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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 ...
Seattle, WA {Section 25.08.501} considers the sound emitted to be in violation if the sound is plainly audible within a dwelling from 10 pm to 7am; the need for a sound level meter is avoided. Chicago, IL {Section 11-4-2805} limits received sound levels to 55 dB(A) inside a residential dwelling unit but if the ambient is greater, the limit is ...
Their purpose is to produce a single-value representation of a complete sound spectrum. International standards organizations ( ISO , [ 2 ] ANSI [ 3 ] and ASA ) recognize the need to objectify judgements on the amount of ambient noise in enclosed spaces, and provide us with definitions for various noise curves. [ 4 ]
In modern recording, this range is often limited through dynamic range compression, which allows for louder volume, but can make the recording sound less exciting or live. [ 50 ] The dynamic range of music as normally perceived in a concert hall does not exceed 80 dB, and human speech is normally perceived over a range of about 40 dB.
The day–evening–night noise level or L den is a 2002 European standard to express noise level over an entire day. It imposes a penalty on sound levels during evening and night [1] and it is primarily used for noise assessments of airports, busy main roads, main railway lines and in cities over 100,000 residents.
A sonority hierarchy or sonority scale is a hierarchical ranking of speech sounds (or phones).Sonority is loosely defined as the loudness of speech sounds relative to other sounds of the same pitch, length and stress, [1] therefore sonority is often related to rankings for phones to their amplitude. [2]
The day-night average sound level (Ldn or DNL) is the average noise level over a 24-hour period. The noise level measurements between the hours of 22:00 and 07:00 are artificially increased by 10 dB before averaging. This noise is weighted to take into account the decrease in community background noise of 10 dB during this period.
The commonly used reference sound exposure in air is [2] E 0 = 400 μ P a 2 ⋅ s . {\displaystyle E_{0}=400~\mathrm {\mu Pa^{2}\cdot s} .} 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 ...