How Pure Tone Audiometry Works and What It Measures

A hearing test helps identify hearing changes early, and one of the most widely used methods is pure tone audiometry. Audiologists use this test to measure how well a person hears sounds at different pitches and volumes. It is commonly used during routine hearing evaluations, workplace hearing conservation programs, medical assessments, and hearing aid fittings.

In this blog, discover how pure tone audiometry helps patients feel more prepared before a hearing appointment. It also makes it easier to understand hearing test results and why professionals use certain treatments or interventions afterward.

What Is Pure Tone Audiometry?

Pure tone audiometry is a behavioral hearing test that measures a person’s hearing sensitivity across a range of frequencies.

A “pure tone” refers to a sound with a single frequency or pitch. These tones allow audiologists to evaluate hearing in a controlled, standardized manner. The test identifies the quietest sound a person can hear at different pitches, known as hearing thresholds.

Pure tone audiometry is considered the standard gold method for assessing hearing ability in older children and adults who can respond reliably during testing. Audiologists often combine it with other hearing assessments, such as speech audiometry and tympanometry, to build a complete picture of hearing health.

The test itself is non-invasive and usually takes less than an hour. Most patients complete it inside a sound-treated booth designed to reduce background noise that could affect the results.

Pure tone audiometry helps diagnose several hearing-related conditions, including:

• Sensorineural hearing loss
• Conductive hearing loss
• Mixed hearing loss
• Noise-induced hearing damage
• Age-related hearing loss
• Hearing changes caused by infections, medications, or injuries

Fun fact: Pure tone audiometry only evaluates your ability to physically detect a specific pitch, completely bypassing the brain’s ability to process and comprehend actual words or conversations.

How It Works

The process is straightforward, but it provides detailed information about hearing ability. Patients usually wear headphones for air conduction testing. The audiologist plays tones in one ear at a time and asks the patient to respond whenever they hear a sound, even if it seems very faint. 

Audiologists typically test frequencies ranging from 250 Hz to 8000 Hz because these frequencies are important for understanding speech and environmental sounds:

• Lower frequencies – deeper sounds, such as vowels.
• Higher frequencies – sharper or higher-pitched sounds, such as consonants.

The test does not just play sounds into your ears; it also uses a specialized vibrating headband placed on your mastoid bone to send sound waves directly through your skull, entirely bypassing the outer and middle ear. This specific method, known as bone conduction testing, may occur during the evaluation.

Accurate results depend on:

• Patient participation
• Proper calibration of the equipment
• Quiet testing environment

Audiologists also consider medical history, symptoms, and other diagnostic findings when interpreting the results.

Types of Testing

Pure tone audiometry includes different testing approaches that help audiologists evaluate the hearing system more thoroughly. Each method provides specific information about how sound travels through the ears and auditory pathways.

Air Conduction Testing

Air conduction testing is the standard form of pure tone audiometry. Sounds travel through headphones or insert earphones into the ear canal, pass through the middle ear, and reach the inner ear. Patients may raise a hand, press a button, or verbally indicate they heard the tone.

This method evaluates the entire hearing pathway, including:

• Outer ear
• Ear canal
• Eardrum
• Middle ear bones
• Inner ear
• Auditory nerve

Air conduction testing helps determine whether hearing falls within normal limits or whether hearing loss exists. However, it does not always identify the exact location of the problem on its own.

The test measures hearing thresholds in decibels hearing level (dB HL). Lower decibel thresholds may indicate better hearing sensitivity, while higher thresholds may suggest hearing loss.

Bone Conduction Testing

Bone conduction testing bypasses the outer and middle ear by sending vibrations directly to the cochlea through the skull bone.

Audiologists use this test to determine whether hearing loss is conductive, sensorineural, or mixed. Comparing air conduction and bone conduction thresholds helps identify where sound transmission becomes impaired.

For example:

• If bone conduction thresholds are normal but air conduction thresholds are reduced, conductive hearing loss may exist.
• If both air and bone conduction thresholds are reduced similarly, sensorineural hearing loss is more likely.

Bone conduction testing provides important diagnostic information that supports treatment planning.

Pure Tone Screening

Pure tone screening is a simplified version of the test often used in schools, workplaces, primary care settings, and community hearing programs. Instead of measuring exact hearing thresholds, screenings identify whether someone may have hearing difficulties that require further evaluation.

A screening does not diagnose hearing loss. It only indicates whether a complete hearing assessment may be necessary.

Manual vs. Automated Audiometry

Some clinics perform manual audiometry, where the audiologist controls tone presentation and adjusts the testing process based on patient responses. Manual testing allows flexibility and clinical judgment during the evaluation.

Meanwhile, automated audiometry uses computerized systems that guide the patient through the test with less direct involvement from the clinician. These systems may help with large-scale screenings or remote testing environments, although full diagnostic evaluations still often rely on audiologist oversight.

What Does Pure Tone Audiometry Measure?

Pure tone audiometry measures several aspects of hearing function. The results help audiologists understand how well a person hears different sounds and where hearing difficulties may originate.

The test does more than confirm whether hearing loss exists. It also helps classify the type, degree, and pattern of hearing loss.

Hearing Thresholds

One of the main goals of pure tone audiometry is to identify hearing thresholds.

A hearing threshold refers to the softest sound a person can hear at a specific frequency at least 50% of the time. Audiologists measure these thresholds in decibels hearing level (dB HL). Normal hearing thresholds for adults generally fall between 0 and 25 dB HL. Thresholds above that range may indicate hearing loss.

The higher the threshold, the louder the sound must become before the person can detect it. For example, someone with mild hearing loss may hear conversational speech but struggle with soft voices or distant sounds. Someone with severe hearing loss may only detect very loud sounds.

Threshold measurements help audiologists determine:

• Whether hearing loss exists
• How severe the hearing loss is
• Which frequencies are affected
• Whether hearing changes over time

Tracking hearing thresholds over multiple appointments can also help monitor progressive hearing loss or evaluate the effects of noise exposure, aging, medical conditions, or treatment.

Frequencies (Pitch)

Pure tone audiometry tests hearing across multiple frequencies because hearing ability can vary depending on pitch.

Frequency refers to the pitch of a sound and is measured in Hertz (Hz). Lower frequencies produce deeper sounds, while higher frequencies produce sharper sounds.

Examples include:

• Low frequencies: thunder, drums, engine noise
• Mid frequencies: most speech sounds
• High frequencies: birds chirping, alarms, consonant sounds like “s” and “f”

Speech understanding depends heavily on hearing across several frequencies, especially between 500 Hz and 4000 Hz.

Some people lose hearing mainly in higher frequencies, which commonly occurs with aging and noise exposure. Others may experience hearing loss across all frequencies or only in low-frequency ranges.

Testing multiple frequencies allows audiologists to identify hearing patterns that may point to specific causes or conditions.

For example:

• Noise-induced hearing loss often affects higher frequencies first
• Ménière’s disease may initially affect lower frequencies
• Age-related hearing loss commonly progresses in the higher pitches

Frequency-specific information also helps audiologists program hearing aids more accurately.

Interpreting Results

Pure tone audiometry provides detailed hearing data, but the numbers alone do not tell the full story. Audiologists interpret the results by reviewing hearing thresholds, comparing air and bone conduction findings, and identifying patterns across frequencies.

The final interpretation helps determine whether hearing loss exists, how severe it is, and which part of the auditory system is involved. These findings guide treatment recommendations, including hearing protection, medical referrals, hearing aids, or additional diagnostic testing.

Hearing loss affects people differently; audiologists consider symptoms, communication difficulties, medical history, and lifestyle factors when reviewing results.

Audiogram

An audiogram is the visual chart used to display pure tone audiometry results. It shows the quietest sounds a person can hear across different frequencies and serves as the primary tool for interpreting hearing ability. The audiogram includes two main measurements:

• Frequency (pitch) along the horizontal axis
• Hearing level in decibels (dB HL) along the vertical axis

Lower frequencies appear on the left side of the graph, while higher frequencies appear on the right. Softer sounds are located near the top of the chart, and louder sounds appear farther down.

Audiologists plot separate results for each ear because hearing ability can differ between ears. Standard symbols identify air conduction and bone conduction thresholds during testing.

An audiogram helps reveal hearing patterns that may not be obvious during everyday conversations. For example, some people hear low-pitched sounds normally but struggle with higher-pitched speech sounds. Others may have hearing loss across nearly all frequencies.

Speech clarity often depends heavily on hearing high-frequency consonants such as: S, F, Th, Sh.

When these frequencies become harder to hear, speech may sound muffled even if overall volume seems adequate.

Audiograms also help monitor hearing changes over time. Audiologists may compare current results with previous tests to evaluate progression caused by aging, occupational noise exposure, illness, or medication effects.

In addition, hearing aid programming relies heavily on audiogram findings. Devices can be adjusted to amplify the specific frequencies where hearing loss exists rather than increasing all sounds equally.

Severity of Hearing Loss

Pure tone audiometry also helps classify the severity of hearing loss. Audiologists determine severity by averaging hearing thresholds at key speech frequencies.

Although classifications may vary slightly between organizations, hearing loss commonly falls into the following categories:

• Normal hearing: 0–25 dB HL
• Mild hearing loss: 26–40 dB HL
• Moderate hearing loss: 41–55 dB HL
• Moderately severe hearing loss: 56–70 dB HL
• Severe hearing loss: 71–90 dB HL
• Profound hearing loss: greater than 90 dB HL

The degree of hearing loss often affects communication differently.

Severity classifications also help determine appropriate management options. These may include:

• Hearing conservation strategies
• Medical treatment
• Hearing aids
• Assistive listening devices
• Cochlear implant evaluations
• Communication therapy

However, hearing thresholds alone do not fully predict communication ability. Some individuals adapt well despite measurable hearing loss, while others experience significant listening fatigue and communication difficulties even with mild impairment.

Audiologists, therefore, combine audiometric data with patient-reported symptoms and functional hearing concerns.

Type of Hearing Loss

Pure tone audiometry helps identify the type of hearing loss by comparing air conduction and bone conduction results. The three main categories include:

• Conductive hearing loss
• Sensorineural hearing loss
• Mixed hearing loss

Each type affects hearing differently and may require different treatment approaches.

Conductive hearing loss occurs when sound cannot travel efficiently through the outer or middle ear. Common causes include:

• Earwax blockage
• Fluid in the middle ear
• Ear infections
• Eardrum perforations
• Abnormalities involving the middle ear bones

In conductive hearing loss, bone conduction thresholds may remain normal while air conduction thresholds appear reduced. This difference is often called an air-bone gap.

Conductive hearing loss may improve with medical treatment or minor procedures, depending on the underlying cause.

Meanwhile, sensorineural hearing loss results from damage involving the inner ear or auditory nerve. This is the most common type of permanent hearing loss.

Possible causes include:

• Aging
• Noise exposure
• Genetic factors
• Viral infections
• Ototoxic medications
• Inner ear disorders

In sensorineural hearing loss, both air and bone conduction thresholds are reduced similarly because the inner ear itself cannot process sound efficiently.

Treatment often focuses on improving communication through hearing aids, assistive devices, hearing rehabilitation, and hearing protection strategies.

Finally, mixed hearing loss combines conductive and sensorineural components. This means problems exist in both the outer or middle ear and the inner ear.

For example, someone with age-related hearing loss may also develop middle ear fluid or chronic ear infections. Audiometric testing helps identify both components so clinicians can create a more accurate treatment plan.

Differentiating hearing loss types is one of the most important functions of pure tone audiometry because treatment options depend heavily on identifying the correct cause.

Conclusion

Many people may not realize how much their hearing has changed until communication difficulties become more noticeable. One of the most important tools to evaluate hearing health is pure tone audiometry. Early testing allows hearing concerns to be identified sooner, which can improve treatment outcomes. Combined with a full clinical evaluation, it provides a clear foundation for understanding a person’s hearing ability and the next steps needed to support better communication and overall hearing health.