How to read an audiogram, explained by someone who had to learn it at 58
The audiologist slid a printout across the desk, and my first thought was that somebody had printed it upside down. The line that was supposed to show my hearing sloped down toward the bottom right corner, and I couldn't tell if down was good or bad.
Down is bad. Everything else took me a while longer, so I've written it out in the order that finally made sense to me, which is not the order the audiologist used.
The two directions on the chart
An audiogram is a grid. Across the top, left to right, is pitch, measured in hertz (Hz). It usually runs from 250 Hz on the left, about middle C, to 8,000 Hz on the right, higher than the top of a piccolo. As a musician I found it easiest to think of it as a keyboard laid sideways.
Down the side is loudness, in decibels of hearing level (dB HL). The top of the chart is very soft and the bottom is very loud. Each mark shows the softest beep you could hear at that pitch about half the time. So a mark near the top means you heard a very quiet tone. A mark lower down means the tone had to be louder before you caught it.
That's the whole trick: the lower the marks, the more hearing loss at that pitch. The American Speech-Language-Hearing Association's audiogram guide has a clean diagram if you want to see a blank one.
An example like mine
I'm not going to post my actual printout, but this is the same shape, rounded off. It's a common pattern for people who spent years around loud sound.
Pitch in Hz across the top, hearing level in dB HL down the side. Red O = right ear, blue X = left ear.
| Ear | 250 Hz | 500 Hz | 1k Hz | 2k Hz | 4k Hz | 8k Hz |
|---|---|---|---|---|---|---|
| Right | 15 | 15 | 20 | 30 | 55 | 45 |
| Left | 10 | 15 | 15 | 25 | 45 | 40 |
Source: Illustrative values in the shape of my own results. The shaded band is roughly normal hearing.
Reading it left to right: both ears are in the normal range at the low pitches, start to slide at 2,000 Hz, and hit their worst point at 4,000 Hz before coming back up a little at 8,000 Hz. The right ear is worse than the left. I stood with my right side to the drumline for a lot of years.
What the symbols mean
| Symbol | Ear | What was tested |
|---|---|---|
| O, usually red | Right | Air conduction, through headphones |
| X, usually blue | Left | Air conduction, through headphones |
| < | Right | Bone conduction, through a small vibrator behind the ear |
| > | Left | Bone conduction |
| [ and ] | Right and left | Bone conduction with masking noise in the other ear |
| Arrow pointing down | Either | No response even at the loudest level tested |
Air conduction tests the whole path, from the ear canal to the brain. Bone conduction skips the outer and middle ear and goes straight to the inner ear. Comparing the two is how the audiologist tells where the problem is.
Air versus bone: where the problem sits
If the air and bone marks sit together, the outer and middle ear are passing sound through fine and the loss is in the inner ear or the nerve. That's sensorineural hearing loss, the kind that comes with age and noise. That was me.
If the bone marks are near normal and the air marks are lower, there's a gap, and something is blocking sound on its way in: wax, fluid behind the eardrum, a hole in the eardrum, or a problem with the tiny bones of the middle ear. That's conductive hearing loss, and unlike my kind, it's often treatable. The MedlinePlus page on audiometry describes both tests and what the results mean.
The speech banana
The audiologist drew a banana-shaped outline on my chart with a pen. That's where the sounds of speech live: roughly 250 to 4,000 Hz in pitch and about 20 to 60 dB in loudness. Any marks that fall below the banana are speech sounds you're missing.
| Pitch range | Speech sounds that live there | What it means if you lose it |
|---|---|---|
| Low, 250 to 500 Hz | Vowel energy, the hum of m and n | Speech sounds quieter overall |
| Middle, 1,000 to 2,000 Hz | Much of the vowel detail, some consonants | Words start to blur together |
| High, 2,000 to 8,000 Hz | s, f, th, sh, k, t | You hear that someone is talking but miss what they said |
Those ranges are approximate and overlap, but they explained my life in one table. Vowels carry the volume of speech, and consonants carry the meaning. Lose the high pitches and speech stays loud but goes mushy. My wife wasn't mumbling. I was missing her s's and t's.
Why the dip at 4,000 Hz
My audiologist pointed at the low point at 4,000 Hz and said "noise notch." Loud sound tends to damage the inner ear's hair cells tuned to around 3,000 to 6,000 Hz first, so years of noise often leave a dip there, with a partial recovery at 8,000 Hz. Age-related loss usually just slopes downward without the dip. The NIDCD's page on noise-induced hearing loss explains how sounds above about 85 dBA cause it over time.
A notch doesn't prove noise was the cause, but on top of my work history it was convincing. For what comes next with a chart shaped like mine, this guide to treatment options for high-frequency loss covers hearing aids, communication habits and protecting what's left.
The other numbers on the page
Below the chart, my report had a few lines I skipped at first. The pure-tone average is the average of your thresholds at a few speech pitches, usually 500, 1,000 and 2,000 Hz, and sometimes 4,000 Hz. It's a one-number summary of each ear, handy for tracking over the years. Word recognition is the percentage of single words you repeated correctly at a comfortable volume. Mine was in the 90s in both ears, which the audiologist said was a good sign for hearing aids, because it meant my ears could still make sense of speech once it was loud enough.
Questions I wish I'd asked
I sat there nodding. Next time I'll bring a list:
- Which category is each ear in, at the pitches that matter for speech?
- Is there any air-bone gap, and if so, is it something treatable?
- How did I do on the word recognition and speech-in-noise tests, not just the beeps?
- Is the difference between my ears big enough to need more testing?
- Would over-the-counter hearing aids suit my results, or do I need a prescription fitting?
- When should I come back to compare?
And ask for a copy. Your audiogram belongs to you, and the next one will only mean something if you have this one to set beside it.