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Example(s) quadr(i)-four Latin quattuor: quadriceps: radi-radiation Latin radiō, I radiate, emit beams; from radius, ray of light, spoke of a wheel radiowave: radic-referring to the beginning, or the root, of a structure, usually a nerve or a vein Latin rādīx, root radiculopathy: re-again, back Latin re-relapse: rect-rectum
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 or root-power quantity on a logarithmic scale. 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). [1] [2]
The term is sometimes used metaphorically to refer to the ratio of useful information to false or irrelevant data in a conversation or exchange. For example, in online discussion forums and other online communities, off-topic posts and spam are regarded as noise that interferes with the signal of appropriate discussion.
dBm or dB mW (decibel-milliwatts) is a unit of power level expressed using a logarithmic decibel (dB) scale respective to one milliwatt (mW). It is commonly used by radio, microwave and fiber-optical communication technicians & engineers to measure the power of system transmissions on a log scale , which can express both very large and very ...
Audiogram. An audiogram is a graph that shows the audible threshold for standardized frequencies as measured by an audiometer.The Y axis represents intensity measured in decibels (dB) and the X axis represents frequency measured in hertz (Hz). [1]
A measure of the power contained in the useful part of the signal, to the power contained in noise. Often measured in decibels; for example, in sound reproduction a 40 or 50 decibel signal to noise ratio would be broadcast quality, whereas a 10 decibel ratio would represent very difficult operating conditions for a voice radio system.
Vinyl microgroove phonograph records typically yield 55-65 dB, though the first play of the higher-fidelity outer rings can achieve a dynamic range of 70 dB. [25] German magnetic tape in 1941 was reported to have had a dynamic range of 60 dB, [26] though modern-day restoration experts of such tapes note 45-50 dB as the observed dynamic range. [27]
Environmental noise regulations usually specify a maximum outdoor noise level of 60 to 65 dB(A), while occupational safety organizations recommend that the maximum exposure to noise is 40 hours per week at 85 to 90 dB(A). For every additional 3 dB(A), the maximum exposure time is reduced by a factor 2, e.g. 20 hours per week at 88 dB(A).