'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.
Audiometry is a test used to measure how well you can hear different sounds. You will put on headphones that are attached to a machine. Sounds will be sent through the headphones. You will press a button or raise your hand when you hear the sounds. Each ear will be tested separately. Another device will be placed on the bone behind your ear. The device will test how well vibration moves through the bones. This is called bone conduction.

The other fluid-filled chambers of the inner ear include three tubes called the semicircular canals (vestibular labyrinth). Hair cells in the semicircular canals detect the motion of the fluids when you move in any direction. They convert the motion into electrical signals that are transmitted along the vestibular nerve to the brain. This sensory information enables you to maintain your sense of balance.
The sound perceived may range from a quiet background noise to one that even is heard over loud external sounds. The specific type of tinnitus called pulsatile tinnitus is characterized by hearing the sounds of one's own pulse or muscle contractions, which is typically a result of sounds that have been created by the movement of muscles near to one's ear, or the sounds are related to blood flow in the neck or face.[8]

Exposure to loud noise. Loud noises, such as those from heavy equipment, chain saws and firearms, are common sources of noise-related hearing loss. Portable music devices, such as MP3 players or iPods, also can cause noise-related hearing loss if played loudly for long periods. Tinnitus caused by short-term exposure, such as attending a loud concert, usually goes away; both short- and long-term exposure to loud sound can cause permanent damage.

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Rapid referral for a comprehensive audiological assessment provides reassurance, and can help control an escalation of symptoms and limit the development of hyperacusis. History taking should document immediate and persistent symptoms since the acoustic incident exposure; prior acoustic incident exposures; and prior otological and psychological history. Significant malingering is rare in ASD clients, in my experience. Most clients are bewildered, frightened or angered by their symptoms and desperate to recover.
Subjective tinnitus is the most frequent type of tinnitus. It may have many possible causes, but most commonly it results from hearing loss. When the tinnitus is caused by disorders of the inner ear or auditory nerve it is called otic (from the Greek word for ear).[23] These otological or neurological conditions include those triggered by infections, drugs, or trauma.[24] A frequent cause is traumatic noise exposure that damages hair cells in the inner ear.
Noise-induced hearing loss (NIHL) typically manifests as elevated hearing thresholds (i.e. less sensitivity or muting). Noise exposure is the cause of approximately half of all cases of hearing loss, causing some degree of problems in 5% of the population globally.[50] The majority of hearing loss is not due to age, but due to noise exposure.[51] Various governmental, industry and standards organizations set noise standards.[52] Many people are unaware of the presence of environmental sound at damaging levels, or of the level at which sound becomes harmful. Common sources of damaging noise levels include car stereos, children's toys, motor vehicles, crowds, lawn and maintenance equipment, power tools, gun use, musical instruments, and even hair dryers. Noise damage is cumulative; all sources of damage must be considered to assess risk. In the US, 12.5% of children aged 6–19 years have permanent hearing damage from excessive noise exposure.[53] The World Health Organization estimates that half of those between 12 and 35 are at risk from using personal audio devices that are too loud.[11] Hearing loss in adolescents may be caused by loud noise from toys, music by headphones, and concerts or events.[54]
Atherosclerosis. With age and buildup of cholesterol and other deposits, major blood vessels close to your middle and inner ear lose some of their elasticity — the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful, making it easier for your ear to detect the beats. You can generally hear this type of tinnitus in both ears.