# Audiometry > Audiometry for FMGE ENT: pure tone air and bone thresholds, the air-bone gap, speech discrimination and rollover, Jerger tympanogram types and OAE or BERA. - Canonical URL: https://prepelephant.com/topics/fmge/ent/audiometry-fmge - Exam / course: FMGE · Subject: ENT - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Audiometry", PrepElephant, https://prepelephant.com/topics/fmge/ent/audiometry-fmge ## Direct answer Reading an audiogram follows three moves: compare air conduction with bone conduction to find an air–bone gap (conductive loss), read the shape for pattern (the 4 kHz noise notch, the rising Meniere curve), and grade the severity from normal (0–25 dB) through mild, moderate and severe to profound. Speech audiometry adds discrimination — disproportionately poor scores or rollover flag retrocochlear disease — while tympanometry (Jerger types A, As, Ad, B, C) and acoustic reflexes probe middle-ear mechanics. Objective tools close the set: otoacoustic emissions screen outer hair cells and newborns, and auditory brainstem response (BERA) gives a threshold without cooperation. ## What you must remember - Pure tone audiometry tests 250–8000 Hz by air conduction and 250–4000 Hz by bone; symbols to recite: right ear red circle, left ear blue cross; bone conduction right red bracket, left blue bracket. - Hearing levels: normal 0–25 dB, mild 26–40, moderate 41–55, moderately severe 56–70, severe 71–90, profound beyond 90 dB. - An air–bone gap above about 10 dB means conductive loss (wax, perforation, effusion, otosclerosis); air and bone lines fallen together mean sensorineural loss; both a gap and depressed bone line mean mixed loss. - Speech reception threshold should agree with the 500–2000 Hz pure tone average within about 6–10 dB — disagreement suggests functional hearing loss or test error. - Speech discrimination disproportionately poor for the degree of loss, or rollover (scores falling as loudness rises), points retrocochlear — vestibular schwannoma — and demands MRI. - Tympanometry by Jerger: type A normal; As low compliance — otosclerosis or ossicular fixation; Ad high compliance — ossicular discontinuity; B flat — effusion or perforation; C negative peak pressure — Eustachian tube dysfunction. - Acoustic (stapedial) reflex is absent in conductive loss and in cochlear loss with recruitment; reflex decay is a retrocochlear sign. - Otoacoustic emissions test outer hair cell function and are the newborn screening tool; BERA/ABR provides objective thresholds and detects retrocochlear delay — the two-tier OAE-then-ABR protocol is the standard screening pathway, promoted in India under the deafness-control programme. ## Reading an audiogram, step by step Take a worked audiogram. Step one: find the bone line. If bone conduction thresholds sit within the normal band, whatever the air line does, the inner ear is innocent. Step two: read the air line. Suppose air conduction on the right sits around 45 dB across frequencies while bone is 10 dB — a 35 dB air–bone gap, a conductive loss; now ask tympanometry to arbitrate the cause: type As with absent reflex argues otosclerosis, type B with a history of otalgia argues effusion. Step three: check the shape of the loss. A 4 kHz notch bilaterally answers noise exposure; a rising low-frequency curve answers early Meniere; a high-frequency slope answers presbycusis. Step four: add speech testing. The speech reception threshold matching the 500–2000 Hz average confirms consistency; then the discrimination score. A patient whose pure tones suggest moderate loss but who scores only 40 percent on phonetically balanced words at comfortable loudness — worse than the audiogram predicts, or falling as intensity rises (rollover) — has a retrocochlear pattern, and the next investigation is gadolinium-enhanced MRI of the internal auditory meatus. Step five, when the patient cannot cooperate — infants, the bedridden, medico-legal cases: OAEs to screen cochlear function, BERA to estimate threshold and interpeak latencies electrophysiologically. ## Where students slip The symbol conventions cost easy marks: right-red-circle, left-blue-cross, with brackets for bone conduction — candidates who never learned them cannot read the plots the stems now print. The second slip is naming type B tympanogram as "otosclerosis"; it is the flat trace of effusion, while otosclerosis is type As with an absent stapedial reflex. The third is forgetting that tympanometry plus reflexes, not pure tones alone, separate the two conductive classics — stiff chain versus disrupted chain. And the SRT-PTA agreement rule is the standard test of malingering, since the exaggerating patient cannot fake a matching speech reception score. ## Frequently asked questions ### What do air conduction and bone conduction curves each represent? Air conduction tests the entire pathway from canal to cortex; bone conduction bypasses outer and middle ear. A gap between them of more than about 10 dB defines conductive hearing loss. ### What does a type As tympanogram indicate? A shallow compliance peak from a stiff ossicular chain — classically otosclerosis — contrasted with type Ad (hypercompliance) of ossicular discontinuity and type B (flat) of middle-ear effusion. ### What is rollover in speech audiometry? A fall in speech discrimination scores as presentation level rises, a retrocochlear sign seen with vestibular schwannoma and other auditory nerve lesions. ### Which tests screen newborn hearing? Otoacoustic emissions for outer hair cell function, followed by auditory brainstem response for babies who fail — the two-tier protocol that assigns risk and threshold objectively. ### How can audiometry help detect functional hearing loss? A speech reception threshold that disagrees with the pure tone average by more than about 10 dB, or absent OAEs/normal BERA against claimed thresholds, exposes non-organic loss.