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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 ASA-1951 standard for example used a level of 16.5 dB SPL at 1 kHz whereas the later ANSI-1969/ISO-1963 standard uses 6.5 dB SPL, and it is common to allow a 10 dB correction for the older standard.
The intensities displayed on the audiogram appear as linear 10 dBHL steps. However, decibels are a logarithimic scale, so that successive 10 dB increments represent greater increases in loudness. For humans, normal hearing is between −10 dB(HL) and 15 dB(HL), [2] [3] although 0 dB from 250 Hz to 8 kHz is deemed to be 'average' normal hearing.
There is a similar metric called day-evening-night average sound level (Lden or DENL) commonly used in other countries, or community noise exposure level (CNEL) used in California legislation; that is, the DNL with the addition of an evening period from 19:00 to 22:00 when noise level measurements are boosted 5 dB (or 4.77 dB in the case of ...
The two different methods produce different thresholds [1] [2] and minimal audible field thresholds are often 6 to 10 dB better than minimal audible pressure thresholds. [2] It is thought that this difference is due to: monaural vs binaural hearing. With minimal audible field both ears are able to detect the stimuli but with minimal audible ...
Logarithmic chart of the hearing ranges of some animals [1] [2] Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high ...
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. [3]
Such a difference can exceed 100 dB which represents a factor of 100,000 in amplitude and a factor 10,000,000,000 in power. [ 4 ] [ 5 ] The dynamic range of human hearing is roughly 140 dB, [ 6 ] [ 7 ] varying with frequency, [ 8 ] from the threshold of hearing (around −9 dB SPL [ 8 ] [ 9 ] [ 10 ] at 3 kHz) to the threshold of pain (from 120 ...