We all remember the school nurse taking us to her office, placing headphones on our ears and asking us to raise our left or right hand when we hear a "beep" in the respective ear. But we didn't know that was just scraping the tip of service in this wonderful science called "Audiology".
Audiologist perfrom testing to determine if one's hearing, balance or processing skills are compromised. Today we will talk about the art of diagnosing hearing loss.
Newborn Hearing Screenings:
Before the hospital will release your newborn, a hearing professional (may or may not be an audiologist) will perform a newborn hearing screeing on your child. If your child is born at home, a hearing screeing should be done within the first 2 weeks of life. The goal is to identify any babies that are "at risk" for hearing loss as quickly as possible. If your baby is "referred" at a newborn hearing screening you MUST follow up with an audiologist to determine IF a hearing loss is present and if so what type of hearing loss your child has.
This tympanometer is used to test the movement of one's ear drum and the 3 small bones in the middle ear. This can be done on babies, children and adults. The rubber tip is placed in the ear canal and a tone is played. This device measures the rate with which this tone bounces off the ear drum (also known as tympanic membrane) attemtping to measure if there is adequate movement and vibration of the tone through the outer and middle ear. Causes that could result in lack of movement: wax build-up or fluid in the middle ear (otherwise known as an ear infection). Difficulty with middle ear movement is called "conductive hearing loss" and can often times be remediated via PE tube placement (for excess and chronic fluid) or simple other measures.
Otoacoustic Emissions Testing (OAEs):
When a sound is played in the inner ear, a different sound actually results demonstrating that the "ear is listening". The OAE is like the tympanometer in that you place rubber tip into the ear and play a tone, but the OAE is measuring the inner ear tone (rather than movement/vibration of the middle ear) to determine if the inner ear is coding sound appropriately. The OAE is not as exact as more involved testing measures but for children this is a good indicator that the inner ear is probably functioning in a typical manner.
Auditory Brain Response (ABR):
Electrodes are placed on the forhead and behind a child's ears. A speaker is placed in the child's ear. The speaker emits clicking sounds at various loudness levels and the electrodes are there to measure the electricity of the nerve responses to the clicking sounds giving the audiologist an indication of how loud a sound must be before the child's brain actually responds to it. Hearing loss measured by this test is called "sensorineural hearing loss" and may or may not be able to be fixed via surgery.
For reliable children and adults the following are the most common tests used:
Air Conduction testing (AC):
This is the type of hearing test most of us think of. An audiologist will have an child (old enough to follow directions) or an adult sit in a sound proof booth and present various tones at various loudness levels and the child/adult must indicate when they hear the sound. This test results in an audiogram which is a diagram and one's hearing threshold at various frquencies (pitch) and decibles (loudness levels).
Bone Conduction testing (BC):
This test is similar to the air conduction test however the device is placed on the mastoid bone (behind one's hear) and the adult/child will still indicate if they "hear" the sounds presented. An audiologist can compare the AC and BC testing results to help differentially diagnose between a conductive or sensorineural hearing loss.
For more information, please contact an audiologist near you!
Stay tuned for tomorrow's installment of our audiology blog-fest focusing on how to read an audiogram and tympanogram!
To find out more about reading Audiograms or Tympanograms click here.
To learn the basics about what Audiology is, click here.