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Hearing

Hearing in noise

Restaurants, meetings, family dinners. This is where hearing loss hurts most, and where the audiogram predicts least.

The cocktail-party problem

In a quiet room, understanding speech is a matter of audibility. In a noisy one, it is a matter of separation: picking one stream of sound out of several that overlap in time and frequency. Normal hearing does this remarkably well, using the fine frequency tuning of the cochlea, the timing precision of the nerve, and the comparison of the two ears in the brainstem. Each of these degrades with hearing loss, and the effects add up.

Why it is so hard with hearing loss

  • Blurred tuning. A damaged cochlea cannot keep neighbouring frequencies apart; the noise leaks into the frequency channels that carry the speech.
  • Lost timing. The tiny, rapid fluctuations that let the brain “glimpse” speech in the dips of a fluctuating noise are less well encoded.
  • One good ear is not enough. Much of the ability to separate voices depends on two ears working together. An untreated one-sided loss removes that advantage entirely.
  • Amplification amplifies everything. A hearing aid makes the noise louder along with the speech. Directional microphones and noise reduction help, but do not restore normal separation.

Measuring it

Speech-in-noise tests present sentences or digits in a background of noise and find the signal-to-noise ratio at which half are understood. A person with normal hearing might manage at −5 dB (speech quieter than the noise); a person with a moderate sensorineural loss may need +5 dB or more. That 10 dB difference is the difference between joining a conversation and giving up on it. These tests are not yet routine everywhere, but they are the most relevant measure for the commonest complaint.

Tests and interpretation

Common instruments include the HINT, QuickSIN, Matrix sentence tests (available in many languages), and the digits-in-noise test, which is language-robust and suitable for screening. Speech reception thresholds in noise correlate only moderately with pure-tone averages; a substantial part of the variance is attributable to supra-threshold processing and cognitive factors. In surgical candidates with unilateral conductive loss, binaural speech-in-noise testing before and after closure of the gap can demonstrate benefit that the monaural audiogram cannot, and is a strong argument for treating the second ear when the first has done well.

What helps

Treating both ears where possible, so that binaural cues are available. Devices with directional microphones and remote microphones for meetings. Positioning — sitting with the back to the noise and the face to the speaker. Lighting for lip-reading. And, less obviously, accepting that listening in noise is work: the effort is real, and planning around it is part of hearing well.

For conductive losses, restoring transmission — by surgery or a device — usually improves hearing in noise substantially, particularly when it restores two-eared hearing. For sensorineural losses, improvement is real but partial, and expectations should be set accordingly.

This page provides general educational information. It cannot replace an individual assessment, which depends on a full history, examination, audiometry and, where relevant, imaging. If you have sudden hearing loss, severe pain, facial weakness, severe dizziness or discharge with fever, seek medical care promptly.