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==Overview==
==Overview==
Sound waves vary in [[amplitude]] and [[frequency]]. Amplitude is that the sound wave's peak pressure variation. [[Frequency]] is that the number of cycles per second of a sinusoidal component of a wave. Loss of the power to detect some frequencies, or to detect low-amplitude sounds, that an organism naturally detects, may be termed as a [[Hearing impairment|hearing disorder]]. Hearing sensitivity is indicated by the quietest sound that a person can detect, termed the hearing [[Threshold potential|threshold]]. The normal hearing threshold is not the same for all [[frequencies]] of sounds. Long-term exposure to environmental noise, [[Genetics]], [[Disease|Disease or illness]], [[Medications]]<ref name="pmid28002638" />, and [[Physical trauma]] are different biological mechanisms for [[hearing loss]].
==Pathophysiology==
==Pathophysiology==
[[Sound wave]]s vary in amplitude and in frequency. Amplitude is the sound wave's peak [[pressure]] variation. [[Frequency]] is the number of cycles per second of a [[sinusoidal]] component of a sound wave.  Loss of the ability to detect some frequencies, or to detect low-amplitude sounds, that an organism naturally detects, is a hearing impairment.


===Loudness, frequency, and discrimination deficiencies===
*Sound waves vary in [[amplitude]] and [[frequency]]. Amplitude is that the sound wave's peak pressure variation. Frequency is that the number of cycles per second of a sinusoidal component of a wave. Loss of the power to detect some frequencies, or to detect low-amplitude sounds, that an organism naturally detects, may be termed as a [[Hearing impairment|hearing disorder]].<ref name="pmid33253610">{{cite journal| author=Nieman CL, Oh ES| title=Hearing Loss. | journal=Ann Intern Med | year= 2020 | volume= 173 | issue= 11 | pages= ITC81-ITC96 | pmid=33253610 | doi=10.7326/AITC202012010 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=33253610  }}</ref>
 
===Loudness, frequency, and discrimination deficiencies<ref name="pmid31846598">{{cite journal| author=Beechey T, Buchholz JM, Keidser G| title=Hearing Impairment Increases Communication Effort During Conversations in Noise. | journal=J Speech Lang Hear Res | year= 2020 | volume= 63 | issue= 1 | pages= 305-320 | pmid=31846598 | doi=10.1044/2019_JSLHR-19-00201 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=31846598  }}</ref>===
 
*Hearing sensitivity is indicated by the quietest sound that a person can detect, termed the hearing [[Threshold potential|threshold]]. This threshold is often accurately measured by a behavioral [[audiogram]], in humans and a few animals. A record is formed of the quietest sound that consistently prompts a response from the listener. The test is administered for sounds of various frequencies. There also are some [[electrophysiological tests]] that will be performed without requiring a behavioral response of the individual.
 
*The normal hearing threshold is not the same for all [[frequencies]] of sounds. If different frequencies of sound are played at an equivalent amplitude, some are going to be loud, quiet, or completely inaudible. Generally, if the amplitude is increased, a sound is more likely to be heard. Ordinarily, when animals use sound to speak, hearing therein sort of animal is most sensitive for the frequencies produced by calls, or, within the case of humans, speech. This tuning of hearing exists at many levels of the [[sensory system]], all the way from the physical characteristics of the ear, to the nerves, and tracts that convey the [[auditory impulses]] to the portion of the brain that is sensitive to hearing sounds.<ref name="pmid26891769">{{cite journal| author=Moser T, Starr A| title=Auditory neuropathy--neural and synaptic mechanisms. | journal=Nat Rev Neurol | year= 2016 | volume= 12 | issue= 3 | pages= 135-49 | pmid=26891769 | doi=10.1038/nrneurol.2016.10 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26891769  }}</ref>
 
*A [[hearing disorder]] exists when a person isn't sensitive to the sounds normally heard by its kind. The term hearing impairment is usually reserved for folks that have relative insensitivity to sound within the speech frequencies. The severity of hearing impairment is defined as; how much louder a sound must be made over the usual levels before the listener can perceive it. In profound [[deafness]], even the loudest sounds which will be produced by the instrument wont to measure hearing like an [[audiometer]], might not be detected.
 
*There is a rare sort of hearing impairment that affects [[speech discrimination]] alone. There is another aspect to hearing that involves the quality of a sound instead of amplitude and frequency. This quality of sound is typically measured by tests of speech discrimination. These tests require that the sound isn't only detected but understood.


Hearing sensitivity is indicated by the quietest sound that an individual can detect, called the [[hearing threshold]]. In the case of people and some animals, this threshold can be accurately measured by a [[audiogram|behavioral audiogram]]. A record is made of the quietest sound that consistently prompts a response from the listener. The test is carried out for sounds of different frequencies. There are also electro-physiological tests that can be performed without requiring a behavioral response.
===Different biological mechanisms===


Normal hearing thresholds are not the same for all frequencies in any species of animal. If different frequencies of sound are played at the same amplitude, some will be loud, and others quiet or even completely inaudible. Generally, if the gain or amplitude is increased, a sound is more likely to be perceived. Ordinarily, when animals use sound to communicate, hearing in that type of animal is most sensitive for the frequencies produced by calls, or, in the case of humans, speechThis tuning of hearing exists at many levels of the auditory system, all the way from the physical characteristics of the ear to the nerves and tracts that convey the nerve impulses of the auditory portion of the brain.
====Long term exposure to environmental noise<ref name="pmid24311120">{{cite journal| author=Hammer MS, Swinburn TK, Neitzel RL| title=Environmental noise pollution in the United States: developing an effective public health response. | journal=Environ Health Perspect | year= 2014 | volume= 122 | issue= 2 | pages= 115-9 | pmid=24311120 | doi=10.1289/ehp.1307272 | pmc=3915267 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24311120  }}</ref><ref name="pmid28182600">{{cite journal| author=Carroll YI, Eichwald J, Scinicariello F, Hoffman HJ, Deitchman S, Radke MS | display-authors=etal| title=Vital Signs: Noise-Induced Hearing Loss Among Adults - United States 2011-2012. | journal=MMWR Morb Mortal Wkly Rep | year= 2017 | volume= 66 | issue= 5 | pages= 139-144 | pmid=28182600 | doi=10.15585/mmwr.mm6605e3 | pmc=5657963 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28182600 }}</ref>====


A hearing impairment exists when an individual is not sensitive to the sounds normally heard by its kind. In human beings, the term hearing impairment is usually reserved for people who have relative insensitivity to sound in the speech frequencies.  The severity of a hearing impairment is categorized according to ''how much'' louder a sound must be made over the usual levels before the listener can detect it. In profound deafness, even the loudest sounds that can be produced by the instrument used to measure hearing (audiometer) may not be detected.
*Populations of individuals living near airports or freeways are exposed to levels of [[noise]] typically > 65 dB. If the lifestyle of a person includes significant outdoor activities, these exposures over time can degrade hearing. Various states have set noise standards to guard people against these adverse sound risks.


There is another aspect to hearing that involves the quality of a sound rather than amplitude. In people, that aspect is usually measured by tests of speech discrimination. Basically, these tests require that the sound is not only detected but understood. There are very rare types of hearing impairments which affect discrimination alone.<ref name="eBook1">eBook: ''Current Diagnosis & Treatment in Otolaryngology: Head & Neck Surgery'', Lalwani, Anil K. (Ed.) Chapter 44: Audiologic Testing by Robert W. Sweetow, PhD, Jennifer McKee Bold, AuD, Access Medicine''</ref>
*The EPA has identified the extent of 70 DB for twenty-four-hour exposure because of the level necessary to guard the general public against deafness (EPA, 1974).


===Hearing impairment comes from different biological mechanisms.===
*Noise-Induced deafness ([[Noise-induced hearing loss|NIHL]]) typically is centered at 4000 Hz.
====Long term exposure to environmental noise====


Populations of people living near airports or freeways are exposed to levels of noise typically in the 65 to 75 dbA range. If lifestyles include significant outdoor or open window conditions, these exposures over time can degrade hearing. The [[United States Environmental Protection Agency|U.S. EPA]] and various states have set noise standards to protect people from these adverse health risks.  The EPA has identified the level of 70 db(A) for 24 hour exposure as the level necessary to protect the public from hearing loss (EPA, 1974).
*The louder the noise is, the shorter is the safe amount of exposure. Normally, the safe amount of exposure is reduced by an element 2 for each additional 3 dB. for instance, the safe daily exposure amount at 85 dB is 8 hours, while the safe exposure at 91 dB is merely 2 hours. Sometimes, an element 2 per 5 dB is employed.


* Noise-Induced Hearing Loss (NIHL) typically is centered at 4000 Hz.
*Personal electronic audio devices, like iPods, can produce powerful enough sound to cause significant [[Noise-induced hearing loss|Noise-Induced deafness]], iPods often reaching 115 decibels or higher, as long as lesser intensities of even 70 dB also can cause deafness.
* The louder the noise is, the shorter the safe amount of exposure is. Normally, the safe amount of exposure is reduced by a factor 2 for every additional 3 dB. For example, the safe daily exposure amount at 85 dB is 8 hours, while the safe exposure at 91 dB(A) is only 2 hours (National Institute for Occupational Safety and Health, 1998). Sometimes, a factor 2 per 5 dB is used.
* Personal electronic audio devices, such as iPods (iPods often reaching 115 decibels or higher), can produce powerful enough sound to cause significant Noise-Induced Hearing Loss, given that lesser intensities of even 70 dB can also cause hearing loss.


====Genetic====
====Genetic<ref name="pmid29331002">{{cite journal| author=Meena R, Ayub M| title=Genetics Of Human Hereditary Hearing Impairment. | journal=J Ayub Med Coll Abbottabad | year= 2017 | volume= 29 | issue= 4 | pages= 671-676 | pmid=29331002 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29331002  }}</ref><ref name="pmid29938425">{{cite journal| author=Ahmed S, Sheraz S, Malik SA, Ahmed NR, Malik SA, Farooq S | display-authors=etal| title=Frequency Of Congenital Hearing Loss In Neonates. | journal=J Ayub Med Coll Abbottabad | year= 2018 | volume= 30 | issue= 2 | pages= 234-236 | pmid=29938425 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29938425  }}</ref>====
Hearing loss can be inherited. Both [[dominant gene|dominant]] and [[recessive gene]]s exist which can cause mild to profound impairment. If a family has a dominant gene for deafness it will persist across generations because it will manifest itself in the offspring even if it is inherited from only one parent. If a family had genetic hearing impairment caused by a recessive gene it will not always be apparent as it will have to be passed onto offspring from both parents
Dominant and recessive hearing impairment can be syndromic or nonsyndromic. Recent gene mapping has identified dozens of nonsyndromic dominant (DFNA#) and recessive (DFNB#) forms of deafness.
*The most common type of congenital hearing impairment in developed countries is DFNB1, also known as Connexin 26 deafness or GJB2-related deafness.
*The most common dominant syndromic forms of hearing impairment include [[Stickler syndrome]] and [[Waardenburg syndrome]].
*The most common recessive syndromic forms of hearing impairment are [[Pendred syndrome]], Large vestibular aqueduct syndrome and [[Usher syndrome]].


====Disease or illness====
*Hearing loss is often [[inherited]]. Both [[Dominant gene|dominant]] and [[recessive]] genes exist which may cause mild to profound impairment. If a family features a gene for deafness it'll persist across generations because it'll happen within the offspring albeit it's inherited from just one parent. If a family had a genetic hearing disorder caused by a gene it'll not always be apparent because it will need to be passed onto offspring from both parents Dominant and recessive hearing disorders are often [[Syndromic HH|syndromic]] or non-syndromic. Recent gene mapping has identified dozens of non-syndromic dominant and recessive sorts of deafness.
*[[Measles]] may result in [[Vestibulocochlear nerve|auditory nerve]] damage
 
*[[Meningitis]] may damage the auditory nerve or the [[cochlea]]
*The most common sort of [[Congenital hearing loss|congenital hearing disorde]]<nowiki/>r in developed countries is non-syndromic recessive, also referred to as Connexin 26 deafness.
*[[Autoimmune disease]] has only recently been recognized as a potential cause for [[cochlea]]r damage. Although probably rare, it is possible for autoimmune processes to target the cochlea specifically, without symptoms affecting other organs. [[Wegener's granulomatosis]] is one of the autoimmune conditions that may precipitate hearing loss.
 
*[[Mumps]] (Epidemic parotitis) may result in profound [[sensorineural hearing loss]] (90 [[Decibel|dB]] or more), unilateral (one ear) or bilateral (both ears).
*The most common dominant syndromic sorts of hearing disorder include [[Stickler syndrome]] and [[Waardenburg syndrome|Waardenburg syndrom]]<nowiki/>[[Waardenburg syndrome|e]].
*[[Presbycusis]] is deafness due to loss of perception to high tones, mainly in the [[elderly]]. It is considered by some to be a degenerative process, although there has never been a proven link to aging.  (See impact of environmental noise exposure above.)
 
*[[Adenoids]] that do not disappear by [[adolescence]] may continue to grow and may obstruct the [[Eustachian tube]], causing conductive hearing impairment and nasal infections that can spread to the [[middle ear]].
*The most common recessive syndromic sorts of the hearing disorder are [[Pendred syndrome]], [[Vestibular aqueduct syndrome|Large vestibular aqueduct syndrome]], and [[Usher syndrome]]
*[[AIDS]] and [[AIDS-related complex|ARC]] patients frequently experience auditory system anomalies.<ref name="faqGal">{{cite web|url=http://library.gallaudet.edu/dr/faq-etiol.html|title=Frequently Asked Questions: Etiologies and Causes of Deafness|accessdate=2006-12-02}}</ref>
 
*[[HIV]] (and subsequent opportunistic infections) may directly affect the cochlea and central auditory system.<ref name="faqGal"/>
====Disease or illness<ref name="pmid28738350">{{cite journal| author=Paul A, Marlin S, Parodi M, Rouillon I, Guerlain J, Pingault V | display-authors=etal| title=Unilateral Sensorineural Hearing Loss: Medical Context and Etiology. | journal=Audiol Neurootol | year= 2017 | volume= 22 | issue= 2 | pages= 83-88 | pmid=28738350 | doi=10.1159/000474928 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28738350  }}</ref>====
*[[Chlamydia]] may cause hearing loss in newborns to whom the disease has been passed at birth.<ref name="faqGal"/>
 
*[[Fetal alcohol syndrome]] is reported to cause hearing loss in up to 64% of infants born to [[alcoholism|alcoholic]] mothers, from the ototoxic effect on the developing fetus plus malnutrition during pregnancy from the excess [[ethanol|alcohol]] intake.<ref name="faqGal"/>
*[[Measles]] can result in [[Auditory|auditory nerve damage.]]
*[[Premature birth]] results in [[sensorineural hearing loss]] approximately 5% of the time.<ref name="faqGal"/>
 
*[[Syphilis]] is commonly transmitted from pregnant women to their fetuses, and about a third of the infected children will eventually become deaf.<ref name="faqGal"/>
*[[Meningitis]] can damage the [[Vestibulocochlear nerve|acoustic nerve]] or the [[cochlea]] of the [[inner ear]].
* [[Otosclerosis]] is a hardening of the stapes (or stirrup) in the middle ear and causes conductive hearing loss.
 
*[[Autoimmune disease]] has only recently been recognized as a possible cause of [[Cochlear nerve|cochlear]] damage. Although probably rare, autoimmune processes can focus on the cochlea specifically, without symptoms affecting other organs. [[Wegener's granulomatosis]] is one of the autoimmune conditions which will precipitate deafness.
 
*[[Mumps]] ([[Epidemic parotitis|Epidemic parotitis)]] may end in profound [[Sensorineural hearing loss|sensorineural deafness]] (90 dB or more), unilateral or bilateral.
 
*[[Presbycusis]] is deaf thanks to the loss of perception to high tones, mainly within the elderly people. It is caused by some to be a [[Degenerative disease|degenerative]] processes within the [[inner ear]], although there is no proven link to aging.<ref name="pmid27392191">{{cite journal| author=Fischer N, Weber B, Riechelmann H| title=[Presbycusis - Age Related Hearing Loss]. | journal=Laryngorhinootologie | year= 2016 | volume= 95 | issue= 7 | pages= 497-510 | pmid=27392191 | doi=10.1055/s-0042-106918 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27392191 }}</ref>
 
*[[Adenoids]] that do not disappear by [[adolescence]] may still grow and should obstruct the [[Eustachian tube]], causing [[Conductive hearing loss|conductive hearing disorder]] and nasal infections which will spread to the center ear.
 
*[[HIV AIDS|AIDS]] patients frequently experience sensory system anomalies.
 
*[[HIV]] and subsequent [[opportunistic infections]] can directly affect the [[cochlea]] and central sensory system.
 
*[[Chlamydia infection|Chlamydia]] may cause [[deafness]] in newborns to whom the disease has been passed at birth through the birth canal during normal vaginal delivery.
 
*[[Fetal alcohol syndrome]] is reported to cause hearing loss in up to 64% of infants born to [[Alcoholic beverages|alcoholic]] mothers, from the [[Ototoxicity|ototoxic]] effect on the developing fetus plus [[malnutrition]] during [[pregnancy]] from the excess alcohol intake.
 
*[[Premature birth]] results in [[sensorineural hearing loss]] approximately 5% of the time.
 
*[[Syphilis]] is usually transmitted from [[Pregnancy|pregnant women]] to their fetuses, and a few thirds of the infected children will eventually become deaf.
 
*[[Otosclerosis]] may be a hardening of the [[stapes]] within the [[tympanic cavity]] in the middle ear and it causes [[Conductive hearing loss|conductive deafness.]]
 
====Medications<ref name="pmid28002638">{{cite journal| author=Lanvers-Kaminsky C, Zehnhoff-Dinnesen AA, Parfitt R, Ciarimboli G| title=Drug-induced ototoxicity: Mechanisms, Pharmacogenetics, and protective strategies. | journal=Clin Pharmacol Ther | year= 2017 | volume= 101 | issue= 4 | pages= 491-500 | pmid=28002638 | doi=10.1002/cpt.603 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28002638  }}</ref>====


====Medications====
:''See also [[Ototoxicity]]''
:''See also [[Ototoxicity]]''
Some medications cause irreversible damage to the ear, and are limited in their use for this reason. The most important group is the [[aminoglycoside]]s (main member [[gentamicin]]).


Various other medications may reversibly affect hearing. This includes some [[diuretic]]s, [[aspirin]] and [[NSAID]]s, and [[macrolide]] antibiotics.
*Some medications cause [[Irreversibility|irreversible]] damage to the ear and are limited in their use for this serious side effect. The foremost important group is that [[aminoglycosides]] ([[gentamicin]]).


Extremely heavy [[hydrocodone|Vicodin]] abuse is known to cause hearing impairment. There has been speculation that radio talk show host [[Rush Limbaugh]]'s hearing loss was at least in part caused by his admitted addiction to narcotic pain killers, in particular Vicodin and [[Oxycodone|OxyContin]].
*Various other medications may cause reversible hearing loss. This includes some [[diuretics]], [[NSAIDs]], [[aspirin]], and [[Macrolide antibiotics|macrolide antibiotics.]]
 
*Extremely heavy [[Vicodin]] and [[Oxycodone|OxyContin]] abuse are understood to cause hearing disorders.


====Physical trauma====
====Physical trauma====
* There can be damage either to the ear itself or to the brain centers that process the aural information conveyed by the ears.
 
* People who sustain head injury are especially vulnerable to hearing loss or [[tinnitus]], either temporary or permanent.
*There is often external damage either to the ear itself or to the [[brain]] centers that process the aural information conveyed by the ears.
* Exposure to very loud [[noise]] (90 [[Decibel|dB]] or more, such as jet engines at close range) can cause progressive hearing loss. Exposure to a single event of extremely loud noise (such as explosions) can also cause temporary or permanent hearing loss. A typical source of acoustic trauma is a too-loud music concert.<ref>http://www.4hearingloss.com/archives/2005/05/sonic_tonic.html</ref>
 
*People who sustain head injury are especially susceptible to [[deafness]] or [[tinnitus]], either temporary or permanent.
 
*Exposure to very bang (90 dB or more, like jet engines at close range) can cause progressive deafness. Exposure to one event of extreme bang (such as explosions) also can cause deafness. A typical source of acoustic trauma may be a too-loud music concert.


==References==
==References==
{{reflist|2}}
{{Reflist|2}}
{{WH}}
[[Category:Geriatrics]]
{{WS}}
[[Category:Communication disorders]]
[[Category:Audiology]]
[[Category:Otolaryngology]]
[[Category:Noise pollution]]

Latest revision as of 18:03, 8 May 2021

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:

Overview

Sound waves vary in amplitude and frequency. Amplitude is that the sound wave's peak pressure variation. Frequency is that the number of cycles per second of a sinusoidal component of a wave. Loss of the power to detect some frequencies, or to detect low-amplitude sounds, that an organism naturally detects, may be termed as a hearing disorder. Hearing sensitivity is indicated by the quietest sound that a person can detect, termed the hearing threshold. The normal hearing threshold is not the same for all frequencies of sounds. Long-term exposure to environmental noise, Genetics, Disease or illness, Medications[1], and Physical trauma are different biological mechanisms for hearing loss.

Pathophysiology

  • Sound waves vary in amplitude and frequency. Amplitude is that the sound wave's peak pressure variation. Frequency is that the number of cycles per second of a sinusoidal component of a wave. Loss of the power to detect some frequencies, or to detect low-amplitude sounds, that an organism naturally detects, may be termed as a hearing disorder.[2]

Loudness, frequency, and discrimination deficiencies[3]

  • Hearing sensitivity is indicated by the quietest sound that a person can detect, termed the hearing threshold. This threshold is often accurately measured by a behavioral audiogram, in humans and a few animals. A record is formed of the quietest sound that consistently prompts a response from the listener. The test is administered for sounds of various frequencies. There also are some electrophysiological tests that will be performed without requiring a behavioral response of the individual.
  • The normal hearing threshold is not the same for all frequencies of sounds. If different frequencies of sound are played at an equivalent amplitude, some are going to be loud, quiet, or completely inaudible. Generally, if the amplitude is increased, a sound is more likely to be heard. Ordinarily, when animals use sound to speak, hearing therein sort of animal is most sensitive for the frequencies produced by calls, or, within the case of humans, speech. This tuning of hearing exists at many levels of the sensory system, all the way from the physical characteristics of the ear, to the nerves, and tracts that convey the auditory impulses to the portion of the brain that is sensitive to hearing sounds.[4]
  • A hearing disorder exists when a person isn't sensitive to the sounds normally heard by its kind. The term hearing impairment is usually reserved for folks that have relative insensitivity to sound within the speech frequencies. The severity of hearing impairment is defined as; how much louder a sound must be made over the usual levels before the listener can perceive it. In profound deafness, even the loudest sounds which will be produced by the instrument wont to measure hearing like an audiometer, might not be detected.
  • There is a rare sort of hearing impairment that affects speech discrimination alone. There is another aspect to hearing that involves the quality of a sound instead of amplitude and frequency. This quality of sound is typically measured by tests of speech discrimination. These tests require that the sound isn't only detected but understood.

Different biological mechanisms

Long term exposure to environmental noise[5][6]

  • Populations of individuals living near airports or freeways are exposed to levels of noise typically > 65 dB. If the lifestyle of a person includes significant outdoor activities, these exposures over time can degrade hearing. Various states have set noise standards to guard people against these adverse sound risks.
  • The EPA has identified the extent of 70 DB for twenty-four-hour exposure because of the level necessary to guard the general public against deafness (EPA, 1974).
  • Noise-Induced deafness (NIHL) typically is centered at 4000 Hz.
  • The louder the noise is, the shorter is the safe amount of exposure. Normally, the safe amount of exposure is reduced by an element 2 for each additional 3 dB. for instance, the safe daily exposure amount at 85 dB is 8 hours, while the safe exposure at 91 dB is merely 2 hours. Sometimes, an element 2 per 5 dB is employed.
  • Personal electronic audio devices, like iPods, can produce powerful enough sound to cause significant Noise-Induced deafness, iPods often reaching 115 decibels or higher, as long as lesser intensities of even 70 dB also can cause deafness.

Genetic[7][8]

  • Hearing loss is often inherited. Both dominant and recessive genes exist which may cause mild to profound impairment. If a family features a gene for deafness it'll persist across generations because it'll happen within the offspring albeit it's inherited from just one parent. If a family had a genetic hearing disorder caused by a gene it'll not always be apparent because it will need to be passed onto offspring from both parents Dominant and recessive hearing disorders are often syndromic or non-syndromic. Recent gene mapping has identified dozens of non-syndromic dominant and recessive sorts of deafness.
  • The most common sort of congenital hearing disorder in developed countries is non-syndromic recessive, also referred to as Connexin 26 deafness.

Disease or illness[9]

  • Autoimmune disease has only recently been recognized as a possible cause of cochlear damage. Although probably rare, autoimmune processes can focus on the cochlea specifically, without symptoms affecting other organs. Wegener's granulomatosis is one of the autoimmune conditions which will precipitate deafness.
  • Presbycusis is deaf thanks to the loss of perception to high tones, mainly within the elderly people. It is caused by some to be a degenerative processes within the inner ear, although there is no proven link to aging.[10]
  • AIDS patients frequently experience sensory system anomalies.
  • Chlamydia may cause deafness in newborns to whom the disease has been passed at birth through the birth canal during normal vaginal delivery.
  • Syphilis is usually transmitted from pregnant women to their fetuses, and a few thirds of the infected children will eventually become deaf.

Medications[1]

See also Ototoxicity
  • Extremely heavy Vicodin and OxyContin abuse are understood to cause hearing disorders.

Physical trauma

  • There is often external damage either to the ear itself or to the brain centers that process the aural information conveyed by the ears.
  • People who sustain head injury are especially susceptible to deafness or tinnitus, either temporary or permanent.
  • Exposure to very bang (90 dB or more, like jet engines at close range) can cause progressive deafness. Exposure to one event of extreme bang (such as explosions) also can cause deafness. A typical source of acoustic trauma may be a too-loud music concert.

References

  1. 1.0 1.1 Lanvers-Kaminsky C, Zehnhoff-Dinnesen AA, Parfitt R, Ciarimboli G (2017). "Drug-induced ototoxicity: Mechanisms, Pharmacogenetics, and protective strategies". Clin Pharmacol Ther. 101 (4): 491–500. doi:10.1002/cpt.603. PMID 28002638.
  2. Nieman CL, Oh ES (2020). "Hearing Loss". Ann Intern Med. 173 (11): ITC81–ITC96. doi:10.7326/AITC202012010. PMID 33253610 Check |pmid= value (help).
  3. Beechey T, Buchholz JM, Keidser G (2020). "Hearing Impairment Increases Communication Effort During Conversations in Noise". J Speech Lang Hear Res. 63 (1): 305–320. doi:10.1044/2019_JSLHR-19-00201. PMID 31846598.
  4. Moser T, Starr A (2016). "Auditory neuropathy--neural and synaptic mechanisms". Nat Rev Neurol. 12 (3): 135–49. doi:10.1038/nrneurol.2016.10. PMID 26891769.
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