'Acoustic shock' is a term used in connection with incidents involving exposure to short duration, high frequency, high intensity sounds through a telephone headset. Some sources suggest that these incidents are associated with a range of physiological and psychological symptoms that have been reported amongst headset wearers. It has not been established whether the reported symptoms are caused directly by exposure to these unexpected sounds. There is no clear single cause of these incidents, but one cause may be interference on the telephone line. Although call handlers may be shocked or startled by the sounds, exposure to them should not cause hearing damage as assessed by conventional methods.
Tinnitus is commonly described as a ringing in the ears, but it also can sound like roaring, clicking, hissing, or buzzing. It may be soft or loud, high pitched or low pitched. You might hear it in either one or both ears. Roughly 10 percent of the adult population of the United States has experienced tinnitus lasting at least five minutes in the past year. This amounts to nearly 25 million Americans.
Tinnitus may be perceived in one or both ears. The noise can be described in many different ways but is reported as a noise inside a person's head in the absence of auditory stimulation. It often is described as a ringing noise, but in some people, it takes the form of a high-pitched whining, electric buzzing, hissing, humming, tinging, whistling, ticking, clicking, roaring, beeping, sizzling, a pure steady tone such as that heard during a hearing test, or sounds that slightly resemble human voices, tunes, songs, or animal sounds such as "crickets", "tree frogs", or "locusts (cicadas)".[4] Tinnitus may be intermittent or continuous: in the latter case, it may be the cause of great distress. In some individuals, the intensity may be changed by shoulder, head, tongue, jaw, or eye movements.[7]
If you think your child has tinnitus, see your child’s GP. They may refer your child to a paediatric ENT specialist for further tests. Therapy and support are available for your child if they are diagnosed with tinnitus and they are bothered or distressed by it. If your child is not bothered by their tinnitus, you may just need reassurance about their condition.
Hearing loss is defined as diminished acuity to sounds which would otherwise be heard normally.[15] The terms hearing impaired or hard of hearing are usually reserved for people who have relative inability to hear sound in the speech frequencies. The severity of hearing loss is categorized according to the increase in intensity of sound above the usual level required for the listener to detect it.
Conductive hearing loss occurs when sounds aren’t able to travel from the outer ear to the eardrum and the bones of the middle ear. When this type of hearing loss occurs, you may find it difficult to hear soft or muffled sounds. Conductive hearing loss isn’t always permanent. Medical interventions can treat it. Treatment may include antibiotics or surgical interventions, such as a cochlear implant. A cochlear implant is a small electrical machine placed under your skin behind the ear. It translates sound vibrations into electrical signals that your brain can then interpret as meaningful sound.
With the identification of ASD, output limiters in headset equipment have been developed to restrict maximum volume levels transmitted down a telephone line. However, ASD continues to occur despite their use. In my opinion, they are of benefit primarily to help reduce the probability of an initial acoustic incident exposure. The dominant factors of an acoustic incident leading to ASD appear related to the sudden onset, unexpectedness and impact quality of loudish sounds outside the person's control near to the ear(s), rather than to high volume levels alone. If TTTS develops, because of the vulnerability of further escalation to acoustic incidents at lower volume levels, it is impossible to give a 100% guarantee of protection.
Conductive hearing loss makes all sounds seem faint or muffled. The hearing loss is usually worse in lower frequencies. Congenital conductive hearing loss is identified through newborn hearing screening or may be identified because the baby has microtia or other facial abnormalities. Conductive hearing loss developing during childhood is usually due to otitis media with effusion and may present with speech and language delay or difficulty hearing. Later onset of conductive hearing loss may have an obvious cause such as an ear infection, trauma or upper respiratory tract infection or may have an insidious onset related to chronic middle ear disease, otosclerosis or a tumour of the naso-pharynx. Earwax is a very common cause of a conductive hearing loss which may present suddenly when the wax blocks sound from getting through the external ear canal to the middle and inner ear.
About half of hearing loss globally is preventable through public health measures.[2] Such practices include immunization, proper care around pregnancy, avoiding loud noise, and avoiding certain medications.[2] The World Health Organization recommends that young people limit exposure to loud sounds and the use of personal audio players to an hour a day in an effort to limit exposure to noise.[11] Early identification and support are particularly important in children.[2] For many, hearing aids, sign language, cochlear implants and subtitles are useful.[2] Lip reading is another useful skill some develop.[2] Access to hearing aids, however, is limited in many areas of the world.[2]
Hearing loss is an increasing concern especially in aging populations, the prevalence of hearing loss increase about two-fold for each decade increase in age after age 40.[29] While the secular trend might decrease individual level risk of developing hearing loss, the prevalence of hearing loss is expected to rise due to the aging population in the US. Another concern about aging process is cognitive decline, which may progress to mild cognitive impairment and eventually dementia.[30] The association between hearing loss and cognitive decline has been studied in various research settings. Despite the variability in study design and protocols, the majority of these studies have found consistent association between age-related hearing loss and cognitive decline, cognitive impairment, and dementia.[31] The association between age-related hearing loss and Alzheimer's disease was found to be nonsignificant, and this finding supports the hypothesis that hearing loss is associated with dementia independent of Alzheimer pathology.[31] There are several hypothesis about the underlying causal mechanism for age-related hearing loss and cognitive decline. One hypothesis is that this association can be explained by common etiology or shared neurobiological pathology with decline in other physiological system.[32] Another possible cognitive mechanism emphasize on individual's cognitive load. As people developing hearing loss in the process of aging, the cognitive load demanded by auditory perception increases, which may lead to change in brain structure and eventually to dementia.[33] One other hypothesis suggests that the association between hearing loss and cognitive decline is mediated through various psychosocial factors, such as decrease in social contact and increase in social isolation.[32] Findings on the association between hearing loss and dementia have significant public health implication, since about 9% of dementia cases can be attributed to hearing loss.[34]
Other potential sources of the sounds normally associated with tinnitus should be ruled out. For instance, two recognized sources of high-pitched sounds might be electromagnetic fields common in modern wiring and various sound signal transmissions. A common and often misdiagnosed condition that mimics tinnitus is radio frequency (RF) hearing, in which subjects have been tested and found to hear high-pitched transmission frequencies that sound similar to tinnitus.[72][73]
Other potential sources of the sounds normally associated with tinnitus should be ruled out. For instance, two recognized sources of high-pitched sounds might be electromagnetic fields common in modern wiring and various sound signal transmissions. A common and often misdiagnosed condition that mimics tinnitus is radio frequency (RF) hearing, in which subjects have been tested and found to hear high-pitched transmission frequencies that sound similar to tinnitus.[72][73]
Ramirez et al (14) aimed to explore the anatomical and physiological connections in TMD patients with secondary aural symptoms and the central and peripheral mechanisms involved. The authors carried out an extensive peer-reviewed literature search, using data from (12), 436 patients in 49 papers, to analyse aural symptoms (otalgia, tinnitus, vertigo, subjective hearing loss and aural fullness) exacerbated by dysfunctional mouth and jaw dynamics. They proposed a range of muscular, bone communication and neural scenarios to explain this relationship, placing emphasis on tensor tympani muscle involvement and trigeminal nerve dysfunction.
Tinnitus is commonly thought of as a symptom of adulthood, and is often overlooked in children. Children with hearing loss have a high incidence of tinnitus, even though they do not express the condition or its effect on their lives.[112][113] Children do not generally report tinnitus spontaneously and their complaints may not be taken seriously.[114] Among those children who do complain of tinnitus, there is an increased likelihood of associated otological or neurological pathology such as migraine, juvenile Meniere's disease or chronic suppurative otitis media.[115] Its reported prevalence varies from 12% to 36% in children with normal hearing thresholds and up to 66% in children with a hearing loss and approximately 3–10% of children have been reported to be troubled by tinnitus.[116]
If you develop hearing loss due to a buildup of wax in the ear canal, you can remove the wax at home. Over-the-counter solutions, including wax softeners, can remove wax from the ear. Syringes can also push warm water through the ear canal to remove the wax. Consult your doctor before attempting to remove any object stuck in your ear to avoid unintentionally damaging your ear.

Because call centres often record conversations between their operatives and customers it has been possible to analyse the sounds that give rise to acoustic shock. Sounds have included electrical interference, acoustic feedback, tones from fax machines and noises produced by disgruntled customers. Work in Denmark5 isolated sounds between 100 Hz and 3.8 kHz with intensities varying from 56 to 100 dB. A similar study in Australia1 showed a frequency range of 2.3 to 3.4 kHz with intensities from 82 to 120 dB. The duration of exposure is very difficult to assess because affected call centre operatives remove the handsets or headsets from their ears as quickly as possible after exposure. Certainly the exposure is unlikely to be more than a few seconds. One feature common to acoustic incident sound is that they have a short rise time varying between 0 and 20 ms, reflecting the sudden and unexpected nature of the sound.
With severe ASD, TTTS symptoms can be involuntarily aggravated by the mere placement of a headset over the ears in the workplace. I consider an ASD client should not return to headset or telephone duties on either ear until the symptoms have fully resolved. A graded return to work can then be carried out with handset use initially on the opposite ear.
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Most causes of conductive hearing loss can be identified by examination but if it is important to image the bones of the middle ear or inner ear then a CT scan is required. CT scan is useful in cases of congenital conductive hearing loss, chronic suppurative otitis media or cholesteatoma, ossicular damage or discontinuity, otosclerosis and third window dehiscence. Specific MRI scans can be used to identify cholesteatoma.
If there is no obvious cause of hearing loss, your doctor can refer you for a hearing assessment with an audiologist or an ear nose and throat (ENT) specialist. They will look into your ears and test your hearing to see how well you can detect different levels of sound. This assessment will help find the cause of your hearing loss and what treatments would work best.
If you have good hearing, your doctor may suggest a sound generator. These used to be called masking devices. There are two main types. One is a portable machine that produces calming sounds. The other fits to your ear like a hearing aid and produces a constant low-level noise or tone, sometimes called white noise, masking (covering up) the tinnitus. This may also help your brain get used to the tinnitus. Some people find that sound generators interfere with their hearing while they’re using them.
An assessment of hyperacusis, a frequent accompaniment of tinnitus,[57] may also be made.[58] The measured parameter is Loudness Discomfort Level (LDL) in dB, the subjective level of acute discomfort at specified frequencies over the frequency range of hearing. This defines a dynamic range between the hearing threshold at that frequency and the loudnes discomfort level. A compressed dynamic range over a particular frequency range is associated with subjectve hyperacusis. Normal hearing threshold is generally defined as 0–20 decibels (dB). Normal loudness discomfort levels are 85–90+ dB, with some authorities citing 100 dB. A dynamic range of 55 dB or less is indicative of hyperacusis.[59][60]
The accepted definition of chronic tinnitus, as compared to normal ear noise experience, is five minutes of ear noise occurring at least twice a week.[51] However, people with chronic tinnitus often experience the noise more frequently than this and can experience it continuously or regularly, such as during the night when there is less environmental noise to mask the sound.
Tinnitus can arise anywhere along the auditory pathway, from the outer ear through the middle and inner ear to the brain's auditory cortex, where it's thought to be encoded (in a sense, imprinted). One of the most common causes of tinnitus is damage to the hair cells in the cochlea (see "Auditory pathways and tinnitus"). These cells help transform sound waves into nerve signals. If the auditory pathways or circuits in the brain don't receive the signals they're expecting from the cochlea, the brain in effect "turns up the gain" on those pathways in an effort to detect the signal — in much the same way that you turn up the volume on a car radio when you're trying to find a station's signal. The resulting electrical noise takes the form of tinnitus — a sound that is high-pitched if hearing loss is in the high-frequency range and low-pitched if it's in the low-frequency range. This kind of tinnitus resembles phantom limb pain in an amputee — the brain is producing abnormal nerve signals to compensate for missing input.
Tinnitus also could be the result of neural circuits thrown out of balance when damage in the inner ear changes signaling activity in the auditory cortex, the part of the brain that processes sound. Or it could be the result of abnormal interactions between neural circuits. The neural circuits involved in hearing aren’t solely dedicated to processing sound. They also communicate with other parts of the brain, such as the limbic region, which regulates mood and emotion.

A study of ASD symptoms in 103 call centre operators exposed to 123 acoustic incidents is reviewed. The proposed neurophysiological mechanism of ASD is discussed, in particular tonic tensor tympani syndrome (TTTS) and temporomandibular disorder (TMD). An understanding of TTTS provides insight into the neurophysiological basis of tinnitus and hyperacusis escalation, in association with high levels of emotional trauma and anxiety. Audiological assessment, diagnosis, rehabilitation and workplace management of ASD is discussed.
Hearing loss is categorized by severity, type, and configuration. Furthermore, a hearing loss may exist in only one ear (unilateral) or in both ears (bilateral). Hearing loss can be temporary or permanent, sudden or progressive. The severity of a hearing loss is ranked according to ranges of nominal thresholds in which a sound must be so it can be detected by an individual. It is measured in decibels of hearing loss, or dB HL. There are three main types of hearing loss: conductive hearing loss, sensorineural hearing loss, and mixed hearing loss.[15] An additional problem which is increasingly recognised is auditory processing disorder which is not a hearing loss as such but a difficulty perceiving sound. The shape of an audiogram shows the relative configuration of the hearing loss, such as a Carhart notch for otosclerosis, 'noise' notch for noise-induced damage, high frequency rolloff for presbycusis, or a flat audiogram for conductive hearing loss. In conjunction with speech audiometry, it may indicate central auditory processing disorder, or the presence of a schwannoma or other tumor.
❒ Hearing Changes: Loss of hearing is quite common in case of inner ear infections. Hearing loss may be partial or total. Some people also complain of distorted or fluctuating hearing. Ringing in the ear as well as other sounds such as popping, cracking, clicking or hissing sounds are also very common. Sensitivity to loud noise can also indicate that the person might be suffering from problems of the inner ear.
People often say that they are aware of noises in the ears when they have a cold, an ear infection or wax blocking the ear. Sometimes people become aware of tinnitus following a really stressful event and once they’re aware of it, seem to notice it more and more, but this usually fades once these things have passed. However, some people continue to notice the tinnitus, for example after an infection has cleared up.

Prelingual deafness is profound hearing loss that is sustained before the acquisition of language, which can occur due to a congenital condition or through hearing loss before birth or in early infancy. Prelingual deafness impairs an individual's ability to acquire a spoken language in children, but deaf children can acquire spoken language through support from cochlear implants (sometimes combined with hearing aids).[42][43] Non-signing (hearing) parents of deaf babies (90-95% of cases) usually go with oral approach without the support of sign language, as these families lack previous experience with sign language and cannot competently provide it to their children without learning it themselves. Unfortunately, this may in some cases (late implantation or not sufficient benefit from cochlear implants) bring the risk of language deprivation for the deaf baby[44] because the deaf baby wouldn't have a sign language if the child is unable to acquire spoken language successfully. The 5-10% of cases of deaf babies born into signing families have the potential of age-appropriate development of language due to early exposure to a sign language by sign-competent parents, thus they have the potential to meet language milestones, in sign language in lieu of spoken language.[45]


Often interventions to prevent noise-induced hearing loss have many components. A 2017 Cochrane review found that stricter legislation might reduce noise levels.[97] Providing workers with information on their noise exposure levels was not shown to decrease exposure to noise. Ear protection, if used correctly, can reduce noise to safer levels, but often, providing them is not sufficient to prevent hearing loss. Engineering noise out and other solutions such as proper maintenance of equipment can lead to noise reduction, but further field studies on resulting noise exposures following such interventions are needed. Other possible solutions include improved enforcement of existing legislation and better implementation of well-designed prevention programmes, which have not yet been proven conclusively to be effective. The conclusion of the Cochrane Review was that further research could modify what is now regarding the effectiveness of the evaluated interventions.[97]
Hearing loss can also result from taking certain medications. “Ototoxic” medications damage the inner ear, sometimes permanently. Some ototoxic drugs include medicines used to treat serious infections, cancer, and heart disease. Some antibiotics are ototoxic. Even aspirin at some dosages can cause problems. Check with your doctor if you notice a problem while taking a medication.
Acoustic shock disorder (ASD) is an involuntary response to a sound perceived as traumatic (usually a sudden, unexpected loud sound heard near the ear), which causes a specific and consistent pattern of neurophysiological and psychological symptoms. These include aural pain/fullness, tinnitus, hyperacusis, muffled hearing, vertigo and other unusual symptoms such as numbness or burning sensations around the ear. Typically, people describe acoustic shock as feeling like they have been stabbed or electrocuted in the ear. If symptoms persist, a range of emotional reactions including post traumatic stress disorder, anxiety and depression can develop.
^ "Childhood hearing loss: act now, here's how!" (PDF). WHO. 2016. p. 6. Archived (PDF) from the original on 6 March 2016. Retrieved 2 March 2016. Over 30% of childhood hearing loss is caused by diseases such as measles, mumps, rubella, meningitis and ear infections. These can be prevented through immunization and good hygiene practices. Another 17% of childhood hearing loss results from complications at birth, including prematurity, low birth weight, birth asphyxia and neonatal jaundice. Improved maternal and child health practices would help to prevent these complications. The use of ototoxic medicines in expectant mothers and newborns, which is responsible for 4% of childhood hearing loss, could potentially be avoided.
Hearing loss is generally measured by playing generated or recorded sounds, and determining whether the person can hear them. Hearing sensitivity varies according to the frequency of sounds. To take this into account, hearing sensitivity can be measured for a range of frequencies and plotted on an audiogram. Other method for quantifying hearing loss is a hearing test using a mobile application or hearing aid application, which includes a hearing test.[81][82] Hearing diagnosis using mobile application is similar to the audiometry procedure.[81] Audiogram, obtained using mobile application, can be used to adjust hearing aid application.[82] Another method for quantifying hearing loss is a speech-in-noise test. which gives an indication of how well one can understand speech in a noisy environment.[83] Otoacoustic emissions test is an objective hearing test that may be administered to toddlers and children too young to cooperate in a conventional hearing test. Auditory brainstem response testing is an electrophysiological test used to test for hearing deficits caused by pathology within the ear, the cochlear nerve and also within the brainstem.
When there does not seem to be a connection with a disorder of the inner ear or auditory nerve, the tinnitus is called nonotic (i.e. not otic). In some 30% of tinnitus cases, the tinnitus is influenced by the somatosensory system, for instance, people can increase or decrease their tinnitus by moving their face, head, or neck.[25] This type is called somatic or craniocervical tinnitus, since it is only head or neck movements that have an effect.[23]
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