IngOehman skrev:Någon verifierad fakta som stöder motsatsen lär du inte hitta.
Påståendet att transienter är extra farliga har säkerligen bara med humanistisk förvirring (läs; ovetenskaplighet) att göra. De glömmer bort att relatera olika ljud till något konkret, de blir representanter för sin rubrik bara. Och då blir lätt resultatet ett missförstånd. Om faktiska hörselskador ofta är orsakade av transienter (på grund av en kombination av extremt höga ljudtryck och ofta även en smalbandig svans, som ju gör ljuden mindre transienta) så tror de som inte förstår de fysikaliska skeendena att det är den transienta naturen som är det farliga, och inte ljudtrycket och den smala bandbredden.
Vh, iö
Jag vet inte hur du tänker o förstår inte vilka studier du bygger dina påståenden på.
En transient ljudimpuls i den medicinska världen är en ljudimpuls kortare än 1 sekund. En kraftig transient ljudimpuls ger typiskt permaneta hårcellsskador kring 4000 Hz. Se ref.
Här kommer ett urplock vetenskapliga studier som visar att kraftfulla transienter är mycket skadliga.
Impulse noise causes evidently more severe hearing loss than steady state noise.
http://www.noiseandhealth.org/article.a ... ast=StarckHöga ljudimpulser typ från pistolskott över 130-140 dB (beroende på vägning) ger snabbt permanent hörselskada kring 4000 hz.
Mer "långvarig" exponering för höga ljud påverkar ffa de högre frekvenserna. (case 2)
En kraftig transient ljudimpuls kan ruptupera trumhinnan, bryta hörselbenen och/eller permanent döda hårceller.
Case 1
A teenaged girl was seen for a school physical examination. Screening audiometry
performed in the office revealed a 30-dB (mild) elevation of hearing thresholds at 4.000 Hz. A
confirmatory audiogram taken by an audiologist showed a sensorineural loss in a "notch" pattern
at 4.000 Hz. In response to questioning, the girl reported spending several hours a day listening
to music through headphones. The previous night, she had spent several hours at a rock concert
without wearing hearing protection. Afterward, she noticed her ears were ringing and "felt like
there was cotton in them". Several days later, her hearing had returned to normal.
This patient is an example of a person who has experienced a "temporary threshold shift".
Temporary threshold shifts are common in persons exposed to excessive noise, and they represent
transient hair cell dysfunction. Although complete recovery from a given episode can occur,
repeated episodes of such shift occurring after noise exposures give way to permanent threshold
shifts because hair cells in the cochlea are progressively lost.
Case 2
A 55-year-old factory worker consulted his family physician because of ringing in his ears
and depression that began soon after the onset of the tinnitus. He had seldom worn hearing
protection at work, where he had to shout to communicate with co-workers. Away from work,
he had difficulty understanding conversations in crowded rooms, and he said he often argued with
his wife about the volume of the television set. His physical findings were normal. An office
audiogram showed a high-frequency hearing loss. The ptient was referred to an audiologist, who
confirmed a sensorineural hearing loss that was probably caused by excessive noise exposure,
with superimposed age-related changes. A hearing aid was prescribed.
http://hannaziegler.tripod.com/ent/varia/rabinowi.pdfSometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16 to 48 hours later. Recent research suggests, however, that although the loss of hearing seems to disappear, there may be residual long-term damage to your hearing.
Most NIHL is caused by the damage and eventual death of these hair cells. Unlike bird and amphibian hair cells, human hair cells don’t grow back. They are gone for good
http://www.nidcd.nih.gov/health/hearing ... noise.aspx
http://hearing.harvard.edu/info/common- ... ngloss.pdf
Noise can cause sudden or gradual sensorineural hearing loss. In acoustic trauma, hearing loss results from exposure to a single, extreme noise (eg, a nearby gunshot or explosion); some patients have tinnitus as well. The loss is usually temporary (unless there is also blast damage, which may destroy the TM, ossicles, or both). In noise-induced hearing loss, the loss develops over time because of chronic exposure to noise > 85 decibels (dB—see Sidebar 1: Sound LevelsSidebars). Although people vary somewhat in susceptibility to noise-induced hearing loss, nearly everyone loses some hearing if they are exposed to sufficiently intense noise for an adequate time. Repeated exposure to loud noise ultimately results in loss of hair cells in the organ of Corti. Hearing loss typically occurs first at 4 kHz and gradually spreads to the lower and higher frequencies as exposure continues. In contrast to most other causes of sensorineural hearing losses, noise-induced hearing loss may be less severe at 8 kHz than at 4 kHz.
http://www.merckmanuals.com/professiona ... _loss.html
Recent animal experiments suggest that free oxygen radicals may mediate noise damage
to hair cells.
Således är kraftiga ljudimpulser inte ofarliga som du antyder.
JM
Annihilerar antimateria. Beauty is in the Brain of the Listener. We are standing on the shoulders of giants.
"Kill your Darlings" => Scientific Progress.
. Dessutom är en kraftig explosion nog inte att betrakta som en transient, I alla fall inte i den bemärkelsen som man använder begreppet i ljudåtergivningssammanhang.
