I never yell at my dog. Never.
Well, okay. There's one exception. And that exception is if: I'm already working with the dog at such a far distance that he can't audibly hear me. And usually this is the case only if I'm teaching the dog to respond to hand signals.
Why don't I ever raise my voice if I'm working with my dog, otherwise?
Because the only thing that raising your voice achieves is to communicate to your dog that you really DO NOT have control.
And since I train with a modified working dog approach, I want my dog to know that I'm ALWAYS in control. Because I'm the "Alpha dog."

Now, if I issue a command, and the dog I'm training does not respond to that command... then I will stop to figure out why he didn't respond. If it's because he didn't understand the command, then I need to go back to basics and do more repetitions. If the dog is simply not responding because he's being stubborn or head-strong, then I'll make my correction more motivational.
But one thing that many observers will realize about the way I work with animals is that my commands are practically whispered. Never yelled or screamed.
In fact, your commands should only be loud enough for your dog to hear. No louder.
So... do you want to know how to spot an amateur dog trainer? He's the one yelling at his dog.
A word or two on consistency and teaching your dog to "come."
If I'm teaching a dog to come on command, it's my job to convince the dog that he MUST come EVERY time I call him. But if he thinks that I'm only going to make him come every other time... or only under certain conditions... then I'll never get the dog to be 100% reliable.

So, where am I going with this line of reasoning? Well, just remember that you should NEVER give a command that you cannot enforce, until your dog is 100%. And you'll know when he is 100% when his responses to commands are immediate! Even when you're asking him to respond around the most tempting of distractions!

Do you want to be able to take your dog anywhere, and KNOW that he'll listen to you... even if tempted by another dog, a cat, or even a piece of food??? Then check out: "Secrets of a Professional Dog Trainer: An Insider's Guide To The Most Jealously Guarded Dog Training Secrets In History!" By Adam G. Katz, Owner of South Bay K-9 Academy and Dog Problems.com. For more information, go to:Secrets of a Professional Dog Trainer!