The problem with crutch words is they make us appear less confident, capable and trustworthy. They generally slip out when we are under pressure, haven't practiced enough or when we're talking about an unfamiliar subject.

Using "ah's" is a bad habit that you can break.

Try this exercise:
Fold your hands together as in prayer, fingers interlocked. Notice which thumb overlaps the other. Now put your hands together again, but this time consciously put the opposite thumb on top. It feels pretty uncomfortable doesn't it? Now take your hands apart and put them back together again 20 times, this time with the "odd" thumb on top. Notice that each time you do it, it feels a little less uncomfortable and easier to do.

Getting rid of "ah's" is like that. Breaking the "ah" habit takes conscious effort, but with practice it gets easier to control those crutch words.

Trick:
If you're stumped for a thought and don't want to use a crutch word, repeat your last phrase. By repeating you move on to the next thought and the audience thinks you're just emphasizing this one point.

The "Ah" Cure !

#1. Be aware that you are using those crutch words.
Many people don't realize their "ah" habit even exists. It's such a natural part of their normal speech, they don't hear it. So the first thing to do is to listen to yourself to detect this problem.

Record your practice or even better a live presentation and listen to it for crutch words. Count the number of times you use a crutch word.

#2. When you catch yourself using a crutch word, do some physical action to remind yourself, like ringing a bell, snapping a rubber band against your wrist, etc.

#3. Speak about subjects that you know or research well. The hesitation of an "ah" is your brain stalling while it tries to come up with more information.

#4. Write your speech out word for word, no matter how good an extemporaneous speaker you are.

#5. Practice speaking more slowly, allowing more time to think.

#6. Practice, practice, practice. If you know your material and go over it frequently, you will use few, if any "ah's."

What do you do instead of using an "ah"? You just pause.
Stop until your next thought comes to you. Although it may seem like eternity, generally it's not long to the audience, and you appear to be more in charge when you do pause.

Zig Ziglar, one of the great motivational speakers, used 187 "ah's" during one of his first 21 minute sales presentations.

Even the best speakers, needed help on this point at one point in their careers.