eh/ɛ/
Drop your jaw moderately. Touch the tongue tip behind the bottom front teeth and lift the mid-front part slightly toward the roof.
How to pronounce efficacy in American English
EH·fuh·kuh·see
Start here
Americans pronounce efficacy as EH-fuh-kuh-see (/ˈɛfəkəsi/). Stress falls on the first syllable — keep everything else short and quick. You'll hear it in sentences like "The clinical trial is testing the safety and efficacy of the drug".
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Sound by sound
Every sound in "efficacy".
4 syllables, 7 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
f/f/
Lift your bottom lip to touch the very bottom of your top front teeth. Blow air through this contact point without voicing.
uh/ʌ/
Relax your lips, jaw, and tongue completely. Drop your jaw slightly and keep the tongue neutral.
k/k/
Raise the back of your tongue to touch the soft palate (velum). Stop the air, then release.
uh/ʌ/
Relax your lips, jaw, and tongue completely. Drop your jaw slightly and keep the tongue neutral.
s/s/
Place your tongue tip near the roof of your mouth behind your top teeth. Push air through the narrow gap. No voicing.
ee/i/
Pull the corners of your lips back slightly. Arch the middle-front of your tongue high toward the roof of the mouth.
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Watch out
Common pronunciation mistakes in American English.
The textbook way isn't wrong — it's just not how anyone actually says it.
01
Stressing the wrong syllable.
Stress falls on the first syllable, not the others. Stretch EH — keep everything else short and quick.
eh·FUH·KUH·SEE→EH·fuh·kuh·see
02
Pronouncing the unstressed syllable too fully.
Don't pronounce the first syllable too fully. The unstressed syllable reduces to a schwa — the lazy "uh" sound — in casual speech.
EH·FUH·kuh·see→EH·fuh·kuh·see
Questions
Questions people ask about this.
How is "efficacy" stressed in American English?
Stress falls on the first syllable — say "EH" with a longer, fuller vowel and keep every other syllable short and quick. The respell "EH-fuh-kuh-see" marks the stressed syllable in capitals so the rhythm is easy to read at a glance.
Why does the second syllable in "efficacy" reduce to "uh"?
Unstressed syllables in American English collapse toward a schwa — a lazy, neutral "uh" sound. The full vowel is what textbooks teach, but in actual American speech every unstressed vowel reduces. The respell "EH-fuh-kuh-see" shows the reduced form so you can hear the casual rhythm directly.
Is the American pronunciation of "efficacy" different from British English?
American English uses different vowel shapes, a relaxed retroflex R, and connected-speech tricks like flap-T and glottal-stop T that British Received Pronunciation generally avoids. The respell "EH-fuh-kuh-see" reflects the casual American form; British dictionaries typically print a citation form with crisper consonants and different vowel choices.
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