• AUDIOMETRÍA examen que evalúa la capacidad de audiciónalmunecar granada
  • AUDIOMETRÍA examen que evalúa la capacidad de audiciónalmunecar granada
  • AUDIOMETRÍA examen que evalúa la capacidad de audiciónalmunecar granada
  • AUDIOMETRÍA examen que evalúa la capacidad de audiciónalmunecar granada
 

Audiometry

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AUDIOMETRYAUDIOMETRÍA

Is an examination that evaluates hearing capacity.  The sounds vary according to intensity (volume or strength) and tone (the vibration speed of the sound waves).


Hearing is produced when the sound waves reach the nerves of the inner ear and then the brain.  Sound waves can travel as far as the inner ear through air conduction (through the external auditory channel, the tympanum and the bones of the middle ear) or though osteoacusis (through the bones around and behind the ear).

The INTENSITY of sound is measured in decibels (dB):
    A whisper has approximately 20dB
   Loud music (some concerts) have around 80 to 120 dB
    A jet engine has more or less 140 to 180 dB

Generally, sounds of more than 85dB can cause loss of hearing within a few hours, while louder sounds may cause immediate pain and the development of loss of hearing within a very short space of time.

The TONE of sound is measured in cycles per second (cps) or Hertz:

    The grave tones of a bass fluctuate between 50 to 60 Hz
   The highest pitch treble tones are of approximately 10.000 Hz or more.

The normal range of hearing in humans is approximately between 20 to 20.000 Hz and some animals can even hear around 50.000 Hz.

Manner in which the test is performed

The first step is to recognise the need for an audiogram.  Specific procedures may vary, but they generally imply the occlusion of one ear at a time in order to evaluate the capacity to hear whispers, then spoken words or the tick-tock of a clock.

A diapason may be used, which is gently struck and maintained in the air to each side of the head to evaluate hearing capacity through air conduction.  Then, it is gently struck once again and placed upon the mastoid bone, located behind each ear, to evaluate hearing capacity through osteoacusis.

Audiometry provides a more precise measurement of hearing.  Aerial conduction is evaluated by placing earphones on the person being tested, which are connected to the audiometer.  The pure tones of controlled intensity are generally transmitted to one ear at a time and the person is asked to signal by raising a hand, pressing a button or in any other way when he or she hears the sound; then the minimum intensity (volume) required to hear each tone is charted.  Finally, an accessory, called a bone oscillator, is placed against the bone behind each ear (mastoid bone) to evaluate osteoacusis.


Preparation for the examination

No special preparation of any kind is required for this test.
This examination does not cause any type of discomfort and its duration varies.  The initial evaluation may take 5 or 10 minutes, while a detailed audiometry may take almost an hour.

This could be an examination to detect the loss of hearing at an early age and can also be used in the event of a hearing difficulty due to any cause whatsoever.

Amongst the most common causes of loss of hearing are:

    Chronic ear infections
    Rupture of the tympanum
    Acoustic trauma
    Occupational loss of hearing
    Cranial trauma
    Hereditary disorders
    Diseases of the inner ear.
    Medications that may be toxic for the inner ear nerve, including certain antibiotics such as neomycin, diuretics and large doses of salicylates such as aspirin.

Normal values

•    The capacity to hear a whisper, normal speech and the tick-tock of a clock is normal
•    The capacity to hear a diapason through both air and bone is normal
•    In detailed audiometry, hearing is normal if tones from 250Hz to 8000Hz can be heard at 25dB or less.

Meaning of abnormal results

There are many types and different levels of hearing loss.  Some only involve a loss in the capacity to hear high or low tones or the loss of only aerial conduction or bone conduction.  The incapacity to hear pure tones below 25dB indicates a certain degree of hearing loss.

The degree and type of hearing loss may give an indication which will help establish the cause and a prognosis (probable result).

The following ailments may affect examination results:

    Acoustic neuroma
    Acoustic trauma
    Age-related loss of hearing
    Alport syndrome
    Labyrinthitis
    Menière’s disease
    Occupational loss of hearing
    Oteosclerosis
    Perforation or rupture of the tympanum