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I 0 is the reference sound intensity; 1 Np = 1 is the neper; 1 B = 1 / 2 ln(10) is the bel; 1 dB = 1 / 20 ln(10) is the decibel. The commonly used reference sound intensity in air is [5] = /. being approximately the lowest sound intensity hearable by an undamaged human ear under room conditions.
10 −1: 1 decihertz (dHz) 189 mHz: Acoustic – frequency of G −7, the lowest note sung by the singer with the deepest voice in the world, Tim Storms. His vocal cords vibrate 1 time every 5.29 seconds. 10 0: 1 hertz (Hz) 1 to 1.66 Hz: Approximate frequency of an adult human's resting heart beat: 1 Hz: 60 bpm, common tempo in music 2 Hz
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 ...
1 dB = 1 / 20 ln 10 is the decibel. The commonly used reference sound exposure in air is [2] = . The proper notations for sound exposure level using this reference are L W/(400 μPa 2 ⋅s) or L W (re 400 μPa 2 ⋅s), but the notations dB SEL, dB(SEL), dBSEL, or dB SEL are very common, even if they are not accepted by the SI.
The frequency range often specified for audio components is between 20 Hz to 20 kHz, which broadly reflects the human hearing range. Well-designed solid-state amplifiers and CD players may have a frequency response that varies by only 0.2 dB between 20 Hz to 20 kHz. [4]
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 ...
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]
It is the property of sound that most determines pitch. [1] The generally accepted standard hearing range for humans is 20 to 20,000 Hz. [2] [3] [4] In air at atmospheric pressure, these represent sound waves with wavelengths of 17 metres (56 ft) to 1.7 centimetres (0.67 in). Frequencies below 20 Hz are generally felt rather than heard ...