Since Proto-Indo-European has been reconstructed, there is no problem with spelling it regularly. A problem does arise, however, from the reconstructions having been made by linguists for their own uses -- PIE words are written phonemically rather than phonetically. That is, they are written so as to reflect their linguistic structure, not the way they're pronounced.
For example, "to be" is *hes-. To form one of the versions of the imperative, this root is put into the zero-grade (which means dumping the vowel), and *-dhi is added, resulting in *hs-dhi. The hyphen is put in to show the separation of the pieces. However, there is a rule of PIE phonology that says that voiced consonants cause voicing in preceding consonants. This means that *s-dhi is actually pronounced [zdhi]. (The "h" disappears here too.) Because most of the material in PIE on this site is intended for speaking I've decided to write the words phonetically. This may cause a bit of confusion for those used to the traditional system, but I think it will make the words easier to read in ritual performances.
Consonants in Proto-Indo-European have the same value as in English, with the following exceptions:
bh, dh, gh, kh - These are aspirated consonants. They are pronounced like the English "b," "d," "g," and "k," followed by a short puff of air. In English, these consonants are always aspirated at the beginning of a word. Thus "pit" has an aspirated "p." Compare the sound to the one in "spit," and will see a difference. In some languages, including English, it makes no difference whether a consonant is aspirated or not. In others, however, like Sanskrit or Proto-Indo-European, a word beginning with an aspirated consonant, and one begining with the same consonant, but unaspirated, have different meanings.
g - Always hard, as in "get."
ǵ - A palatalized "g." If you say the sound "g," you will see that it is done at the back of the mouth, by the entrance to the throat, the vellum, which is why a "g" is called a velar sound. A "ǵ, however, is pronounced at the palate, the roof of your mouth. It is the sound made by the first "g" in "gewgaw" (as in "gimcracks and gewgaws"), except that in that word there is a bit of a glide after the "g," a little bit of a "y." In PIE "ǵ,"there isn't that glide. See the description of "ḱ" for a more common English word that has the unvoiced version of this. In older printed material you will sometimes see this represented with a circumflex rather than an accent.
gʷ - A labialized "g," a "labio-velar." Round your lips as if you were going to say "o," but say "g." A voiced form of "kʷ.
ḱ - A palatalized "k." Just like the "gy," only voiced. Compare the initial sound in "call" with that in "cute." The "cute" version of "c" is a palatal one. In "cute" this is followed by an off-glide sound, like a "y;" in the Proto-Indo-European "ky" there isn't that glide. In older printed material you will sometimes see this represented with a circumflex rather than an accent.
kʷ - A labialized "k," a "labio-velar." Pronounced just like a labial-velar "g" (i.e., "gʷ"), only unvoiced. Round your lips as if you were going to say "o," but instead say "k." This is actually how the English "qu" is pronounced, despite your English teacher telling you it was a k followed by a w..
l - when this is found with a dot under it, it is pronounced the way you would answer if someone asked what sound an "l" made.
n - when this is found with a dot under it, it is pronounced the way you would answer if somebody asked what sound an "n" made.
qʷ - A voiced velar fricative (the same sound as "x," only voiced), a sort of gargling noise, which has been labialized. The "q" is usually represented by the Greek letter "gamma," but"q" is more browser friendly. Without the labialization, it is pronounced similar to the way some Parisians pronounce the "r" in "Paris." I've used this to indicate the sound I think was the PIE laryngeal H3. (In earlier versions of this site and in Deep Ancestors I maintained that this was simply [q], but I've now changed my mind. I'll be changing all the PIE q's on this site to "qʷ;" if you stumble across one that hasn't been changed yet, just assume that it should be.)
r - There is no way of knowing if the Proto-Indo-European "r" was trilled, rolled, or pronounced like the English "r." It is a matter of personal taste, then. I like to give it a bit of a trill, just because I think it sounds pretty. When it has a dot under it, it is pronounced like the "ur" in "fur," only with a shortened vowel.
x - The final sound in German "Bach;" a voiceless velar fricative. I've used this for the PIE laryngeal "H2."
The short vowels have what is called their "Italian values." In English terms:
It's important to know, however, that English long "a," which is what we call the sound in "weight," is actually a diphthong, with an off-glide at the end. This is one of the things that has to be beaten out of English-speakers when they learn other languages, in which the sound is a single one. There's also a touch of [u] at the end of English "o," so be careful with that one.
Long vowels are just that - the short vowels held a little longer, and with an accent.
Some linguists think that the PIE accent was one of pitch rather then stress, but that's debatable, and I'm not convinced. Since a stress accent has a pitch component (compare the pitch of the second syllables of "desert" and "dessert"), and pitch accents have stress components, I don't think it's a big deal for our purposes.
ai - Like the English long "i."
ei - Like the English long "e," which, unlike that in Spanish or most other languages, has a touch of off-glide at the end; that is, it's not actually a single sound. As in "day."
eu - We don't have this sound in English. As a dipthong, it's made by quickly switching from the [e] to the [u].
oi - Like the Yiddish "Oy!"
In PIE there are cases where vowels ablaut. That means that they change according to how a word is used. We have that in English in some of our old irregular verbs: sing, sang, sung. In PIE, ablaut can be even more radical; a vowel can disappear completely, forming what is called the "zero-grade." When this happens, a following consonant can become a vowel, and these consonants are therefore called "semi-vowels." We have these in English too, although they generally aren't recognized. "Button," for example, is usually said to be pronounced [bút-ən], but it really isn't; there isn't a schwa there. Instead, the "n" is serving as a vowel. The same thing is true of "butter," "bottle," and, to a lesser degree, "bottom." PIE has the same semi-vowels, with the addition of a vowel version of "w."
Semi-vowels are spelled with a dot under them: ḷ, ṃ, ṇ. Linguists write the "w," whether as a consonant or a vowel, as a "u" with an upside down short vowel sign (a breve) underneath. (I can't find how to write this in html; if anyone knows how to do it, I would love to know.) This is to indicate that it can be either a [u] or a [w], depending on where it is found, and to distinguish it from the superscript "w" used to indicate labialization for [k] and [g]. I've just used "w" for both the vowel and the consonant version of this. It's easy enough to seen when it's a vowel; it's a vowel when it's found between two consonants. As a vowel, it's pronounced like the "oo" in "book."