Pronunciation exercises: "of" vs "off"

Many students believe the words "of" and "off" are pronounced the same. However "of" ends in /v/ and "off" ends in /f/.

Received Pronunciation
In Received Pronunciation both words have the same vowel: "of" is /ɒv/ and "off" is /ɒf/. But "of" has a weak form, /əv/, which is much more common.

As in most cases, to go from a strong form to a weak form the vowel is replaced by /ə/.

General American
In General American the strong form of "of" is (probably) derived from the weak form. That's why its strong form is /ʌv/.

The word "off" is pronounced /ɔːf/ with the same vowel as many other words such as "cloth" and "long". See Phoneme /ɔː/ in General American.

Summary
Arrows indicate the direction of the derivation.

Homophones
The weak forms of "of" and "have" are the same: /əv/.

The words /ˈkʊd əv/ are correctly spelled "could've", but a confused writer may spell because the pronunciation is the same. The same happens with other contractions such as "should've", "would've", etc.

/v/ devoicing

 * “of course” can be pronounced /əv kɔːrs/ or /əf kɔːrs/

Informal spelling
Most dictionaries have helluva /ˈheləvə/ meaning "hell of a". Urban Dictionary also has sonova /ˈsʌnəvə/ meaning son of a.

Sometimes "of" is pronounced /ə/ and spelled "a" as in "lotsa" (lots of) or "kinda" (kind of).