Pure Tone Audiometry — Cost, Top Hospitals & Success Rates | MyMedicPlus

Pure tone audiometry (PTA) is the gold-standard diagnostic test for quantifying hearing sensitivity across a range of frequencies. It measures the softest sound (in decibels hearing level, dB HL) that a patient can detect at each of the standard test frequencies — 250, 500, 1,000, 2,000, 4,000, and 8,000 Hz — and plots these thresholds on an audiogram, a graphical display of hearing sensitivity across frequency and intensity.

The test measures two routes of sound transmission to the cochlea: air conduction (AC), in which pure tones are presented via calibrated headphones or insert earphones and travel through the external auditory canal, tympanic membrane, middle ear ossicles, and finally the cochlea; and bone conduction (BC), in which tones are delivered through a bone vibrator placed on the mastoid process or forehead, bypassing the outer and middle ear to stimulate the cochlea directly. Comparison of AC and BC thresholds identifies whether hearing loss is conductive (outer/middle ear), sensorineural (cochlear or retrocochlear), or mixed in origin.

The test is conducted in a calibrated soundproofed audiometric booth to eliminate ambient noise interference, ensuring threshold accuracy within the standard tolerance of ±5 dB HL. Stimuli are presented using a modified Hughson-Westlake ascending protocol (presenting tones from below threshold, increasing in 5 dB steps until response), which is the BSA and ASHA-recommended method for reliable threshold determination.

PTA is non-invasive, requires no injections or contrast, and is the cornerstone investigation for any patient presenting with hearing loss, tinnitus, aural fullness, or otological symptoms. Results directly guide the audiological management pathway — from hearing aid fitting and medical or surgical referral to cochlear implant candidacy assessment.

Pure tone audiometry is a diagnostic procedure rather than a treatment, and is used to characterise, quantify, and monitor hearing loss arising from a wide range of pathologies.

• Conductive hearing loss: An air-bone gap exceeding 10–15 dB HL at one or more frequencies, with bone conduction thresholds within normal limits, indicates a conductive mechanism — middle ear fluid (otitis media with effusion), ossicular discontinuity, otosclerosis, tympanic membrane perforation, or cerumen impaction. Conductive loss is potentially reversible with medical or surgical treatment.
• Sensorineural hearing loss (SNHL): Both AC and BC thresholds are elevated equally, with no significant air-bone gap. SNHL reflects cochlear hair cell damage, auditory nerve dysfunction, or central pathology. Common causes include presbycusis (age-related SNHL), noise-induced hearing loss (NIHL), sudden SNHL, and Ménière's disease.
• Mixed hearing loss: A combination of elevated BC thresholds (cochlear component) and a superimposed air-bone gap (middle ear component) — seen in conditions such as chronic suppurative otitis media with cochlear involvement, or otosclerosis with cochlear spread.
• Otosclerosis — Carhart notch: A characteristic dip in bone conduction thresholds at 2,000 Hz (the Carhart notch) is a mechanical artefact of otosclerotic stapes fixation rather than true sensorineural loss. It resolves after successful stapedectomy. Recognition of the Carhart notch avoids misclassification of otosclerosis as mixed or sensorineural loss.
• Noise-induced hearing loss (NIHL) and ototoxicity monitoring: A high-frequency notch at 4,000 Hz (or 3,000–6,000 Hz) is characteristic of NIHL from occupational or recreational noise exposure. Extended high-frequency audiometry (9,000–16,000 Hz) detects ototoxicity from aminoglycosides, cisplatin, loop diuretics, or quinine earlier than conventional PTA, as high-frequency cochlear hair cells are damaged first.
• Asymmetric SNHL: An interaural difference in hearing thresholds of ≥15 dB at three or more frequencies, or ≥20 dB at any single frequency, triggers urgent MRI investigation to exclude retrocochlear pathology including acoustic neuroma (vestibular schwannoma).

Pure tone audiometry is appropriate for any patient with hearing-related symptoms or with clinical indications requiring audiometric baseline or monitoring assessment.

• New-onset hearing difficulty: Any patient reporting difficulty understanding speech in noise, asking for repetition, turning up the television volume, or noticing asymmetric hearing should undergo PTA as the initial audiological investigation.
• Tinnitus: All patients with persistent unilateral or bilateral tinnitus require baseline audiometric evaluation, as the majority have an underlying audiometric abnormality — most commonly SNHL — that guides management and may warrant further investigation including MRI if asymmetric.
• Ototoxic drug monitoring: Patients receiving cisplatin, aminoglycoside antibiotics (gentamicin, amikacin), loop diuretics (furosemide at high doses), or quinine require baseline PTA and serial monitoring at treatment intervals. ASHA ototoxicity monitoring guidelines recommend high-frequency audiometry (HFA) up to 16,000 Hz as the most sensitive early detection method.
• Occupational noise exposure surveillance: Health and safety legislation in most countries (UK: Control of Noise at Work Regulations 2005; US: OSHA 29 CFR 1910.95) requires pre-employment baseline PTA and annual audiometric surveillance for workers exposed to noise above 85 dB(A) time-weighted average.
• Pre-operative ENT assessment: Baseline PTA is required before stapedectomy, cochlear implant candidacy assessment, middle ear surgery, and vestibular nerve section to document preoperative hearing and guide postoperative comparison.
• Paediatric and school screening: Sweep screening audiometry at 25 dB HL across standard frequencies (500–4,000 Hz) is performed in UK schools at ages 4–5 (school entry). Failures are referred for full diagnostic PTA.

PTA requires active, reliable behavioural responses and so is less suitable for infants and very young children (under 2.5–3 years), for whom objective threshold estimation using auditory brainstem response (ABR) or auditory steady-state response (ASSR) is used instead.

PTA forms the core of a comprehensive audiological assessment, typically complemented by several related investigations to fully characterise the type, degree, and site of hearing loss.

• Air conduction audiometry: Pure tones (250 Hz to 8,000 Hz) are presented via calibrated supra-aural or insert earphones to each ear separately. Thresholds are determined using the modified Hughson-Westlake ascending method. Results are plotted using standard audiogram symbols — circles for right ear AC (red), crosses for left ear AC (blue). Normal AC thresholds are 0–25 dB HL.
• Bone conduction audiometry: A bone vibrator on the mastoid bone delivers tones (250–4,000 Hz) directly to the cochlea, bypassing the middle ear. The difference between AC and BC thresholds constitutes the air-bone gap. A gap exceeding 15 dB at two or more consecutive frequencies indicates significant conductive pathology.
• Masking principles and effective masking levels: When the test ear has significantly better thresholds than the non-test ear, sound presented to the test ear may cross the head by bone conduction (cross-hearing), giving falsely good thresholds. Masking — delivering broadband or narrowband noise to the non-test ear — prevents this. Effective masking levels (EML) are calculated using the Hood plateau method. Inadequate or excessive masking produces erroneous results; masking dilemmas arise when the air-bone gap in the non-test ear is too large to apply adequate masking without overmasking.
• High-frequency audiometry (9,000–16,000 Hz): Standard PTA extends only to 8,000 Hz. Extended high-frequency audiometry to 16,000 Hz detects early cochlear damage from ototoxic drugs and noise exposure before changes appear at conventional frequencies, improving monitoring sensitivity. Requires specialist equipment (Interacoustics Equinox, Grason-Stadler GSI61).
• Tympanometry and correlation with PTA: Jerger Type A tympanogram (normal peak admittance at 0 daPa) confirms normal middle ear function. Type B (flat, no peak) indicates fluid or perforation. Type C (peak shifted to negative pressure) indicates Eustachian tube dysfunction. Correlation with the air-bone gap on PTA enables precise classification of conductive hearing loss.
• Speech audiometry — SRT and WRS: Speech Reception Threshold (SRT) — the level at which 50% of spondee words are correctly repeated — should approximate the pure tone average (PTA) at 500, 1,000, and 2,000 Hz within ±6 dB. Word Recognition Score (WRS, also called speech discrimination) at suprathreshold levels assesses cochlear or retrocochlear function; WRS below 70% at optimum presentation level, particularly with a large rollover effect (worsening WRS at higher levels), suggests retrocochlear pathology warranting MRI investigation.
• Auditory Brainstem Response (ABR) correlation: For uncooperative patients, medicolegal assessments (non-organic hearing loss), or suspected retrocochlear pathology, ABR provides an objective electrophysiological threshold estimate. Frequency-specific ABR using tone-burst stimuli provides threshold estimates at individual audiometric frequencies within approximately 10–15 dB of behavioural PTA thresholds.

Pure tone audiometry offers numerous practical advantages as the primary audiological assessment tool, and its results are directly linked to clinical decision-making across ENT, audiology, and primary care.

• Objective, reproducible frequency-specific thresholds: PTA provides a precise, frequency-by-frequency map of hearing sensitivity that cannot be obtained by subjective history alone or by whisper tests. Inter-session test-retest reliability for experienced audiologists is within ±5 dB HL — sufficient precision to detect clinically meaningful progression in monitoring settings.
• Non-invasive and well-tolerated: PTA involves no injections, contrast agents, radiation, or discomfort. It is suitable for children from approximately 3.5–4 years (using play audiometry adaptations) through to elderly patients, and can be completed within a 30–60 minute outpatient appointment.
• Differentiation of hearing loss type: The air-bone gap pattern reliably distinguishes conductive from sensorineural loss, directly informing the decision between surgical management (stapedectomy, ossicular chain reconstruction, grommets) and audiological rehabilitation (hearing aids, cochlear implants).
• Early detection of ototoxicity and NIHL: Serial audiometry enables early identification of ototoxic cochlear damage or noise-induced change before patients notice symptomatic hearing loss, allowing drug dose modification, noise exposure control, or hearing protection measures to prevent further deterioration.
• Guides hearing aid fitting: The audiogram provides the prescriptive target for hearing aid fitting. Modern hearing aid fitting protocols (NAL-NL2, DSL v5.0) use pure tone thresholds to calculate frequency-specific gain and maximum output targets, ensuring amplification is matched to the individual's hearing loss profile.
• Cochlear implant candidacy: PTA results (particularly aided speech discrimination scores and unaided thresholds) form a key criterion for cochlear implant candidacy assessment under NICE guidelines — adults with bilateral severe-to-profound SNHL (typically average thresholds above 70–80 dB HL) who gain insufficient benefit from optimally fitted hearing aids are referred for cochlear implant evaluation.

Pure tone audiometry is safe and non-invasive, but the clinician should be aware of factors that can limit test reliability or clinical interpretation.

• Patient reliability and cooperation: PTA is a behavioural, subjective test dependent on the patient providing consistent, honest responses. Fatigue, anxiety, deliberate exaggeration (non-organic hearing loss or functional overlay), or cognitive impairment may compromise threshold accuracy. Speech-to-noise ratio screening tests, tympanometry, and ABR can help identify unreliable PTA results.
• Non-organic hearing loss (functional hearing loss): Some patients — particularly in medicolegal or compensation contexts — may exaggerate hearing thresholds. Stenger test (for unilateral exaggeration), ABR, or ASSR provide objective verification. Discrepancy between PTA thresholds and speech reception threshold exceeding ±6 dB raises suspicion of non-organic overlay.
• Masking dilemma: In cases of severe asymmetric hearing loss, applying sufficient masking to the better ear to prevent cross-hearing may cause overmasking of the test ear (masking noise crosses to the test ear and elevates apparent thresholds). This masking dilemma complicates interpretation and may require bone anchored hearing assessment or ABR for reliable threshold estimation.
• Calibration and ambient noise requirements: Audiometric accuracy depends on calibrated equipment (annual UKAS-accredited calibration per BS EN ISO 8253 standards) and testing in a soundproofed booth with ambient noise levels within ISO 8253-1 permissible limits. Testing outside a properly calibrated booth degrades threshold accuracy significantly.
• Limited frequency resolution: Standard PTA at octave and inter-octave frequencies (250–8,000 Hz) may miss notches or sharply contoured audiometric changes in narrow frequency bands. Detailed audiometric patterns in medico-legal or specialist monitoring contexts may require additional half-octave frequencies or extended high-frequency testing.
• Testing limitations in young children: Play audiometry adaptations (visual reinforcement audiometry, conditioned play audiometry) extend PTA to children aged 2.5–4 years, but neonates, infants, and uncooperative young children require objective testing (DPOAE, AABR, ABR) for threshold assessment.

The results of pure tone audiometry directly determine the next steps in the audiological management pathway. A structured follow-up approach ensures that hearing loss is appropriately investigated, managed, and monitored.

• Normal audiogram with ongoing symptoms: If PTA is normal (thresholds ≤25 dB HL at all frequencies) but the patient reports hearing difficulty, further investigation should include speech-in-noise testing (HINT, QuickSIN), central auditory processing evaluation, or ENT review for structural pathology. Tinnitus management through psychology-led tinnitus retraining therapy (TRT) or CBT-based tinnitus therapy is indicated if tinnitus is the primary complaint.
• Conductive hearing loss: Referral to ENT for examination, tympanometry review, and consideration of surgical management — myringotomy and grommets for otitis media with effusion, stapedectomy for otosclerosis, or ossicular chain reconstruction for ossicular discontinuity. Hearing aid fitting provides immediate hearing benefit while awaiting surgery or when surgical management is not appropriate.
• Sensorineural hearing loss — hearing aid fitting: For mild to moderate SNHL (average threshold 26–70 dB HL), NHS or private digital hearing aid fitting using validated real-ear measurement (REM) and prescriptive targets (NAL-NL2) is the first-line management. Follow-up at 6–12 weeks post-fitting for acclimatisation assessment and fine-tuning.
• Severe-to-profound SNHL — cochlear implant evaluation: Patients with bilateral severe or profound SNHL (average threshold above 70–80 dB HL) who gain insufficient benefit from optimally fitted hearing aids are referred for cochlear implant candidacy assessment per NICE guidelines (TA566). Assessment includes aided PTA in a soundfield, speech discrimination testing, imaging (MRI cochlea), and medical suitability evaluation.
• Asymmetric SNHL — urgent MRI: Any asymmetric SNHL (threshold difference ≥15 dB at three frequencies, or ≥20 dB at any frequency) should trigger urgent MRI of the internal auditory meati (IAMs) and posterior fossa to exclude vestibular schwannoma (acoustic neuroma). Even small asymmetries warrant investigation.
• Serial monitoring programmes: For ototoxicity monitoring, occupational noise surveillance, or tracking progressive SNHL, PTA is repeated at 3–6 month intervals. A shift of ≥10 dB at two consecutive frequencies, or ≥15 dB at one frequency confirmed at two consecutive sessions, constitutes a significant audiometric shift requiring action.

Pure tone audiometry costs vary substantially between NHS or publicly funded settings and private or specialist audiological practice.

• United Kingdom (NHS): PTA is freely available on the NHS when referred by a GP, ENT consultant, or occupational health physician. NHS community audiology assessment (including PTA, tympanometry, and hearing aid fitting assessment) is fully funded. Private audiology clinic PTA appointments cost approximately £80–£200 depending on the clinic and comprehensiveness of the assessment.
• India: Audiometric assessment is available at ENT departments of major public hospitals free of charge or at nominal cost. Private audiology clinics charge approximately INR 500–2,000 (USD 6–25) for a standard PTA. Specialist centres (AIIMS, Manipal, Amrita) offer comprehensive audiological assessment including ABR and ASSR at higher but still accessible costs (INR 3,000–8,000).
• United States: Private audiology clinic PTA typically costs USD 100–250 per session without insurance. Medicare Part B covers diagnostic audiological assessments when referred by a physician for a medical reason (not for routine hearing screening). Out-of-pocket costs may include specialist fees for extended high-frequency audiometry or ABR supplementation.
• Australia: Audiometric assessment for occupational noise surveillance is typically employer-funded under WorkSafe requirements. Medicare-rebated audiology services are available for eligible patients via a chronic disease management plan. Private clinic costs are AUD 100–300 for a comprehensive PTA assessment.
• Specialist investigations (ABR, ASSR, OAE): Supplementary investigations used in conjunction with PTA carry additional costs: distortion product OAE (DPOAE) USD 80–150; ABR click and tone-burst threshold testing USD 200–500; ASSR multi-frequency threshold testing USD 250–600. These are covered by NHS audiology pathways when clinically indicated.

For occupational health or medicolegal audiometry, accreditation of the testing facility and audiologist to national standards (UKSOC or BSA registration in the UK; ASHA CCC-A in the USA) is essential to ensure results are legally defensible and clinically valid.

While pure tone audiometry remains the standard diagnostic hearing test, several complementary and alternative assessments address specific clinical scenarios where PTA alone is insufficient or inapplicable.

• Auditory Brainstem Response (ABR / BAER): An objective electrophysiological test measuring neural responses to click or tone-burst stimuli at the level of the auditory nerve and brainstem. Used as the gold standard for threshold estimation in neonates and infants (automated ABR, AABR, forms part of the NHS Newborn Hearing Screening Programme), uncooperative patients, medico-legal assessments, and retrocochlear (acoustic neuroma) investigation. Frequency-specific tone-burst ABR estimates thresholds within 10–15 dB of behavioural PTA.
• Auditory Steady-State Response (ASSR): Uses multiple simultaneous modulated carrier tones at 250–4,000 Hz to generate frequency-specific threshold estimates for all four frequencies simultaneously, with statistical detection of the response. Particularly valuable in neonates and infants for frequency-specific threshold estimation and hearing aid prescription target calculation. Provides reliable estimates even in anaesthesia or natural sleep.
• Otoacoustic Emissions (OAEs): Transient-evoked OAEs (TEOAEs) or distortion product OAEs (DPOAEs) provide a rapid, non-invasive assessment of outer hair cell function independent of patient cooperation. Used for neonatal hearing screening, ototoxicity monitoring, and distinguishing cochlear from retrocochlear SNHL. OAEs are present in normal hearing and mild SNHL, absent in moderate-severe SNHL — providing a quick binary cochlear assessment.
• Automated audiometry (Bekesy audiometry): Self-recording audiometry where the patient controls the stimulus intensity by pressing a button, tracing a sweeping tone. Used in some occupational health and screening contexts. Jerger's Bekesy audiogram classification types I–V can suggest retrocochlear pathology (Type IV and V).
• Speech-in-noise testing: Hearing in Noise Test (HINT), Quick Speech-in-Noise test (QuickSIN), or BKB-SIN assess functional ability to understand speech in background noise — a common complaint where conventional PTA thresholds are near-normal. These tests detect auditory processing difficulties, cochlear synaptopathy ("hidden hearing loss"), and high-frequency SNHL affecting speech understanding disproportionate to the audiogram.
• Tympanometry and stapedial reflex testing: Middle ear assessment using immittance audiometry provides complementary information about tympanic membrane integrity, middle ear pressure, and stapedial reflex thresholds (for facial nerve and retrocochlear screening). Essential for complete audiological assessment but does not replace PTA for threshold determination.