What Traci is talking about is called "flooding". What Freedom's post was mentioning was desensitization and counter-conditioning. Look up the two and "sound sensitivity" while you're at it.

Your choice which method you want to use. I'm personally a fan of counter-conditioning and desensitization, but I've seen a lot of dogs who've been 'flooded' and have done well with that method. It depends a lot on your dog's individual temperament