As we know, sometimes the letter "i" is prononced "aï" like in "ice" and sometime is prononced "i" like in " ship".
So I have a question for you. Is there any rule in the word where there is the letter "i" in order to use the right pronunciation ?
Yes, it's called the magic ''e'' rule. ''When'' you add ''e'' to the end of the word it makes the vowel say it's name.
There's also the "gh" rule that does the same thing the final "e" does. Although, I think "i" is the only single-standing vowel that ever precedes "gh" (usually, it's a diphthong: ai, ei, ou). I could be wrong though.
nit - night
sit - sight
lit - light
fit - fight
flit - flight
There is a letter called "yogh". Yogh used to be used in English until they invented "g". Then there's Vincent van Gogh but this is a name not a word and he wasn't from an English speaking country.
"Ai", "ei" and "ou" are not really diphthongs but digraphs.
Besides the magic "e" and the "gh" there are also some words without a pattern, e.g. "child", "find" and "mind". There is an interesting pair of words both spelt "wind", one pronounced /wind/ and the other /waind/.
No, only "ou" is a digraph. "Ai" and "ei" are actually two different phones made into one sound, which is the definiton of a diphthong, not a digraph.
Oh, okay. I stand corrected. I've never heard of "yogh" before, but then there's "yoghurt", which is also spelled "yogurt".
Someone once corrected me that Van Gogh is pronounced something like "fen go:C" (the "C" is pronounced like the "ch" in "loch" or "reich", but I don't know how this is represented in the ASCII phonetic alphabet). But as Jim said, this is not an English name and doesn't follow the "gh" rule.
Speaking of interesting pairs, there's also the anomaly of "minute", where both the "i" and "u" change sounds depending on usage.
No, a diphthong is a sound those are paired letters. Paired letters are digraphs.
I am very glad people master english language. This is the interesting discussion because in english language the vowel always change the pronunciation, especially "i" and "u".
So I'm waiting about your comments in order to learn something about you.
Thanks for that
Paired letters can still be a diphthong. The term "digraph" is usually reserved for singular sounds represented by two letters, such as "ch" or "sh."
A diphthong is a sound. A letter is not a sound. A pair of letters are no more a sound than a single letter. Thus paired letters cannot be a diphthong. Certainly they can represent a diphthong, for example the "ei" and "ai" in "vein" and "vain", but they cannot be a diphthong.
Here's a definition of "digraph" from http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=digraph+definition&btnG=Google+Search
"Digraph - A pair of signs or symbols (two graphs), which together represent a single sound or a single linguistic unit. The English writing system employs many digraphs (for example, th, ch, sh, qu, and so on). The same two symbols may not always be interpreted as a digraph (for example, cathode versus cathouse). When three signs are so combined, they are called a trigraph. More than three are usually called an n-graph."
So the question therefore is whether a diphthong is "a single sound or a single linguistic unit". I say it is. The diphthong mentioned above (represented "ei" and "ai" in "vein" and "vain"), for example, is not simply two distinct sounds run together but a single vowel albeit a gliding one.
How this vowel is pronounced depends on your accent. I pronounce it as [æI], others pronounce it as [eI], for others still it isn't even a diphthong but just [e:] (a long version of [e])*. That said, how could you call it anything but "a single linguistic unit"? The same goes for any vowel whether long, short or diphthong. Thus the "ei" and "ai" are digraphs.
* Not to be confused with Antimoon's [e:] as in "turn" = [te:(r)n].
British RP [eI]
US Midwest [eI]