What Is Pure Tone Audiometry and How It Assesses Hearing

Pure tone audiometry is a standard hearing test that measures how well a person can hear sounds at different pitches and volumes. Audiologists use it to identify hearing loss, determine its severity, and understand where the issue occurs within the auditory system. The test focuses on detecting the faintest tones a person can hear across a range of frequencies, typically from low (250 Hz) to high (8,000 Hz).

For a long time, clinicians have relied on pure tone audiometry because it provides clear, quantifiable results. It helps guide diagnosis and supports decisions about treatment, such as hearing aids or further medical evaluation. The test is non-invasive, widely available, and suitable for most age groups who can respond reliably.

How the Pure Tone Audiometry Test Works

During the test, the patient wears headphones or inserts earphones and sits in a quiet, sound-treated room. The audiologist plays a series of pure tones—single-frequency sounds—into one ear at a time. These tones vary in pitch and loudness.

Each time the patient hears a sound, they respond by pressing a button, raising a hand, or giving a verbal signal. The audiologist adjusts the intensity of the tones to find the softest level the patient can detect. This level is called the hearing threshold.

The test usually includes both air conduction and bone conduction methods. Air conduction measures how sound travels through the outer, middle, and inner ear. Bone conduction bypasses the outer and middle ear by sending vibrations directly to the inner ear through a small device placed behind the ear. 

What Are the Key Aspects of Pure-Tone Audiometry?

Pure tone audiometry focuses on several essential elements that together give a complete picture of hearing ability.

First, it measures hearing sensitivity across frequencies that are important for understanding speech. Human speech falls mostly between 500 Hz and 4,000 Hz, so this range receives particular attention.

Second, it establishes hearing thresholds in decibels hearing level (dB HL). These thresholds show how soft a sound must be for a person to detect it. Lower thresholds indicate better hearing, while higher thresholds suggest hearing loss.

Third, the test evaluates each ear separately. This helps detect asymmetrical hearing loss, where one ear performs differently from the other. Identifying this difference is important because it may point to specific medical conditions that require further evaluation.

How Pure Tone Audiometry Assesses Hearing

Procedure

The audiologist begins by explaining the process and ensuring the patient understands how to respond. The patient then enters a soundproof booth or a quiet testing area. Headphones or earphones are placed securely to deliver sound.

In the process:

• The audiologist presents tones at different frequencies and gradually changes their intensity.
• Testing typically starts at a level that is easy to hear, then decreases until the patient can no longer detect the sound.
• This step-by-step approach ensures accurate threshold measurement.

Response

Patient response plays a critical role in the test process. The patient must respond consistently each time they hear a tone, even if it is very faint. Reliable responses allow the audiologist to map hearing thresholds precisely.

For individuals who cannot provide standard responses, such as very young children, clinicians may use alternative methods like conditioned play audiometry or objective tests. However, pure tone audiometry remains the primary behavioral test for cooperative patients.

Threshold Discovery

Threshold discovery refers to identifying the quietest sound a person can hear at each frequency. Audiologists often use a “down 10 dB, up 5 dB” method. They decrease the sound level until it is no longer heard, then increase it slightly until the patient responds again.

This process repeats to confirm consistency. The final threshold is recorded as the lowest level at which the patient responds to the tone at least half of the time. These values form the basis of the audiogram.

Air Conduction (AC)

Air conduction testing measures the entire hearing pathway using headphones or earphones. Sound travels through the ear canal, vibrates the eardrum, moves through the middle ear bones, and reaches the inner ear (cochlea). This method provides an overall view of hearing ability. If results show reduced sensitivity, further testing helps determine whether the issue lies in the outer, middle, or inner ear.

Bone Conduction (BC)

Bone conduction testing bypasses the outer and middle ear. A small vibrating device placed on the mastoid bone sends sound directly to the cochlea.

Comparing bone conduction results with air conduction results helps differentiate types of hearing loss. For example, if bone conduction thresholds are normal but air conduction thresholds are elevated, the issue likely involves the outer or middle ear (conductive hearing loss).

What Are the Key Aspects of the Assessment?

Pure tone audiometry does more than measure thresholds. It organizes results into a format that clinicians can interpret and use for diagnosis. The assessment highlights patterns, differences between ears, and how hearing loss may affect everyday communication.

Audiologists analyze the results in context. They consider patient history, symptoms such as tinnitus or dizziness, and any exposure to noise or ototoxic medications. This broader view ensures that the findings lead to meaningful conclusions rather than just raw numbers.

Audiogram

The audiogram is the visual output of the test. It plots frequency (pitch) on the horizontal axis and intensity (loudness in dB HL) on the vertical axis. Each ear has its own set of symbols, allowing clinicians to compare performance side by side.

Normal hearing typically falls between 0 and 25 dB HL. Thresholds above this range indicate varying degrees of hearing loss, from mild to profound. The shape of the audiogram also matters. For example, a sloping pattern may suggest high-frequency hearing loss, which often affects speech clarity, especially in noisy environments.

Types of Hearing Loss Identified

Pure tone audiometry helps distinguish between the main types of hearing loss:

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

Conductive hearing loss develops when the outer or middle ear cannot transmit sound effectively to the inner ear. Common causes include earwax buildup, fluid in the middle ear, or problems with the ossicles.

Sensorineural hearing loss develops when structures in the inner ear or the auditory nerve no longer function properly. It is often permanent and may result from aging, noise exposure, or certain medical conditions.

Mixed hearing loss combines both conductive and sensorineural components. The comparison between air conduction and bone conduction thresholds plays a key role here. A noticeable gap between them (air-bone gap) usually points to a conductive component, while similar elevated thresholds suggest sensorineural loss.

Read More: Conductive Hearing Loss vs Sensorineural Hearing Loss

Diagnostic Use

Clinicians use pure tone audiometry as a foundation for further evaluation and treatment planning. It helps determine whether a patient may benefit from hearing aids, medical treatment, or referral to a specialist such as an otolaryngologist.

The test also supports early detection. Regular hearing assessments can identify changes before they significantly impact communication. This is especially important for individuals exposed to occupational noise or those at risk of age-related hearing loss.

In addition, audiometry results can guide decisions about additional tests, such as speech audiometry, tympanometry, or imaging studies, when the pattern of hearing loss raises specific concerns.

Conclusion

Pure tone audiometry is a widely available and reliable tool for assessing hearing. It measures how well a person detects sound across different frequencies and intensities, providing clear data that supports diagnosis and treatment.

By combining structured procedures, patient responses, and detailed analysis through the audiogram, clinicians can identify the type and extent of hearing loss.