scale of sound exposure times to decibels

The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels. Instead, the decibel is used for a wide variety of measurements in science and engineering, most prominently for sound power in acoustics, in electronics and control theory. The bel was named in honor of Alexander Graham Bell, but the bel is seldom used. The definition of the decibel originated in the measurement of transmission loss and power in telephony of the early 20th century in the Bell System in the United States. The decibel scales differ by a factor of two, so that the related power and root-power levels change by the same value in linear systems, where power is proportional to the square of amplitude. When expressing root-power quantities, a change in amplitude by a factor of 10 corresponds to a 20 dB change in level. That is, a change in power by a factor of 10 corresponds to a 10 dB change in level.

When expressing a power ratio, it is defined as ten times the logarithm in base 10. Two principal types of scaling of the decibel are in common use. For example, for the reference value of 1 volt, a common suffix is ' V' (e.g., '20 dBV').

In the latter case, the numeric value expresses the ratio of a value to a fixed reference value when used in this way, the unit symbol is often suffixed with letter codes that indicate the reference value. The unit expresses a relative change or an absolute value. Two signals whose levels differ by one decibel have a power ratio of 10 1/10 (approximately 1.26) or root-power ratio of 10 1⁄ 20 (approximately 1.12). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel ( B). For other uses, see Decibel (disambiguation). For use of this unit in sound measurements, see Sound pressure level. 23).This article is about the logarithmic unit. Amendment of group heading filed 6-3-97 operative 7-3-97 (Register 97, No. Amendment filed 10-3-83 effective thirtieth day thereafter (Register 83, No. Repealer of Group 15 (Article 105, Sections 5095-5099) and new Group 15 (Article 105, Sections 5095-5100 and Appendices A-E) filed 6-28-82 effective thirtieth day thereafter (Register 82, No. NOTE: Authority and reference cited: Section 142.3, Labor Code.ġ. An instrument for the measurement of sound level. For use with this regulation, SLOW time response, in accordance with ANSI S1.4-1971 (R1976), is required. Ten times the common logarithm of the ratio of the square of the measured A-weighted sound pressure to the square of the standard reference pressure of 20 micropascals. Measurements of an employee's noise dose or 8-hour time-weighted average sound level that the employer deems to be representative of exposures of other employees in the workplace.

A physician specializing in diagnosis and treatment of disorders of the ear, nose and throat. For purposes of this regulation, a condition or disease affecting the ear, which should be treated by a physician specialist. Unit of measurement of frequency, numerically equal to cycles per second. A unit of measurement of sound level corrected to the A-weighted scale, as defined in ANSI S1.4-1971 (R1976), using a reference level of 20 micropascals (0.00002 Newton per square meter). Unit of measurement of sound level.ĭBA (Decibels-A-Weighted). A sound level of 90 decibels.ĭecibel (dB). The audiogram against which future audiograms are compared.Ĭriterion Sound Level. A professional, specializing in the study and rehabilitation of hearing, who is certified by the American Speech, Hearing and Language Association or licensed by a state board of examiners.īaseline Audiogram. A chart, graph, or table resulting from an audiometric test showing an individual's hearing threshold levels as a function of frequency.Īudiologist. An 8-hour time-weighted average of 85 decibels measured on the A-scale, slow response, or equivalently, a dose of fifty percent.Īudiogram. Agriculture, construction, and oil and gas well drilling and servicing operations are exempt from the provisions of Sections 5097 through 5100.Īction Level. Article 105 establishes requirements for controlling occupational exposures to noise. Control of Noise Exposure Return to index General Industry Safety OrdersĪrticle 105.

Scale of sound exposure times to decibels