WHAT IS AN AUDIOGRAM?
An audiogram is a graph of the softest levels at which your child can hear sound. It is a picture of the results of a test that is done by an audiologist. Your child’s audiogram will often be used to describe his/her hearing loss.
The audiogram shows two things: Intensity and Frequency. Intensity, the loudness of sound, is measured in decibels (dB). Loudness levels are located along the lines on the audiogram that are drawn up and down. Intensities usually go from 0 dB to 110 dB; with 0 dB being very quiet and 110 dB being very loud. Frequency, the pitch of the sound, is measured in Hertz (Hz). The different frequencies are found along the vertical lines of the audiogram. Frequencies range from 250 Hz to 8000 Hz, although other frequencies may be tested at the audiologist’s discretion. 250 Hz is a very low-pitched sound and 8000 Hz is a very high- pitched sound.
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 audiogran 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 right and blue for left.
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.
Word recognition or speech discrimination testing may also be done using hearing alone or using hearing and looking at the audiologist’s face. A variety of stimuli are used with this type of test and it is usually recorded in percentages.