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English Vowel Length   

First, what do we mean by "vowel length"? - We simply mean the length of time it takes to pronounce the vowel. We can measure this length in centiseconds - hundredths of a second.
Some languages, like both English and Icelandic, vary the lengths of their vowels according to certain rules.
Below you can see the typical or average length of some of the vowels in English

RP English                  (American English below )

The general rule is:
  • lax vowels () are short
  • tense () vowels (including diphthongs: ) are variable in length, and often longer than lax vowels.
  • Clipping of tense vowels and diphthongs

    We find that vowels are clipped (shortened) when they are followed by UNVOICED consonants in RP English. (As we shall see the term "unvoiced" is not an exact one, but it will do for the moment -we'll deal with this later under the heading "Fortis and lenis". See Fortis -Lenis for more details from another course (use BACK button to return)

    The unvoiced-voiced pairs of English consonants are:

    These are the sounds heard at the end of the following words:

    Unvoiced: keep (), sweet (), leak (), leaf (), path ()*, lease (), leash (), leech ()
    Voiced: cab (), feed (), league (), leave (), bathe (), please (), rouge () and bridge ()

    or þ? - Note that outside Iceland, linguists usually use the Greek theta instead of our 'thorn' .

    RP vowel length: some details

    As we'll see, there isn't a clear-cut long/short distinction. Typically, each vowel has its own length, with for instance /æ/ holding a half-way position between lax and tense vowels. Also, lengths of different vowels overlap in different contexts: looking at /i:/ and // we found the following situation. The lengths are given in centiseconds:

    (Data from Gimson 1980:98)

    The point to remember here is that clipped "long" vowels can sometimes be shorter than unclipped "short" vowels. Also, it's not correct to say that only tense vowels ("long" vowels and diphthongs) are clipped by a following fortis - all vowels are, but lax vowels are so short anyway that the difference is not easy to hear.

    American English vowel length

    In General American English (GenAm), vowel length is not as distinctive as in RP. Clipping still occurs, but the American equivalent of the RP lax (SHORT) vowels are not always so short - in many American accents, all vowels can become lengthened for emphasis. Some writers therefore leave out the special length mark () for the tense vowels, and simply write them , , , and .
    In his Pronunciation Dictionary, Wells gives the American equivalents WITH the length marks, however. See Wells's introduction on American pronunciation, section 2.3

    Lax vowels are always short

    This point is sometimes difficult for Icelanders to remember.
    This is because there is a basic difference between vowel length in Icelandic and English.

    So the Icelandic and English rules for vowel length are different, and Icelanders unconsciously use Icelandic rules in English. Take for instance the English words:

    bit ever many book

    These all have lax vowels: bit has KIT , ever and many have DRESS ,
    and book has FOOT . All short, even book, which is written with 2 o's!. But Icelanders want to pronounce them long, because they have only single consonants following them.

    NOW DO THE EXERCISES in section 1.4.1 on p. 14 of the booklet English Pronunciation for Icelanders.

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