Hi,
1/ Stressed, it is also called "short u".
It = the sound in "ago". Right?
2/
In bird, the ir together gives a new sound unlike the sound in ago or love.
So /^/ in /^r/ is entirely different from /^/ in other contexts. Usually "er", "ir", and "ur" all have this same "R-colored schwa" sound (her, term, shirt, bird, dirt, hurt, fur), as does "ear" followed by a consonant (pearl, earth, learn, heard), and "or" preceded by "w" (work, worm, worth).
How can I pronounce this sound? (/^/ in "bird", "her", "worm", "learn"...)?
How to distinguish this sound with /^/ in "love" ?
Quoc