CI Atlas · Audiological Evaluation · Module 15

15Loudness, tinnitus & non-organic hearing loss

Threshold is only the floor of hearing; what happens above it can matter just as much. In a damaged cochlea, loudness grows abnormally fast, so the comfortable window between the faintest audible sound and the merely tolerable shrinks — sometimes to a sliver — and speech can no longer be fitted into it, which is part of why amplification fails. The same suprathreshold domain holds tinnitus and hyperacusis, documented before any implant because the device may change them. And it holds one of audiology's subtler challenges: the loss that the tests cannot quite believe — non-organic hearing loss, where the behavioural audiogram and the objective measures disagree, and the cross-check exists precisely to catch it. This module covers measuring loudness, characterising tinnitus, and unmasking a functional overlay before it leads anyone astray.

TLoudness & the dynamic range

Loudness measures — growth, the uncomfortable loudness level, and the dynamic range between threshold and discomfort — characterise the suprathreshold percept the audiogram misses. Recruitment(abnormally rapid loudness growth) narrows the usable range in cochlear loss, so speech can no longer fit comfortably — the deeper mechanism explored in the When-Hearing-Aids-Aren't-Enough chapter.[2020]

CTinnitus & hyperacusis

Tinnitus and hyperacusis are quantified with pitch and loudness matching, minimum masking level, residual inhibition, and validated handicap questionnaires, and are documented before implantation — because the implant can change tinnitus (often suppressing it), and severe tinnitus can itself become a reason to implant.

CNon-organic hearing loss

Non-organic hearing loss — any loss not explained by organic pathology — spans a continuum from conscious malingering, through an intermediate factitious category, to subconscious conversion, and its incidence among candidates may be rising with medico-legal stakes. Behavioural red flags include test–retest inconsistency, an SRT that disagrees with the pure-tone average, absent shadow curves in a claimed unilateral total loss, and the Stenger principle for feigned one-sided loss.

A non-organic (functional) component — from conscious malingering through factitious to subconscious conversion — is caught by the cross-check. Red flags: an SRT that disagrees with the pure-tone average, test–retest inconsistency, absent shadow curves in a claimed unilateral “total” loss, and the Stenger principle for feigned one-sided loss. Objective tests — OAE, reflexes and especially ABR/ASSR — establish the true organic floor, and resolving the overlay is essential before any implant (wrongly implanting carries medico-legal risk). Schematic.

CThe objective cross-check

Objective measures settle it: OAEs, acoustic reflexes and especially ABR/ASSR establish the true organic threshold, and ABR is recommended on any candidate whose validity is in doubt. Resolving a non-organic overlay is essential before implantation — wrongly implanting such a patient carries medico-legal risk — and psychological referral is part of completing the assessment.

Tinnitus can be characterised psychoacoustically by pitch matching (the frequency that best resembles it), loudness matching (how far above threshold it sits — usually only a few decibels, even when it feels loud), and the minimum masking level. The matched pitch typically lies in the region of greatest hearing loss, tying the symptom to the underlying cochlear damage. These measures document a complaint that is otherwise entirely subjective and guide counselling and management. Illustrative; schematic.

Case 10.15 · The audiogram the tests don't believe

An adult claims a 70 dB loss on behavioural testing, but the SRT is 25 dB, OAEs are present and the ABR shows normal thresholds. There is a compensation claim.

How should this be handled?

Self-assessment — Module 152 questions

Question 1 · Trainee

What does loudness recruitment do to the dynamic range?

Question 2 · Clinician

Which finding suggests a non-organic component?

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