Pure Tone Audiometry: How Your Hearing Test Works

Pure tone audiometry is universally recognised as the gold-standard diagnostic method for assessing hearing sensitivity. It is the foundational test upon which all audiological diagnoses and subsequent rehabilitation plans are built. At Buckinghamshire Hearing, our private audiology clinic in High Wycombe, we utilise this precise measurement technique to map your exact hearing thresholds across a comprehensive range of frequencies. This detailed mapping allows our clinical audiologists to determine not only the degree of any hearing loss but also its specific nature, providing the crucial data needed to recommend the most effective interventions.

The procedure is entirely painless and non-invasive, typically taking between 20 and 30 minutes to complete. You will be seated comfortably in a sound-treated environment, designed to eliminate background noise and ensure the highest level of accuracy. The audiologist will place calibrated headphones or insert earphones into your ears. You will be instructed to respond—usually by pressing a button or raising your hand—every time you hear a sound, no matter how faint it may seem.

The test is divided into two distinct phases: air conduction and bone conduction. This dual approach is essential for pinpointing the exact location of any auditory dysfunction within the ear's complex anatomy.

Air Conduction Testing

During the air conduction phase, sounds are presented through the headphones. These sounds travel through the outer ear canal, vibrate the eardrum, pass through the middle ear ossicles, and finally reach the cochlea (the inner ear). This pathway represents how you naturally hear sounds in your everyday environment. By measuring your responses, we establish your overall hearing sensitivity.

Bone Conduction Testing

Following the air conduction test, a small vibrating device called a bone oscillator is placed behind your ear, resting directly on the mastoid bone. This device bypasses the outer and middle ear entirely, sending sound vibrations directly to the cochlea through the skull. Comparing the results of air and bone conduction is a critical diagnostic step. If your bone conduction thresholds are significantly better than your air conduction thresholds, it indicates a problem in the outer or middle ear, known as a conductive hearing loss. If both are equally reduced, it points to a sensorineural hearing loss originating in the inner ear or auditory nerve.

"The distinction between air and bone conduction is the cornerstone of audiological diagnosis. It is the difference between identifying a potentially reversible condition, such as fluid in the middle ear, and diagnosing a permanent change in the inner ear's sensory cells. This clarity is what allows us to provide targeted, effective care at our High Wycombe clinic."

Human hearing encompasses a wide spectrum of sounds, but pure tone audiometry focuses on the frequencies most critical for understanding speech and environmental sounds. We systematically test frequencies ranging from 250 Hertz (Hz), which represents low-pitched sounds like a bass drum or the hum of a refrigerator, up to 8,000 Hz (8 kHz), which encompasses high-pitched sounds such as birdsong or the consonant sounds in speech like 's', 'f', and 'th'.

By testing this specific range, we can create a detailed profile of your hearing capabilities. For instance, age-related hearing loss typically affects the higher frequencies first, which is why many individuals struggle to hear clearly in noisy environments despite perceiving overall volume adequately. You can learn more about how we conduct these assessments on our hearing tests page.

The results of your pure tone audiometry test are plotted on a graph known as an audiogram. This visual representation is a vital tool for both the audiologist and the patient. The vertical axis of the audiogram represents the intensity or volume of the sound, measured in decibels (dB HL). The horizontal axis represents the frequency or pitch of the sound, measured in Hertz (Hz).

Your hearing thresholds—the softest sounds you can reliably detect—are marked on this graph. The right ear is typically denoted by red circles, while the left ear is marked with blue crosses. By connecting these points, we create a visual pattern that reveals the specific configuration of your hearing profile. For a more detailed explanation of how to interpret these graphs, please refer to our understanding your audiogram guide.

Common Audiogram Patterns

The shape of the curve on your audiogram provides significant clinical insight into the nature and potential cause of your hearing loss. Several distinct patterns are commonly observed in clinical practice:

While pure tone audiometry is the gold standard, it is important to acknowledge that it is a subjective test. Its accuracy relies heavily on the patient's active participation, attention, and ability to respond consistently. Factors such as fatigue, tinnitus, or cognitive difficulties can occasionally influence the results.

Furthermore, while the audiogram provides an excellent measure of hearing sensitivity, it does not fully capture how well an individual can process and understand complex sounds, particularly speech in noisy environments. This is why at Buckinghamshire Hearing, we always complement pure tone audiometry with speech audiometry and other diagnostic tools to gain a comprehensive understanding of your auditory function.

The data gathered from pure tone audiometry is the cornerstone of the Auditory Rehabilitation Process. It dictates whether medical referral is necessary, for instance, if a conductive hearing loss is identified. If a sensorineural hearing loss is diagnosed, the audiogram provides the precise prescription required for hearing aid fitting.

Modern hearing aids are highly sophisticated devices that are programmed to amplify specific frequencies based on your unique audiogram. By accurately mapping your hearing thresholds, we ensure that the hearing aids provide the exact amount of amplification needed at each pitch, maximising speech clarity while maintaining comfort. This tailored approach is fundamental to achieving successful outcomes and improving your quality of life.