How Do I Read My Hearing Test?
The sample audiogram below consists of four parts: Otoscopy & Acoustic Reflexes, Tympanometry, Pure Tone Audiometry, and Speech Testing.
OTOSCOPY & ACOUSTIC REFLEXES
Otoscopy is an indication of how the ear canal and eardrum look when viewed through an otoscope. If the ear canal is clear and there are no signs of damage, infection, or inflammation, then Y will be marked under Canal Clear. Otherwise there will be a note indication what abnormalities were found.
An acoustic reflex is an involuntary contraction of a muscle behind the eardrum when a loud sound occurs. We can measure the contraction of that muscle using a quick and painless tool called an immittance bridge, and if the reflex is present it indicates normal function of several of the nerves in the auditory system. An acoustic reflex might be absent due to any number of factors, the most common being moderate to severe hearing loss.
A tympanometer consists of three parts: a speaker, a microphone, and a pump. The speaker plays a hum into the ear canal, the microphone measures the echo off of the eardrum, and the pump causes slight pressure changes.
Using a tympanometer we can measure the volume of the ear canal and the flexibility of the eardrum and middle ear, as well as detect any pressure abnormalities in the middle ear space. A normal tymp (short for tympanogram) indicates a healthy eardrum and middle ear, while an abnormal tymp is generally a sign of perforation or infection.
PURE TONE AUDIOMETRY
This is what most people think of when they imagine a hearing test. It consists of sitting in a sound booth and listening for beeps at different pitches and volumes. The results are plotted on an audiogram, which is the graph at the bottom left of the page above.
To understand the graph, imagine a piano keyboard with low pitches on the left side and high pitches going to the right. Pitch is measured by frequency, with low frequency representing bass sounds and high frequency representing treble. In terms of speech, vowels are low frequency and consonants like s and t are high frequency. Up is better on an audiogram, so lines toward the top mean better hearing, and lines toward the bottom mean a more severe hearing loss. Red is for the right ear and blue is for the left. If the black line is within 10 decibels of the red or blue lines it means your hearing loss is sensorineural, and if it is further apart than that then there is a conductive hearing loss.
The above individual has a mild to moderate high frequency sensorineural hearing loss, and will have difficulty understanding speech if she is in a noisy place or if she cannot see the person she is speaking with. She hears vowels well, and does not feel that volume is missing, but rather that people do not speak carefully and clarity is lacking. She gets very good benefit from hearing aids and feels like she has cotton in her ears when she takes her hearing aids out.
We do speech testing to see how well a person understands words when the volume is loud enough for them to hear every part of a word. If a person has a high word recognition score, it means that they will do well with a hearing aid because they make good use of sound when they can hear it. If the word recognition score is poor, it means that there is distortion in the nerve, and making speech louder will not necessarily make it clearer.
This is rather like a faulty speaker wire, where turning up the amplifier only results in louder distortion. Poor word recognition scores generally result from strokes, or from auditory neglect, which happens when a person goes many years with an untreated hearing loss.
The other two numbers on the speech testing table indicate the softest volume at which a person can repeat a two-syllable word (speech reception threshold) and the volume at which sound is uncomfortable, bordering on painful (uncomfortable loudness level). These help in programming a hearing aid, and also serve to validate other parts of the test with which they usually match up.