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Otoacoustic emissions (OAE): TEOAE, DPOAE and SOAE
OAEs are faint sounds the cochlea itself produces thanks to outer hair cell motility, and they travel back through the middle ear to a microphone in the canal. A normal response says the middle ear and the outer cells work — not that the nerve is normal, and not what the threshold is.
Why it matters in the exam
The bank asks what is needed to obtain emissions: a normal middle ear in both directions and active outer cells. So present emissions rule out significant middle-ear fluid and a moderate or greater cochlear loss in that region, but not auditory neuropathy — the false negative of screening. Absent emissions may come from fluid, cochlear loss or a blocked canal, and do not show the degree of loss. OAEs are unaffected by sleep and sedation, so they suit infants; they are not a threshold test. Deciding that a response is present rests on a signal-to-noise ratio of at least about 6 dB in several frequency bands, together with good reproducibility.
How the types differ: TEOAEs are evoked by a broadband click, give information mainly at 1000–4000 Hz and usually vanish once the loss passes about 20–30 dB HL. DPOAEs are evoked by two tones (f2 ÷ f1 roughly 1.2); in humans the largest emission is at 2f1 − f2 (f1 = 2000, f2 = 2400 → 1600 Hz), they can be measured up to about 8000–10,000 Hz, and they sometimes persist with slightly greater losses (up to about 40 dB HL) — so DPOAEs are sometimes present without TEOAEs. SOAEs occur with no stimulus in a sizeable share of normal ears, so their absence is not pathological. Uses: newborn screening, ototoxic and noise monitoring (an early change before the audiogram), suspected functional loss, diagnosing ANSD and testing the efferent system.
Key points
- Source: outer hair cells; route: the middle ear both ways.
- TEOAE — click, 1000–4000 Hz, vanish above about 20–30 dB HL.
- DPOAE — 2f1 − f2, up to about 8000–10,000 Hz.
- Criterion: a signal-to-noise ratio of 6 dB and reproducibility.
- Uses: screening, ototoxicity, noise, functional loss, ANSD.
Summary table
| Type | Stimulus and features | Use and limit |
|---|---|---|
| TEOAE | Broadband click; information mainly 1000–4000 Hz | Vanish above about 20–30 dB HL; newborn screening |
| DPOAE | Two tones, f2 ÷ f1 roughly 1.2; emission at 2f1 − f2 | Up to about 8000–10,000 Hz; ototoxic monitoring |
| SOAE | No stimulus; narrow tones | Missing in many normal ears too — not diagnostic |
| Response criterion | Signal-to-noise ratio of at least 6 dB and good reproducibility | In several frequency bands, not just one |
| Present emissions | Outer cells and middle ear working | Do not rule out ANSD; do not set a threshold |
| Absent emissions | Fluid, cochlear loss or blockage | Do not show the degree of loss |
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Sources
- Robinette & Glattke (eds.), Otoacoustic Emissions: Clinical Applications, 3rd edition (2007) — TEOAE and DPOAE
- Kemp, British Medical Bulletin, 2002 — Otoacoustic emissions, their origin in cochlear function, and use
- Joint Committee on Infant Hearing, Journal of Early Hearing Detection and Intervention, 2019 — Year 2019 Position Statement
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.