Use of an or a

[Unregistered]

Is it correct to use the word 'an' or singular 'a' when preceding an acronym, even though the leading letter is not a vowel?

Using spoken english, the use of a singular 'a' does not sound correct.

For example - The groups signed an MOU or The groups signed a MOU

[Raymott]

Is it correct to use the word 'an' or singular 'a' when preceding an acronym, even though the leading letter is not a vowel?

Using spoken english, the use of a singular 'a' does not sound correct.

For example - The groups signed an MOU or The groups signed a MOU

If you say an "em o u", then you use "an".
If you say a "mou", then you use "a".

The same applies to other acronyms and initialisations:
A NATO meeting; an OPEC meeting; a UN (you en) meeting...