Noise masks consonants because they are about 20 dB quieter than vowels, harming intelligibility.

Evidence

The effect of noise, like reverberation, is to mask the stops and bursts associated with consonants. This is because the consonants are typically 20 dB quieter than the vowels. They can also blur the rapid formant transitions, which are also important cues to different consonant types. Because of the importance of consonants to intelligibility, it is therefore important to maintain a high signal-to-noise ratio. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2475

Categorization

• SHARE: The 20 dB consonant-vowel gap is a great nerdy fact for anyone into audio or speech.
• XREF: Connects to psychoacoustic masking concepts central to this reader’s interest in voice and intelligibility.