Numbers 80 and 18

How do I teach my taiwanese gf how to pronounce numbers so that I can understand the difference. I was taught eighTY and eightTEEEEEEEEEEEEN, but she says eighTI and eighTIN.

The key is in the stress.

80: EIGH-ty
18: eigh-TEEN.

There’s the stress, yes, but the other difference is the consonant sound.

Eighty = EY-dee
Eighteen = ey-TEEN

The “t” in 80 is voiced, while the one in 18 is not.

[quote=“Hokwongwei”]There’s the stress, yes, but the other difference is the consonant sound.

Eighty = EY-dee
Eighteen = ey-TEEN

The “t” in 80 is voiced, while the one in 18 is not.[/quote]
I think this is only true for an american English. When I lived in South Africa I never heard this “dee” sound, same goes with UK.

[quote=“Hokwongwei”]There’s the stress, yes, but the other difference is the consonant sound.

Eighty = EY-dee
Eighteen = ey-TEEN

The “t” in 80 is voiced, while the one in 18 is not.[/quote]
In American English.

Technically it’s a flap, not a d. But the reduction of the t to a flap is a function of the stress.

[quote=“Hokwongwei”]There’s the stress, yes, but the other difference is the consonant sound.

Eighty = EY-dee
Eighteen = ey-TEEN

The “t” in 80 is voiced, while the one in 18 is not.[/quote]

Sounds Australian

Depends on how slowly you say it. When really slow, it seems like a D to me.