Is it /paˈraːmetɐ/ or /paraˈmeːtɐ/?
In other words, which syllable is stressed?
As it would be more logical to pronounce this compound loanword from Greek stressed on the first syllable of "meter" this is not the case in standard German where the second syllable will be emphasized:
paˈʀaːmetɐ (IPA) - Parameter
Listen also to this sound file found on Wiktionary: Parameter
The following dictionaries list it emphasized on the second syllable:
Of course regionally the pronunciation of any word differs very much. You may find dialects that would emphasize the first syllable, or others that put emphasis on the third syllable of "parameter".
Actually, both versions are admissible. If you stress the e instead of the second a, that's perfectly fine, at least in common speech.
I am impressed by the search for sources Takkat conducted, but I hope they will forgive me if I scold them harshly and friendly at the same time for this:
As it would be more logical to pronounce this compound loanword from Greek stressed on the first syllable of "meter"
But, let us keep their Ansatz for exploring the Greek roots and let us look closer! Below I juxtaposed Greek roots with German derivatives. I don't use Greek accents, which were a late invention anyway, because I can't typeset them. Instead, I indicate the location of the ancient tonal accent (coinciding locally with the modern Greek stress accent) by use of bolder typeface.
ΠΑΡΑΜΕΤΡΟΣ : Parameter
ΔΙΑΜΕΤΡΟΣ : Diameter
ΠΕΡΙΜΕΤΡΟΣ: Perimeter
Thus, indeed, Takkats method supports what they sought to support!
Fit of pedantry: I intentionally omitted similar examples with different Gender.