As the audiologist tests your child’s hearing, they will make marks using different symbols on the audiogram that represent the softest levels at which your child consistently responds. This level of sound is called the threshold. The location of each symbol will tell you how loud a certain pitch has to be for your child to hear it.
Many of the speech sounds are made in the pitches between 250 and 5000 Hz and are spoken at a loudness of 20 to 60 dB. Sometimes an audiogram will have shading on it that resembles a banana and falls in between pitch and loudness levels. This is put on the audiogram to show where speech sounds typically occur. This is where the term “speech banana” comes from. If the audiologist fits a hearing aid on your child, they will try to make sure that your child can hear sounds in this area. The pictures on the audiogram are sounds that present themselves at certain decibels. For example, the picture of the piano on the audiogram is the sound level that a piano is at.
The audiologist may also use the audiogram to chart what sounds your child can hear with hearing aids on. The softest sounds your child can hear with hearing aids is called the aided threshold. Many times the letter A will be the symbol used to represent aided thresholds. Ideally, these A’s will be within the banana lines.
What do the symbols and drawn lines mean?
If your child is tested with earphones, it is called Air Conduction Testing. Because sound is presented to each individual ear, information can be gathered about hearing in each ear, separately. The symbols used to represent Air Conduction testing are an “X” for the left ear and an “O” for the right ear. Sometimes colors are used for all of the different symbols: red for the right ear and blue for the left ear.
If your child does not hear the sound at the loudest level of the audiometer (the machine used to test hearing), it may be indicated several different ways, with a NR (no response), a squiggly downward line or an arrow downward from the X or O.
If your child is tested using a bone conduction vibrator (a vibrating piece of plastic placed behind the ear) then brackets [ ] will be used. The symbol > is used to show the left ear results and < for right ear.
After the audiologist has information about various pitches, they will connect the symbols to make a line on the graph for each ear. This line is the configuration of the audiogram. Configurations vary due to each child’s individual hearing loss. Sometimes configurations go somewhat straight across. These are called flat hearing losses. Some configurations will angle downward, either gently or sharply. These are called sloping losses. Professionals may use these configurations to describe your child’s hearing level. Given the varied reasons for hearing loss in children, each audiogram is unique, reflecting a multitude of factors.
OBJECTIVE TESTS
Objective tests of hearing do not require active participation from the child and are often very helpful in assessing hearing levels .
How it is done: A small probe is placed in the child’s ear canal. A sound, generated by the testing equipment is sent to the cochlea (inner ear). If the hair cells in the cochlea are functioning normally, they generate an otoacoustic emission that is generated by the testing equipment.
What it will show: If an emission is present, it suggests normal cochlear function. If an emission is not present, then further testing is needed. Generally, children with typical hearing or mild hearing levels will have otoacoustic emissions present. Otoacoustic emissions alone are not enough to diagnose typical hearing.
Who is it for: This test is used for infants, for children who cannot respond to other types of hearing tests, and for children with disabilities. OAEs can be used regardless of a client’s age at testing; as another way to cross-check test results; to help diagnose auditory neuropathy and to monitor hearing when an individual has had noise exposure.
Different types of testing may be known as: Brainstem Audiometry Evoked Response, BSER, BAER, ABR, ASSR
How it is done: This tests hearing from the level of the outer ear through the lower brainstem. This test can be done if the child is either sedated or asleep. Electrodes are attached to the child’s head and earphones are placed on the child’s ears. Sounds are played through the earphones and the electrodes measure how the child’s brain responds. This test gathers specific information about the child’s hearing at different pitches and loudness levels. This test is completely painless.
What it will show: This test gives a close approximation of the child’s hearing sensitivity.
Who is it for: This test is used for infants, for children who cannot respond to other types of hearing tests and for children with severe disabilities.
Also known as: Impedance testing, immittance testing, or tympanometry
May also include: acoustic reflexes
How it is done: A probe is placed in your child’s ear and a signal is presented. There may be a change in pressure depending on what information the audiologist is trying to gather. The signal bounces off the eardrum and back to the probe. It only takes between 3-30 seconds per ear.
What it will show: Tympanometry will chart the way sound enters into the middle ear which shows how the middle ear is functioning. It can help determine if there is a hole in the ear drum or if there is fluid behind the eardrum. This is part of one test that audiologists use to assess eardrum movement, but is not always clear-cut.
Who is it for: Any child.