The decibel is a logarithmic unit used to express the ratio between two values of a physical quantity, often power or intensity. One of these quantities is often a reference value, and in this case the decibel can be used to express the absolute level of the physical quantity. The number of decibels is ten times the logarithm to base 10 of the ratio of the two power quantities. One decibel is one tenth of one bel. The bel is named in honor of Alexander Graham Bell, but is seldom used.
The definition of the decibel is based on the measurement practices in telephony of the early 20th century in the Bell System in the United States. Today, the unit is used for a wide variety of measurements in science and engineering, most prominently in acoustics, electronics, and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels. The decibel confers a number of advantages, such as the ability to conveniently represent very large or small numbers, and the ability to carry out multiplication of ratios by simple addition and subtraction.
A change in power by a factor of 10 corresponds to a 10 dB change in level.
Der Präsident des Deutschen Bauernverbands (DBV), Joachim Rukwied, hat neue bundesweite Proteste der Landwirte angekündigt. „Wir werden weiterhin für eine angemessene Lösung beim Agrardiesel kämpfen“, stellte sich Rukwied erneut gegen die von der Regierung geplanten Subventionskürzungen.Jetzt lesen »