Compressing a signal’s amplitude damages the syllabic variation listeners use to decode words.

Evidence

Sometimes communication can be assisted by using speakers with good elocution, especially female ones, because their voices’ higher pitch tends to be less masked by the reverberation and noise typically present. … Paradoxically, electronic volume compression does not improve intelligibility; in many cases it makes it worse, because it can distort the syllabic amplitude variations that help us understand words. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2492

Categorization

• QUESTION: Why does higher pitch resist masking better — is it a frequency-place effect or a harmonicity cue, and does it help with hearing loss too?
• SEED: Possible essay: ‘Why shouting into a microphone makes you harder to understand’ — the counterintuitive acoustics of public address.