7Tinnitus Loudness Matching

FWhat loudness matching measures

Loudness matching is a psychoacoustic bedside procedure that asks a simple question: how intense must an external sound be before it sounds as loud as the patient’s tinnitus? Having first established the tinnitus pitch, the examiner presents a tone (or narrowband noise) at that frequency and raises its level in small steps until the patient judges it equal to their tinnitus.

The result is conventionally expressed not in absolute decibels but in decibels of sensation level (dB SL) — that is, decibels above the patient’s own hearing threshold at the matched frequency. Reporting in dB SL is essential because most tinnitus patients have hearing loss at the relevant frequency; a match of 60 dB HL in an ear with a 55 dB threshold is only 5 dB SL [2000].

FThe low-loudness paradox

The most clinically important — and counter-intuitive — finding is that matched loudness is almost always low. Across large series the tinnitus of most sufferers matches to only a few decibels of sensation level, frequently in the 5–15 dB SL range, even when the same patient rates the tinnitus as severely intrusive [2003].

This dissociation between a near-threshold acoustic match and profound subjective distress is one of the central lessons of tinnitus medicine. It tells us that the burden of tinnitus is not encoded in its raw sensory magnitude but in how the brain — its attentional and limbic networks — reacts to the signal [2013]. A clinician who reassures a patient that the matched loudness is “tiny” without acknowledging the genuine distress will lose the consultation.

TWhy a few dB SL can feel intolerable: recruitment

Part of the explanation lies in loudness recruitment. In an ear with cochlear (outer-hair-cell) hearing loss, the loudness-growth function is abnormally steep: once a sound becomes audible above the elevated threshold, perceived loudness climbs far faster than in a normal ear, reaching normal loudness levels over a compressed intensity range.

Because dB SL is referenced to the raised threshold, a match expressed as a small SL value can correspond to a substantial perceived loudness once recruitment is taken into account. This is why loudness matched in dB SL systematically underestimates the loudness the patient actually experiences, and why magnitude-estimation or categorical loudness-scaling methods sometimes give a fuller picture [2014].

TTechnique and pitfalls

Match at or very near the previously determined tinnitus pitch; matching at an unrelated frequency confounds the result. Ascend in 1–2 dB steps and bracket around the equal-loudness point rather than approaching from one direction only, because patients tend to anchor on the first audible level. The contralateral ear is often used for the comparison tone when tinnitus is unilateral, but inter-ear loudness differences must then be allowed for.

Test–retest variability is real: matched loudness can shift several decibels between sessions and even within a session, reflecting fluctuating attention and tinnitus state [2024]. Repeat the match and report a representative value, not a single reading.

CClinical value and limits

Loudness matching has modest diagnostic value but real uses: it provides an objective-ish baseline for documenting the percept, supports counselling (demonstrating to the patient how their distress exceeds the acoustic match can itself be therapeutic), and offers a crude outcome measure when repeated. Matched pitch and loudness together also localise the percept against the audiogram, reinforcing the link between the tinnitus and the region of cochlear damage [2024].

Its limits are equally important. Matched loudness correlates poorly with handicap questionnaire scores, so it must never be used to validate or dismiss a patient’s suffering. It is unreliable in hyperacusis, severe hearing loss, and complex or polyphonic tinnitus, and it does not by itself predict treatment response [2013].