Presbycusis is age-related hearing loss — the cumulative, sensorineural decline in hearing that accompanies ageing. It is the most common sensorineural loss, and its audiogram is the baseline against which other high-frequency losses are compared.

The audiometric signature

The presbycusic audiogram is a symmetrical, gently sloping, high-frequency sensorineural loss. Thresholds are near normal in the low frequencies and worsen progressively toward the high frequencies, with the two ears closely matched and no air–bone gap. The slope is gradual — the curve descends steadily rather than dipping and recovering.

Normal hearing

Presbycusis

O Right ear, air
X Left ear, air
< Right ear, bone
> Left ear, bone

Signature: Symmetrical, gently sloping high-frequency sensorineural loss; air and bone conduction track together.

Figure 1. Presbycusis versus normal hearing. A symmetrical, gently sloping high-frequency sensorineural loss; air and bone conduction track together with no air–bone gap.

Telling it apart from noise damage

The most common point of confusion is noise-induced hearing loss, which is also bilateral, symmetrical and high-frequency. The distinguishing feature is the shape: presbycusis slopes steadily downward and is usually worst at 8 kHz, whereas noise-induced loss notches at 4 kHz with relative recovery at 8 kHz. In practice the two often coexist, and a long-standing noise notch can be progressively obscured by a superimposed age-related slope.

Trainee Presbycusis is not a single entity. It reflects several processes — loss of cochlear hair cells, degeneration of the stria vascularis, loss of cochlear neurons — that contribute in differing proportions between individuals. This is partly why the audiometric slope and the degree of speech difficulty vary so much from one older patient to another, and why the audiogram alone does not fully predict how well someone manages with hearing aids.

Clinician Two cautions. First, symmetry matters: presbycusis is symmetrical, so a high- frequency loss that is clearly asymmetric should not simply be attributed to age — that pattern still calls for the retrocochlear question to be asked. Second, the speech difficulty of presbycusis is often disproportionate to the pure-tone loss, reflecting the neural component; a patient who struggles in background noise more than the audiogram predicts is showing exactly that, not exaggerating.

Special tests

Presbycusis is predominantly a cochlear loss, so recruitment is generally present and the SISI tends to be positive in the affected high frequencies, while tone decay is not a feature. Where a significant neural component is present the picture is less clean — another reason the audiogram is read alongside speech testing and the clinical context rather than in isolation.