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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.
Sample hypnogram showing one sleep cycle (the first of the night) from NREM through REM The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep . It is sometimes called the ultradian sleep cycle , sleep–dream cycle , or REM-NREM cycle , to distinguish it from the circadian alternation between sleep and ...
The programme is a rebranded version of Night Waves, "Radio 3's flagship arts and ideas programme". [2] Night Waves was broadcast every Monday to Thursday evening, except during the Proms season . Radio 3 rebranded Night Waves as Free Thinking from 7 January 2014, and reduced the number of first-time broadcasts per week from four to three (plus ...
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In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges, allowing some to even hear ultrasounds
In addition, sounds can also be long and soft as well as short and loud. [7] Onset time of the noise during the night: The ISCD-2 established latency of noises after falling asleep ranging from 2 to 6 h. [11] However, in some published cases the onset time of the noises is reported as being shorter (3 min [16]). Association with respiratory ...
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Slow-wave sleep (SWS), often referred to as deep sleep, is the third stage of non-rapid eye movement sleep (NREM), where electroencephalography activity is characterised by slow delta waves. [2] Slow-wave sleep usually lasts between 70 and 90 minutes, taking place during the first hours of the night. [3]