Prefix "de" English pronunciation

[MarianoM]

Hi guys, I need some English expert to help me with this prefix. I can't find on the Internet any clear rule about it's pronunciation.

When do I pronunce it "dee"? like in: decrease

and when do I pronounce it "deh"? like in: desert

I read something about the pronunciation as "dee" when it's a VERB, and as "deh" when it's a NOUN, but I'm not convinced.

Any idea?

Thanks

[rdearman]

Like most native speakers I have no idea why we pronounce things one way not the other. I just know !

The verb/noun things seems like a "rule of thumb" you can use. I googled for a list of words beginning with DE and spent 10 minutes pronouncing a load of them and the majority of the time this rule of thumb seems to work. However, there are some which didn't hit the rule. For example, I've heard the word "Decanter" pronounced both ways.

[Deinonysus]

Don't expect English spelling to make sense. There are some general rules but they are very inconsistant and your best bet is to just look up any word you don't know. Wiktionary and Forvo are good resources for pronunciation.

https://en.wiktionary.org/wiki/decrease
You can see that the verb "decrease" starts with an unstressed /ɪ/ sound (this is the same vowel as the word "pin"), and the main stress goes on the second vowel: "It will decréase". The exact vowel sound can vary based on the dialect, it could also be a schwa /ə/ like the sound at the end of the word "comma".

But the noun "decrease" starts with a stressed /i:/ sound (as in "fleece"): "There will be a décrease".

That is the general rule, but "desert" is an exception when it is a noun meaning "a dry place". But as a verb meaning "abandon" it does follow the general rule and it is pronounced with the same unstressed /ɪ/ or /ə/ sound as in the verb "decrease".