PTA Test and Impedance Audiometry: How These Two Hearing Tests Work Together

Pure tone audiometry measures the softest sounds a person can reliably detect across a defined range of frequencies.

The result is a hearing threshold profile, expressed as an audiogram, that documents how hearing sensitivity varies across the audible frequency range at a specific point in time.

The patient sits in a sound-treated booth wearing headphones or insert earphones.

Pure tones at specific frequencies, typically 250 Hz through 8,000 Hz, are presented at varying intensity levels. The patient signals each time a tone is perceived, even faintly.

This is air conduction testing; sound travels through the outer ear canal and middle ear before reaching the cochlea.

A second phase replaces the headphones with a bone conductor, a small vibrating device placed against the mastoid bone behind the ear. This delivers sound vibrations directly to the cochlea, bypassing the outer and middle ear entirely.

Comparing air conduction and bone conduction thresholds at the same frequencies is the central diagnostic step of pure tone audiometry.

Reading the audiogram

The audiogram plots frequency in Hertz along the horizontal axis and hearing level in decibels along the vertical axis.

Softer thresholds, better hearing, sit higher on the chart; thresholds requiring louder sounds sit lower.

Air conduction results are marked with circles for the right ear and crosses for the left. Bone conduction uses bracket symbols.

Impedance audiometry measures how the middle ear responds to changes in air pressure and to sound; it assesses the mechanical function of the tympanic membrane and ossicular chain, not hearing sensitivity.

This is the fundamental distinction from the PTA test: while PTA answers how well someone hears, impedance audiometry answers why the middle ear is or is not transmitting sound effectively.

The two core components are tympanometry and acoustic reflex testing.

Tympanometry

A soft probe is placed snugly in the ear canal, creating a sealed chamber. The probe varies the air pressure in the canal across a defined range while simultaneously delivering a tone.

It measures the proportion of sound the eardrum reflects back at each pressure level; higher reflection indicates reduced eardrum mobility.

The output is a tympanogram, a pressure-mobility curve that reveals the functional state of the middle ear.

Three tympanogram types carry the most clinical significance.

A Type A tympanogram shows a normal peak at or near ambient pressure; the middle ear is functioning normally.

A Type B tympanogram is flat with no identifiable peak, indicating either fluid accumulation behind the eardrum (otitis media with effusion) or a tympanic membrane perforation.

A Type C tympanogram shows a peak shifted into negative pressure, indicating eustachian tube dysfunction and reduced middle ear ventilation.

Acoustic reflex testing

The stapedius muscle, located in the middle ear, contracts reflexively when exposed to loud sounds. This contraction stiffens the ossicular chain and is detectable through the impedance probe as a change in acoustic admittance.

Acoustic reflex testing measures whether this reflex is present, at what intensity it activates, and whether it is symmetrical between ears.

Absent or elevated acoustic reflexes carry diagnostic significance beyond the middle ear.

Absent reflexes with normal tympanometry may suggest ossicular chain fixation, facial nerve pathology, or retrocochlear hearing loss, findings that would not be apparent from the PTA test alone and that may warrant imaging.

When PTA and impedance audiometry results are interpreted together, the diagnostic picture is substantially clearer than either test provides independently.

Scenario 1, conductive hearing loss: A child presents with reduced hearing. The PTA test shows elevated thresholds across low and mid frequencies; the child needs louder sounds to hear.

The tympanogram shows a flat Type B curve. Together, these results point toward otitis media with effusion, fluid in the middle ear reducing eardrum mobility. The combination produces a working diagnosis without requiring further complex investigation.

Scenario 2, sensorineural hearing loss: An adult shows the same degree of hearing loss on PTA but a normal Type A tympanogram and presents acoustic reflexes at expected levels.

The normal middle ear mechanics exclude a conductive cause; the loss is sensorineural, pointing toward cochlear or auditory nerve involvement. Management planning shifts accordingly.

Scenario 3, Retrocochlear pathology: An adult presents with asymmetric PTA thresholds, one ear significantly worse than the other, and absent acoustic reflexes on the same side at lower-than-expected intensity levels.

The combination of asymmetric PTA and abnormal acoustic reflexes raises concern for retrocochlear pathology, such as a vestibular schwannoma, and prompts MRI referral. Neither finding alone would carry the same diagnostic weight.

Hearing assessments, particularly PTA and impedance audiometry, are among the most underutilized diagnostic tools in corporate health benefit packages, despite occupational noise exposure being one of the most prevalent and preventable causes of hearing loss in India's workforce.

Diagnostics, 8,500+ NABL-Accredited Labs and Clinics. Employees can book audiological evaluations, including PTA and impedance audiometry, cashlessly through Visit Health's diagnostic network across India.

Results are tracked digitally through the app without requiring physical report collection.

Teleconsultation, ENT, and Audiology: A PTA audiogram showing asymmetric thresholds or an impedance result showing absent reflexes with normal tympanometry requires ENT specialist interpretation and a management plan.

Visit Health's teleconsultation platform connects employees with ENT specialists across 30+ specialties, same day, without a hospital visit or a separate referral queue.

AI-Powered Smart Reports: An audiological report containing audiogram thresholds, tympanogram classification, and acoustic reflex results is not straightforward for most patients to interpret together.

Visit Health's Smart Reports to convert findings into plain-language summaries of what the audiogram pattern indicates, what the tympanogram type means, and what the recommended next step is.

Visit Clinic, Bengaluru (Marathahalli, Outer Ring Road): For employees in Bengaluru who need an in-person ENT consultation or audiological assessment, particularly when surgical management or hearing aid evaluation is being considered, Visit Clinic provides on-ground appointments connected to the broader diagnostic and specialist ecosystem

PTA and impedance audiometry are complementary tools that answer different questions about the same auditory system. The PTA test establishes how well someone hears and quantifies the degree and frequency pattern of any loss. Impedance audiometry establishes whether the middle ear is mechanically functioning and whether the acoustic reflex arc is intact. The combination is what allows a clinician to locate where in the hearing pathway the problem originates and to plan management accordingly.

What is a PTA test used for? 

It measures hearing sensitivity across a range of frequencies to determine whether hearing loss is present, how severe it is, and whether the pattern suggests a conductive, sensorineural, or mixed cause.

How long does a PTA test take? 

A standard PTA test including air and bone conduction typically takes 20-40 minutes, depending on the number of frequencies tested and whether masking is required to prevent the better ear from influencing results from the worse ear.

What is the difference between PTA and impedance audiometry? 

The PTA test measures how well a person hears by finding the softest audible tones across frequencies. Impedance audiometry measures how the middle ear functions mechanically. One assesses sensitivity; the other assesses structure and reflex integrity. Both are needed for a complete audiological assessment.

What does a Type B tympanogram mean?

A flat Type B tympanogram indicates the eardrum is not responding normally to pressure changes, most commonly caused by fluid accumulation in the middle ear (otitis media with effusion) or a tympanic membrane perforation.

Can a PTA test diagnose the cause of hearing loss? 

Not independently. It identifies that hearing loss exists and characterizes its pattern, but determining the underlying cause and the site of the lesion requires combining PTA results with impedance audiometry findings and clinical history.

Is impedance audiometry painful or uncomfortable? 

No. The probe sits in the outer ear canal, and the pressure variations are mild. Most patients describe a brief sensation of fullness lasting a few seconds during tympanometry. No pain, no needles, and no recovery time are involved.

What is a normal hearing threshold on a PTA test? 

Thresholds of 25 dB HL or better across tested frequencies are generally considered within normal limits for adults. Values above 25 dB indicate some degree of hearing loss, mild, moderate, severe, or profound, depending on the level.

When are both PTA and impedance audiometry ordered together? 

In almost all standard hearing evaluations. Any complaint of hearing loss, ear fullness or pressure, recurrent ear infections, tinnitus, or a failed hearing screening warrants the combined battery because neither test alone provides a complete diagnostic picture.

Book a cashless PTA and impedance audiometry evaluation through Visit Health and receive same-day ENT specialist interpretation today.