Audiometer

Hearing occurs when sound waves stimulate nerves in the inner ear, which transmit auditory messages to the brain. An audiometer is a functional test that determines the level of hearing, and is used to diagnose hearing loss. Audiometry involves the measurement of the intensity (loudness) of sound in decibels (dB) and the tone of the sound (vibrations of sound waves) in cycles per second (cps) or Hertz (Hz).

Indications

An audiometry test is indicated to screen for hearing ability. Common causes that lead to loss of hearing include:

  • Ear injury
  • Diseases of the inner ear
  • Inherited conditions or birth defects
  • Medications that harm the inner ear
  • Regular exposure to loud sound
  • Ruptured eardrum
  • Chronic ear infections

Procedure

An audiologist will perform the audiometry test by using an audiometer.You will be asked to wear headphones connected to the audiometer to listen to various sounds of tones and speech played at different intervals; one ear at a time. You will be asked to inform the audiologist of the sounds that you are able to hear. This helps measure the lowest intensity of sound that you can hear.

When sound waves hit the ear, vibrations are passed on across tiny bones present in the ear. Your audiologist may use vibrating forks to measure the vibrations that you can hear. Your ability to hear vibrations through air conduction will be determined by tapping the vibrating fork and holding it on each side of your head.

This conduction of vibration from one inner bone to another will be tested by tapping and placing the forks against the bone behind the ear. A device known as a bone oscillator may be placed behind each ear to transmit vibrations.

Results

You have normal hearing if you are able to hear

  • Normal speech, the sound of a ticking watch or a whisper
  • Vibrations through air and bone
  • Tones from 250 Hz – 8,000 Hz at 25 dB or lower

Based on your hearing ability, your doctor will discuss measures to prevent or correct hearing problems.