OMFG!! Finding a sound key to learn to pronounce words was (and still kind of is) next to impossible! There are plenty of well meaning helpful people out there who want to encourage you to learn Welsh. They provide you a sound key and say "it's English equivalent is *insert sound here*."
On first glance, you breathe a collective sigh of relief and you thank the good Lord above for guiding you here. Then you think about that for a moment. Go ahead. Think! Did you come up with the problem that I did? The question becomes "what English?"
For the most part, on paper English is the same with the exception of a few words that Americans decided they liked spelled another way. The rest of the English speaking world, spell them another way. Those are few and far between. The most glaring example is color vs. colour. So Americans don't like U's, so what?
Still, when you read English, you are reading it in YOUR dialect, not someone else's. Right? So when one says "English equivalent" then what English equivalent? American? Australian? London English? Yorkshire English? Scottish English? Irish English? Nigerian English? What English because every single one of those pronounces words differently. Take the word have. To an American ear, the English say hauff, Yorkies say 'auff, Scots say huff, and so on.
I hope you do not think that I'm unappreciative on the matter, because I am certainly not. It's just that I don't think those folks have thought about that. One site recommended a certain book which I bought. It's called Teach Yourself Living Welsh by T. J. Rhys Jones (can't get more Welsh than that name). His sound key has this same problem and then add to that, he also tells us the International Phonetic Alphabet sound.
If you're a linguist, then you know what it is and if you're a linguist, you wouldn't need to learn the sounds! For those of us just wanting to learn, without pre-knowledge of diphthongs and pure sounds and types of guttural sounds (or perhaps not even knowing what guttural sounds are) and so on, you're simply out of luck.
Not only did the author Jones tell us word comparison's without any hint of what dialect the pronunciation was, but it the author took it a step further providing an alphabet (the International Phonetic) that most are unfamiliar with. This was at literally the very beginning of the book. How deflating! I was so looking forward to that book arriving, only to be disappointed within two minutes.
I have a book on Welsh mythology. I don't know why I dug it out again, but I did. I once tried reading it but the names were so difficult to read that I finally tossed it aside. I don't know what made me pull the book out again yesterday. Maybe it was to see if I had progressed any, but that shouldn't be because I felt as if I had gone in absolutely no direction so far.
I looked to see if she had an appendix. Maybe I was hoping for a sound key or some hint of pronunciation. Then voila! A sound key. With trepidation I read the explanation of sounds and lo and behold, the author actually said, "Equivalences are given in American-English, unless otherwise stated." WOOHOO! I thought, now we're in business.
Except that when I read the explanations, they didn't seem right. Some sounds are guttural and none of that was pointed out. Basically, it said that all consonants are breathy. I swear, I felt like crying.
One key I remember finding had written things like "spoken like Scottish boat". That was actually very explanatory and you simply cannot spell that sound. The truth is that unless you can find some volunteer to sound out all the alphabet on a mp3 (if you want to do this for me, PLEASE do, you can email me at my username here at gmail dot com), you really will never know. This is something a book simply cannot tell you and until you can get that, you're screwed. That or you have to learn the Phonetic alphabet and then go from there.
In the meantime, I've spent way too much time trying to figure this out. Jason Shepherd's podcasts are tremendously helpful, but he hasn't done the alphabet, which is too bad; I posted a question there but I doubt it'll ever be answered. Also, Forvo.com has a Welsh section that will pronounce Welsh words. At least that way you can pick up the letter sound you're looking for. On the flip side, some of those recordings are just plain awful. Some you can't hear at all and others have such a large buzz you cannot hear them either. Some talk incredibly fast so that I'm not sure what I just heard and worst of all, Forvo won't let me vote on sounds if I'm not native to it. As if one that cannot be heard or understood at all isn't recognized by a non-native speaker. NOT!
Whatever you do, don't (yet) use Google Translate for speaking Welsh, unless an incredibly fast talking Welsh Stephen Hawking is easy to understand by you.
In any case, that's a lot of jumping around and ceaseless searching.
I would love to start a community of Welsh speaking volunteers that would be willing to record themselves in a way that would be understandable. For example, say the alphabet slowly, sounding it out, and offering silence between each letter. Then when we get to words and phrases, saying those too. I would love for this to be a creative commons license, as well for the future of language and learning.