TYPES OF TEST FOR HEARING IMPAIRED

TESTS TO DIAGNOSE HEARING LOSS INCLUDE

• Physical exam. Your doctor will look in your ear for possible causes of your hearing loss, such as earwax or inflammation from an infection. Your doctor will also look for any structural causes of your hearing problems.
• General screening tests. Your doctor may ask you to cover one ear at a time to see how well you hear words spoken at various volumes and how you respond to other sounds.
• Tuning fork tests. Tuning forks are two-pronged, metal instruments that produce sounds when struck. Simple tests with tuning forks can help your doctor detect hearing loss. A tuning fork evaluation may also reveal whether hearing loss is caused by damage to the vibrating parts of your middle ear (including your eardrum), damage to sensors or nerves of your inner ear, or damage to both.
• Audiometer tests. During these more-thorough tests conducted by an audiologist, you wear earphones and hear sounds directed to one ear at a time. The audiologist presents a range of sounds of various tones and asks you to indicate each time you hear the sound.

Each tone is repeated at faint levels to find out when you can barely hear. The audiologist will also present various words to determine your hearing ability.

PURE TONE TEST

A pure-tone air conduction hearing test determines the faintest tones a person can hear at selected pitches (frequencies), from low to high. During this test, earphones are worn so that information can be obtained for each ear.

Sometimes, use of earphones for the test is not possible, such as when a child refuses to wear them. In these cases, sounds are presented through speakers inside a sound booth (called sound-field screening). Since sound-field screening does not give ear-specific information, a unilateral hearing loss (hearing loss in only one ear) may be missed.

The person taking the test may be asked to respond to the sounds in a variety of ways, such as by:

• Raising a finger or hand
• Pressing a button, pointing to the ear where the sound was received
• Saying "yes" to indicate that the sound was heard

The results are recorded in an audiogram.

Sometimes, young children are given a more play-like activity to indicate response. The most common techniques involve visual reinforcement audiometry (VRA) and conditioned play audiometry (CPA).

·         Visual reinforcement audiometry

i\  Is the method of choice for screening children between 6 months and 2 years of age. The child is trained to look toward a sound source. When the child gives a correct response (e.g., looking to a source of sound when it is presented), the child is "rewarded" through a visual reinforcement. Example rewards include getting to watch a toy that moves or a flashing light.

·         Conditioned play audiometry 

     Can be used as the child matures and is commonly used with toddlers and preschoolers (ages 2–5). The child is trained to perform an activity each time a sound is heard. The activity may involve putting a block in a box, placing pegs in a hole, or putting a ring on a cone.

If there is a blockage, such as wax or fluid, in the outer or middle ears, a method called pure- tone bone conduction testing may be used. With this technique, the blockage is bypassed by sending a tone through a small vibrator placed behind the ear (or on the forehead). The signal reaches the inner ear (or cochlea) directly through gentle vibrations of the skull. This testing can measure response of the inner ear to sound independently of the outer and middle ears. In these cases, this test helps the audiologist determine the type of hearing loss being measured.

·         Bone conduction test: 

     A bone conduction test is often carried out as part of a routine pure tone audiometry (PTA) test in adults.Bone conduction involves placing a vibrating probe against the mastoid bone behind the ear. It tests how well sounds transmitted through the bone are heard. Bone conduction is a more sophisticated version of the tuning fork test, and when used together with PTA, it can help determine whether hearing loss comes from the outer and middle ear, the inner ear, or both. Bone conduction measures how well your inner ear and hearing nerves are working. The vibrations from the tuning fork go straight to the hearing nerve and bypass any problems in the ear canal, eardrum or hearing bones.

·         Whispered voice test: 

     The whispered voice test is a very simple hearing test. It involves the tester blocking one of your ears and testing your hearing by whispering words at varying volumes. You will be asked to repeat the words out loud as you hear them.

·         Speech perception: 

      The speech perception test, also sometimes known as a speech discrimination test or speech audiometry, involves testing your ability to hear words without using any visual information. The words may be played through headphones or a speaker, or spoken by the tester.Sometimes, you are asked to listen to words while there is a controlled level of background noise.

·         Tympanometry: 

       The eardrum should allow as much sound as possible to pass into the middle ear. If sound is reflected back from the eardrum, hearing will be impaired. During tympanometry, a small plastic bung seals your ear and the machine gently changes the pressure in your ear canal. 
       The test can be used to confirm whether there is any fluid behind the eardrum and can indicate if the Eustachian tube is working normally.Tympanometry measures the movement of the eardrum and the pressure behind the eardrum.