[mikekchar]

Yeah, it doesn't really exist in English. I'd even argue that the Australian pronunciation doesn't change the vowel length as much as it adds a chain shift [1] (similar to the Canadian/Algonquin "ou" pronunciation).

It's one of the most difficult things to pick up when learning Japanese as well. There are lots of words that are basically homophones except for vowel length and tone. To an English speaker they tend to sound identical, but to a Japanese speaker if you get it wrong the result is unintelligible. For example "地図" (in romaji: chizu and pronounce cheezu with a short "ee") is "map" and "チーズ" (in romaji: chiizu and pronounced cheezu with a long "ee") is "cheese" (though they have the same tones... I'm struggling to think of an example with different tones as well as vowel length).

The thing that helped me the most for this was singing songs. Once you understand that there is a necessary rhythm to the words, it makes it much easier to use that rhythm in speaking. Or at least it did for me -- YMMV.

[1] - https://en.wikipedia.org/wiki/Chain_shift

[blacksmythe]

Fun for foreigners (both in Tokyo area):

Itabashi Station: https://en.wikipedia.org/wiki/Itabashi_Station

Iidabashi_Station https://en.wikipedia.org/wiki/Iidabashi_Station

(the major difference you hear is the long ii, rather than the t/d difference)

[taejo]

Even if it's not really a vowel length change in Australian English, I'm pretty confident it is in South African English (as spoken by me and many others). Ferry/fairy are distinguished by vowel length only.