Many deaf people can read lips to some degree, but only the most practiced lip-readers can get even a basic idea of what the conversation is about from lip-reading alone. Since most of the sounds hearing people make are located in the base of the throat, many sounds are not even visible on the lips. People who use this method regularly in conversation with hearing people report that it is exhausting work, can only be done in very short segments, and the major portion is guess work at best obtaining less than half of the information with the rest filled in with previous knowledge. It requires that the lip-reader has a very good prior understanding of the topic being discussed. For any new information, it is like a hearing person plugging his ears and trying to lip-read Japanese or Russian. Many deaf people choose American Sign Language and their preferred language mode. It is best to ask the deaf person what they prefer before embarking on a discussion of importance.