Straightforward Information About Tinnitus
If you've had a hearing test, you've probably seen the chart with X's and O's plotted on a grid. This chart is your audiogram, and understanding it can help you make sense of your tinnitus and your hearing overall.
An audiogram is a graph with two axes:
Horizontal axis (top) — Frequency, measured in Hertz (Hz). Low frequencies (like a bass drum) are on the left; high frequencies (like a whistle) are on the right. Standard audiograms test from 250 Hz to 8,000 Hz.
Vertical axis (side) — Loudness, measured in decibels hearing level (dB HL). Soft sounds are at the top; loud sounds are at the bottom. This can be counterintuitive: a mark near the top of the chart means you can hear soft sounds (good hearing), while a mark near the bottom means you need louder sounds (more hearing loss).
The standard symbols are O for the right ear (usually plotted in red) and X for the left ear (usually plotted in blue). Each mark shows the softest sound you could detect at that frequency.
| Threshold (dB HL) | Degree |
|---|---|
| -10 to 25 | Normal |
| 26 to 40 | Mild |
| 41 to 55 | Moderate |
| 56 to 70 | Moderately severe |
| 71 to 90 | Severe |
| 91+ | Profound |
High-frequency sloping loss — This is the most common audiogram pattern in tinnitus patients. Hearing is normal or near-normal in the low frequencies but drops off in the higher frequencies (typically 2,000–8,000 Hz). This pattern is associated with both noise-induced damage and age-related hearing loss, and is often accompanied by high-pitched tinnitus. See Noise-Induced Tinnitus and Tinnitus and Hearing Loss.
Notch at 4,000 Hz — A characteristic dip in hearing at 4,000 Hz with recovery at 8,000 Hz is a classic sign of noise-induced hearing loss.
Flat loss — Hearing is reduced equally across all frequencies. This can be caused by various conditions and does not point to a single cause.
Normal audiogram — If your audiogram is normal but you still have tinnitus, see the section on hidden hearing loss for possible explanations.
Standard audiograms have limitations. They only test up to 8,000 Hz, but human hearing can extend to 20,000 Hz. Extended high-frequency audiometry (testing above 8,000 Hz) can sometimes reveal hearing loss that the standard test misses. Additionally, standard audiograms do not detect cochlear synaptopathy (hidden hearing loss), which may require specialized testing.