Tullio phenomenon, sound-induced vertigo, dizziness, nausea or eye movement (nystagmus) was first described in 1929 by the Italian biologist Prof. Pietro Tullio. (1881–1941) During his experiments on pigeons, Tullio discovered that by drilling tiny holes in the semicircular canals of his subjects, he could subsequently cause them balance problems when exposed to sound.

The cause is usually a fistula in the middle or inner ear, allowing abnormal sound-synchronized pressure changes in the balance organs. Such an opening may be caused by a barotrauma (e.g. incurred when diving or flying), or may be a side effect of fenestration surgery, syphilis or Lyme disease.

Patients with this disorder may also experience vertigo, imbalance and eye movement set off by changes in pressure, e.g. when nose-blowing, swallowing or when lifting heavy objects.

Tullio phenomenon is also one of the common symptoms of superior canal dehiscence syndrome (SCDS), first diagnosed in 1998 by Dr. Lloyd B. Minor, The Johns Hopkins University, Baltimore, United States.

The most common cause of hyperacusis is overexposure to excessively high decibel (sound pressure) levels.

Some come down with hyperacusis suddenly as a result of taking ear sensitizing drugs, Lyme disease, Ménière's disease, head injury, or surgery. Others are born with sound sensitivity, develop superior canal dehiscence syndrome, have had a history of ear infections, or come from a family that has had hearing problems.

Some psychoactive drugs such as LSD, methaqualone, or phencyclidine ("angel-dust") can cause hyperacusis. An antibiotic, ciprofloxacin has also been seen to be a cause, known as "ciprofloxacin-related hyperacusis".

Some conditions that are associated with hyperacusis include:

- Acoustic shock

- Adverse drug reaction

- Anxiety

- Autism spectrum

- Lyme disease

- Migraine

- Ménière's disease

- Endolymphatic hydrops

- Multiple Sclerosis

- Noise-induced hearing loss

- Posttraumatic stress disorder

- Severe head trauma

- Superior canal dehiscence syndrome (SCDS)

- Systemic lupus erythematosus (SLE)

- Tay–Sachs disease

- Williams syndrome

Within the labyrinth of the inner ear lie collections of calcium crystals known as otoconia or otoliths. In patients with BPPV, the otoconia are dislodged from their usual position within the utricle, and migrate over time into one of the semicircular canals (the posterior canal is most commonly affected due to its anatomical position). When the head is reoriented relative to gravity, the gravity-dependent movement of the heavier otoconial debris (colloquially "ear rocks") within the affected semicircular canal causes abnormal (pathological) endolymph fluid displacement and a resultant sensation of vertigo. This more common condition is known as canalithiasis.

In rare cases, the crystals themselves can adhere to a semicircular canal cupula, rendering it heavier than the surrounding endolymph. Upon reorientation of the head relative to gravity, the cupula is weighted down by the dense particles, thereby inducing an immediate and sustained excitation of semicircular canal afferent nerves. This condition is termed cupulolithiasis.

There is evidence in the dental literature that malleting of an osteotome during closed sinus floor elevation, otherwise known as "osteotome sinus elevation" or "lift", transmits percussive and vibratory forces capable of detaching otoliths from their normal location and thereby leading to the symptoms of BPPV.

It can be triggered by any action which stimulates the posterior semi-circular canal, including:

- Looking up or down

- Preceding head injury

- Sudden head movement

- Rolling over in bed

- Tilting the head

BPPV may be made worse by any number of modifiers which may vary between individuals:

- Changes in barometric pressure — patients may feel increased symptoms up to two days before rain or snow

- Lack of sleep (required amounts of sleep may vary widely)

- Stress

An episode of BPPV may be triggered by dehydration, such as that caused by diarrhea. For this reason, it commonly occurs in post-operative patients who have diarrhea induced by post-operative antibiotics.

BPPV is one of the most common vestibular disorders in patients presenting with dizziness; migraine is implicated in idiopathic cases. Proposed mechanisms linking the two are genetic factors and vascular damage to the labyrinth.

Although BPPV can occur at any age, it is most often seen in people over the age of 60. Besides aging, there are no major risk factors known for developing BPPV, although previous episodes of trauma to the head, or inner ear infections known as labyrinthitis, may predispose individuals to future development of BPPV.

Alternobaric vertigo is caused by a pressure difference between the middle ear cavities, usually due to blockage or partial blockage of one eustachian tube, usually when flying or diving underwater. It is most pronounced when the diver is in the vertical position; the spinning is towards the ear with the higher pressure and tends to develop when the pressures differ by 60 cm of water or more.

Benign paroxysmal positional vertigo (BPPV) is a disorder arising from a problem in the inner ear. Symptoms are repeated, brief periods of vertigo with movement, that is, of a spinning sensation upon changes in the position of the head. This can occur with turning in bed or changing position. Each episode of vertigo typically lasts less than one minute. Nausea is commonly associated. BPPV is one of the most common causes of vertigo.

BPPV can result from a head injury or simply occur among those who are older. A specific cause is often not found. The underlying mechanism involves a small calcified otolith moving around loose in the inner ear. It is a type of balance disorder along with labyrinthitis and Ménière's disease. Diagnosis is typically made when the Dix–Hallpike test results in nystagmus (a specific movement pattern of the eyes) and other possible causes have been ruled out. In typical cases medical imaging is not needed.

BPPV is often treated with a number of simple movements such as the Epley maneuver or Brandt–Daroff exercises. Medications may be used to help with nausea. There is tentative evidence that betahistine may help with the vertigo but its use is not generally needed. BPPV is not a serious condition. Typically it resolves in one to two weeks. It however may recur in some people.

The first medical description of the condition occurred in 1921 by Robert Barany. About 2.4% of people are affected at some point in time. Among those who live until their 80s, 10% have been affected. BPPV affects females twice as often as males. Onset is typically in the person's 50s to 70s.

A stroke (either ischemic or hemorrhagic) involving the posterior fossa is a cause of central vertigo. Risk factors for a stroke as a cause of vertigo include increasing age and known vascular risk factors. Presentation may more often involve headache or neck pain, additionally, those who have had multiple episodes of dizziness in the months leading up to presentation are suggestive of stroke with prodromal TIAs. The HINTS exam as well as imaging studies of the brain (CT, CT angiogram, and/or MRI) are helpful in diagnosis of posterior fossa stroke.

While there is no cure, most people with tinnitus get used to it over time; for a minority, it remains a significant problem.

The aging process has three distinct components: physiologic degeneration, extrinsic damage (nosocusis), and intrinsic damage (sociocusis). These factors are superimposed on a genetic substrate, and may be overshadowed by general age-related susceptibility to diseases and disorders.

Hearing loss is only weakly correlated with age. In preindustrial and non-industrial societies, persons retain their hearing into old age. In the Framingham cohort study, only 10% of the variability of hearing with age could be explained by age-related physiologic deterioration. Within family groups, heredity factors were dominant; across family groups, other, presumably sociocusis and nosocusis factors were dominant.

- Heredity: factors like early aging of the cochlea and susceptibility of the cochlea for drug insults are genetically determined.

- Oxidative stress

- General inflammatory conditions

According to current research, in approximately 2.5% of the general population the bones of the head develop to only 60–70% of their normal thickness in the months following birth. This genetic predisposition may explain why the section of temporal bone separating the superior semicircular canal from the cranial cavity, normally 0.8 mm thick, shows a thickness of only 0.5 mm, making it more fragile and susceptible to damage through physical head trauma or from slow erosion. An explanation for this erosion of the bone has not yet been found.

About 22 million workers are exposed to hazardous noise, with additional millions exposed to solvents and metals that could put them at increased risk for hearing loss. Occupational hearing loss is one of the most common occupational diseases. 49% of male miners have hearing loss by the age of 50. By the age of 60, this number goes up to 70%. Construction workers also suffer an elevated risk. A screening program focused on construction workers employed at US Department of Energy facilities found 58% with significant abnormal hearing loss due to noise exposures at work. Occupational hearing loss is present in up to 33% of workers overall. Occupational exposure to noise causes 16% of adult disabling hearing loss worldwide.

The following is a list of occupations that are most susceptible to hearing loss:

- Agriculture

- Mining

- Construction

- Manufacturing

- Utilities

- Transportation

- Military

- Musicians

- Orchestra conductors

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. Children do not generally report tinnitus spontaneously and their complaints may not be taken seriously. 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. 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 310% of children have been reported to be troubled by tinnitus.

Once diagnosed, the gap in the temporal bone can be repaired by surgical resurfacing of the affected bone or plugging of the superior semicircular canal. These techniques are performed by accessing the site of the dehiscence either via a middle fossa craniotomy or via a canal drilled through the transmastoid bone behind the affected ear. Bone cement has been the material most often used, in spite of its tendency to slippage and resorption, and a consequent high failure rate; recently, soft tissue grafts have been substituted.

Nosocusis factors are those that can cause hearing loss, which are not noise-based and separate from pure presbycusis. They may include:

- Ototoxic drugs: Ingestion of ototoxic drugs like aspirin may hasten the process of presbycusis.

- vascular degeneration

- Atherosclerosis: May diminish vascularity of the cochlea, thereby reducing its oxygen supply.

- Dietary habits: Increased intake of saturated fat may accelerate atherosclerotic changes in old age.

- Smoking: Is postulated to accentuate atherosclerotic changes in blood vessels aggravating presbycusis.

- Diabetes: May cause vasculitis and endothelial proliferation in the blood vessels of the cochlea, thereby reducing its blood supply.

- Hypertension: causes potent vascular changes, like reduction in blood supply to the cochlea, thereby aggravating presbycusis.

However, a recent study found that diabetes, atherosclerosis and hypertension had no correlation to presbycusis, suggesting that these are nosocusis (acquired hearing loss) factors, not intrinsic factors.

Gradually developing NIHL refers to permanent cochlear damage from repeated exposure to loud sounds over a period of time. Unlike acoustic trauma, this form of NIHL does not occur from a single exposure to a high-intensity sound pressure level. Gradually developing NIHL can be caused by multiple exposures to excessive noise in the workplace or any source of repetitive, frequent exposures to sounds of excessive volume, such as home and vehicle stereos, concerts, nightclubs, and personal media players.

AIED is generally caused by either antibodies or immune cells that cause damage to the inner ear. There are several theories that propose a cause of AIED:

- Bystander damage – Physical damage to the inner ear may lead to cytokine release that signals for an immune response. This may be a component of the "attack/remission cycle" of Meniere's disease.

- Cross-reactions – Accidental damage of the inner ear by antibodies or T-cells that recognize an inner ear antigen that is similar to a bacterial or viral antigen

- Genetic factors – Predisposition to developing an autoimmune disorder based on genes inherited

- Intolerance – The immune system may not be aware of all the antigens present in the inner ear until physical damage releases some of these antigens. As a result, the immune system treats these unfamiliar antigens as foreign and mounts an immune response.

Currently, the cross-reactions theory appears to be the favored mechanism of AIED pathogenesis.

There are several factors that may not be harmful to the auditory system by themselves, but when paired with an extended noise exposure duration have been shown to increase the risk of auditory fatigue. This is important because humans will remove themselves from a noisy environment if it passes their pain threshold. However, when paired with other factors that may not physically recognizable as damaging, TTS may be greater even with less noise exposure. One such factor is physical exercise. Although this is generally good for the body, combined noise exposure during highly physical activities was shown to produce a greater TTS than just the noise exposure alone. This could be related to the amount of ROS being produced by the excessive vibrations further increasing the metabolic activity required, which is already increased during physical exercise. However, a person can decrease their susceptibility to TTS by improving their cardiovascular fitness overall.

Heat exposure is another risk factor. As blood temperature rises, TTS increases when paired with high-frequency noise exposure. It is hypothesized that hair cells for high-frequency transduction require a greater oxygen supply than others, and the two simultaneous metabolic processes can deplete any oxygen reserves of the cochlea. In this case, the auditory system undergoes temporary changes caused by a decrease in the oxygen tension of the cochlear endolymph that leads to vasoconstriction of the local vessels. Further research could be done to see if this is a reason for the increased TTS during physical exercise that is during continued noise-exposure as well.

Another factor that may not show signs of being harmful is the current workload of a person. Exposure to noise greater than 95 dB in individuals with heavy workloads was shown to cause severe TTS. In addition, the workload was a driving factor in the amount of recovery time required to return threshold levels to their baselines.

There are some factors that are known to directly affect the auditory system. Contact with ototoxic chemicals such as styrene, toluene and carbon disulfide heighten the risk of auditory damages. Those individuals in work environments are more likely to experience the noise and chemical combination that can increase the likelihood of auditory fatigue. Individually, styrene is known to cause structural damages of the cochlea without actually interfering with functional capabilities. This explains the synergistic interaction between noise and styrene because the cochlea will be increasingly damaged with the excessive vibrations of the noise plus the damage caused by the chemical itself. Specifically, noise damage typically damages the first layer of the outer hair cells. The combined effects of styrene and noise exposure shows damages to all three rows instead, reinforcing previous results. Also, the combined effects of these chemicals and the noise produce greater auditory fatigue than when an individual is exposed to one factor immediately followed by the next.

It is important to understand that noise exposure itself is the main influential factor in threshold shifts and auditory fatigue, but that individuals may be at greater risk when synergistic effects take place during interactions with the above factors.

Occupational hearing loss is defined as damage to either or both ears, at the inner ear or auditory nerve, that results from an exposure in a person's occupation. Although high levels of noise are the main cause of occupational hearing loss (also called noise-induced hearing loss) there are also other factors in the work environment that can result in it. Chemicals, foreign bodies, vibration, barotrauma, along with other hazards can result in hearing loss. These losses that these workers obtain, affect many aspects of their life, mainly social interactions.

Within the United States of America, approximately 10 million people have noise-related hearing loss. Over twice that number are occupationally exposed to dangerous noise levels. Hearing loss accounted for a sizable percentage of occupational illness in 2007, at 14% of cases. As in many countries, in the US organizations like the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) are working to understand the causes of occupational hearing loss and how it can be prevented. They work to produce regulations and guidelines to help protect the hearing of workers in all occupations.

Chemically-induced hearing loss (CIHL) is a potential result of occupational exposures. Certain chemical compounds may have ototoxic effects. Exposure to organic solvents, heavy metals, and asphyxiants such as carbon monoxide can all cause hearing loss. These chemicals can be inhaled, ingested, or absorbed through the skin. Damage can occur to either the inner ear or the auditory nerve.

Both noise and chemical exposures are common in many industries, and can both contribute to hearing loss simultaneously. Damage may be more likely or more severe if both are present. Industries in which combinations of exposures may exist include construction, fiberglass, metal manufacturing, and many more.

Certain medications may also have the potential to cause hearing loss.

It is estimated that over 22 million workers are exposed to dangerous noise levels, and 10 million are exposed to solvents that could potentially cause hearing loss every year, with an unknown number exposed to other ototoxic chemicals.

Some over-the-counter as well as prescription drugs and certain industrial chemicals are ototoxic. Exposure to

these can result in temporary or permanent hearing loss.

Some medications cause irreversible damage to the ear, and are limited in their use for this reason. The most important group is the aminoglycosides (main member gentamicin). A rare mitochondrial mutation, m.1555A>G, can increase an individual's susceptibility to the ototoxic effect of aminoglycosides. Long term hydrocodone (Vicodin) abuse is known to cause rapidly progressing sensorineural hearing loss, usually without vestibular symptoms. Methotrexate, a chemotherapy agent, is also known to cause hearing loss. In most cases hearing loss does not recover when the drug is stopped. Paradoxically, methotrexate is also used in the treatment of autoimmune-induced inflammatory hearing loss.

Various other medications may reversibly degrade hearing. This includes loop diuretics, sildenafil (Viagra), high or sustained dosing of NSAIDs (aspirin, ibuprofen, naproxen, and various prescription drugs: celecoxib, etc.), quinine, and macrolide antibiotics (erythromycin, etc.).

Prolonged or repeated environmental or work-related exposure to ototoxic chemicals can also result in sensorineural hearing loss. Some of these chemicals are:

- butyl nitrite - chemical used recreationally known as 'poppers'

- carbon disulfide - a solvent used as a building block in many organic reactions

- styrene, an industrial chemical precursor of polystyrene, a plastic

- carbon monoxide, a poisonous gas resulting from incomplete combustion

- heavy metals: tin, lead, manganese, mercury

- hexane, an industrial solvent and one of the significant constituents of gasoline

- ethylbenzene, an industrial solvent used in the production of styrene

- toluene and xylene, highly poisonous petrochemical solvents. Toluene is a component of high-octane gasolne; xylene is used in the production of polyester fibers and resins.

- trichloroethylene, an industrial degreasing solvent

- Organophosphate pesticides

Although auditory fatigue and NIHL protective measures would be helpful for those who are constantly exposed to long and loud noises, current research is limited due to the negative associations with the substances. Furosemide is used in congestive heart failure treatments because of its diuretic properties. Salicylic acid is a compound most frequently used in anti-acne washes, but is also an anticoagulant. Further uses of these substances would need to be personalized to the individual and only under close monitoring. Antioxidants do not have these negative effects and therefore are the most commonly researched substance for the purpose of protecting against auditory fatigue. However, at this time there has been no marketed application. In addition, no synergistic relationships between the drugs on the degree of reduction of auditory fatigue have been discovered at this time.

There can be damage either to the ear itself or to the central auditory pathways that process the information conveyed by the ears. People who sustain head injury are susceptible to hearing loss or tinnitus, either temporary or permanent. Contact sports like football (U.S. NFL), hockey and cricket have a notable incidence of head injuries (concussions). In one survey of retired NFL players, all of whom reported one or more concussions during their playing careers, 25% had hearing loss and 50% had tinnitus.

Dysacusis is a hearing impairment characterized by difficulty in processing details of sound due to distortion in frequency or intensity, but not primarily a loss of the ability to perceive sound. The term is sometimes used to describe pain or discomfort due to sound, a condition also known as auditory dysesthesia.

Autoimmune inner ear disease (AIED) was first defined by Dr. Brian McCabe in a landmark paper describing an autoimmune loss of hearing. The disease results in progressive sensorineural hearing loss (SNHL) that acts bilaterally and asymmetrically, and sometimes affects an individual's vestibular system. AIED is used to describe any disorder in which the inner ear is damaged as a result of an autoimmune response. Some examples of autoimmune disorders that have presented with AIED are Cogan's syndrome, relapsing polychondritis, systemic lupus erythematosus, granulomatosis with polyangiitis, polyarteritis nodosa, Sjogren's syndrome, and Lyme disease.

Research has come to the consensus that AIED is the result of antibodies or other immune cells that cause damage to structures of the inner ear such as the cochlea and vestibular system. Of note, AIED is the only known SNHL that responds to medical treatment, but withholding treatment for longer than three months may result in permanent hearing loss and the need for cochlear implant installation.

Although AIED has been studied extensively over the past 25 years, no clear mechanism of pathogenesis has emerged. A recent paper performed a literature review of all relevant articles dating back to 1980, and proposed a mechanism of pathogenesis which includes an inflammatory response and immune cell attack on inner ear structures. This response leads to an over-activation of other immune cells such as T helper cells, resulting in vascular changes and cochlear harm. AIED appears to be a consequence of damaged sensorineural hearing due to electrochemical disturbances, microthrombosis, and immune cell deposition. Additionally, self-reactive antibodies and T-cells contribute to the aforementioned damage. Research has suggested a valuable next step in uncovering AIED pathogenesis is inquiry into the role of interleukin-1β (IL-1β).

Alexanders law refers to spontaneous nystagmus that occurs after an acute unilateral vestibular loss. It was first described in 1912 and has three elements to explain how the vestibulo-ocular reflex responds to an acute vestibular insult. The first element says that spontaneous nystagmus after an acute vestibular impairment has the fast phase directed toward the healthy ear. The direction of the nystagmus, by convention, is named for the fast phase, so the spontaneous nystagmus is directed toward the healthy ear. The second element says nystagmus is greatest when gaze is directed toward the healthy ear, is attentuated at central gaze and may be absent when gaze is directed toward the impaired ear. The third element says that spontaneous nystagmus with central gaze is augmented when vision is denied. This became apparent with the implementation of electrographic testing.

Alexander's law states that in individuals with nystagmus, the amplitude of the nystagmus increases when the eye moves in the direction of the fast phase (saccade).

It is manifested during spontaneous nystagmus in a patient with a vestibular lesion. The nystagmus becomes more intense when the patient looks in the quick-phase than in the slow-phase direction.

The law was named after Gustav Alexander who described it in 1912.