I disagree with the first response given. I have a reactive dog and she has been improving over the three years I've had her. She is fearful of people. When a dog is fearful, they go into fight or flight mode, but a dog that is on a leash can't flee or fight, so they make themselves loud and intimidating to deter the threat.
You don't want a tight leash if possible- increasing leash pressure can increase frustration and tension. Sometimes in a tight situation (like if another dog is within reach of yours) you have to just keep your dog close to you and walk out of that situation. But when you're training don't keep the tension on the leash. There are ways to use leash pressure to train, but I wouldn't suggest it in this situation.
I took a reactive rover class with a brilliant trainer, and he actually suggested the opposite of not making noise. He taught us to use "happy voice"
1) to surprise a dog that might be used to being scolded when she reacts. If the dog is surprised and stops barking to look at you, you can reward!
2) to help keep the dog focused on the handler and
3) because in stressful situations WE tend to react as well and may get tense and stop breathing or change our breathing pattern, and acting happy and relaxed sends a message to our dogs but also help change our own reactions.
There are a couple of different techniques you can use to build your dog's confidence around dogs on leash and decrease the reaction.
One is counter conditioning. As soon as your dog *notices* another dog you start feeding them high value treats. The noticing should be at a far enough distance that your dog hasn't started reacting yet. If you're walking your dog and you see another dog coming down the street start rewarding when your dog sees them. If they are coming towards you create distance by crossing the road or going off the sidewalk. You don't want them to get close enough that your dog starts reacting. This isn't always possible in the real world but ideally you want to be conscious of the distance between your dog and the trigger and not get too close/push your dog past her comfort level. The goal is not to reward your dog for any particular behavior but just to get them to associate the presence of another dog with good things (treats! praise! tug toy! whatever your dog LOVES) and positive emotions that stem from those things. Create a positive association, change your dog's emotional response, then they don't feel threatened or like they have to defend themselves.
The other option which is similar but which does more reinforcing of behavior vs just conditioning associations is called the Look at That game. You need a clicker or a marker word (like "yes" or "good"). If you haven't done marker training before basically you click or say your word and then give them a treat. This teaches them that the marker means they are going to be given a treat. The marker will mark a specific behavior (which will be looking at the trigger) so the dog knows they're getting a treat because they looked at the trigger. These behaviors can happen fast so it's important to mark them so the dog doesn't get confused.
I personally think a clicker is a stronger marker than just saying yes or something because the dog is used to the owner talking but a clicker has a sharp, novel sound that will more likely draw their attention in a stressful or distracting situation.
So once your dog knows a marker you can start this. When your dog looks at another dog, you mark them looking, and then give them a treat. Like with counter conditioning, this should be done at a distance where the dog isn't reacting. However, you can still mark the dog looking at the other if your dog does bark. The dog is looking at the trigger, you click and the dog looks at you for the treat. Then they look back at the trigger and as soon as they do you click again and treat them. Soon, with enough repetition, your dog will be looking for other dogs, just to look back at you expecting a reward for finding more dogs. It will become like a game to her. You can add a cue when your dog looks at another dog. I simply use the word "look" to tell my dog to look at the trigger. Some people actually use "look at that" but that's a mouthful to me.