Air conduction / unmasked
Earphones, no masking
A tone is delivered through an earphone or insert. The mark names the ear being tested.
Right ear
O circle
Left ear
X cross
TEL-REF / Audiogram reference
Audiogram symbols key
A visual guide to the marks that can appear on an audiogram. Learn how ear side, test path, masking, sound field testing, and no response are shown.
Important
Symbol sets can vary by clinic, country, and test setup. Start with the legend printed on your own report.
Interactive reference
Every mark, in context.
Shape first, color second
All six symbol groups are shown.
Air conduction / masked
Earphones, with masking
The non-test ear receives masking noise so the plotted result can be assigned to the intended ear.
Right ear
triangle
Left ear
square
Bone conduction / unmasked
Vibrator, no masking
A bone vibrator sends vibration through the skull. An unmasked result may not identify which cochlea responded.
Right mastoid
< open angle
Left mastoid
> open angle
Bone conduction / masked
Vibrator, with masking
Masking makes the bone result ear-specific for the test condition. The bracket faces the frequency line.
Right ear
[ bracket
Left ear
] bracket
No response
The arrow is part of the mark
A down arrow means no response at the maximum available output for that frequency, transducer, and audiometer.
Right ear
O + down-left
Left ear
X + down-right
Sound field
A loudspeaker result
The capital S marks a sound-field threshold that cannot be assigned to one ear by default.
Response
S sound field
No response
S + down
Always-readable legend
Keep this table beside the audiogram.
These are common ASHA recommended symbols for conventional pure-tone threshold recording. The exact key on a report wins when a clinic uses a local or different standard.
| Test condition | Right ear | Left ear | What the mark tells you |
|---|---|---|---|
| Air conductionUnmasked | O circle | X cross | Earphone or insert result without masking noise. |
| Air conductionMasked | Triangle | Square | Earphone or insert result with masking noise in the non-test ear. |
| Bone conductionUnmasked / mastoid | < open angle | > open angle | Bone vibrator result without masking. It may not be assignable to one cochlea. |
| Bone conductionMasked / mastoid | [ bracket | ] bracket | Bone vibrator result with masking. The open side faces the frequency line. |
| No responseAny ear-specific symbol | Base mark + down-left arrow | Base mark + down-right arrow | No response at the maximum output for that test condition. The limit varies. |
| Sound fieldResponse | S capital S, not assigned to one ear | Loudspeaker result. By default, it does not identify a single ear. | |
| Sound fieldNo response | S + straight down arrow | Sound field no response at the available output limit. | |
Practical examples
Read the mark before the color.
A single plotted mark only tells you about the test condition. Its meaning comes from the full legend, the frequency, the hearing level, and the rest of the audiogram.
1 kHzO rightX left
Two unmasked air-conduction results
At the 1 kHz column, an O and an X at different heights are the right and left ear air-conduction thresholds. The height is the hearing level, not part of the symbol.
2 kHztriangle air[ bone
Masked air and bone results
A triangle and a bracket at the same frequency can both belong to the right ear when masking was used. The pairing may help a clinician compare test paths, but it is not a diagnosis by itself.
4 kHzS no response
Sound-field no response
An S with a straight down arrow means no response to a loudspeaker presentation at the available output limit. It does not say which ear failed to respond.
How to use the key
The test path matters.
Air conduction
Earphones or inserts send sound through the outer and middle ear to the cochlea. O, X, triangle, and square are air-conduction families in the common set.
Bone conduction
A vibrator sends vibration through the skull. Without masking, the response may not be assignable to one cochlea. Do not read < or > as a simple second air test.
Masking
Masking places noise in the non-test ear to reduce the chance that it responds to a sound meant for the test ear. The symbol tells you masking was used, not why.
No response
The arrow marks the maximum output reached without a response. That maximum can change with frequency, transducer, and audiometer, so do not turn the arrow into an exact number.
Sound field
A loudspeaker presents the signal in the room. An S result is usually not ear-specific unless the report explains an ear-specific setup.
Color and copies
Red right and blue left are common screen conventions, but color can disappear in a scan or photocopy. Shape and the printed legend are more reliable.
Limits of a symbol key
This page explains common plotting conventions. It does not read an audiogram, identify a type of hearing loss, or decide whether a result is normal. A clinician needs the complete graph, the test frequencies and levels, the transducers, masking details, calibration information, symptoms, and history.
Some clinics use alternate symbols for inserts, aided testing, visual reinforcement, sound field conditions, or local reporting systems. When a mark on your report does not match this page, use that report's own legend or ask the audiologist who made it.
A no-response arrow is especially easy to overread. It means the test did not produce a response at the output limit used for that condition. It does not prove that no sound could ever be heard, and the output limit is not necessarily the same across frequencies.
Next steps
Our guide to reading an audiogram explains the axes, thresholds, and common patterns. If you already have the numbers from a calibrated test, the pure-tone average calculator can summarize selected thresholds, but it still cannot diagnose hearing loss or replace a full clinical interpretation.
Primary sources
- ASHA: Audiometric Symbols Guidelines, including air conduction, bone conduction, sound field, no response, masking, and color guidance.
- ANSI Webstore: ASA/ANSI S3.21-2004 (R2023), Methods for Manual Pure-Tone Threshold Audiometry, the current standards catalog record for the manual pure-tone procedure.
Questions readers ask
Audiogram symbol questions
- What do O and X mean on an audiogram?
- In the common ASHA recommended set, O is right ear unmasked air conduction and X is left ear unmasked air conduction. Always check the legend on the report because local symbol sets can differ.
- Why are triangles and squares used?
- They commonly mark masked air-conduction thresholds: triangle for the right ear and square for the left ear. Masking noise is used in the non-test ear to help assign the result.
- Does an arrow mean a threshold of 120 dB?
- No. It means no response at the maximum output for that specific frequency, transducer, and audiometer. The maximum may be different from one test condition to another.
- Can this page tell me whether I have hearing loss?
- No. It is an educational symbol reference only. Ask a qualified hearing professional to explain your complete audiogram and any speech or middle-ear tests.
Educational use only.
This page does not diagnose, treat, or rule out a hearing condition. Sudden hearing loss is a medical emergency and needs prompt clinical care.