How do surgical and N95 masks affect listening in noise?

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Everyday conversation relies on perceiving speech both in quiet and in noise. During the COVID-19 pandemic, face masks became mandatory in many situations. Mask material can attenuate sound pressure and reduce speech perception, especially in noise. Masks can also hide mouth movements, interfering with lip reading and speech comprehension.

In a prospective observational, cross-sectional study, researchers studied 17 participants with normal hearing. They measured how acoustic attenuation from medical face masks covering the mouth and nose, according to EN 14683, and N95 masks according to EN 1149 (EN 14683) affected speech recognition thresholds and listening effort in various types of background noise.

Averaged across all noise signals, the speech perception threshold in noise was significantly reduced by 1.6 dB with a surgical mask (95% confidence interval [CI], 1.0 to 2.1) and by 2.7 dB with an N95 mask (95% CI, 2.2 to 3.2). The 50% listening-effort signal-to-noise ratio did not increase significantly with a surgical mask: the increase was 0.58 dB (95% CI, 0.4 to 1.5). It increased significantly with an N95 mask, by 2.2 dB (95% CI, 1.2 to 3.1).

Acoustic measurements showed that mask material reduced amplitudes by up to 8 dB at frequencies above 1 kHz, while no reduction was observed below 1 kHz. The researchers concluded that masks reduce speech perception and increase listening effort across different noise signals. They suggested that this combined with interference from obstructed lip reading could meaningfully affect everyday communication, even for people with normal hearing.