Hindi hears four different consonants where English only hears one

Where English treats 'p' and 'b' as just two sounds, Hindi and related languages contrast four versions of the same consonant: voiceless unaspirated, voiceless aspirated, voiced unaspirated, and breathy-voiced. Native speakers produce and perceive all four automatically, while English speakers learning Hindi often can't hear the difference between pairs at first.

— Peter Ladefoged, Ian Maddieson, The Sounds of the World's Languages — Blackwell, 1996
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