ECochG Atlas · Practice

Practice

Two-part practice mode. First, the SP/AP ratio calculator that applies all four published cutoffs from the disease modules. Second, four cross-module pattern-recognition vignettes that test diagnostic reasoning across the atlas — new cases, not duplicates of the in-module exercises. See also /cases, /quiz, and /compare.

SP/AP ratio calculator

Enter measured SP and AP amplitudes (µV); the ratio is computed live and compared against Ferraro (0.40), Gibson (0.30), Adams (0.34), and Liberman (0.35–0.60). The ratio is electrode-independent — the same number from a tiptrode, TM, transtympanic, or intracochlear recording. The full interpretive caveats live in Module 14 · Tools.

µV
µV
SP/AP ratio—
Ferraro 0.40Classical Ménière's amplitude-ratio threshold (Module 5)—
Gibson 0.30Alternative more-sensitive Ménière's threshold (Module 5)—
Adams 0.34Superior canal dehiscence; 92.3% sens, 94% spec (Module 6)—
Liberman 0.35–0.60Cochlear synaptopathy group-level range (Module 11)—

The ratio is electrode-independent — the same number from a tiptrode, TM, transtympanic, or intracochlear recording. Absolute amplitudes scale roughly 1× / 3× / 10× / 25× with electrode site, but the ratio does not. Cutoffs are interpretive anchors, not standalone diagnostic criteria — see the linked module for the clinical context that has to accompany the number.

Pattern recognition — four mixed vignettes

Four short cross-module scenarios. Each vignette is a fresh case (not duplicated from the modules) testing whether you can place the finding in the right disease. Click any option to reveal its rationale and the teaching point.

Practice 1 · Trainee level
A 35-year-old has 6 months of episodic vertigo, tinnitus, and aural fullness in the left ear. The audiogram is normal on the day of testing. Left-ear ECochG (tiptrode, alternating polarity, 90 dB nHL click): SP 0.6 µV, AP 1.0 µV. Right-ear ECochG: SP 0.2 µV, AP 1.6 µV.

Which finding most strongly supports a hydrops interpretation?

Practice 2 · Trainee level
A 7-year-old presents with delayed language and parents describe inconsistent responses to speech. OAEs are present bilaterally. Click ABR shows no identifiable wave V to 95 dB nHL. ECochG with alternating polarity shows what appears to be a waveform — but with rarefaction-only and condensation-only runs separated, the waveform inverts cleanly across the entire latency window with no residual neural component.

What is the most likely diagnosis and the operative interpretation?

Practice 3 · Clinician level
A 55-year-old has 18 months of progressive asymmetric hearing loss on the right with mild tinnitus and no vertigo. The audiogram shows a 30 dB high-frequency SNHL on the right with a normal left ear. Right-ear ECochG is unremarkable: SP/AP 0.18, normal latency. Left-ear ECochG is also normal.

What does the normal ECochG tell you about a possible vestibular schwannoma?

Practice 4 · Trainee level
Cochlear implant surgery, lateral-wall electrode, slow insertion under intraoperative ECochG monitoring via the implant's own apical electrode. The CM amplitude is stable through the first 18 mm; between 18 and 22 mm insertion depth, the CM amplitude falls progressively from baseline by 35%.

What is the most appropriate immediate response?

About these vignettes.All four practice cases are deliberately written to cross module boundaries — the answers require recognising the diagnostic pattern, not just recalling a single fact. For module-specific clinical cases see /cases; for multi-question self-assessment quizzes see /quiz.