While it is common to pronounce ancient Greek words with the same sounds and intonation of the speaker's native language, modern Greek has its own system of pronunciation. For example, modern Greeks pronounce the "eu" sound at the beginning of "euphony" as "ef," making it "ef-phony."
In both ancient and modern Greek, the vowels are pronounced the same. The one exception to this is upsilon (?) which has, in modern Greek, a "y" sound. Diphthongs (combined vowels) in ancient Greek combine the sound of the two vowels into one; in modern Greek, all diphthongs form an "i" sound, save for "??," which has a simple "u" sound.
Simple consonants have one sound, like "b" for beta (?). Again, it is acceptable to pronounce beta as "b" in ancient Greek. In modern Greek the letter has a "v" sound, making it "veta." Similarly, delta (?) has gone from a "d" sound to a soft "th" sound. Complex consonants are combinations of two different sounds. For example, xi (?) has a "ks" sound (as in the end of the word "box"), while psi (?) is a "ps" sound, as in "psychic."
Lastly, in both versions of Greek the letter chi (?) retains its guttural pronunciation, similar to the "ch" in "loch." In English transliterations, chi is usually written as "ch," and it is acceptable to pronounce it with a hard "k" sound.