Mark_W wrote:I'm a native speaker of English, but this has bugged me. It seems to me that the letter i, when lengthened, makes two different sounds.
For example, compare the i in right, to the i in ride. To me, they sound different.
My theory is that it depends on whether the consonant after the lengthened i is voiced.
"Bite", "Like", "Might", and "Ice" all share the same sound, because they have an unvoiced consonant after the i.
"Ride", "Tiger", "Slide", and "Rise" all share the same sound, because they have a voiced consonant after the i.
Does anyone else have more information about this?
From your description, I would guess you have what's known in phonology as "Canadian Raising." I haven't looked at your profile details but I would guess you either are from Canada or live in some part of the Northern US. Here's a link explaining the basics of Canadian Raising:
http://en.wikipedia.org/wiki/Canadian_raising
Essentially what happens is the diphthongs [aɪ] (as in "eye") and [aʊ] (as in "cow") raise to [əɪ] and [əʊ], respectively, before unvoiced stops.
"tide" [taɪd]
"tight" [təɪt]
"bowed" [baʊd]
"bout" [bəʊt]
What's even more interesting about this is what happens when an underlying unvoiced vowel becomes voiced in a certain phonological position--in that case the sound is still given the raised vowel, showing it's the underlying form that counts. So, for example, in dialects with Canadian Raising:
"writing" underlying /ɹəɪtɪŋ/ --> [ɹəɪɾɪŋ]
"riding" underlying /ɹaɪdɪŋ/ --> [ɹaɪɾɪŋ]
Besides all this, it's normal in all English dialects for vowels to become longer before voiced sounds, so even if you don't have Canadian Raising (I don't), your vowel will be the same, but longer, before voiced vowels (I do have this). Thus, in (non-Canadian Raised) English:
"tight" [taɪt]
"tide" [[taɪːd]
Of course, this difference isn't contrastive, so it isn't always marked when phonetically transcribing because it's simply assumed, but it is a phonological feature common to English the world around.
Hope that helped