Smashing the Sound Barrier 239 · Repeat questions from the audience into the microphone. This helps everyone hear the question that was asked. If you're going to be moving around during your presentation, make sure that a clip-on (Lavalier) microphone is available. If you're using a Lavalier, be aware of where it's attached to your clothing. Also keep in mind where the cord and battery pack are located. This will help prevent you from disconnecting the microphone or yanking on the cord. Attach the Lavalier to a jacket, lapel, collar, neckline, or tie above the mid-chest level, but not against the larynx--otherwise, your voice will become muffled. Listen Up About 14 million Americans have some kind of hearing impairment. About 2 million of these people are deaf, which means they can't hear or understand speech. Deaf people use several methods to understand what others are saying. It's especially important to be aware of these methods when you are making public speeches so you don't ostracize anyone in your audience. Some people who are deaf use lip-reading to understand what others are saying. This means that you should be careful not to turn your head away from the audience. It's also important to move your lips clearly. People with hearing impairments also use two kinds of manual communication. Sign language uses hand and arm gestures to represent words and ideas. The manual alphabet uses the fingers to represent each letter of the alphabet. You can address these issues in several ways. Here are two effective methods to make sure you address all members of your audience: