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The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a ...
The decibel (dB) is a dimensionless unit, used for quantifying the ratio between two values, such as signal-to-noise ratio. The dBm is also dimensionless, [1][2] but since it compares to a fixed reference value, the dBm rating is an absolute one. The dBm is not a part of the International System of Units (SI) and therefore is discouraged from ...
The decibel watt (dBW or dB W) is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt.It is used because of its capability to express both very large and very small values of power in a short range of number; e.g., 1 milliwatt = −30 dBW, 1 watt = 0 dBW, 10 watts = 10 dBW, 100 watts = 20 dBW, and 1,000,000 W = 60 dBW.
Sound power level (SWL) or acoustic power level is a logarithmic measure of the power of a sound relative to a reference value. Sound power level, denoted LW and measured in dB, [9] is defined by: [10] where. P is the sound power; P0 is the reference sound power; 1 Np = 1 is the neper; 1 B = 1 / 2 ln 10 is the bel;
Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area. The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m 2). One application is the noise measurement of sound intensity in the air at a listener's location ...
0.7375621 ft⋅lbf/s = 0.001341022 hp. The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m 2 ⋅s −3. [1][2][3] It is used to quantify the rate of energy transfer. The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish inventor ...
While 1 atm (194 dB peak or 191 dB SPL) [11] [12] is the largest pressure variation an undistorted sound wave can have in Earth's atmosphere (i. e., if the thermodynamic properties of the air are disregarded; in reality, the sound waves become progressively non-linear starting over 150 dB), larger sound waves can be present in other atmospheres ...
Many high-quality domestic speakers have a sensitivity between ~84 dB and ~94 dB, but professional speakers can have a sensitivity between ~90 dB and ~100 dB. An '84 dB' source would require a 400-watt amplifier to produce the same acoustical power (perceived loudness) as a '90 dB' source being driven by a 100-watt amplifier, or a '100 dB ...