Pure-Tone Audiometry Explained

What is a pure tone?

A pure tone is a sound concentrated at one frequency. It is different from speech, music and most environmental sounds, which contain many frequencies at once.

Using controlled tones allows an audiologist to measure hearing sensitivity at specific points across the hearing range. These points help show whether hearing is similar across pitches or whether certain frequency regions are more affected.

The tones may sound like beeps, whistles or low hums. Some are pulsed or warbled to make them easier to distinguish from tinnitus or room noise.

What does pure-tone audiometry measure?

The test estimates a **hearing threshold** for each frequency. A threshold is the lowest level at which a person responds consistently under controlled conditions.

It is not necessarily the faintest sound ever detected. Responses naturally vary slightly, and the audiologist uses a standardized procedure to establish a reliable threshold.

Pure-tone results can help describe:

Hearing sensitivity in the right and left ears

Which frequencies are affected

The degree of hearing loss

The shape, or configuration, of the hearing pattern

Whether the ears are symmetric or asymmetric

Whether a conductive component may be present

Whether more testing or medical referral is appropriate

The test does not directly measure how well someone understands conversation, especially in noise. Speech tests and the person’s real-life report provide that additional information.

Frequency: the pitch of the tone

Frequency is measured in hertz, abbreviated Hz. Lower frequencies sound deeper; higher frequencies sound sharper.

Common clinical test frequencies include points between approximately 250 and 8,000 Hz. The exact range depends on the purpose of the evaluation, equipment and person being tested.

Speech uses a broad range of frequencies. Vowels often carry lower-frequency energy, while many soft consonant cues occur at higher frequencies. Missing particular frequency regions can therefore affect speech differently even when the overall degree of loss appears similar.

Hearing level: how soft or loud the test signal is

Audiograms use **decibels hearing level**, written as dB HL. This is a calibrated clinical scale that allows thresholds at different test frequencies to be plotted together.

dB HL is not the same as the sound-level readings shown by a consumer noise meter, which may use dB SPL or an A-weighted scale such as dBA. A value on an audiogram should not be interpreted as a direct measurement of environmental noise exposure.

On a standard audiogram, softer hearing levels appear near the top and louder levels appear farther down. A mark lower on the chart means the tone had to be made louder before it was detected.

What happens during the test?

Instructions

The audiologist explains how to respond. A person may press a button, raise a hand, say “yes” or use another agreed response.

The instruction is usually to respond whenever the tone is heard, no matter how soft it seems. Guessing at random is not helpful, but responding to a very faint tone is appropriate.

Earphone placement

Insert earphones, headphones or other calibrated transducers are positioned carefully. Each ear is tested separately.

The fit matters. Poor placement, a collapsed ear canal or excessive background noise can affect results. The audiologist checks the test conditions before interpreting the thresholds.

Finding thresholds

The audiologist presents a tone, changes its level and repeats it. A standardized pattern of softer and louder presentations helps identify the lowest level that produces consistent responses.

The process is repeated at several frequencies in each ear. The tones may seem unpredictable because unpredictability helps prevent responses based only on timing.

Bone-conduction testing

When needed, a small vibrator is placed behind the ear or on the forehead. This sends vibration through the skull to the inner ear, bypassing much of the outer and middle ear.

Comparing air- and bone-conduction thresholds helps the audiologist classify the hearing loss.

Air conduction versus bone conduction

Air-conduction testing

Air-conduction tones travel through the outer ear, middle ear and inner ear. The results therefore reflect the entire auditory pathway up to the person’s behavioral response.

Air-conduction testing shows the overall hearing sensitivity of each ear, but it cannot by itself identify where the reduction occurs.

Bone-conduction testing

Bone-conduction tones bypass much of the outer and middle ear and stimulate the inner ears through skull vibration.

If bone-conduction thresholds are better than air-conduction thresholds by a clinically meaningful amount, the pattern may indicate a conductive component. Interpretation depends on the full test, not on one isolated point.

| Pattern | General interpretation |
|---|---|
| Air and bone thresholds reduced by similar amounts | May indicate sensorineural hearing loss |
| Air thresholds reduced while bone thresholds are better | May indicate conductive hearing loss |
| Air and bone thresholds both reduced, with air poorer | May indicate mixed hearing loss |

Only a qualified clinician should interpret the pattern. Equipment limits, test reliability and other findings must be considered.

What is masking?

Although earphones are used to test one ear at a time, a sufficiently loud test tone may sometimes be detected by the opposite ear. Bone-conduction stimulation can also reach both inner ears.

**Masking** is controlled noise presented to the non-test ear so that the audiologist can be confident the measured response belongs to the intended ear.

Masking noise may sound like static or rushing air. It does not mean anything went wrong. It is a standard technique used when the difference between ears or between air- and bone-conduction results makes cross-hearing possible.

Masked and unmasked results use different audiogram symbols.

How to read an audiogram

An audiogram is a graph:

The horizontal axis shows frequency from low pitches on the left to high pitches on the right.

The vertical axis shows dB HL, with softer levels near the top and louder levels lower down.

Symbols mark thresholds for each ear and test pathway.

Common symbols include:

**O** for unmasked right-ear air conduction

**X** for unmasked left-ear air conduction

Bracket-like symbols for bone conduction

Triangle or square symbols for masked air conduction

Arrows when no response occurred at the equipment’s output limit

Symbol conventions can vary slightly by clinic or record system. The audiogram should include a legend.

Lines may connect thresholds to make the overall shape easier to see, but hearing was measured only at the marked frequencies.

Degrees of hearing loss

Clinicians may group thresholds into categories such as normal or within expected limits, slight, mild, moderate, moderately severe, severe and profound.

Classification systems vary. Degree may be described at individual frequencies or by an average of selected thresholds. A label should never replace the actual audiogram or explanation of how the pattern affects communication.

Two people with the same average can have different configurations and speech-understanding abilities.

Common audiogram configurations

Flat

Thresholds are relatively similar across the tested frequencies.

Sloping

Hearing is better in lower frequencies and poorer in higher frequencies. This is common in age- and noise-related patterns, although the audiogram alone does not establish the cause.

Rising

Lower-frequency thresholds are poorer than higher-frequency thresholds.

Notched

A specific frequency region is poorer, with some recovery at adjacent frequencies. Certain notches may be consistent with noise exposure, but history and other findings are required.

Asymmetric

One ear is significantly poorer than the other at one or more frequencies. Asymmetry may prompt additional testing or medical referral depending on the degree, symptoms and clinical criteria.

No response

An arrow may show that no response occurred at the equipment’s maximum test level. This does not prove there is absolutely no hearing; it means a threshold could not be established within the available output at that frequency.

What the test feels like

Pure-tone audiometry is noninvasive and usually painless. The person sits in a quiet room or sound-treated booth and listens through earphones.

Bone-conduction equipment applies gentle pressure behind the ear or on the forehead. Tell the audiologist if the placement is uncomfortable or if earphones cause pain.

The quiet can make tinnitus more noticeable. Inform the audiologist so pulsed or warbled tones and careful instructions can help distinguish the test signal.

How long does pure-tone testing take?

Basic threshold testing may take approximately 15 to 30 minutes, but timing varies. Masking, inconsistent responses, profound loss, pediatric methods or additional frequencies can make the test longer.

Pure-tone audiometry is only one part of a full hearing evaluation, which may take 30 to 60 minutes or longer depending on the services needed.

How reliable are the results?

Pure-tone audiometry depends on the person’s responses, calibrated equipment and an appropriate test environment. Audiologists look for consistency within the tone responses and agreement with speech and other measures.

Results may be affected by:

Background noise

Poor earphone placement

Earwax or ear-canal conditions

Tinnitus

Fatigue or reduced attention

Unclear instructions

Difficulty using the response method

Temporary hearing change after noise exposure

Intentional or unintentional inconsistent responses

When results are uncertain, the audiologist may reinstruct, retest, change the response method or add objective measures.

Pure-tone testing for children

Children can be tested using methods matched to their developmental age.

Visual reinforcement audiometry

An infant or young child learns to turn toward a sound and receives a visual reward, such as a lighted toy or animation.

Conditioned play audiometry

A child performs a simple play action—such as placing a block in a container—whenever a tone is heard.

Conventional testing

Older children may press a button or raise a hand, similar to adults.

When ear-specific behavioral thresholds are incomplete, objective tests such as OAEs or ABR may contribute information. A response obtained through speakers cannot be assigned to a specific ear unless the test setup provides ear-specific stimulation.

What pure-tone audiometry cannot tell you by itself

Pure-tone testing does not independently determine:

The exact medical cause of hearing loss

How well speech is understood

How someone performs in every noisy environment

Whether tinnitus is present or how severe it feels

Whether hearing aids will provide a particular amount of benefit

Whether a person has an auditory-processing disorder

Whether a cochlear implant is appropriate

These questions require other tests, history, professional interpretation or a specialized evaluation.

Why speech testing still matters

An audiogram measures detection of simple tones. Conversation requires recognition and processing of complex speech.

Speech testing can measure the softest level at which speech is recognized, word-recognition performance at controlled levels and, when appropriate, understanding in background noise.

Someone may have relatively mild thresholds but substantial difficulty in noise. Another person may have greater threshold loss with better-than-expected word recognition. Recommendations should consider both the audiogram and functional communication.

Pure-tone testing and hearing-aid decisions

The audiogram helps determine whether amplification may be appropriate and provides information used in hearing-aid programming. It does not complete the fitting process.

Good hearing-aid care may also include:

Communication-needs assessment

Device selection

Real-ear or other objective verification

Aided speech testing

Orientation and counseling

Follow-up adjustments

Outcome measurement

Hearing-aid benefit should be evaluated rather than assumed from the audiogram.

Can an online pure-tone test replace clinical audiometry?

No. Online tests may offer a useful screening, but consumer headphones and devices are not usually calibrated like clinical audiometric equipment. Background noise, fit and volume settings can substantially affect results.

Most online tests cannot perform bone conduction, masking, otoscopy, tympanometry or a complete speech assessment. They cannot reliably identify the type or cause of hearing loss.

Do not use an online test for sudden hearing change, head trauma, severe dizziness, neurological symptoms, pain, bleeding or drainage. Seek professional care.

How to prepare

Bring previous hearing-test results if available.

List hearing concerns and when they began.

Tell the audiologist about tinnitus, dizziness, ear pain, drainage or pressure.

Share relevant noise, medication and medical history.

Bring current hearing aids and accessories.

Request communication accommodations in advance.

Avoid unnecessary hazardous noise and report recent loud exposure.

Do not insert cotton swabs or other tools into the ear canal before testing.

Questions to ask your audiologist

What do my air-conduction thresholds show?

Why was bone conduction performed?

Was masking needed, and what did it clarify?

Which frequencies are affected in each ear?

What is the degree and configuration of the loss?

Is the pattern conductive, sensorineural or mixed?

Are the ears significantly different?

How do my speech results compare with the tones?

Do I need medical referral or additional testing?

When should the audiogram be repeated?

The bottom line

Pure-tone audiometry measures the softest tones a person reliably detects across different frequencies. Air-conduction and bone-conduction results help an audiologist describe hearing sensitivity and classify the hearing-loss pattern.

The audiogram is a foundation—not a complete diagnosis. Speech tests, middle-ear measures, symptoms and everyday communication needs are also important. Sudden hearing change requires immediate medical evaluation.

Use the **Audiology.md provider directory** or **Request Hearing Help** to connect with local hearing care near you.