Hi all, new to the forum and haven’t played SF since SF 2 in the arcades when I was a kid. Right now I just have Super SFIV haven’t got Ultra yet. So I used to play Guile all the time back then and his Basic Sonic Boom was so easy for me, obviously it should be easy for anyone, just back forward punch right? So how come the only times it will work for me is when I hold down back for like 5 seconds and then input forward and punch?? Just quickly inputting back forward punch never works. I have a lot of trouble with most of the characters moves when they get to like the #6 trial when they start to get more complex but this simple #1 trial for Guile, the Basic Sonic Boom almost gives me more trouble than anything else, it just seems to never work like it should! So is it my controller or something? I’m using a Power A Mini Pro EX controller for Xbox 360 and it is kind of crappy but when I last played SF in the arcades it was much easier, what do you all think? Thanks for opinions and any advice.
you have to hold back for a certain amount of time before pressing forward and punch to do it
this is called a charge motion
Ooooh. That would explain it then, thanks very much for the insight, come to think of it I have heard that term “charge motion” before when watching streams and YouTube. 
SF4 runs at 60 frames per second. Sonic Boom requires 50 frames of charge time which is just under 1 second. Holding up-back, back, or down-back all begin building charge so once you reach the 50 frames required you can execute with forward + punch to Sonic Boom or, because the input window is so lenient, you can also go to the forward position then quickly return to down-back before pressing punch which will let you begin a new charge while your Sonic Boom is coming out.
Many other moves in the game (such as Flash Kick) require a full second of charge so it depends.
Thanks @phantasy and @Ahgama . Yeah I’ve noticed now that (at least in Super) the solid black arrows in the input description mean regular inputs and the hollow or just not filled in arrows must mean charge motion because a few of Guile’s moves have the charge motions like you said. Any tips on how to execute properly when you need to do full circle directional inputs twice in a row or should I post for tips on that in a different sub-forum? It seems like I never do it fast enough because I always end up jumping and that kind of ruins the whole move because your most of the time not supposed to be jumping.
doing a 720 motion without jumping is hard. it is possible, but hard.
the point of them though is to do them when you can’t jump: for example, you are already in the air, OR you are doing some other move. you have to be pretty fast to do the 720 when you are doing a dash, or a jab, for example.
gotcha, i’m beginning to understand slowly how the game’s combos work lol.
It’s so incredibly easy you are gonna laugh once you get it down
Also another tip I find useful is immediately after throwing the sonic bomb hold down back again to store up another charge. This called charge “buffering” I believe. This has helped me a ton when playing a fireball game with Ryu. This way your booms come out one after another.
You’re supposed to return to down-back BEFORE pressing punch so that you’re already at that position when the charge is spent. This is usually called pre-charge.