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Graph showing a typical Auditory Brainstem Response. The auditory brainstem response (ABR), also called brainstem evoked response audiometry (BERA) or brainstem auditory evoked potentials (BAEPs) or brainstem auditory evoked responses (BAERs) [1] [2] is an auditory evoked potential extracted from ongoing electrical activity in the brain and recorded via electrodes placed on the scalp.
An audiogram is a graph that shows the audible threshold for standardized frequencies as measured by an audiometer. The Y axis represents intensity measured in decibels (dB) and the X axis represents frequency measured in hertz (Hz). [ 1 ]
The result of most audiometry is an audiogram plotting some measured dimension of hearing, either graphically or tabularly. The most common type of audiogram is the result of a pure tone audiometry hearing test which plots frequency versus amplitude sensitivity thresholds for each ear along with bone conduction thresholds at 8 standard ...
The shape of the audiogram resulting from pure-tone audiometry gives an indication of the type of hearing loss as well as possible causes. Conductive hearing loss due to disorders of the middle ear shows as a flat increase in thresholds across the frequency range. Sensorineural hearing loss will have a contoured shape depending on the cause.
The result of the test is an audiogram diagram which plots a person's hearing sensitivity at the tested frequencies. On an audiogram an "x" plot represents the softest threshold heard at each specific frequency in the left ear, and an "o" plot represents the softest threshold heard at each specific frequency in the right ear.
Since the inner ear is not directly accessible to instruments, identification is by patient report of the symptoms and audiometric testing. Of those who present to their doctor with sensorineural hearing loss, 90% report having diminished hearing, 57% report having a plugged feeling in ear, and 49% report having ringing in ear ().
The stimulus level is increased if the subject does not respond and decreased when a response occurs. Similar to the method of limits, the stimuli are adjusted in predetermined steps. After obtaining from six to eight reversals, the first one is discarded and the threshold is defined as the average of the midpoints of the remaining runs.
The acoustic reflex (also known as the stapedius reflex, [1] stapedial reflex, [2] auditory reflex, [3] middle-ear-muscle reflex (MEM reflex, MEMR), [4] attenuation reflex, [5] cochleostapedial reflex [6] or intra-aural reflex [6]) is an involuntary muscle contraction that occurs in the middle ear in response to loud sound stimuli or when the person starts to vocalize.