Pure Tone Audiometry — Procedure Guide, Recovery & Risks | MyMedicPlus

Pure tone audiometry (PTA) is a standardised audiometric test that measures hearing sensitivity across frequencies from 250 Hz to 8000 Hz by presenting pure tones through headphones or a bone-conduction vibrator. The patient signals each time they hear a tone, and the audiologist plots hearing thresholds in decibels (dB HL) on an audiogram. PTA establishes the degree (mild, moderate, severe, profound), type (conductive, sensorineural, mixed), and configuration of hearing loss, guiding decisions on hearing aid fitting, medical treatment, or surgical intervention. It is the cornerstone diagnostic tool in audiology and ENT practice. Pure tone audiometry (PTA) is a standardised audiometric test that measures hearing sensitivity across frequencies from 250 Hz to 8000 Hz by presenting pure tones through headphones or a bone-conduction vibrator. The patient signals each time they hear a tone, and the audiologist plots hearing thresholds on an audiogram — a frequency-versus-intensity graph measured in decibels hearing level (dB HL). Normal hearing is defined as thresholds of 0–25 dB HL across all tested frequencies. Hearing loss is classified as mild (26–40 dB), moderate (41–55 dB), moderately severe (56–70 dB), severe (71–90 dB), or profound (over 90 dB). Air conduction testing (via headphones) measures the entire hearing pathway from outer ear to brain. Bone conduction testing (via mastoid vibrator) bypasses the outer and middle ear, testing inner ear (cochlear) function directly. The air-bone gap — difference between air and bone conduction thresholds — distinguishes conductive from sensorineural hearing loss: a gap over 10 dB indicates a conductive component. PTA is the cornerstone of audiological assessment, required before any hearing device fitting, hearing surgery, or medicolegal hearing evaluation. It typically takes 20–40 minutes and is administered by a registered audiologist in a calibrated soundproofed booth meeting ANSI/BSA standards.

PTA is indicated for anyone reporting hearing difficulty, tinnitus, vertigo, or ear-related symptoms. It is required before hearing aid dispensing, before and after ear surgery (stapedectomy, mastoidectomy, tympanoplasty), and for infants failing newborn otoacoustic emission (OAE) screening. Occupational audiometry programs use PTA for noise-exposed workers under OSHA and HSE surveillance requirements. Medicolegal hearing assessments, monitoring of ototoxic medications (aminoglycosides, cisplatin, loop diuretics), and routine hearing screening for adults over 60 years are additional indications. Children with speech delay, recurrent ear infections, or suspected glue ear require PTA as part of their audiological assessment. PTA is indicated for anyone reporting hearing difficulty, tinnitus, vertigo, or ear-related symptoms. It is required before hearing aid dispensing, before and after ear surgery (stapedectomy, mastoidectomy, tympanoplasty), and for infants failing newborn otoacoustic emission (OAE) screening. Occupational health PTA is mandatory for workers in noisy industries and armed forces personnel to establish baseline thresholds and monitor noise-induced hearing loss. School entry audiometry identifies previously undetected childhood hearing loss. Elderly adults over 65 benefit from routine PTA as presbycusis (age-related hearing loss) is underdiagnosed. PTA is essential before and after ototoxic medication exposure (cisplatin chemotherapy, aminoglycoside antibiotics) to monitor for treatment-induced hearing loss.

The patient sits in a calibrated soundproofed audiometric booth. Supra-aural or insert earphones are fitted for air-conduction testing. The audiologist presents pure tones at each frequency (250, 500, 1000, 2000, 4000, 8000 Hz) using the Hughson-Westlake modified ascending method to determine the minimum hearing level detectable 50% of the time. Bone conduction is tested by placing a mastoid vibrator behind the ear, bypassing the outer and middle ear to assess cochlear function directly. Narrow-band masking noise is applied to the non-test ear to prevent crossover. Speech audiometry (word recognition scores) is commonly added. The full test takes 20–40 minutes and requires patient cooperation. Paediatric modifications use play audiometry or visual reinforcement for young children. The patient sits in a calibrated soundproofed audiometric booth. Supra-aural or insert earphones are fitted for air-conduction testing. The audiologist presents pure tones at each frequency (250, 500, 1000, 2000, 4000, 8000 Hz) using the Hughson-Westlake modified ascending method to determine the minimum level at which the patient responds 50% of the time. Bone conduction testing at 500–4000 Hz is performed with a vibrator placed on the mastoid process. Masking (introducing narrow-band noise into the non-test ear) prevents cross-hearing when there is asymmetric hearing loss. Results are plotted as an audiogram with air conduction thresholds (O for right, X for left) and bone conduction symbols. Additional extended high-frequency testing (9000–16000 Hz) may be performed for ototoxicity monitoring. Speech audiometry — word recognition testing at threshold and supra-threshold levels — may accompany PTA to assess functional hearing.

PTA provides a complete frequency-specific hearing profile that enables precise diagnosis and targeted management. It differentiates conductive from sensorineural hearing loss, directing patients to the appropriate intervention — hearing aids for sensorineural loss, or surgery or medical treatment for conductive causes. Audiograms guide hearing aid programming to amplify selectively at affected frequencies, improving speech clarity without over-amplification. Serial testing every 6–12 months monitors disease progression or confirms treatment response after stapedectomy, grommets, or medical therapy. PTA is non-invasive, painless, and reproducible within 5 dB when standardised protocols are followed. PTA provides a complete frequency-specific hearing profile that enables precise diagnosis and targeted management. It differentiates conductive from sensorineural hearing loss, directing patients to the appropriate intervention — hearing aids for sensorineural loss, or surgery or medical treatment for conductive loss (otosclerosis, otitis media with effusion). PTA results guide hearing aid selection, programming, and outcome verification. Serial PTA charts disease progression in conditions like Ménière disease, autoimmune inner ear disease, and ototoxicity monitoring, providing objective evidence for clinical decisions and medicolegal purposes.

Pure tone audiometry carries no physical risks and is entirely non-invasive. However, test accuracy depends on patient cooperation and reliable responses. False thresholds may result from patient fatigue, inability to follow instructions, deliberate feigning (pseudohypacusis — detected by comparing PTA with objective tests such as ABR), poor sound booth calibration, or inappropriate masking technique. Elevated thresholds from temporary threshold shift (TTS) occur if the patient was exposed to loud noise immediately before testing; a minimum 16-hour quiet period before audiometry is recommended. Results must be interpreted in clinical context alongside tympanometry, otoscopy, and speech audiometry. Pure tone audiometry carries no physical risks and is entirely non-invasive. However, test accuracy depends on patient cooperation and reliable responses. False thresholds may result from patient fatigue, inability to follow instructions, deliberate feigning (pseudohypacusis — detected by comparing behavioural thresholds with objective tests like ABR and OAE), or inadequate masking technique. Background noise contamination above ANSI standard limits in the test environment can elevate apparent thresholds. Shadow responses (hearing the test tone in the non-test ear through bone conduction despite masking) are addressed with appropriate masking levels.

No recovery is required after pure tone audiometry. Results are discussed with the patient at the appointment and a written audiogram copy is provided. If hearing loss is confirmed, the audiologist or ENT specialist recommends next steps: hearing aid referral for sensorineural loss, GP or ENT referral for middle ear disease, or tympanometry and imaging for complex cases. Follow-up audiograms are typically scheduled every 6–12 months to monitor progression in confirmed hearing loss, or annually for occupational noise surveillance. Children with fluctuating conductive loss from glue ear are monitored every 3 months during the period of active disease management. No recovery is required after pure tone audiometry. Results are discussed with the patient at the appointment and a written audiogram copy is provided. If hearing loss is confirmed, the audiologist or ENT specialist recommends next steps: hearing aid referral for sensorineural loss, GP or ENT referral for conductive loss evaluation, or specialist paediatric audiology for children. A follow-up audiogram is arranged at intervals depending on the clinical situation — 3-monthly for ototoxicity monitoring, 6-monthly for Ménière disease, annually for stable presbycusis. Digital audiogram records are maintained for serial comparison.