leq when a time period is involved. The acoustic pressure of 120 dB is thus one million times that of 0 dB. Decibels are measured on a logarithmic scale, which means that an increase of 10 dB corresponds to an increase in intensity by a factor of 10. 0 dB is barely perceivable by human beings, while 120 dB is considered the threshold of pain and hearing damage. A decibel is a unit of measure of the intensity of acoustic pressure.
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