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  2. Closed-eye hallucination - Wikipedia

    en.wikipedia.org/wiki/Closed-eye_hallucination

    Additionally, retinal noise can be produced by touching near the rear of the eyeball producing pressure phosphenes (for example, if one closes one's eyes, looks all the way left, and lightly touches the rightmost part of the eye socket, this produces visual noise in the shape of a circle that appears at the left side of the visual field – a ...

  3. Auditory hallucination - Wikipedia

    en.wikipedia.org/wiki/Auditory_hallucination

    An auditory hallucination, or paracusia, [ 1] is a form of hallucination that involves perceiving sounds without auditory stimulus. While experiencing an auditory hallucination, the affected person hears a sound or sounds that did not come from the natural environment. A common form of auditory hallucination involves hearing one or more voices ...

  4. Visual snow syndrome - Wikipedia

    en.wikipedia.org/wiki/Visual_snow_syndrome

    Uncommon (understudied) Visual snow syndrome ( VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or colored dots across the whole visual field. [ 7][ 4] Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and ...

  5. Cosmic ray visual phenomena - Wikipedia

    en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena

    Cosmic ray visual phenomena, or light flashes ( LF ), also known as Astronaut's Eye, are spontaneous flashes of light visually perceived by some astronauts outside the magnetosphere of the Earth, such as during the Apollo program. While LF may be the result of actual photons of visible light being sensed by the retina, [1] the LF discussed here ...

  6. Sonic boom - Wikipedia

    en.wikipedia.org/wiki/Sonic_boom

    Observers hear nothing until the shock wave, on the edges of the cone, crosses their location. Mach cone angle NASA data showing N-wave signature. [1] Conical shockwave with its hyperbola-shaped ground contact zone in yellow. A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed ...

  7. Health effects from noise - Wikipedia

    en.wikipedia.org/wiki/Health_effects_from_noise

    Elevated workplace or environmental noise can cause hearing impairment, tinnitus, hypertension, ischemic heart disease, annoyance, and sleep disturbance. [ 3][ 4] Changes in the immune system and birth defects have been also attributed to noise exposure. [ 5] Although age-related health effects ( presbycusis) occur naturally with age, [ 6] in ...

  8. Noise barrier - Wikipedia

    en.wikipedia.org/wiki/Noise_barrier

    A noise barrier (also called a soundwall, noise wall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect inhabitants of sensitive land use areas from noise pollution. Noise barriers are the most effective method of mitigating roadway, railway, and industrial noise sources – other than cessation of ...

  9. Acoustic shadow - Wikipedia

    en.wikipedia.org/wiki/Acoustic_shadow

    A short-distance acoustic shadow occurs behind a building or a sound barrier. The sound from a source is shielded by the obstruction. Due to diffraction around the object, it will not be completely silent in the sound shadow. The amplitude of the sound can be reduced considerably, however, depending on the additional distance the sound has to ...