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  2. Hearing range - Wikipedia

    en.wikipedia.org/wiki/Hearing_range

    The human range is commonly given as 20 to 20,000 Hz, [3] [4] [note 1] although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies with age is considered normal. Sensitivity also varies with frequency, as shown by equal-loudness contours.

  3. Slow-wave sleep - Wikipedia

    en.wikipedia.org/wiki/Slow-wave_sleep

    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 ]

  4. Room modes - Wikipedia

    en.wikipedia.org/wiki/Room_modes

    Most rooms have their fundamental resonances in the 20 Hz to 200 Hz region, each frequency being related to one or more of the room's dimensions or a divisor thereof. These resonances affect the low-frequency low-mid-frequency response of a sound system in the room and are one of the biggest obstacles to accurate sound reproduction.

  5. Orders of magnitude (frequency) - Wikipedia

    en.wikipedia.org/.../Orders_of_magnitude_(frequency)

    100 Hz 100 Hz: Cyclic rate of a typical automobile engine at redline (equivalent to 6000 rpm) 261.626 Hz: Acoustic – the musical note middle C (C 4) 440 Hz: Acoustic – concert pitch (A above middle C; A 4), used for tuning musical instruments 716 Hz: Rotational period of one of the fastest known millisecond pulsars, PSR J1748−2446ad [4] 10 3

  6. National Sleep Foundation - Wikipedia

    en.wikipedia.org/wiki/National_Sleep_Foundation

    As part of addressing one of NSF's goals – that sleep science is rapidly incorporated into products and services – NSF launched the SleepTech program to advance innovations in sleep technology. [22] Each year the National Sleep Foundation recognizes innovative sleep products by giving out the SleepTech Awards, the world's first innovation ...

  7. Mel scale - Wikipedia

    en.wikipedia.org/wiki/Mel_scale

    Some non-mel auditory-frequency-scale formulas use the same form but with much lower break frequency, not necessarily mapping to 1000 at 1000 Hz; for example the ERB-rate scale of Glasberg and Moore (1990) uses a break point of 228.8 Hz, [15] and the cochlear frequency–place map of Greenwood (1990) uses 165.3 Hz.

  8. Sleep efficiency - Wikipedia

    en.wikipedia.org/wiki/Sleep_efficiency

    Sleep efficiency (SE) is the ratio between the time a person spends asleep, and the total time dedicated to sleep (i.e. both sleeping and attempting to fall asleep or fall back asleep). It is given as a percentage. [1] SE of 80% or more is considered normal/healthy with most young healthy adults displaying SE above 90%.

  9. Music and sleep - Wikipedia

    en.wikipedia.org/wiki/Music_and_sleep

    An artwork featuring a mother putting her baby to sleep with her music. Sleep problems are found to be correlated with poor well-being and low quality of life. [1] Persistent sleeping disturbances can lead to fatigue, irritability, and various health issues. Numerous studies have examined the positive impact of music on sleep quality.