If some one does not Prolong the sound of the letter under "~" would that change the meanings ?
Praise be to Allaah.This symbol "~" is used to indicate places where a Madd (elongation) that is longer than the regular elongation is required. It is used in places where the Madd is compulsory (Madd laazim), as in the word "At-Taammah ", where the elongation is six harakaat or counts. One harakah is equal to the time taken to curl or stretch one finger. This symbol is also used for al-Madd al-Muttasal (where a long vowel is followed by a hamzah in one word), such as "sawaa'un 'alaynaa ", where the Madd is between four and six harakaat. And it is used for al-Madd al-Munfassal, (where one word ends with a long vowel and is immediately followed by a word that starts with a hamzah), as in the phrase "fee aadhaaninaa waqar ", where the Madd is four or five harakaat.
This symbol does not have any effect on the meanings of the words; it is only used to indicate some kinds of Madds or elongations, as explained above. The Madd which is longer than the regular elongation (two harakaat) does not change the meaning when you do it. But we have to follow the Sunnah of recitation, and the Prophet (peace and blessings of Allaah be upon him) used to elongate some vowels in his recitation. And Allaah knows best.