4The audiometric criteria
Candidacy ultimately comes down to numbers, and the numbers reward careful interpretation. The degree of loss sets the scene, but the decisive figure is the best-aided sentence score, which must fall below a criterion that has crept upward over the years toward fifty or sixty per cent. A subtlety underpins it all: the score depends heavily on how loud the test speech is. Played loudly, the same patient scores far better than they ever do in real conversation; played at conversational or soft levels, the score drops to reflect the everyday difficulty that actually warrants an implant. Candidacy testing therefore deliberately uses softer presentation levels, and the exact criterion is shaped further by device labelling, programme rules and which ear is being considered. This module is about reading those numbers honestly.
TTwo numbers
Two figures anchor the audiometric criteria. The degree of loss (pure-tone average) describes severity, and most candidates sit in the severe-to-profound range — though, as the criteria expanded, the decisive figure shifted to the second: the best-aided sentence score, which must fall below a criterion for the patient to qualify.
CWhy the level matters
The same patient can pass or fail depending on how loud the test speech is. Presented at 70 dB SPL — louder than typical conversation — scores are higher and more reproducible but unrealistic. Dropped to 60 or 50 dB SPL, scores fall, exposing the difficulty the patient meets in life. Candidacy therefore tests at conversational and soft levels, which better reflect real listening, so a struggling patient is not excluded by an artificially easy test.[2004]
CWhere the line sits
The exact criterion is not universal. It is shaped by regulatory labelling (FDA-approved indications for a given device), by funding/programme rules (which can differ from device labels), and by the accumulating evidence that has pushed the allowable aided-speech ceiling toward 50–60%. The principle beneath the moving number is constant: implant when the best aided performance is poor enough that the implant is likely to do better.[2004]
CWhich ear is tested
Criteria also specify which ear the scores apply to. Historically the better ear had to be poor enough to qualify; expanded indications now allow implantation of a much poorer ear alongside an aidable better ear (asymmetric loss and single-sided deafness, Module 9), and the ear-specific aided scores feed directly into the ear-selection decision (Module 11). Reading the criteria means knowing not just the cut-off but which ear it is being applied to, and at what level.
TCDevice-specific cutoffs
The exact numbers are device- and condition-specific. A typical adult FDA criterion asks for sentence recognition around ≤50% in the ear to be implanted and ≤60% in the contralateral ear, with ≤50% best-aided for bilateral implantation; CMS is tighter at ≤40% best-aided. The electric-acoustic (EAS) window is different again — good low-frequency hearing (normal through ~1500 Hz) sloping to ≥80 dB in the highs, with generous word-score limits. The reason candidacy tests at conversational ~60 dB SPL rather than a loud 70 dB SPL is methodological: ordinary conversation sits near 60 dB SPL, and while post-operative scores are similar at the two levels, pre-operative scores are poorer at 60 — so testing loud artificially inflates the pre-op score and can wrongly disqualify a true candidate.
Which level is more appropriate, and why?
Why does candidacy testing use conversational/soft presentation levels rather than loud ones?
What shapes exactly where the candidacy speech-score line sits?