How to Read an Audiogram

An audiogram is the chart from a hearing test. For each ear, it shows the quietest sound you can hear (your hearing threshold) at each pitch, from low to high. Lower thresholds are better: 0 dB HL is the hearing of a typical young adult, and anything up to 20 dB HL counts as normal. The average of four of those thresholds, the pure-tone average, gives your hearing a single number, which the World Health Organization (WHO) uses to grade hearing loss.

This article is general information, not medical advice.

Reading the Chart

• Across the bottom: frequency, in hertz (Hz), from low pitches (250 Hz) to high ones (8,000 Hz). Speech sits mostly between 500 and 4,000 Hz.
• Down the side: hearing level, in decibels hearing level (dB HL). The scale runs downwards: 0 at the top, louder sounds lower on the chart. A point further down means you needed a louder sound to hear it.
• Symbols: by convention, a red circle (O) marks the right ear and a blue cross (X) the left ear for air conduction (sound through headphones).

The Pure-Tone Average

The pure-tone average (PTA) used by the WHO is the mean of an ear’s thresholds at 500, 1,000, 2,000, and 4,000 Hz. Thresholds of 15, 20, 25, and 40 dB HL give a PTA of 25 dB HL.

The WHO’s Grades

The WHO’s World report on hearing (2021) grades hearing by the pure-tone average of the better ear:

Pure-tone average (dB HL)	Grade
Under 20	Normal hearing
20 to under 35	Mild hearing loss
35 to under 50	Moderate hearing loss
50 to under 65	Moderately severe hearing loss
65 to under 80	Severe hearing loss
80 to under 95	Profound hearing loss
95 or more	Complete or total hearing loss

The report also notes that a difference of 15 dB or more between the two ears’ averages is unilateral hearing loss, which matters even when the better ear is normal. The WHO projects that by 2050 nearly 2.5 billion people will have some degree of hearing loss.

Patterns Worth Knowing

• Sloping down at high frequencies, in both ears, is typical of age-related hearing loss.
• A dip around 4,000 Hz that recovers at 8,000 Hz is the classic sign of noise damage; see What Does a Dip at 4,000 Hz on Your Audiogram Mean?
• A sudden change in one ear needs prompt medical attention, since sudden hearing loss is treated as an emergency.

Comparing Tests Over Time

Compare each frequency, not only the average, since early changes often show at high pitches first. Results from an app or headphone test are less precise than a booth test with an audiologist, so compare like with like.

Following It in Kaizora

Kaizora keeps each ear’s threshold at each frequency from 250 to 8,000 Hz as its own metric on the Hearing page, from audiograms you log or import from Apple Health. From each audiogram it derives Right Ear Pure-Tone Average and Left Ear Pure-Tone Average, the WHO’s mean of 500, 1,000, 2,000, and 4,000 Hz. Higher values are worse. The better ear’s average and the WHO’s grades as default reference ranges are planned.

The Short Version

• An audiogram shows each ear’s quietest audible sound at each pitch; lower is better.
• The pure-tone average is the mean at 500, 1,000, 2,000, and 4,000 Hz.
• Under 20 dB HL is normal; 20 to 35 is mild loss, by the WHO’s grades of the better ear.

Sources

• World Health Organization, World report on hearing (2021).
• World Health Organization, Deafness and hearing loss (fact sheet).