7Reduced temporal resolution
Speech unfolds in time, and the ear must follow it on a millisecond scale — the brief silences between words, the rapid onsets of consonants, the dips in a noisy background through which a listener catches glimpses of a target voice. Healthy hearing resolves these fine temporal details; the impaired ear, processing over a longer effective window, smears them. Gaps fill in, the envelope flattens, and the cues that separate one sound from another are blunted. This temporal blurring is least obvious in a quiet room and most punishing in noise and reverberation, exactly the situations where hearing-aid users say they struggle most. Like the other suprathreshold deficits, it is a distortion within the ear that amplification cannot reach.
THearing in time
Much of speech's information is temporal: the envelope — the pattern of rises and dips in amplitude over time — carries the rhythm of syllables, the brief gaps that mark word boundaries, and the rapid transitions of consonants. Resolving these requires fine temporal resolution, the ability to track quick changes moment to moment.
CA longer integration window
Sensorineural loss tends to lengthen the ear's effective integration window, so brief events are smeared together. Short gaps fill in; the sharp dips of the envelope soften; rapid modulations are flattened. The listener loses the crisp temporal structure that the healthy ear uses to parse the stream of speech.[1991]
CWhy noise is so hard
Temporal blurring matters most in noise and reverberation. A normal-hearing listener exploits the momentary dipsin a fluctuating background — “listening in the gaps” — to catch pieces of the target voice. The impaired ear, having smeared those dips, cannot glimpse through them, so performance in noise collapses far more than the quiet audiogram would predict. This is the single most common complaint of hearing-aid users: “I hear you, but not in a crowd.”
CWhy processing can't restore it
Could the hearing aid pre-process the signal to compensate — stretching or sharpening the temporal envelope? Researchers have tried temporally altered speech, but no practical, real-time scheme has improved recognition, and laboratory results have disappointed. Worse, some aggressive compression can itself distort the temporal envelope, flattening the very consonant–vowel intensity differences speech depends on. Lost timing, like lost frequency selectivity, is a property of the damaged ear that amplification cannot give back.
Why does the noisy setting collapse her understanding?
What happens to temporal processing in sensorineural loss?
Why does reduced temporal resolution hit hardest in noise?