Weak Vowel Merger

The weak vowel merger refers to the neutralization of the schwa and the unstressed  high front unrounded lax vowel. The merger is common in Canadian English, Australian English and New Zealand English. With the exception of the southern United States, it is also common in American English.

Speakers with the weak vowel merger make no distinction between addition and edition. The schwa is used in the first syllable of both. Speakers with the merger have the schwa in the first syllable of addition and the high front unrounded lax vowel in the first syllable of edition.

Many speakers with the weak vowel merger pronounce roses and Rosa's identically. They produce a schwa in the second syllable of both words. Those who do not have the weak vowel merger have the high front unrounded lax vowel in the second syllable of roses and the schwa in the second syllable of Rosa's. Though I have the weak vowel merger, I maintain a distinction between roses and Rosa's. I pronounce roses with a central schwa and Rosa's with a lower schwa similar to the vowel of but. 

Many English speakers have the weak vowel merger. However, it is not found in the English of England or the southern United States. Though many speakers who have the merger pronounce roses and Rosa's identically, this is not the case for all speakers.